Bacterial sensing of bacteriophages in communities: the search for the Rosetta stone.
Abstract Billions of years of evolution have resulted in microbial viruses and their hosts communicating in such a way that neither of these antagonists can dominate the other definitively. Studies of the molecular mechanisms underlying this dialog, initially in bacteriophages, rapidly identified several of the ways in which bacteria resist bacteriophage infections and bacteriophages defeat bacterial defenses. From an ecological perspective, recent data have raised many questions about the dynamic interactions between bacteria and bacteriophages, the densities of which, in complex microbial populations, are only b...
Source: Current Opinion in Microbiology - June 18, 2014 Category: Microbiology Authors: Debarbieux L Tags: Curr Opin Microbiol Source Type: research
Metabolomic analysis of Entamoeba: applications and implications.
Abstract Entamoeba histolytica is an enteric protozoan parasite that causes hemorrhagic dysentery and extraintestinal abscesses in millions of inhabitants of endemic areas. The genome of E. histolytica has already been sequenced and used to predict the metabolic potential of the organism. Since nearly 56% of the E. histolytica genes remain unannotated, correlative 'omics' analyses of genomics, transcriptomics, proteomics, and biochemical metabolic profiling are essential in uncovering new, or poorly understood metabolic pathways. Metabolomics aims at understanding biology by comprehensive metabolite profiling. In ...
Source: Current Opinion in Microbiology - June 17, 2014 Category: Microbiology Authors: Jeelani G, Nozaki T Tags: Curr Opin Microbiol Source Type: research
Human health impacts of antibiotic use in agriculture: A push for improved causal inference.
Abstract Resistant bacterial infections in humans continue to pose a significant challenge globally. Antibiotic use in agriculture contributes to this problem, but failing to appreciate the relative importance of diverse potential causes represents a significant barrier to effective intervention. Standard epidemiologic methods alone are often insufficient to accurately describe the relationships between agricultural antibiotic use and resistance. The integration of diverse methodologies from multiple disciplines will be essential, including causal network modeling and population dynamics approaches. Because intuit...
Source: Current Opinion in Microbiology - June 16, 2014 Category: Microbiology Authors: Singer RS, Williams-Nguyen J Tags: Curr Opin Microbiol Source Type: research
Epigenetic memory takes center stage in the survival strategy of malaria parasites.
fai R Abstract Malaria parasites run through a complex life cycle in the vertebrate host and mosquito vector. This not only requires tightly controlled mechanisms to govern stage-specific gene expression but also necessitates effective strategies for survival under changing environmental conditions. In recent years, the combination of different -omics approaches and targeted functional studies highlighted that Plasmodium falciparum blood stage parasites use heterochromatin-based gene silencing as a unifying strategy for clonally variant expression of hundreds of genes. In this article, we describe the epigenetic c...
Source: Current Opinion in Microbiology - June 16, 2014 Category: Microbiology Authors: Voss TS, Bozdech Z, Bártfai R Tags: Curr Opin Microbiol Source Type: research
Functional duality of the cell wall.
ais A Abstract The polysaccharide cell wall is the extracellular armour of the fungal cell. Although essential in the protection of the fungal cell against aggressive external stresses, the biosynthesis of the polysaccharide core is poorly understood. For a long time it was considered that this cell wall skeleton was a fixed structure whose role was only to be sensed as non-self by the host and consequently trigger the defence response. It is now known that the cell wall polysaccharide composition and localization continuously change to adapt to their environment and that these modifications help the fungus to esc...
Source: Current Opinion in Microbiology - June 14, 2014 Category: Microbiology Authors: Latgé JP, Beauvais A Tags: Curr Opin Microbiol Source Type: research
Transcript maturation in apicomplexan parasites.
Abstract The complex life cycles of apicomplexan parasites are associated with dynamic changes of protein repertoire. In Toxoplasma gondii, global analysis of gene expression demonstrates that dynamic changes in mRNA levels unfold in a serial cascade during asexual replication and up to 50% of encoded genes are unequally expressed in development. Recent studies indicate transcription and mRNA processing have important roles in fulfilling the 'just-in-time' delivery of proteins to parasite growth and development. The prominence of post-transcriptional mechanisms in the Apicomplexa was demonstrated by mechanistic st...
Source: Current Opinion in Microbiology - June 13, 2014 Category: Microbiology Authors: Suvorova ES, White MW Tags: Curr Opin Microbiol Source Type: research
Segmented negative-strand RNA viruses and RIG-I: divide (your genome) and rule.
