Enhanced dynamics of conformationally heterogeneous T7 bacteriophage lysozyme native state attenuates its stability and activity
Proteins are dynamic in nature and exist in a set of equilibrium conformations on various timescale motions. The flexibility of proteins governs various biological functions, and therefore elucidation of such functional dynamics is essential. In this context, we have studied the structure–dynamics–stability–activity relationship of bacteriophage T7 lysozyme/endolysin (T7L) native-state ensemble in the pH range of 6–8. Our studies established that T7L native state is conformationally heterogeneous, as several residues of its C-terminal half are present in two conformations (major and minor) in the sl...
Source: Biochemical Journal - February 14, 2019 Category: Biochemistry Authors: Sharma, M., Jaiswal, N., Kumar, D., Poluri, K. M. Tags: Research Articles Source Type: research
Group A Streptococcus co-ordinates manganese import and iron efflux in response to hydrogen peroxide stress
Bacterial pathogens encounter a variety of adverse physiological conditions during infection, including metal starvation, metal overload and oxidative stress. Here, we demonstrate that group A Streptococcus (GAS) utilises Mn(II) import via MtsABC during conditions of hydrogen peroxide stress to optimally metallate the superoxide dismutase, SodA, with Mn. MtsABC expression is controlled by the DtxR family metalloregulator MtsR, which also regulates the expression of Fe uptake systems in GAS. Our results indicate that the SodA in GAS requires Mn for full activity and has lower activity when it contains Fe. As a consequence, ...
Source: Biochemical Journal - February 14, 2019 Category: Biochemistry Authors: Turner, A. G., Djoko, K. Y., Ong, C.-l. Y., Barnett, T. C., Walker, M. J., McEwan, A. G. Tags: Research Articles Source Type: research
LHC-like proteins involved in stress responses and biogenesis/repair of the photosynthetic apparatus
LHC (light-harvesting complex) proteins of plants and algae are known to be involved both in collecting light energy for driving the primary photochemical reactions of photosynthesis and in photoprotection when the absorbed light energy exceeds the capacity of the photosynthetic apparatus. These proteins usually contain three transmembrane (TM) helices which span the thylakoid membranes and bind several chlorophyll, carotenoid and lipid molecules. In addition, the LHC protein family includes LHC-like proteins containing one, two, three or even four TM domains. One-helix proteins are not only present in eukaryotic photosynt...
Source: Biochemical Journal - February 14, 2019 Category: Biochemistry Authors: Rochaix, J.-D., Bassi, R. Tags: Review Articles Source Type: research
Kinase activity of mutant LRRK2 manifests differently in hetero-dimeric vs. homo-dimeric complexes
The Parkinson's disease (PD) protein leucine-rich repeat kinase 2 (LRRK2) exists as a mixture of monomeric and dimeric species, with its kinase activity highly concentrated in the dimeric conformation of the enzyme. We have adapted the proximity biotinylation approach to study the formation and activity of LRRK2 dimers isolated from cultured cells. We find that the R1441C and I2020T mutations both enhance the rate of dimer formation, whereas, the G2019S kinase domain mutant is similar to WT, and the G2385R risk factor variant de-stabilizes dimers. Interestingly, we find a marked departure in the kinase activity between G20...
Source: Biochemical Journal - February 8, 2019 Category: Biochemistry Authors: Leandrou, E., Markidi, E., Memou, A., Melachroinou, K., Greggio, E., Rideout, H. J. Tags: Research Articles Source Type: research
High intensity exercise inhibits carnitine palmitoyltransferase-I sensitivity to L-carnitine
The decline in fat oxidation at higher power outputs of exercise is a complex interaction between several mechanisms; however, the influence of mitochondrial bioenergetics in this process remains elusive. Therefore, using permeabilized muscle fibers from mouse skeletal muscle, we aimed to determine if acute exercise altered mitochondrial sensitivity to (1) adenosine diphosphate (ADP) and inorganic phosphate (Pi), or (2) carnitine palmitoyltransferase-I (CPT-I) independent (palmitoylcarnitine, PC) and dependent [palmitoyl-CoA (P-CoA), malonyl-CoA (M-CoA), and l-carnitine] substrates, in an intensity-dependent manner. As the...
