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

Iron uptake and virulence in Histoplasma capsulatum.
Abstract Histoplasma capsulatum (Hc) is the causative organism of a spectrum of disease affecting both the immunocompetent and the immunocompromised host. Hc is a dimporhic fungus that converts from conidia to the pathogenic yeast phase after entry into the mammalian host. Despite rapid ingestion by macrophages, it survives intracellularly within the macrophage. The intracellular survival strategy of Hc yeasts focuses on regulating the phagosomal compartment by modulating the intraphagosomal pH to 6.5. As an intracellular pathogen of MΦ, Hc obtains iron from Fe-transferrin, ferritin, or both, via the productio...
Source: Current Opinion in Microbiology - October 1, 2013 Category: Microbiology Authors: Newman SL, Smulian AG Tags: Curr Opin Microbiol Source Type: research

Prokaryotic cell division: flexible and diverse.
Abstract Gram-negative rod-shaped bacteria have different approaches to position the cell division initiating Z-ring at the correct moment in their cell division cycle. The subsequent maturation into a functional division machine occurs in vastly different species in two steps with appreciable time in between these. The function of this time delay is unclear, but may partly be explained by competition for Lipid-II between proteins involved in length growth that interact directly with the Z-ring early in the maturation phase and the proteins involved in septum synthesis. A second possible activity of the early Z-ri...
Source: Current Opinion in Microbiology - September 28, 2013 Category: Microbiology Authors: den Blaauwen T Tags: Curr Opin Microbiol Source Type: research

Iron in eukaryotic microbes: regulation, trafficking and theft.
PMID: 24074556 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - September 25, 2013 Category: Microbiology Authors: Kronstad JW Tags: Curr Opin Microbiol Source Type: research

Cytoskeletal proteins participate in conserved viral strategies across kingdoms of life.
Abstract The discovery of tubulin-like cytoskeletal proteins carried on the genomes of bacteriophages that are actively used for phage propagation during both the lytic and lysogenic cycle have revealed that there at least two ways that viruses can utilize a cytoskeleton; co-opt the host cytoskeleton or bring their own homologues. Either strategy underscores the deep evolutionary relationship between viruses and cytoskeletal proteins and points to a conservation of viral strategies that crosses the kingdoms of life. Here we review some of the most recent discoveries about tubulin cytoskeletal elements encoded by p...
Source: Current Opinion in Microbiology - September 19, 2013 Category: Microbiology Authors: Erb ML, Pogliano J Tags: Curr Opin Microbiol Source Type: research

The role of hydrolases in bacterial cell-wall growth.
Abstract Although hydrolysis is known to be as important as synthesis in the growth and development of the bacterial cell wall, the coupling between these processes is not well understood. Bond cleavage can generate deleterious pores, but may also be required for the incorporation of new material and for the expansion of the wall, highlighting the importance of mechanical forces in interpreting the consequences of hydrolysis in models of growth. Critically, minimal essential subsets of hydrolases have now been identified in several model organisms, enabling the reduction of genetic complexity. Recent studies in Ba...
Source: Current Opinion in Microbiology - September 12, 2013 Category: Microbiology Authors: Lee TK, Huang KC Tags: Curr Opin Microbiol Source Type: research

Establishing polar identity in gram-negative rods.
Abstract In rod shaped bacteria, numerous cellular components are targeted to the cell poles, and such localization is often important for optimal function. In particular, recognition of poles is often linked to division site selection, chromosome segregation, chemotactic signaling, and motility. Recent advances in understanding polarity include identification of a Vibrio cholerae protein that mediates polar localization of a chromosome origin and chemotaxis clusters, as well as a downstream protein that contributes solely to localization of chemotaxis proteins. In Caulobacter crescentus, the molecular mechanisms ...
Source: Current Opinion in Microbiology - September 9, 2013 Category: Microbiology Authors: Davis BM, Waldor MK Tags: Curr Opin Microbiol Source Type: research

