You are here

Journal of Bacteriology

Mon, 08/19/2019 - 11:10
Staphylococcus aureus has evolved a complex regulatory network that controls a multitude of defense mechanisms against the deleterious effects of oxidative stress stimuli subsequently leading to the pathogen's survival and persistence in the hosts. Previously, we characterized the msaABCR operon as a regulator of virulence, antibiotic resistance, and the formation of persister cells in S. aureus...
Mon, 08/12/2019 - 12:29
Cyclic di-GMP (c-di-GMP) is a bacterial second messenger molecule that is important in the biology of Vibrio cholerae, but the molecular mechanisms by which this molecule regulates downstream phenotypes have not been fully characterized. We have previously shown that the Vc2 c-di-GMP-binding riboswitch, encoded upstream of the gene tfoY, functions as an off-switch in response to c-di-GMP. However...
Mon, 07/29/2019 - 11:30
Vibrio parahaemolyticus RIMD2210633 secretes both chitinase and chitin oligosaccharide deacetylase and produces β-N-acetyl-d-glucosaminyl-(1,4)-d-glucosamine (GlcNAc-GlcN) from chitin. Previously, we reported that GlcNAc-GlcN induces chitinase production by several strains of Vibrio harboring chitin oligosaccharide deacetylase genes (Hirano et al. Glycobiology 19:1049-1053, 2009). The...
Mon, 07/22/2019 - 11:21
Outer membrane vesicles (OMVs) are continuously produced by Gram-negative bacteria, and are increasingly recognized as ubiquitous mediators of bacterial physiology. In particular, OMVs are powerful effectors in inter-organismal interactions, driven largely by their molecular contents. These impacts have been studied extensively in bacterial pathogenesis, but have not been well documented within...
Mon, 07/01/2019 - 11:32
In open environments such as water, enterohemorrhagic Escherichia coli O157:H7 responds to inorganic phosphate (Pi) starvation by inducing the Pho regulon controlled by PhoB. This activates the phosphate-specific transport (Pst) system that contains a high-affinity Pi transporter. In the pst mutant, PhoB is constitutively activated and regulates the expression of genes in the Pho regulon. Here we...
Mon, 07/01/2019 - 11:32
Salmonella enterica serovar Typhimurium induces inflammatory diarrhea and bacterial uptake into intestinal epithelial cells using the Salmonella pathogenicity island 1 (SPI1) type III secretion system (T3SS). HilA activates transcription of the SPI1 structural components and effector proteins. Expression of hilA is activated by HilD, HilC, and RtsA, which act in a complex feed-forward regulatory...
Mon, 06/24/2019 - 11:16
Enteroaggregative Escherichia coli (EAEC) from the O104:H4 specific serotype caused a large outbreak of bloody diarrhea with some complicated cases of hemolytic uremic syndrome (HUS) in Europe in 2011. The outbreak strain consisted in an EAEC capable to produce the Shiga toxin (Stx) subtype 2a, a characteristic from enterohemorrhagic E. coli (EHEC). QseBC 2-component system detects AI-3/Epi/NE...
Mon, 06/10/2019 - 12:53
Salmonella must rapidly adapt to various niches in the host during infection. Relevant virulence factors must be appropriately induced, and systems that are detrimental in a particular environment must be turned off. Salmonella infects intestinal epithelial cells using a type 3 secretion system (T3SS) encoded on Salmonella pathogenicity island 1 (SPI1). The system is controlled by three AraC-like...
Mon, 06/10/2019 - 12:53
Salmonella virulence requires the initial invasion of host cells followed by the modulation of the intracellular environment for survival and replication. In an effort to characterize the role of small RNAs in Salmonella pathogenesis, we inadvertently identified a 5 kD protein named YshB that is involved in the intracellular survival of Salmonella. We show here that yshB expression is upregulated...
Mon, 05/20/2019 - 11:20
The Zur-regulon is central to zinc homeostasis in the zinc-resistant bacterium Cupriavidus metallidurans. It comprises the transcription regulator Zur, the zinc importer ZupT, and three members of the COG0523 family of metal-chaperoning G3E-type GTPases, annotated as CobW1, CobW2, and CobW3. The operon structures of the zur and cobW1 loci were determined. To analyze the interplay between the Zur...
Mon, 04/29/2019 - 11:34
Vibrio cholerae, the facultative pathogen responsible for cholera disease, continues to pose a global health burden. Its persistence can be attributed to a flexible genetic toolkit that allows for adaptation to different environments with distinct carbon sources, including the six-carbon sugar alcohol mannitol. V. cholerae takes up mannitol through the transporter protein MtlA, whose production...
Mon, 04/29/2019 - 11:34
Capsular polysaccharides (CPSs) are virulence factors for many important pathogens. In Escherichia coli, CPSs are synthesized via two distinct pathways, but both require proteins from the outer membrane polysaccharide export (OPX) family to complete CPS export from the periplasm to the cell surface. In this study, we compare the properties of the OPX proteins from the prototypical group 1 (Wzy-...