Abstract The group of negative-stranded RNA viruses (NSVs) with a segmented genome comprises pathogens like influenza virus (eight segments), Rift Valley fever virus and Hantavirus (three segments), or Lassa virus (two segments). Partitioning the genome allows rapid evolution of new strains by reassortment. Each segment carries a short double-stranded (ds) 'panhandle' structure which serves as promoter. Similar dsRNA structures, however, represent the optimal ligand for RIG-I, a cytoplasmic pathogen sensor of the antiviral interferon response. Thus, segmenting a virus genome can entail an increased RIG-I sensitivi...
Source: Current Opinion in Microbiology - June 12, 2014 Category: Microbiology Authors: Weber M, Weber F Tags: Curr Opin Microbiol Source Type: research
Mannosylation of fungal glycoconjugates in the Golgi apparatus.
Abstract Glycosylation is a crucial step in the modification of proteins or sphingolipids that then play a prominent role in fungal biology. Glycosylation controls the structure and plasticity of the fungal cell wall and fungi-host interactions. Non-pathogenic and pathogenic yeasts, such as Saccharomyces cerevisiae and Candida albicans, respectively, have been useful models for analyzing the mannosylation of proteins and sphingolipids, which mainly takes place in the Golgi apparatus. Studies of these yeasts have identified different mannosyltransferases that belong to separate families of glycosyltransferases. The...
Source: Current Opinion in Microbiology - June 12, 2014 Category: Microbiology Authors: Fabre E, Hurtaux T, Fradin C Tags: Curr Opin Microbiol Source Type: research
An evolving arsenal: viral RNA detection by RIG-I-like receptors.
Abstract RIG-I-like receptors (RLRs) utilize a specialized, multi-domain architecture to detect and respond to invasion by a diverse set of viruses. Structural similarities among these receptors provide a general mechanism for double strand RNA recognition and signal transduction. However, each RLR has developed unique strategies for sensing the specific molecular determinants on subgroups of viral RNAs. As a means to circumvent the antiviral response, viruses escape RLR detection by degrading, or sequestering or modifying their RNA. Patterns of variation in RLR sequence reveal a continuous evolution of the protei...
Source: Current Opinion in Microbiology - June 6, 2014 Category: Microbiology Authors: Fitzgerald ME, Rawling DC, Vela A, Pyle AM Tags: Curr Opin Microbiol Source Type: research
To sense or not to sense viral RNA-essentials of coronavirus innate immune evasion.
Abstract An essential function of innate immunity is to distinguish self from non-self and receptors have evolved to specifically recognize viral components and initiate the expression of antiviral proteins to restrict viral replication. Coronaviruses are RNA viruses that replicate in the host cytoplasm and evade innate immune sensing in most cell types, either passively by hiding their viral signatures and limiting exposure to sensors or actively, by encoding viral antagonists to counteract the effects of interferons. Since many cytoplasmic viruses exploit similar mechanisms of innate immune evasion, mechanistic ...
Source: Current Opinion in Microbiology - June 5, 2014 Category: Microbiology Authors: Kindler E, Thiel V Tags: Curr Opin Microbiol Source Type: research
Induced antiviral innate immunity in Drosophila.
Abstract Immunity to viral infections in the model organism Drosophila melanogaster involves both RNA interference and additional induced responses. The latter include not only cellular mechanisms such as programmed cell death and autophagy, but also the induction of a large set of genes, some of which contribute to the control of viral replication and resistance to infection. This induced response to infection is complex and involves both virus-specific and cell-type specific mechanisms. We review here recent developments, from the sensing of viral infection to the induction of signaling pathways and production o...
Source: Current Opinion in Microbiology - June 4, 2014 Category: Microbiology Authors: Lamiable O, Imler JL Tags: Curr Opin Microbiol Source Type: research
Are mitochondria the Achilles' heel of the Kingdom Fungi?
Abstract A founding event in the origin of eukaryotes is the acquisition of an extraordinary organelle, the mitochondrion, which contains its own genome. Being linked to energy metabolism, oxidative stress, cell signalling, and cell death, the mitochondrion to a certain extent controls life and death in eukaryotic cells. The large metabolic diversity and living strategies of the Kingdom Fungi make their mitochondria of particular evolutionary interest. The review focuses first on the characteristics of mitochondria in the Kingdom Fungi, then on their implications in the organism survival, pathogenicity and resista...
Source: Current Opinion in Microbiology - June 3, 2014 Category: Microbiology Authors: Chatre L, Ricchetti M Tags: Curr Opin Microbiol Source Type: research
The conformational and subcellular compartmental dance of plant NLRs during viral recognition and defense signaling.