The FUN of identifying gene function in bacterial pathogens; insights from Salmonella functional genomics.
JC Abstract The availability of thousands of genome sequences of bacterial pathogens poses a particular challenge because each genome contains hundreds of genes of unknown function (FUN). How can we easily discover which FUN genes encode important virulence factors? One solution is to combine two different functional genomic approaches. First, transcriptomics identifies bacterial FUN genes that show differential expression during the process of mammalian infection. Second, global mutagenesis identifies individual FUN genes that the pathogen requires to cause disease. The intersection of these datasets can reveal ...
Source: Current Opinion in Microbiology - September 7, 2013 Category: Microbiology Authors: Hammarlöf DL, Canals R, Hinton JC Tags: Curr Opin Microbiol Source Type: research

The phenomenon of microbial uncultivability.
Abstract Most of the microbial diversity on our planet cannot be cultivated, and remains inaccessible. To bring the missing species into culture, microbiologists have introduced over the past decade a number of innovations aiming to meet the demands of new microbes and better mimic their natural conditions. This resulted in a significant increase in microbial recovery yet the real reasons why so many microbes do not grow on artificial media remain largely unknown. The recently proposed scout model of microbial life cycle may provide a partial explanation for the phenomenon. It postulates that transition from dorma...
Source: Current Opinion in Microbiology - September 3, 2013 Category: Microbiology Authors: Epstein S Tags: Curr Opin Microbiol Source Type: research

New strategies and compounds for anti-infective treatment.
PMID: 23998895 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - August 30, 2013 Category: Microbiology Authors: Hancock RE, Sahl HG Tags: Curr Opin Microbiol Source Type: research

Coprophilous fungi: antibiotic discovery and functions in an underexplored arena of microbial defensive mutualism.
Abstract Microbial antibiotics can mediate mutualisms and interorganism communications. Herbivorous animal dung offers opportunities for discovery of new antibiotics from microbial communities that compete for a nutrient-rich, ephemeral resource. Distinct lineages form a specialized community of coprophilous (dung-colonizing) fungi. Bacteria, protists, invertebrates, the mammalian digestive system, and other fungi can pose challenges to their fitness in the dung environment. The well-characterized diversity of dung fungi offers accessible systems for dissecting the function of antibiotics and for exploring fungal ...
Source: Current Opinion in Microbiology - August 23, 2013 Category: Microbiology Authors: Bills GF, Gloer JB, An Z Tags: Curr Opin Microbiol Source Type: research

Pathways of iron acquisition and utilization in Leishmania.
Abstract Iron is essential for many metabolic pathways, but is toxic in excess. Recent identification of the ferric iron reductase LFR1, the ferrous iron transporter LIT1, and the heme transporter LHR1 greatly advanced our understanding of how Leishmania parasites acquire iron and regulate its uptake. LFR1 and LIT1 have close orthologs in plants, and are required for Leishmania virulence. Consistent with the lack of heme biosynthesis in trypanosomatids, LHR1 and LABCG5, a protein involved in heme salvage from hemoglobin, seem essential for Leishmania survival. LFR1, LIT1 and LHR1 are upregulated under low iron ava...
Source: Current Opinion in Microbiology - August 17, 2013 Category: Microbiology Authors: Flannery AR, Renberg RL, Andrews NW Tags: Curr Opin Microbiol Source Type: research

Iron sparing and recycling in a compartmentalized cell.
Abstract This review focuses on economizing, prioritizing and recycling iron in Chlamydomonas, a reference organism for discovering mechanisms of acclimation to poor iron nutrition in the plant lineage. The metabolic flexibility of Chlamydomonas offers a unique opportunity to distinguish the impact of iron nutrition on photosynthetic versus respiratory metabolism, and the contribution of subcellular compartments to iron storage and mobilization. Mechanisms of iron sparing include down regulation of protein abundance by transcript reduction or protein degradation. Two well-studied examples of hierarchical iron allo...
Source: Current Opinion in Microbiology - August 17, 2013 Category: Microbiology Authors: Blaby-Haas CE, Merchant SS Tags: Curr Opin Microbiol Source Type: research