Source: Biochemical Journal - February 8, 2019 Category: Biochemistry Authors: Petrick, H. L., Holloway, G. P. Tags: Research Articles Source Type: research
Niclosamide-induced Wnt signaling inhibition in colorectal cancer is mediated by autophagy
The Wnt signaling pathway, known for regulating genes critical to normal embryonic development and tissue homeostasis, is dysregulated in many types of cancer. Previously, we identified that the anthelmintic drug niclosamide inhibited Wnt signaling by promoting internalization of Wnt receptor Frizzled 1 and degradation of Wnt signaling pathway proteins, Dishevelled 2 and β-catenin, contributing to suppression of colorectal cancer growth in vitro and in vivo. Here, we provide evidence that niclosamide-mediated inhibition of Wnt signaling is mediated through autophagosomes induced by niclosamide. Specifically, niclosami...
Source: Biochemical Journal - February 8, 2019 Category: Biochemistry Authors: Wang, J., Ren, X.-r., Piao, H., Zhao, S., Osada, T., Premont, R. T., Mook, R. A., Morse, M. A., Lyerly, H. K., Chen, W. Tags: Research Articles Source Type: research
Endothelin-converting enzyme-1 regulates glucagon-like peptide-1 receptor signalling and resensitisation
Following nutrient ingestion, glucagon-like peptide 1 (GLP-1) is secreted from intestinal L-cells and mediates anti-diabetic effects, most notably stimulating glucose-dependent insulin release from pancreatic β-cells but also inhibiting glucagon release, promoting satiety and weight reduction and potentially enhancing or preserving β-cell mass. These effects are mediated by the GLP-1 receptor (GLP-1R), which is a therapeutic target in type 2 diabetes. Although agonism at the GLP-1R has been well studied, desensitisation and resensitisation are perhaps less well explored. An understanding of these events is import...
Source: Biochemical Journal - February 8, 2019 Category: Biochemistry Authors: Lu, J., Willars, G. B. Tags: Research Articles Source Type: research
Identification of substrate-specific inhibitors of cathepsin K through high-throughput screening
Cathepsin K (CatK) is a cysteine protease and drug target for skeletal disorders that is known for its potent collagenase and elastase activity. The formation of oligomeric complexes of CatK in the presence of glycosaminoglycans has been associated with its collagenase activity. Inhibitors that disrupt these complexes can selectively block the collagenase activity without interfering with the other regulatory proteolytic activities of the enzyme. Here, we have developed a fluorescence polarization (FP) assay to screen 4761 compounds for substrate-specific ectosteric collagenase inhibitors of CatK. A total of 38 compounds w...
Source: Biochemical Journal - February 5, 2019 Category: Biochemistry Authors: Law, S., Du, X., Panwar, P., Honson, N. S., Pfeifer, T., Roberge, M., Brömme, D. Tags: Research Articles Source Type: research
CGA-N9, an antimicrobial peptide derived from chromogranin A: direct cell penetration of and endocytosis by Candida tropicalis
CGA-N9 is a peptide derived from the N-terminus of human chromogranin A comprising amino acids 47–55. Minimum inhibitory concentration (MIC) assays showed that CGA-N9 had antimicrobial activity and exhibited time-dependent inhibition activity against Candida tropicalis, with high safety in human red blood cells (HRBCs) and mouse brain microvascular endothelial cells (bEnd.3). According to the results of transmission electron microscopy (TEM), flow cytometry and confocal microscopy, CGA-N9 accumulated in cells without destroying the integrity of the cell membrane; the peptide was initially localized to the cell membra...
Source: Biochemical Journal - February 5, 2019 Category: Biochemistry Authors: Li, R., Chen, C., Zhu, S., Wang, X., Yang, Y., Shi, W., Chen, S., Wang, C., Yan, L., Shi, J. Tags: Research Articles Source Type: research
MOV10 sequesters the RNP of influenza A virus in the cytoplasm and is antagonized by viral NS1 protein
MOV10 has emerged as an important host antiviral factor. MOV10 not only inhibits various viruses, including human immunodeficiency virus type 1, hepatitis C virus and vesicular stomatitis virus, but also restricts the activity of retroelements long interspersed nucleotide element-1, Alu, SVA and intracisternal A particles. Here, we report that MOV10 suppresses influenza A virus infection through interacting with viral nucleoprotein (NP), sequestering viral RNP in the cytoplasm and causing the degradation of viral vRNA. The antiviral activity of MOV10 depends on the integrity of P-bodies. We also found that the antiviral ac...