We describe some of the physical and functional interactions these NLRs undertake. We elaborate on the intra-molecular and homotypic association of NLRs that function in self-regulation and activation. Nuclear role for some viral NLRs is discussed as well as the emerging importance of the RNAi pathway in regulating the NLR family. PMID: 24906192 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - June 3, 2014 Category: Microbiology Authors: Padmanabhan MS, Dinesh-Kumar SP Tags: Curr Opin Microbiol Source Type: research
Interdependence of the actin and the microtubule cytoskeleton during fungal growth.
r R Abstract Cell polarization is a theme in biology conserved from bacteria to man. One of the most extremely polarized cells in nature is the hyphae of filamentous fungi. A continuous flow of secretion vesicles from the hyphal cell body to the tip is essential for cell wall and membrane extension. Microtubules (MTs) and actin, along with their corresponding motor proteins, are involved in the secretion process. Therefore, the arrangement of the cytoskeleton is a crucial step to establish and maintain polarity. Here we review recent findings unraveling the mechanism of polarized growth with special emphasis on th...
Source: Current Opinion in Microbiology - May 27, 2014 Category: Microbiology Authors: Takeshita N, Manck R, Grün N, de Vega SH, Fischer R Tags: Curr Opin Microbiol Source Type: research
Fungal pathogens are platforms for discovering novel and conserved septin properties.
Abstract Septins are filament-forming GTP-binding proteins that act as scaffolds in diverse cell functions including division, polarity and membrane remodeling. In a variety of fungal pathogens, it has been observed that septins are required for virulence because cells are unable to survive or are misshapen when septins are mutated. Cell morphology is interconnected with pathogenesis and thus septin mutants displaying aberrant cell morphologies are commonly deficient in host tissue invasion. The degree to which septins orchestrate versus maintain changes in fungal cell morphology during pathogenesis remains to be ...
Source: Current Opinion in Microbiology - May 27, 2014 Category: Microbiology Authors: Bridges AA, Gladfelter AS Tags: Curr Opin Microbiol Source Type: research
The Spitzenkörper: a choreographer of fungal growth and morphogenesis.
The Spitzenkörper: a choreographer of fungal growth and morphogenesis. Curr Opin Microbiol. 2014 May 21;20C:27-33 Authors: Riquelme M, Sánchez-León E Abstract The Spitzenkörper (SPK) is a multicomponent pleomorphic structure found at hyphal apices. It is necessary to maintain hyphal growth and morphogenesis in numerous fungal species, including plant and human pathogens. At the turn of the 21st century extraordinary advances in protein tagging technology and live microscopy allowed uncovering the main molecular constituents of the SPK. Distinct layers of macrovesicles and micro...
Source: Current Opinion in Microbiology - May 21, 2014 Category: Microbiology Authors: Riquelme M, Sánchez-León E Tags: Curr Opin Microbiol Source Type: research
Variability of chromosome structure in pathogenic fungi-of 'ends and odds'
Abstract Chromatin structure can affect the organization and maintenance of chromosomes. Recent discoveries in several filamentous fungi suggest mechanisms for the clustering and co-regulation of secondary metabolite genes or pathogenicity islands. An extreme case of this may be fungal 'accessory', 'conditionally dispensable', or 'supernumerary' chromosomes that often confer beneficial traits. Fungal supernumerary chromosomes may be derived by similar mechanisms as animal or plant B chromosomes, and we thus propose that this term should be reconsidered to capture the wide variety of fungal accessory chromosomes. I...
Source: Current Opinion in Microbiology - May 15, 2014 Category: Microbiology Authors: Galazka JM, Freitag M Tags: Curr Opin Microbiol Source Type: research
Vesicle trafficking, organelle functions, and unconventional secretion in fungal physiology and pathogenicity.
Abstract Specific localization of appropriate sets of proteins and lipids is central to functions and integrity of organelles, which in turn underlie cellular activities of eukaryotes. Vesicle trafficking is a conserved mechanism of intracellular transport, which ensures such a specific localization to a subset of organelles. In this review article, we summarize recent advances in our understanding of how vesicle trafficking and related organelles support physiology and pathogenicity of filamentous fungi. Examples include a link between Golgi organization and polarity maintenance during hyphal tip growth, a new ro...
Source: Current Opinion in Microbiology - May 14, 2014 Category: Microbiology Authors: Shoji JY, Kikuma T, Kitamoto K Tags: Curr Opin Microbiol Source Type: research
Endocytosis and early endosome motility in filamentous fungi.