Iron sensing and regulation in Saccharomyces cerevisiae: Ironing out the mechanistic details.
Abstract Regulation of iron metabolism in Saccharomyces cerevisiae is achieved at the transcriptional level by low (Aft1 and Aft2) and high iron-sensing (Yap5) transcription factors, and at the post-transcriptional level by mRNA-binding proteins (Cth1 and Cth2). In this review we highlight recent studies unveiling the critical role that iron-sulfur clusters play in control of Aft1/2 and Yap5 activity, as well as the complex relationship between iron homeostasis and thiol redox metabolism. In addition, new insights into the localization and regulation of Cth1/Cth2 have added another layer of complexity to the cell'...
Source: Current Opinion in Microbiology - August 17, 2013 Category: Microbiology Authors: Outten CE, Albetel AN Tags: Curr Opin Microbiol Source Type: research

The crucial role of iron uptake in Aspergillus fumigatus virulence.
Abstract Aspergillus fumigatus is an opportunistic fungal pathogen that causes life-threatening infections in immunocompromised individuals. Siderophore-mediated iron acquisition has been shown to be essential for virulence. New studies have revealed that enzymes involved in siderophore biosynthesis and uptake are compartmentalized in peroxisomes and endosome-like vesicles, respectively. Gene and protein expression studies have revealed coordinated regulation of siderophore and sterol metabolism linked to the common precursor mevalonate. Several A. fumigatus transcription factors have been identified that are unex...
Source: Current Opinion in Microbiology - August 17, 2013 Category: Microbiology Authors: Moore MM Tags: Curr Opin Microbiol Source Type: research

Progress in understanding fungal pathogenesis.
PMID: 23948072 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - August 12, 2013 Category: Microbiology Authors: Casadevall A Tags: Curr Opin Microbiol Source Type: research

Protein interaction networks as starting points to identify novel antimicrobial drug targets.
Abstract Novel classes of antimicrobials are needed to address the challenge of multidrug-resistant bacteria. Current bacterial drug targets mainly consist of specific proteins or subsets of proteins without regard for either how these targets are integrated in cellular networks or how they may interact with host proteins. However, proteins rarely act in isolation, and the majority of biological processes are dependent on interactions with other proteins. Consequently, protein-protein interaction (PPI) networks offer a realm of unexplored potential for next-generation drug targets. In this review, we argue that th...
Source: Current Opinion in Microbiology - August 9, 2013 Category: Microbiology Authors: Zoraghi R, Reiner NE Tags: Curr Opin Microbiol Source Type: research

Bacterial cell division as a target for new antibiotics.
t H Abstract Bacterial resistance to currently applied antibiotics complicates the treatment of infections and demands the evaluation of new strategies to counteract multidrug-resistant bacteria. In recent years, the inhibition of the bacterial divisome, mainly by targeting the central cell division mediator FtsZ, has been recognized as a promising strategy for antibiotic attack. New antibiotics were shown to either interfere with the natural dynamics and functions of FtsZ during the cell cycle or to activate a bacterial protease to degrade FtsZ and thus bring about bacterial death in a suicidal manner. Their effi...
Source: Current Opinion in Microbiology - August 8, 2013 Category: Microbiology Authors: Sass P, Brötz-Oesterhelt H Tags: Curr Opin Microbiol Source Type: research

The asexual cycle of apicomplexan parasites: new findings that raise new questions.
PMID: 23932517 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - August 8, 2013 Category: Microbiology Authors: Meissner M Tags: Curr Opin Microbiol Source Type: research

Cryptic organelle homology in apicomplexan parasites: insights from evolutionary cell biology.
Abstract The economic and clinical significance of apicomplexan parasites drives interest in their many evolutionary novelties. Distinctive intracellular organelles play key roles in parasite motility, invasion, metabolism, and replication, and understanding their relationship with the organelles of better-studied eukaryotic systems suggests potential targets for therapeutic intervention. Recent work has demonstrated divergent aspects of canonical eukaryotic components in the Apicomplexa, including Golgi bodies and mitochondria. The apicoplast is a relict plastid of secondary endosymbiotic origin, harboring metabo...
Source: Current Opinion in Microbiology - August 7, 2013 Category: Microbiology Authors: Klinger CM, Nisbet RE, Ouologuem DT, Roos DS, Dacks JB Tags: Curr Opin Microbiol Source Type: research

