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Molecular Microbiology

Austin B Mogen, Ronan K Carroll, Kimberly L James, Genevy Lima, Dona Silva, Jeffrey A Culver, Christopher Petucci, Lindsey N Shaw, Kelly C Rice
Nitric oxide (NO) is generated from arginine and oxygen via NO synthase (NOS). Staphylococcus aureus NOS (saNOS) has previously been shown to affect virulence and resistance to exogenous oxidative stress, yet the exact mechanism is unknown. Herein, we report a previously-undescribed role of saNOS in S. aureus aerobic physiology. Specifically, aerobic S. aureus nos mutant cultures presented with elevated endogenous reactive oxygen species (ROS) and superoxide levels, as well as increased membrane potential, increased respiratory dehydrogenase activity, and slightly elevated oxygen consumption...
April 21, 2017: Molecular Microbiology
Yury A Barbitoff, Andrew G Matveenko, Svetlana E Moskalenko, Olga M Zemlyanko, Gary P Newnam, Ayesha Patel, Tatiana A Chernova, Yury O Chernoff, Galina A Zhouravleva
Yeast self-perpetuating protein aggregates (prions) provide a convenient model for studying various components of the cellular protein quality control system. Molecular chaperones and chaperone-sorting factors, such as yeast Cur1 protein, play key role in proteostasis via tight control of partitioning and recycling of misfolded proteins. In this study, we show that, despite the previously described ability of Cur1 to antagonize the yeast prion [URE3], it enhances propagation and phenotypic manifestation of another prion, [PSI(+) ]...
April 21, 2017: Molecular Microbiology
Cyril Guilhen, Christiane Forestier, Damien Balestrino
In most environments, microorganisms evolve in a sessile mode of growth, designated as biofilm, which is characterized by cells embedded in a self-produced extracellular matrix. Although a biofilm is commonly described as a "cozy house" where resident bacteria are protected from aggression, bacteria are able to break their biofilm bonds and escape to colonize new environments. This regulated process is observed in a wide variety of species; it is referred to as biofilm dispersal, and is triggered in response to various environmental and biological signals...
April 19, 2017: Molecular Microbiology
Maude F Lévêque, Laurence Berry, Yoshiki Yamaryo-Botté, Hoa Mai Nguyen, Marine Galera, Cyrille Y Botté, Sébastien Besteiro
Patatin-like phospholipases are involved in numerous cellular functions, including lipid metabolism and membranes remodeling. The patatin-like catalytic domain, whose phospholipase activity relies on a serine-aspartate dyad and an anion binding box, is widely spread among prokaryotes and eukaryotes. We describe TgPL2, a novel patatin-like phospholipase domain-containing protein from the parasitic protist Toxoplasma gondii. TgPL2 is a large protein, in which the key motifs for enzymatic activity are conserved in the patatin-like domain...
April 17, 2017: Molecular Microbiology
Shishen Du, Joe Lutkenhaus
Cell division in Escherichia coli is mediated by a large protein complex called the divisome. Most of the divisome proteins have been identified, but how they assemble onto the Z ring scaffold to form the divisome and work together to synthesize the septum is not well understood. In this review, we summarize the latest findings on divisome assembly and activation as well as provide our perspective on how these two processes might be regulated. This article is protected by copyright. All rights reserved.
April 17, 2017: Molecular Microbiology
Yujie Wu, Kuan Hu, Defeng Li, Lin Bai, Shaoqing Yang, Jordan B Jastrab, Shuhao Xiao, Yonglin Hu, Susan Zhang, K Heran Darwin, Tao Wang, Huilin Li
Mycobacterium tuberculosis (Mtb) has a proteasome system that is essential for its ability to cause lethal infections in mice. A key component of the system is the proteasomal adenosine triphosphatase (ATPase) Mpa, which captures, unfolds, and translocates protein substrates into the Mtb proteasome core particle for degradation. Here, we report the crystal structures of near full-length hexameric Mtb Mpa in apo and ADP-bound forms. Surprisingly, the structures revealed a ubiquitin-like β-grasp domain that precedes the proteasome-activating carboxyl terminus...