Abstract Hyphal growth of filamentous fungi requires microtubule-based long-distance motility of early endosomes. Since the discovery of this process in Ustilago maydis, our understanding of its molecular basis and biological function has greatly advanced. Studies in U. maydis and Aspergillus nidulans reveal a complex interplay of the motor proteins kinesin-3 and dynein, which co-operate to support bi-directional motion of early endosomes. Genetic screening has shed light on the molecular mechanisms underpinning motor regulation, revealing Hook protein as general motor adapters on early endosomes. Recently, fascin...
Source: Current Opinion in Microbiology - May 14, 2014 Category: Microbiology Authors: Steinberg G Tags: Curr Opin Microbiol Source Type: research
Editorial overview: Cell regulation: Microbial cell regulation-looking in from the outside.
PMID: 24704057 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - April 2, 2014 Category: Microbiology Authors: Arraiano CM, Cook GM Tags: Curr Opin Microbiol Source Type: research
The role of RNases in the regulation of small RNAs.
no CM Abstract Ribonucleases (RNases) are key factors in the control of biological processes, since they modulate the processing, degradation and quality control of RNAs. This review gives many illustrative examples of the role of RNases in the regulation of small RNAs (sRNAs). RNase E and PNPase have been shown to degrade the free pool of sRNAs. RNase E can also be recruited to cleave mRNAs when they are interacting with sRNAs. RNase III cleaves double-stranded structures, and can cut both the sRNA and its RNA target when they are hybridized. Overall, ribonucleases act as conductors in the control of sRNAs. There...
Source: Current Opinion in Microbiology - April 2, 2014 Category: Microbiology Authors: Saramago M, Bárria C, Dos Santos RF, Silva IJ, Pobre V, Domingues S, Andrade JM, Viegas SC, Arraiano CM Tags: Curr Opin Microbiol Source Type: research
The cyanobacterial clock and metabolism.
Abstract Cyanobacteria possess the simplest known circadian clock, which presents a unique opportunity to study how rhythms are generated and how input signals from the environment reset the clock time. The kaiABC locus forms the core of the oscillator, and the remarkable ability to reconstitute oscillations using purified KaiABC proteins has allowed researchers to study mechanism using the tools of quantitative biochemistry. Autotrophic cyanobacteria experience major shifts in metabolism following a light-dark transition, and recent work suggests that input mechanisms that couple the day-night cycle to the clock ...
Source: Current Opinion in Microbiology - March 22, 2014 Category: Microbiology Authors: Pattanayak G, Rust MJ Tags: Curr Opin Microbiol Source Type: research
Biofilm dispersion and quorum sensing.
Abstract Biofilm development and quorum sensing (QS) are closely interconnected processes. Biofilm formation is a cooperative group behaviour that involves bacterial populations living embedded in a self-produced extracellular matrix. QS is a cell-cell communication mechanism that synchronizes gene expression in response to population cell density. Intuitively, it would appear that QS might coordinate the switch to a biofilm lifestyle when the population density reaches a threshold level. However, compelling evidence obtained in different bacterial species coincides in that activation of QS occurs in the formed bi...
Source: Current Opinion in Microbiology - March 19, 2014 Category: Microbiology Authors: Solano C, Echeverz M, Lasa I Tags: Curr Opin Microbiol Source Type: research
Gene regulation by engineered CRISPR-Cas systems.
Abstract The clustered regularly interspaced short palindromic repeat (CRISPR) arrays and their CRISPR associated (Cas) proteins constitute adaptive immune systems in bacteria and archaea that provide protection from bacteriophages, plasmids and other mobile genetic elements (MGEs). Recently, the ability to direct these systems to DNA in a sequence-specific manner has led to the emergence of new technologies for engineered gene regulation in bacteria and eukaryotes. These systems have the potential to enable facile high-throughput functional genomics studies aimed at identifying gene function and will be a crucial...
Source: Current Opinion in Microbiology - March 14, 2014 Category: Microbiology Authors: Fineran PC, Dy RL Tags: Curr Opin Microbiol Source Type: research
Synthetic microbial communities.
r OS Abstract While natural microbial communities are composed of a mix of microbes with often unknown functions, the construction of synthetic microbial communities allows for the generation of defined systems with reduced complexity. Used in a top-down approach, synthetic communities serve as model systems to ask questions about the performance and stability of microbial communities. In a second, bottom-up approach, synthetic microbial communities are used to study which conditions are necessary to generate interaction patterns like symbiosis or competition, and how higher order community structure can emerge fr...