Iron and heme metabolism in Plasmodium falciparum and the mechanism of action of artemisinins.
Abstract During the asexual blood stage of its lifecycle, the malaria parasite Plasmodium falciparum grows and multiplies in the hemoglobin-rich environment of the human erythrocyte. Although the parasite has evolved unique strategies to survive in this environment, its interaction with iron represents an Achilles' heel that is exploited by many antimalarial drugs. Recent work has shed new light on how the parasite deals with hemoglobin breakdown products and on the role of iron as a mediator of the action of the antimalarial drug, artemisinin. PMID: 23932203 [PubMed - as supplied by publisher] (Source: Curre...
Source: Current Opinion in Microbiology - August 7, 2013 Category: Microbiology Authors: Klonis N, Creek DJ, Tilley L Tags: Curr Opin Microbiol Source Type: research

Organelle transcriptomes: products of a deconstructed genome.
Abstract Genetic drift and mutational pressure have shaped the evolution of mitochondrial and chloroplast genomes, giving rise to mechanisms that regulate their gene expression, which often differ from those in their prokaryotic ancestors. Advances in next generation sequencing technologies have enabled highly detailed characterization of organelle transcriptomes and the discovery of new transcripts and mechanisms for controlling gene expression. Here we discuss the common features of organelle transcriptomes that stem from their prokaryotic origin and some of the new innovations that are unique to organelles of m...
Source: Current Opinion in Microbiology - August 7, 2013 Category: Microbiology Authors: Small ID, Rackham O, Filipovska A Tags: Curr Opin Microbiol Source Type: research

The metabolic roles of the endosymbiotic organelles of Toxoplasma and Plasmodium spp.
Abstract The apicoplast and the mitochondrion of Apicomplexa cooperate in providing essential metabolites. Their co-evolution during the ancestral acquisition of a plastid and subsequent loss of photosynthesis resulted in divergent metabolic pathways compared with mammals and plants. This is most evident in their chimerical haem synthesis pathway. Toxoplasma and Plasmodium mitochondria operate canonical tricarboxylic acid (TCA) cycles and electron transport chains, although the roles differ between Toxoplasma tachyzoites and Plasmodium erythrocytic stages. Glutamine catabolism provides TCA intermediates in both pa...
Source: Current Opinion in Microbiology - August 5, 2013 Category: Microbiology Authors: Sheiner L, Vaidya AB, McFadden GI Tags: Curr Opin Microbiol Source Type: research

Iron acquisition in the human fungal pathogen Cryptococcus neoformans.
Abstract Iron sequestration by the vertebrate host is considered an efficient defense mechanism against pathogenic microbes. However, this mechanism, so called nutritional immunity, is often overcome by the iron acquisition systems that have evolved in microbial pathogens. Numerous studies have been carried out to identify the key components of these systems and to understand their underlying mechanisms, including recent investigations in the basidiomycete fungal pathogen Cryptococcus neoformans. Iron acquisition is essential for the survival and pathogenesis of this fungus within vertebrate hosts. Growing evidenc...
Source: Current Opinion in Microbiology - August 5, 2013 Category: Microbiology Authors: Jung WH, Do E Tags: Curr Opin Microbiol Source Type: research

Virus diversity and evolution.
PMID: 23927896 [PubMed - as supplied by publisher] (Source: Current Opinion in Microbiology)
Source: Current Opinion in Microbiology - August 5, 2013 Category: Microbiology Authors: Arias CF Tags: Curr Opin Microbiol Source Type: research

Iron uptake and regulation in Schizosaccharomyces pombe.
es JF Abstract Schizosaccharomyces pombe is a useful model system for understanding many aspects of eukaryotic cell growth. Studies of S. pombe have identified novel genes that function in the regulation of iron homeostasis. In response to high levels of iron, Fep1 represses the expression of several genes involved in the acquisition of iron. When iron levels are limited, optimization of cellular iron utilization is coordinated by Php4, which represses genes encoding iron-using proteins. Results from studies in yeast have shed new light on the role of monothiol glutaredoxins (Grxs) in iron homeostasis. In S. pombe...
Source: Current Opinion in Microbiology - August 2, 2013 Category: Microbiology Authors: Labbé S, Khan MG, Jacques JF Tags: Curr Opin Microbiol Source Type: research