Source: Biochemical Journal - February 5, 2019 Category: Biochemistry Authors: Li, J., Hu, S., Xu, F., Mei, S., Liu, X., Yin, L., Zhao, F., Zhao, X., Sun, H., Xiong, Z., Zhang, D., Cen, S., Wang, J., Liang, C., Guo, F. Tags: Research Articles Source Type: research
The transmembrane autophagy cargo receptors ATI1 and ATI2 interact with ATG8 through intrinsically disordered regions with distinct biophysical properties
Selective autophagy has emerged as an important mechanism by which eukaryotic cells control the abundance of specific proteins. This mechanism relies on cargo recruitment to autophagosomes by receptors that bind to both the ubiquitin-like AUTOPHAGY8 (ATG8) protein through ATG8-interacting motifs (AIMs) and to the cargo to be degraded. In plants, two autophagy cargo receptors, ATG8-interacting protein 1 (ATI1) and 2 (ATI2), were identified early on, but their molecular properties remain poorly understood. Here, we show that ATI1 and ATI2 are transmembrane proteins with long N-terminal intrinsically disordered regions (IDRs)...
Source: Biochemical Journal - February 5, 2019 Category: Biochemistry Authors: Sjogaard, I. M. Z., Bressendorff, S., Prestel, A., Kausika, S., Oksbjerg, E., Kragelund, B. B., Brodersen, P. Tags: Research Articles Source Type: research
Antibody specificity and promiscuity
The immune system is capable of making antibodies against anything that is foreign, yet it does not react against components of self. In that sense, a fundamental requirement of the body's immune defense is specificity. Remarkably, this ability to specifically attack foreign antigens is directed even against antigens that have not been encountered a priori by the immune system. The specificity of an antibody for the foreign antigen evolves through an iterative process of somatic mutations followed by selection. There is, however, accumulating evidence that the antibodies are often functionally promiscuous or multi-specific...
Source: Biochemical Journal - February 5, 2019 Category: Biochemistry Authors: Jain, D., Salunke, D. M. Tags: Review Articles Source Type: research
Solution structure of TbTFIIS2-2 PWWP domain from Trypanosoma brucei and its binding to H4K17me3 and H3K32me3
Posttranslational modifications (PTMs) of core histones, such as histone methylation, play critical roles in a variety of biological processes including transcription regulation, chromatin condensation and DNA repair. In T. brucei, no domain recognizing methylated histone has been identified so far. TbTFIIS2-2, as a potential transcription elongation factors in T. brucei, contains a PWWP domain in the N-terminus which shares low sequence similarity compared with other PWWP domains and is absent from other TFIIS factors. In the present study, the solution structure of TbTFIIS2-2 PWWP domain was determined by NMR spectroscop...
Source: Biochemical Journal - January 31, 2019 Category: Biochemistry Authors: Wang, R., Gao, J., Zhang, J., Zhang, X., Xu, C., Liao, S., Tu, X. Tags: Research Articles Source Type: research
Silencing of type II phosphatidylinositol 4-kinase {beta} stabilizes prostate apoptosis response-4 and induces apoptosis in cancer cells
Type II phosphatidylinositol 4-kinase β (PtdIns 4-kinase II β) is an enigma among the phosphatidylinositol 4-kinase family. The role of PtdIns 4-kinase II β in MCF-7 cells was addressed with the help of short hairpin RNA (shRNA). PtdIns 4-kinase II β shRNA transfection increased pan-caspase activity and induced apoptosis in cancerous MCF-7 cells. Non-cancerous MCF-10A cells were resistant to PtdIns 4-kinase II β shRNA-induced apoptosis. Caspase 8 and 9 inhibitors rescued MCF-7 cells from apoptosis. Shotgun proteomic studies with Flag-tagged PtdIns 4-kinase II β immunoprecipitates showed tumor ...
Source: Biochemical Journal - January 31, 2019 Category: Biochemistry Authors: Chaudhry, S., Joshi, V., Bojjireddy, N., Thoh, M., Sandur, S. K., Subrahmanyam, G. Tags: Research Articles Source Type: research
ZNF300 stimulates fatty acid oxidation and alleviates hepatosteatosis through regulating PPAR{alpha}
ZNF300 plays an important role in the regulation of HBV-related hepatocellular carcinoma. However, little is known about the role of ZNF300 in lipid metabolism and NAFLD. In the present study, we observed that ZNF300 expression was markedly decreased in free fatty acid (FFA)-induced fatty liver. Overexpressed ZNF300 alleviated hepatic lipid accumulation, whereas knockdown of ZNF300 enhanced the FFA-induced lipid accumulation. Investigations of the underlying mechanisms revealed that ZNF300 directly binds to and regulates the PPARα expression, thus promoting fatty acid oxidation. Furthermore, bisulfite pyrosequencing ...
Source: Biochemical Journal - January 31, 2019 Category: Biochemistry Authors: Yan, F.-J., Wang, Y.-J., Yan, S.-R., Lu, J., Zheng, Y.-L. Tags: Research Articles Source Type: research