April 17, 2017: Molecular Microbiology
Christina Meinert, Jana Senger, Marco Witthohn, Jan Hendrik Wübbeler, Alexander Steinbüchel
In this study, we investigated an SBP (DctPAm) of a tripartite ATP-independent periplasmic transport system (TRAP) in Advenella mimigardefordensis strain DPN7(T) . Deletion of dctPAm as well as of the two transmembrane compounds of the tripartite transporter, dctQ and dctM, impaired growth of A. mimigardefordensis strain DPN7(T) , if cultivated on mineral salt medium supplemented with D-glucose, D-galactose, L-arabinose, D-fucose, D-xylose or D-gluconic acid, respectively. The wild type phenotype was restored during complementation studies of A...
April 13, 2017: Molecular Microbiology
Gavin Thomas
No abstract text is available yet for this article.
April 13, 2017: Molecular Microbiology
Doreen Haase, Bianca Hermann, Oliver Einsle, Jorg Simon
Members of the multihaem cytochrome c (MCC) family such as pentahaem cytochrome c nitrite reductase (NrfA) or octahaem hydroxylamine oxidoreductase (Hao) are involved in various microbial respiratory electron transport chains. Some members of the Hao subfamily, here called εHao proteins, have been predicted from the genomes of nitrate/nitrite-ammonifying bacteria that usually lack NrfA. Here, εHao proteins from the host-associated Epsilonproteobacteria Campylobacter fetus and Campylobacter curvus and the deep-sea hydrothermal vent bacteria Caminibacter mediatlanticus and Nautilia profundicola were purified as εHao-maltose binding protein fusions produced in Wolinella succinogenes...
April 7, 2017: Molecular Microbiology
Hokuto Ohtsuka, Masahiro Takinami, Takafumi Shimasaki, Takahide Hibi, Hiroshi Murakami, Hirofumi Aiba
Nutritional restrictions such as calorie restrictions are known to increase the lifespan of various organisms. Here we found that a restriction of sulfur extended the chronological lifespan (CLS) of the fission yeast Schizosaccharomyces pombe. The restriction decreased cellular size, RNA content, and ribosomal proteins and increased sporulation rate. These responses depended on Ecl1 family genes, the overexpression of which results in the extension of CLS. We also showed that the Zip1 transcription factor results in the sulfur restriction-dependent expression of the ecl1(+) gene...
April 7, 2017: Molecular Microbiology
Klas Flärdh, Joseph R McCormick
The study of Streptomyces development has made significant advances in the past few years and ongoing work is poised to add even more. One key to advancing the field has been the application of genome-wide approaches using S. venezuelae, which is capable of fairly synchronous sporulation in submerged growth conditions. WhiA and WhiB are well-known transcriptional regulators governing the pathway for spore formation in aerial hyphae. Recent ChIP-seq and RNA expression analyses indicated that WhiA and WhiB regulate the same set of genes, each being dependent on the presence of the other to exert control...
April 7, 2017: Molecular Microbiology
Marion Herisse, Yohann Duverger, Isabelle Martin-Verstraete, Frédéric Barras, Benjamin Ezraty
The predicted shortage in new antibiotics has prompted research for chemicals that could act as adjuvant and enhance efficacy of available antibiotics. In this study, we tested the effects of combining metals with aminoglycosides on Escherichia coli survival. The best synergising combination resulted from mixing aminoglycosides with silver. Using genetic and aminoglycoside uptake assays, we showed that silver potentiates aminoglycoside action in by-passing the PMF-dependent step, but depended upon protein translation...
April 6, 2017: Molecular Microbiology
Ewa Bukowska-Faniband, Lars Hederstedt
Endospore cortex peptidoglycan synthesis is not required for bacterial growth but essential for endospore heat resistance. It therefore constitutes an amenable system for research on peptidoglycan biogenesis. The Bacillus subtilis sporulation-specific class B penicillin-binding protein (PBP) SpoVD and many homologous PBPs contain two conserved cysteine residues of unknown function in the transpeptidase domain - one as residue x in the SxN catalytic site motif and the other in a flexible loop near the catalytic site...
April 6, 2017: Molecular Microbiology
Yanli Cao, Fanglin Zheng, Lei Wang, Guolei Zhao, Guanjun Chen, Weixin Zhang, Weifeng Liu
Cellulase gene expression in the model cellulolytic fungus Trichoderma reesei is supposed to be controlled by an intricate regulatory network involving multiple transcription factors. Here, we identified a novel transcriptional repressor of cellulase gene expression, Rce1. Disruption of the rce1 gene not only facilitated the induced expression of cellulase genes but also led to a significant delay in terminating the induction process. However, Rce1 did not participate in Cre1-mediated catabolite repression...