Mon, 04/22/2019 - 11:14
The bacterial flagellum is a sophisticated self-assembling nanomachine responsible for motility in many bacterial pathogens including Pseudomonas aeruginosa, Vibrio spp., and Salmonella enterica. The bacteria flagellum has been studied extensively in the model systems Escherichia coli and Salmonella Typhimurium, yet the range of variation in flagellar structure and assembly remains incompletely...
Mon, 04/15/2019 - 11:36
Bacterial lipoproteins are globular proteins anchored to the extracytoplasmic surfaces of cell membranes through lipidation at a conserved N-terminal cysteine. Lipoproteins contribute to an array of important cellular functions for bacteria, as well as being a focal point for innate immune system recognition through binding to Toll-like receptor 2 (TLR2) heterodimer complexes. Although...
Mon, 04/08/2019 - 11:17
Typhoid fever, a human-specific disease, is primarily caused by the pathogen Salmonella enterica serovar Typhi (S. Typhi). It is estimated that 3-5% of people infected with typhoid fever become chronic carriers. Studies have demonstrated that a mechanism of chronic carriage involves biofilm formation on gallstone surfaces. In the course of a previous study using a chronic carriage mouse model, a...
Mon, 04/01/2019 - 11:50
Typhoid fever is caused primarily by Salmonella enterica serovar Typhi (S. Typhi). Approximately 3-5% of individuals infected with S. Typhi become chronic carriers with the gallbladder (GB) as the site of persistence, as gallstones within the GB are a platform on which the bacteria form a biofilm. S. Typhi is a human-restricted pathogen; therefore, asymptomatic carriers represent a critical...
Mon, 04/01/2019 - 11:50
The Gram-negative cell envelope is a remarkable structure with core components that include an inner membrane, an outer membrane, and a peptidoglycan layer in the periplasmic space between. Multiple molecular systems function to maintain integrity of this essential barrier between the interior of the cell and its surrounding environment. We show that a conserved DUF1849-family protein, EipB, is...
Mon, 03/25/2019 - 11:20
The Type VI secretion system (T6SS) is an injection apparatus that uses a spring-like mechanism for effector delivery. The contractile tail is composed of a needle tipped by a sharpened spike and wrapped by the sheath that polymerizes in an extended conformation on the assembly platform or baseplate. Contraction of the sheath propels the needle and effectors associated with it into target cells....
Mon, 03/18/2019 - 11:18
Elongation factor P (EF-P) facilitates the translation of certain peptide motifs, including those with multiple proline residues. EF-P must be post-translationally modified for full functionality; in Enterobacteria this is accomplished by two enzymes, EpmA and EpmB, which catalyze the β-lysylation of EF-P at a conserved lysine position. Mutations to efp or its modifying enzymes produce...
Mon, 03/11/2019 - 11:32
Korormicin is an antibiotic, produced by some Pseudoalteromonads, which selectively kills gram negative bacteria that express the Na+-pumping NADH:quinone oxidoreductase (Na+-NQR.) We show that, although korormicin is an inhibitor of Na+-NQR, the antibiotic action is not a direct result of inhibiting enzyme activity. Instead, perturbation of electron transfer inside the enzyme promotes a reaction...
Mon, 03/11/2019 - 11:32
Conjugative plasmids of the IncC group, formerly known as A/C2, disseminate antibiotic resistance genes globally in diverse pathogenic species of Gammaproteobacteria. Salmonella genomic island 1 (SGI1) can be mobilized by IncC plasmids and was recently shown to reshape the conjugative type IV secretion system (T4SS) encoded by these plasmids to evade entry exclusion. Entry exclusion blocks DNA...
Mon, 03/11/2019 - 11:32
The phage shock protein (Psp) system is a stress response pathway that senses and responds to inner membrane damage. The genetic components of the Psp system are present in several clinically relevant Gram-negative bacteria, including Vibrio cholerae. However, most of the current knowledge about the Psp response stems from in vitro studies in Escherichia coli and Yersinia enterocolitica. In fact...
Tue, 02/19/2019 - 11:27
Prophage mediated horizontal gene transfer (HGT) plays a key role in the evolution of bacteria, enabling access to new environmental niches, including pathogenicity. Citrobacter rodentium is a host-adapted intestinal mouse pathogen and important model organism for attaching and effacing (A/E) pathogens including the clinically significant enterohaemorrhagic (EHEC) and enteropathogenic (EPEC)...
Mon, 02/11/2019 - 11:14
Coxiella burnetii, the etiological agent of Q fever, undergoes a unique biphasic developmental cycle where bacteria transition from a replicating (exponential phase) large cell variant (LCV) form to a non-replicating (stationary phase) small cell variant (SCV) form. The alternative sigma factor RpoS is an essential regulator of stress responses and stationary phase physiology in several bacterial...