Source: Current Opinion in Microbiology - March 13, 2014 Category: Microbiology Authors: Großkopf T, Soyer OS Tags: Curr Opin Microbiol Source Type: research
NusG/Spt5: are there common functions of this ubiquitous transcription elongation factor?
Abstract NusG/Spt5 is a transcription elongation factor that assists in DNA-templated RNA synthesis by cellular RNA polymerases (RNAP). The modular domain composition of NusG/Spt5 and the way it binds to RNAP are conserved in all three domains of life. NusG/Spt5 closes RNAP around the DNA binding channel, thereby increasing transcription processivity. Recruitment of additional factors to elongating RNAP may be another conserved function of this ubiquitous protein. Eukaryotic Spt5 couples RNA processing and chromatin modification to transcription elongation, whereas bacterial NusG participates in a wide variety of ...
Source: Current Opinion in Microbiology - March 12, 2014 Category: Microbiology Authors: Yakhnin AV, Babitzke P Tags: Curr Opin Microbiol Source Type: research
Retroviral strategy to stabilize viral RNA.
Abstract Unspliced Rous sarcoma virus (RSV) retroviral mRNA undergoes nonsense-mediated RNA decay (NMD) if it has premature termination codons in the gag gene. However, its normal gag termination codon is not subject to NMD despite being 7kb from the 3' poly(A) sequence. An RNA stability element (RSE) has been identified immediately downstream of gag in the RSV genome. It appears to determine the proper context for translation termination and protects the RNA from NMD. The viral stability element may prevent Up-frameshift 1 (Upf1) protein from interacting with the terminating ribosome and release factors to initia...
Source: Current Opinion in Microbiology - March 12, 2014 Category: Microbiology Authors: Quek BL, Beemon K Tags: Curr Opin Microbiol Source Type: research
To divide or not to divide: control of the bacterial cell cycle by environmental cues.
Abstract Whether to divide or not is an important decision that nearly all cells have to make, especially bacteria that are exposed to drastic environmental changes. Under adverse conditions proliferation and growth could compromise cellular integrity and hence must be downregulated. To this end, bacteria have evolved sophisticated mechanisms to transduce environmental information into the cell cycle engine. Recent studies in Escherichia coli, Bacillus subtilis and Caulobacter crescentus indicate that these mechanisms often involve small molecule-based signaling, regulated proteolysis, as well as protein-protein i...
Source: Current Opinion in Microbiology - March 11, 2014 Category: Microbiology Authors: Jonas K Tags: Curr Opin Microbiol Source Type: research
The mystery of aging and rejuvenation-a budding topic.
u B Abstract In the process of yeast budding, an aged and deteriorated mother cell gives rise to a youthful and pristine daughter cell. This remarkable event offers a tractable model system for identifying factors affecting life expectancy and it has been established that multiple aging factors operate in parallel. Herein, we will highlight the identity of such aging factors, how they are asymmetrically segregated, and whether the knowledge of their deteriorating effects might be utilized to approach cellular and tissue rejuvenation in metazoans, including humans. PMID: 24631930 [PubMed - as supplied by publi...
Source: Current Opinion in Microbiology - March 11, 2014 Category: Microbiology Authors: Nyström T, Liu B Tags: Curr Opin Microbiol Source Type: research
Peptidoglycan plasticity in bacteria: emerging variability of the murein sacculus and their associated biological functions.
Abstract The peptidoglycan (PG) sacculus once thought to be just a reinforcing, static and uniform structure, is fast becoming recognized as a dynamic cell constituent involved in every aspect of bacterial physiology. Recent advances showed that in addition to 'classical' tasks-as an essential element to define bacterial shape, size, division and resistance to osmotic stress-the sacculus plays very important roles in many other fields. The very few chemical and structural changes that were once considered as bizarre, or maybe exotic exceptions, are now universally accepted as fundamental pieces in bacterial cell w...
Source: Current Opinion in Microbiology - March 6, 2014 Category: Microbiology Authors: Cava F, de Pedro MA Tags: Curr Opin Microbiol Source Type: research
Bacterial mechanosensitive channels: progress towards an understanding of their roles in cell physiology.
Abstract Bacterial mechanosensitive channels sense the changes in lateral tension in the bilayer of the cytoplasmic membrane generated by rapid water flow into the cell. Two major structural families are found widely distributed across bacteria and archaea: MscL and MscS. Our understanding of the mechanisms of gating has advanced rapidly through genetic analysis, structural biology and electrophysiology. It is only recently that the analysis of the physiological roles of the channels has kept pace with mechanistic studies. Recent advances have increased our understanding of the role of the channels in preventing s...