April 5, 2017: Molecular Microbiology
Xuehuan Feng, Ramamoorthy Vellaisamy, Sandesh S Pandit, Alicia Prieto, Eduardo A Espeso, Ana M Calvo
The model fungus Aspergillus nidulans synthesizes numerous secondary metabolites, including sterigmatocystin (ST). The production of this toxin is positively controlled by the global regulator veA. In the absence of veA (ΔveA), ST biosynthesis is blocked. Previously we performed random mutagenesis in a ΔveA strain and identified revertant mutants able to synthesize ST, among them RM1. Complementation of RM1 with a genomic library revealed that the mutation occurred in a gene designated as cpsA. While in the ΔveA genetic background cpsA deletion restores ST production, in a veA wild-type background absence of cpsA reduces and delays ST biosynthesis decreasing the expression of ST genes...
March 31, 2017: Molecular Microbiology
Mikolaj Olejniczak, Gisela Storz
Small RNAs (sRNAs), particularly those that act by limited base pairing with mRNAs, are part of most regulatory networks in bacteria. In many cases, the base-pairing interaction is facilitated by the RNA chaperone Hfq. However, not all bacteria encode Hfq and some base-pairing sRNAs do not require Hfq raising the possibility of other RNA chaperones. Candidates are proteins with homology to FinO, a factor that promotes base pairing between the FinP antisense sRNA and the traJ mRNA to control F plasmid transfer...
March 30, 2017: Molecular Microbiology
Constanze Homburg, Martin Bommer, Steven Wuttge, Carolin Hobe, Sebastian Beck, Holger Dobbek, Josef Deutscher, Anke Licht, Erwin Schneider
Catabolite repression is a mechanism that enables bacteria to control carbon utilization. As part of this global regulatory network, components of the phosphoenolpyruvate:carbohydrate phosphotransferase system inhibit the uptake of less favourable sugars when a preferred carbon source such as glucose is available. This process is termed inducer exclusion. In bacteria belonging to the phylum Firmicutes, HPr, phosphorylated at serine 46 (P-Ser46-HPr) is the key player but its mode of action is elusive. To address this question at the level of purified protein components, we have chosen a homolog of the E...
March 30, 2017: Molecular Microbiology
Chengjun Cao, Mei Wu, Jian Bing, Li Tao, Xuefen Ding, Xiaoyun Liu, Guanghua Huang
The conserved cAMP-dependent protein kinase (PKA) plays critical roles in the regulation of morphological transitions and virulence in the human fungal pathogen Candida albicans. It has long been thought that the PKA catalytic subunit is essential for cell viability in this fungus. Paradoxically, the single adenylyl cyclase-encoding gene, CYR1, which is required for the production of cAMP in C. albicans, is not essential for cell growth. Here, we successfully generated a double mutant of TPK1 and TPK2 (tpk2/tpk2 tpk1/tpk1, t2t1), which encode two isoforms of the PKA catalytic subunit, suggesting that it is not essential for cell viability...
March 30, 2017: Molecular Microbiology
Yu-Chih Peng, ChienYi Lu, Guoqing Li, Zehava Eichenbaum, Chung-Dar Lu
Growth of Pseudomonas aeruginosa on spermine requires a functional γ-glutamylpolyamine synthetase PauA2. Not only subjected to growth inhibition by spermine, the pauA2 mutant became more sensitive to β-lactam antibiotics in human serum. To explore PauA2 as a potential target of drug development, suppressors of the pauA2 mutant, which alleviated toxicity, were isolated from selection plates containing spermine. These suppressors share common phenotypic changes including delayed growth rate, retarded swarming motility, and pyocyanin overproduction...
March 29, 2017: Molecular Microbiology
Chaitanya R Tabib, Eveline Brodl, Peter Macheroux
The genes responsible for the light production in bioluminescent bacteria are present as an operon, luxCDABEG. Many strains of Photobacteria carry an additional gene, termed luxF. X-ray crystallographic analysis of LuxF revealed the presence of four molecules of a flavin derivative, i.e. 6-(3'-(R)-myristyl) flavin adenine mononucleotide (myrFMN) non-covalently bound to the homodimer. In the present study, we exploited the binding of myrFMN to recombinant apo-LuxF to explore the occurrence of myrFMN in various bioluminescent bacteria...
March 27, 2017: Molecular Microbiology
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