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Molecular Microbiology

Matteo P Ferla, Jodi L Brewster, Kelsi R Hall, Gary B Evans, Wayne M Patrick
The first cells probably possessed rudimentary metabolic networks, built using a handful of multifunctional enzymes. The promiscuous activities of modern enzymes are often assumed to be relics of this primordial era; however, by definition these activities are no longer physiological. There are many fewer examples of enzymes using a single active site to catalyze multiple physiologically-relevant reactions. Previously, we characterized the promiscuous alanine racemase (ALR) activity of Escherichia coli cystathionine β-lyase (CBL)...
June 22, 2017: Molecular Microbiology
Jeroen Corver, Valentina Cordo', Hans C van Leeuwen, Oleg I Klychnikov, Paul J Hensbergen
In the past decade, Clostridium difficile has emerged as an important gut pathogen. This anaerobic, Gram-positive bacterium is the main cause of infectious nosocomial diarrhea. Whereas much is known about the mechanism through which the C. difficile toxins cause diarrhea, relatively little is known about the dynamics of adhesion and motility, which is mediated by cell surface proteins. This review will discuss the recent advances in our understanding of the sortase-mediated covalent attachment of cell surface (adhesion) proteins to the peptidoglycan layer of C...
June 21, 2017: Molecular Microbiology
Yong Yang, Joseph Thomas, Yunlong Li, Catherine Vilchèze, Keith M Derbyshire, William R Jacobs, Anil K Ojha
Most mycobacterial species spontaneously form biofilms, inducing unique growth physiologies and reducing drug sensitivity. Biofilm growth progresses through three genetically programmed stages: substratum attachment, intercellular aggregation and architecture maturation. Growth of Mycobacterium smegmatis biofilms requires multiple factors including a chaperonin (GroEL1) and a nucleoid-associated protein (Lsr2), although how their activities are linked remains unclear. Here we show that Lsr2 participates in intercellular aggregation, but substratum attachment of Lsr2 mutants is unaffected, thereby genetically distinguishing these developmental stages...
June 19, 2017: Molecular Microbiology
Lingling Li, Ankan Banerjee, Lisa Franziska Bischof, Hassan Ramadan Maklad, Lena Hoffmann, Anna-Lena Henche, Fabian Veliz, Wolfgang Bildl, Uwe Schulte, Alvaro Orell, Lars-Oliver Essen, Eveline Peeters, Sonja-Verena Albers
In response to a variety of environmental cues, prokaryotes can switch between a motile and a sessile, biofilm-forming mode of growth. The regulatory mechanisms and signaling pathways underlying this switch are largely unknown in archaea but involve small winged helix-turn-helix DNA-binding proteins of the archaea-specific Lrs14 family. Here, we study the Lrs14 member AbfR1 of Sulfolobus acidocaldarius. Small-angle X-ray scattering data are presented, which are consistent with a model of dimeric AbfR1 in which dimerization occurs via an antiparallel coiled coil as suggested by homology modeling...
June 19, 2017: Molecular Microbiology
Des R Kashyap, Marcin Kuzma, Dominik A Kowalczyk, Dipika Gupta, Roman Dziarski
Mammalian Peptidoglycan Recognition Proteins (PGRPs) kill both Gram-positive and Gram-negative bacteria through simultaneous induction of oxidative, thiol, and metal stress responses in bacteria. However, metabolic pathways through which PGRPs induce these bactericidal stress responses are unknown. We screened Keio collection of Escherichia coli deletion mutants and revealed that deleting genes for respiratory chain flavoproteins or for tricarboxylic acid (TCA) cycle resulted in increased resistance of E. coli to PGRP killing...
June 16, 2017: Molecular Microbiology
Amy Diallo, Hannah R Foster, Katarzyna A Gromek, Thomas N Perry, Annick Dujeancourt, Petya V Krasteva, Francesca Gubellini, Tanya G Falbel, Briana M Burton, Rémi Fronzes
Pneumococcal natural transformation contributes to genomic plasticity, antibiotic resistance development, and vaccine escape. Streptococcus pneumoniae, like many other naturally transformable species, has evolved sophisticated protein machinery for the binding and uptake of DNA. Two proteins encoded by the comF operon, ComFA and ComFC, are involved in transformation but their exact molecular roles remain unknown. In this study, we provide experimental evidence that ComFA binds to single stranded DNA (ssDNA) and has ssDNA-dependent ATPase activity...
June 15, 2017: Molecular Microbiology
Nina K Broeker, Stefanie Barbirz
Tailed bacteriophages specific for Gram-negative bacteria encounter lipopolysaccharide (LPS) during the first infection steps. Yet, it is not well understood how biochemistry of these initial interactions relates to subsequent events orchestrating phage adsorption and tail rearrangements to initiate cell entry. For many phages, long O-antigen chains found on the LPS of smooth bacterial strains serve as essential receptor recognized by their tailspike proteins (TSP). Many TSP are depolymerases and O-antigen cleavage was described as necessary step for subsequent orientation towards a secondary receptor...