Source: Current Opinion in Microbiology - March 5, 2014 Category: Microbiology Authors: Booth IR Tags: Curr Opin Microbiol Source Type: research
Allostery and compartmentalization: old but not forgotten.
Abstract Homeostasis is an essential capability of all cells mediated by complex and diverse regulatory networks. Despite this complexity, many of the fundamental regulatory mechanisms used by cells have been evolutionarily conserved. It is thus somewhat surprising that the apparent physiologic significance of these mechanisms has been experimentally neglected. Here, we review 2 widely recognized regulatory mechanisms, allostery and compartmentalization, which exemplify this dissociation in our current understanding of the microbial pathogen, Mycobacterium tuberculosis. PMID: 24607642 [PubMed - as supplied by...
Source: Current Opinion in Microbiology - March 4, 2014 Category: Microbiology Authors: Eoh H, Rhee KY Tags: Curr Opin Microbiol Source Type: research
Integration of hydrogenase expression and hydrogen sensing in bacterial cell physiology.
Abstract Hydrogenases are ubiquitous in ecosystems and widespread in microorganisms. In bacteria, hydrogen metabolism is a facultative trait that is tightly regulated in response to both external factors (e.g. gas concentrations) and internal factors (e.g. redox state). Here we consider how environmental and pathogenic bacteria regulate [NiFe]-hydrogenases to adapt to chemical changes and meet physiological needs. We introduce this concept by exploring how Ralstonia eutropha switches between heterotrophic and lithotrophic growth modes by sensing hydrogen and electron availability. The regulation and integration of...
Source: Current Opinion in Microbiology - March 4, 2014 Category: Microbiology Authors: Greening C, Cook GM Tags: Curr Opin Microbiol Source Type: research
Redox-driven regulation of microbial community morphogenesis.
Abstract During growth on surfaces, diverse microbial communities display topographies with captivating patterns. The quality and quantity of matrix excreted by resident cells play major roles in determining community architecture. Two current publications indicate that the cellular redox state and respiratory activity are important parameters affecting matrix output in the divergent bacteria Pseudomonas aeruginosa and Bacillus subtilis. These and related studies have identified regulatory proteins with the potential to respond to changes in redox state and respiratory electron transport and modulate the activity ...
Source: Current Opinion in Microbiology - March 4, 2014 Category: Microbiology Authors: Okegbe C, Price-Whelan A, Dietrich LE Tags: Curr Opin Microbiol Source Type: research
Salmonellae PhoPQ regulation of the outer membrane to resist innate immunity.
Abstract Salmonellae sense host cues to regulate properties important for bacterial survival and replication within host tissues. The PhoPQ two-component regulatory system senses phagosome acidification and cationic antimicrobial peptides (CAMP) to regulate the protein and lipid contents of the bacterial envelope that comprises an inner and outer membrane. PhoPQ-regulated lipid components of the outer membrane include lipopolysaccharides and glycerophospholipids. Envelope proteins regulated by PhoPQ, include: components of virulence associated secretion systems, the flagellar apparatus, membrane transport systems,...
Source: Current Opinion in Microbiology - February 13, 2014 Category: Microbiology Authors: Dalebroux ZD, Miller SI Tags: Curr Opin Microbiol Source Type: research
The involvement of transport proteins in transcriptional and metabolic regulation.
MH Abstract Transport proteins have sometimes gained secondary regulatory functions that influence gene expression and metabolism. These functions allow communication with the external world via mechanistically distinctive signal transduction pathways. In this brief review we focus on three transport systems in Escherichia coli that control and coordinate carbon, exogenous hexose-phosphate and phosphorous metabolism. The transport proteins that play central roles in these processes are: first, the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS), second, the glucose-6-phosphate receptor, UhpC, ...
Source: Current Opinion in Microbiology - February 7, 2014 Category: Microbiology Authors: Västermark A, Saier MH Tags: Curr Opin Microbiol Source Type: research
Cyclic-AMP and bacterial cyclic-AMP receptor proteins revisited: adaptation for different ecological niches.
Abstract Escherichia coli cyclic-AMP receptor protein (CRP) represents one of the paradigms of bacterial gene regulation. Yet despite decades of intensive study, new information continues to emerge that prompts reassessment of this classic regulatory system. Moreover, in recent years CRPs from several other bacterial species have been characterized, allowing the general applicability of the CRP paradigm to be tested. Here the properties of the E. coli, Mycobacterium tuberculosis and Pseudomonas putida CRPs are considered in the context of the ecological niches occupied by these bacteria. It appears that the cyclic...
Source: Current Opinion in Microbiology - February 5, 2014 Category: Microbiology Authors: Green J, Stapleton MR, Smith LJ, Artymiuk PJ, Kahramanoglou C, Hunt DM, Buxton RS Tags: Curr Opin Microbiol Source Type: research
Editorial overview: Host-microbe interactions: bacteria: War and peace: the fragile equilibrium between bacteria and host.
PMID: 24503282 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - February 3, 2014 Category: Microbiology Authors: Steele-Mortimer O, Subtil A Tags: Curr Opin Microbiol Source Type: research
Salmonella vaccines: lessons from the mouse model or bad teaching?
Abstract Salmonella enterica subsp. enterica includes several very important human serovars including Typhi, Paratyphi, Typhimurium and Enteritidis. These bacteria cause a significant global burden of disease, typically classified into enteric fever, gastroenteritis and, more recently, invasive non-typhoidal salmonellosis (iNTS). Vaccines have been developed for one of these serovars, S. Typhi and the recent increase in iNTS cases has resulted in a push to develop new vaccines that will inhibit disease by S. Typhimurium and S. Enteritidis, the most common iNTS S. enterica serovars. The development of new human vac...
Source: Current Opinion in Microbiology - January 16, 2014 Category: Microbiology Authors: Strugnell RA, Scott TA, Wang N, Yang C, Peres N, Bedoui S, Kupz A Tags: Curr Opin Microbiol Source Type: research
Intestinal barrier dysfunction triggered by invasive bacteria.
Abstract The ability to control uptake across the mucosa and to protect the gut from harmful substances present in the lumen is defined as intestinal barrier function. Two routes are usually distinguished for transepithelial transport. The paracellular route allows the passage of ions and small molecules and is mainly regulated by tight junctions (TJ). The transcellular route concerns large molecules or small particles (including bacteria) and is mediated by cell endocytosis and intracellular vesicular traffic. Enteropathogenic bacteria increase the transcellular permeability, especially in the follicle-associated...
Source: Current Opinion in Microbiology - January 14, 2014 Category: Microbiology Authors: Barreau F, Hugot J Tags: Curr Opin Microbiol Source Type: research
Mechanisms of bacterial morphogenesis and their subversion by phages.
PMID: 24183843 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - October 31, 2013 Category: Microbiology Authors: Bernhardt TG, Vollmer W Tags: Curr Opin Microbiol Source Type: research
Stabilizing the foundation of the house that 'omics builds: the evolving value of cultured isolates to marine microbiology.
e; MS Abstract The value of cultivating microbial strains that are representative of abundant microorganisms in situ is generally acknowledged amongst marine microbial ecologists, primarily because they provide the means to determine phenotypic properties and detailed physiological characteristics of living cells in a controlled setting. In the shadow of the rapid, ongoing expansion in environmental genomic, transcriptomic, and proteomic surveys of marine systems, a minor resurgence in experiments designed to isolate and grow free-living marine microorganisms has met some success. Interestingly, the most immediate...
Source: Current Opinion in Microbiology - October 29, 2013 Category: Microbiology Authors: Rappé MS Tags: Curr Opin Microbiol Source Type: research
Bringing the gut microbiota into focus through microbial culture: recent progress and future perspective.
Abstract Ever-more-powerful 'omics'-based technologies are allowing us to pry deeper and more clearly into the workings of the human gut microbiota. Culture of the component microbes has fallen somewhat behind these efforts for a number of reasons, not least of which being the perceived difficulty in growing microbial species that have previously eluded all efforts to tame them. However, recent advances in the field are beginning to bring success in this area, allowing holistic study of microbes and microbial communities in defined systems. Innovative approaches to the culture and study of the human microbiota wil...
Source: Current Opinion in Microbiology - October 19, 2013 Category: Microbiology Authors: Allen-Vercoe E Tags: Curr Opin Microbiol Source Type: research
On the essentiality of lipopolysaccharide to Gram-negative bacteria.