June 15, 2017: Molecular Microbiology
Selamawit Woldemeskel, Ryan McQuillen, Alex M Hessel, Jie Xiao, Erin D Goley
The cytoskeletal GTPase FtsZ assembles at midcell, recruits the division machinery, and directs envelope invagination for bacterial cytokinesis. ZapA, a conserved FtsZ-binding protein, promotes Z-ring stability and efficient division through a mechanism that is not fully understood. Here we investigated the function of ZapA in Caulobacter crescentus. We found that ZapA is encoded in an operon with a small coiled-coil protein we named ZauP. ZapA and ZauP co-localized at the division site and were each required for efficient division...
June 14, 2017: Molecular Microbiology
Sadiya Parveen, Manjula Reddy
Peptidoglycan (PG) is an essential, envelope-fortifying macromolecule of eubacterial cell walls. It is a large polymer with multiple glycan strands interconnected by short peptide chains forming a sac-like structure around cytoplasmic membrane. In most bacteria, the composition of the peptide chain is well-conserved and distinctive; in E. coli, the peptide chain length varies from two to five amino acids with a tetrapeptide consisting of L-alanine-D-glutamic acid-meso-diaminopimelic acid-D-alanine. However, it is not known how bacteria conserve the composition and sequence of peptide chains of PG...
June 14, 2017: Molecular Microbiology
David P Giedroc
Although hydrogen sulfide (H2 S) is perhaps best known as a toxic gas, the electron-rich H2 S functions as an energy source and electron donor for chemolithotrophic and photosynthetic bacteria, via sulfide oxidation, and is a universal substrate for cysteine biosynthesis. These distinct harmful and beneficial roles of H2 S suggest the need to "sense" prevailing concentrations of sulfide and downstream reactive sulfur species (RSS) and regulate the expression of genes mediating sulfide homeostasis. The paper by Li et al...
June 14, 2017: Molecular Microbiology
Huanjie Li, Juan Li, Chuanjuan Lü, Yongzhen Xia, Yufeng Xin, Honglei Liu, Luying Xun, Huaiwei Liu
Some heterotrophic bacteria are able to oxidize sulfide (H2 S, HS(-) , and S(2-) ) to sulfite and thiosulfate via polysulfide. The genes coding for the oxidation enzymes in Cupriavidus pinatubonensis JMP134 have recently been identified; however, their regulation is unknown. A regulator gene is adjacent to the operon of the sulfide-oxidizing genes, encoding a σ(54) -dependent transcription factor (FisR) with three domains: an R domain, an AAA+ domain, and a DNA-binding domain. We report here that the regulator responds to the presence of sulfide and activates the sulfide-oxidizing genes...
June 14, 2017: Molecular Microbiology
Fernando H Ramírez-Guadiana, Alexander J Meeske, Xindan Wang, Christopher D A Rodrigues, David Z Rudner
During sporulation in Bacillus subtilis, germinant receptors assemble in the inner membrane of the developing spore. In response to specific nutrients these receptors trigger germination and outgrowth. In a transposon-sequencing screen, we serendipitously discovered that loss of function mutations in the gerA receptor partially suppress the phenotypes of >25 sporulation mutants. Most of these mutants have modest defects in the assembly of the spore protective layers that are exacerbated in the presence of a functional GerA receptor...
June 12, 2017: Molecular Microbiology
Peng Wang, Hai-Yan Cao, Xiu-Lan Chen, Chun-Yang Li, Ping-Yi Li, Xi-Ying Zhang, Qi-Long Qin, Jonathan D Todd, Yu-Zhong Zhang
Dimethylsulfoniopropionate (DMSP) cleavage, yielding dimethyl sulfide (DMS) and acrylate, provides vital carbon sources to marine bacteria, is a key component of the global sulfur cycle and effects atmospheric chemistry and potentially climate. Acrylate and its metabolite acryloyl-CoA are toxic if allowed to accumulate within cells. Thus, organisms cleaving DMSP require effective systems for both the utilization and detoxification of acrylate. Here, we examine the mechanism of acrylate utilization and detoxification in Roseobacters...
June 9, 2017: Molecular Microbiology
Anna F Wang Erickson, Padraig Deighan, Shanshan Chen, Kelsey Barrasso, Cinthia P Garcia, Santiago Martínez-Lumbreras, Caterina Alfano, Ewelina M Krysztofinska, Arjun Thapaliya, Amy H Camp, Rivka L Isaacson, Ann Hochschild, Richard Losick
Sporulation in Bacillus subtilis is governed by a cascade of alternative RNA polymerase sigma factors. We previously identified a small protein Fin that is produced under the control of the sporulation sigma factor σ(F) to create a negative feedback loop that inhibits σ(F) -directed gene transcription. Cells deleted for fin are defective for spore formation and exhibit increased levels of σ(F) -directed gene transcription. Based on pull-down experiments, chemical crosslinking, bacterial two-hybrid experiments, and nuclear magnetic resonance chemical shift analysis, we now report that Fin binds to RNA polymerase and specifically to the coiled-coil region of the β' subunit...