Abstract Lipopolysaccharide is a highly acylated saccharolipid located on the outer leaflet of the outer membrane of Gram-negative bacteria. Lipopolysaccharide is critical to maintaining the barrier function preventing the passive diffusion of hydrophobic solutes such as antibiotics and detergents into the cell. Lipopolysaccharide has been considered an essential component for outer membrane biogenesis and cell viability based on pioneering studies in the model Gram-negative organisms Escherichia coli and Salmonella. With the isolation of lipopolysaccharide-null mutants in Neisseria meningitidis, Moraxella catarrh...
Source: Current Opinion in Microbiology - October 19, 2013 Category: Microbiology Authors: Zhang G, Meredith TC, Kahne D Tags: Curr Opin Microbiol Source Type: research
Microbiology in the 'omics era: from the study of single cells to communities and beyond.
asa I PMID: 24139987 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - October 17, 2013 Category: Microbiology Authors: Methé BA, Lasa I Tags: Curr Opin Microbiol Source Type: research
Candida albicans specializations for iron homeostasis: from commensalism to virulence.
Abstract Candida albicans is a fungal commensal-pathogen that persistently associates with its mammalian hosts. Between the commensal and pathogenic lifestyles, this microorganism inhabits host niches that differ markedly in the levels of bioavailable iron. A number of recent studies have exposed C. albicans specializations for acquiring iron from specific host molecules in regions where iron is scarce, while also defending against iron-related toxicity in regions where iron occurs in surfeit. Together, these results point to a central role for iron homeostasis in the evolution of this important human pathogen. ...
Source: Current Opinion in Microbiology - October 10, 2013 Category: Microbiology Authors: Noble SM Tags: Curr Opin Microbiol Source Type: research
Peptidoglycan hydrolases, bacterial shape, and pathogenesis.
Abstract Bacterial shape has always been hypothesized to play an important role in the biology of a species and in the ability of certain bacteria to influence human health. The recent discovery of peptidoglycan hydrolases that modulate shape has now allowed this hypothesis to be addressed directly. Genetic, biochemical, and phenotypic studies have found that changes in shape and underlying peptidoglycan structure influence many pathogenic attributes including surviving unfavorable conditions, predation, transmission, colonization, and host interactions. The diversity of bacterial shapes, niches, and lifestyles is...
Source: Current Opinion in Microbiology - October 10, 2013 Category: Microbiology Authors: Frirdich E, Gaynor EC Tags: Curr Opin Microbiol Source Type: research
Phage lysis: do we have the hole story yet?
Abstract In infections of Gram-negative bacteria, lysis is a three step process, with a choice of two effectors for each step. At a precise, allele-specific time, the inner membrane (IM) is fatally permeabilized by either a holin or a pinholin. This allows a muralytic enzyme, either a canonical endolysin, escaping from the cytoplasm, or a SAR endolysin, activated in the periplasm, to degrade the peptidoglycan. Surprisingly, a third class of lysis protein, the spanin, is required for disruption of the outer membrane (OM). Key steps are regulated by membrane protein dynamics, both in terms of bilayer topology and su...
Source: Current Opinion in Microbiology - October 7, 2013 Category: Microbiology Authors: Young R Tags: Curr Opin Microbiol Source Type: research
Modes of cell wall growth differentiation in rod-shaped bacteria.
Abstract A bacterial cell takes on the challenge to preserve and reproduce its shape at every generation against a substantial internal pressure by surrounding itself with a mechanical support, a peptidoglycan cell wall. The enlargement of the cell wall via net incorporation of precursors into the pre-existing wall conditions bacterial growth and morphology. However, generation, reproduction and/or modification of a specific shape requires that the incorporation takes place at precise locations for a defined time period. Much has been learnt in the past few years about the biochemistry of the peptidoglycan synthes...
Source: Current Opinion in Microbiology - October 1, 2013 Category: Microbiology Authors: Cava F, Kuru E, Brun YV, de Pedro MA Tags: Curr Opin Microbiol Source Type: research
Do the divisome and elongasome share a common evolutionary past?
e J Abstract The divisome and elongasome are bacterial protein complexes responsible for peptidoglycan (PG) synthesis during cell division and elongation, respectively. We review several lines of evidence, arguing for a shared evolutionary past of the divisome and elongasome. Both integrate closely related penicillin-binding proteins (PBPs) for PG synthesis, use proteins of the RodA/FtsW (SEDS, shape, elongation, division and sporulation) family for Lipid II export and interact with MraY/Mur proteins for Lipid II synthesis. It was recently shown that the actin-like protein FtsA of the divisome polymerises on membr...
Source: Current Opinion in Microbiology - October 1, 2013 Category: Microbiology Authors: Szwedziak P, Löwe J Tags: Curr Opin Microbiol Source Type: research