June 8, 2017: Molecular Microbiology
Anne-Xander van der Stel, Fred C Boogerd, Steven Huynh, Craig T Parker, Linda van Dijk, Jos P M van Putten, Marc M S M Wösten
The generation of a membrane potential (Δψ), the major constituent of the proton motive force (pmf), is crucial for ATP synthesis, transport of nutrients and flagellar rotation. Campylobacter jejuni harbors a branched electron transport chain, enabling respiration with different electron donors and acceptors. Here, we demonstrate that a relatively high Δψ is only generated in the presence of either formate as electron donor or oxygen as electron acceptor, in combination with an acceptor/donor, respectively...
June 6, 2017: Molecular Microbiology
Stavroula L Kastora, Carmen Herrero-de-Dios, Gabriela M Alvelar, Carol A Munro, Alistair J P Brown
The pathogenicity of the clinically important yeast, Candida albicans, is dependent on robust responses to host-imposed stresses. These stress responses have generally been dissected in vitro at 30°C on artificial growth media that do not mimic host niches. Yet host inputs, such as changes in carbon source or temperature, are known to affect C. albicans stress adaptation. Therefore, we performed screens to identify novel regulators that promote stress resistance during growth on a physiologically relevant carboxylic acid and at elevated temperatures...
June 2, 2017: Molecular Microbiology
John P Bannantine, Gilles Etienne, Françoise Laval, Judith R Stabel, Anne Lemassu, Mamadou Daffé, Darrell O Bayles, Christelle Ganneau, Frédéric Bonhomme, Maxime Branger, Thierry Cochard, Sylvie Bay, Franck Biet
Mycobacteria have a complex cell wall structure that includes many lipids; however, even within a single subspecies of Mycobacterium avium these lipids can differ. Total lipids from an M. avium subsp. paratuberculosis (Map) ovine strain (S-type) contained no identifiable glycopeptidolipids or lipopentapeptide (L5P), yet both lipids are present in other M. avium subspecies. We determined the genetic and phenotypic basis for this difference using sequence analysis as well as biochemical and physico-chemical approaches...
May 30, 2017: Molecular Microbiology
Miki Kinoshita, Shin-Ichi Aizawa, Yumi Inoue, Keiichi Namba, Tohru Minamino
The bacterial flagellar export switching machinery consists of a ruler protein, FliK, and an export switch protein, FlhB and switches substrate specificity of the flagellar type III export apparatus upon completion of hook assembly. An interaction between the C-terminal domain of FliK (FliKC ) and the C-terminal cytoplasmic domain of FlhB (FlhBC ) is postulated to be responsible for this switch. FliKC has a compactly folded domain termed FliKT3S4 (residues 268-352) and an intrinsically disordered region composed of the last 53 residues, FliKCT (residues 353-405)...
May 29, 2017: Molecular Microbiology
Junfeng Liu, Renxia Gao, Chengtao Li, Jinfeng Ni, Zhaojie Yang, Qi Zhang, Haining Chen, Yulong Shen
The archaea Sulfolobus utilizes the ESCRT-III-based machinery for cell division. This machinery comprises three proteins: CdvA, Eukaryotic-like ESCRT-III and Vps4. In addition to ESCRT-III, Sulfolobus cells also encode three other ESCRT-III homologs termed ESCRT-III-1, -2 and -3. Herein, we show that ESCRT-III-1 and -2 in S. islandicus REY15A are localized at midcell between segregating chromosomes, indicating that both are involved in cell division. Genetic analysis reveals that escrt-III-2 is indispensable for cell viability and cells with reduced overall level of ESCRT-III-1 exhibit growth retardation and cytokinesis defect with chain-like cell morphology...
May 29, 2017: Molecular Microbiology
Rolando A Cuevas, Rory Eutsey, Anagha Kadam, Jacob A West-Roberts, Carol A Woolford, Aaron P Mitchell, Kevin M Mason, N Luisa Hiller
Streptococcus pneumoniae (pneumococcus) is a major human pathogen. It is a common colonizer of the human respiratory track, where it utilizes cell-cell communication systems to coordinate population-level behaviors. We reasoned that secreted peptides that are highly expressed during infection are pivotal for virulence. Thus, we used in silico pattern searches to define a pneumococcal secretome, and analyzed the transcriptome of the clinically important PMEN1 lineage to identify which peptide-encoding genes are highly expressed in vivo...
May 29, 2017: Molecular Microbiology
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