Mon, 02/11/2019 - 11:14
Bacteria deploy global programs of gene expression, including components of the SOS-response, to counteract the cytotoxic and genotoxic effects of environmental DNA damaging factors. Here, we report that genetic damage promoted by hexavalent chromium elicited the SOS-response in Bacillus subtilis, as evidenced by the induction of transcriptional uvrA-lacZ, recA-lacZ and PrecA-gfp fusions....
Mon, 02/11/2019 - 11:14
Bacteria sense environmental chemicals using chemosensor proteins, most of which are present in the cytoplasmic membrane. Canonical chemoreceptors bind their specific ligands in their periplasmic domain, and the ligand binding creates a molecular stimulus that is transmitted into the cytoplasm, leading to various cellular responses, such as chemotaxis and specific gene expression. Vibrio cholerae...
Mon, 02/04/2019 - 12:19
H-NS-mediated repression of acquired genes and the subsequent adaptation of regulatory mechanisms that counteract this repression have played a central role in the Salmonella pathogenicity evolution. The Salmonella pathogenicity island 2 (SPI-2) is an acquired chromosomal region containing genes necessary for Salmonella to colonize and replicate in different niches of hosts. The ssrAB operon,...
Mon, 01/28/2019 - 15:58
Campylobacter jejuni and Campylobacter coli are the most common cause of bacterial gastroenteritis in the world. Ganglioside mimicry by C. jejuni lipooligosaccharide (LOS) is the triggering factor of Guillain-Barré syndrome (GBS), an acute polyneuropathy. Sialyltransferases from the glycosyltransferase (GT) family 42 are essential for the expression of ganglioside mimics in C. jejuni....
Mon, 01/14/2019 - 12:47
Lag is a temporary period of non-replication seen in bacteria that are introduced to new media. Despite latency being described by Müller in 1895, until only recently have we gained insights into the cellular processes characterizing lag phase. This review covers literature to date on the transcriptomic, proteomic, metabolomic, physiological, biochemical, and evolutionary features of...
Mon, 12/17/2018 - 11:19
The flagellar lipoprotein FlgP has been identified in several species of bacteria and, its absence provokes different phenotypes. In this work we show that in the α proteobacterium Rhodobacter sphaeroides, a flgP mutant is unable to assemble the hook and the filament. In contrast, the MS ring and the flagellar rod appear to be assembled. In the absence of FlgP a severe defect in the...
Mon, 12/03/2018 - 11:34
The Salmonella Typhimurium RcsCDB system regulates the synthesis of colanic acid and flagellum as well as the expression of virulence genes. We previously demonstrated that the rcsC11 mutant, which constitutively activates the RcsB regulator, attenuates Salmonella virulence in an animal model. This attenuated phenotype could be also produced by deletion of the slyA gene. In this work, we...
Mon, 11/12/2018 - 11:43
Escherichia coli and many other bacterial species can enter into a viable but nonculturable (VBNC) state, which is a survival strategy adopted by cells exposed to adverse environmental conditions. Pyruvate is known to be one factor that promotes resuscitation of VBNC cells. Here we studied the role of a pyruvate-sensing network, composed of the two histidine kinase/response regulator systems BtsS...
Mon, 10/22/2018 - 12:48
The histidine ATP-binding cassette (ABC) transporter of Salmonella enterica serovar Typhimurium is among the best-studied type I ABC import systems. The transporter consists of two transmembrane subunits, HisQ and HisM, and a homodimer of the nucleotide-binding subunit, HisP. Substrates are delivered by two periplasmic solute binding proteins, HisJ and LAO, with preferences for histidine and...
Mon, 10/01/2018 - 11:39
Pyruvate kinase plays a central role in glucose catabolism in bacteria, and efficient utilization of this hexose has been linked to the virulence of Brucella strains in mice. The brucellae produce a single pyruvate kinase which is an ortholog of the Bradyrhizobium manganese (Mn)-dependent pyruvate kinase PykM. Biochemical analysis of the Brucella pyruvate kinase and phenotypic analysis of a B....
Mon, 09/24/2018 - 11:46
Cyclic-di-GMP (c-di-GMP) is a bacterial second messenger that regulates processes such as biofilm formation and virulence. During degradation, c-di-GMP is first linearized to pGpG and subsequently hydrolyzed to two GMPs by a previously unknown enzyme, which was recently identified in Pseudomonas aeruginosa as the 3' to 5' exoribonuclease Oligoribonuclease (Orn). Mutants of orn accumulated pGpG,...
Mon, 09/17/2018 - 11:20
Vibrio cholerae controls the pathogenicity of interactions with arthropod hosts via the activity of the CrbS/R two component system. This signaling pathway regulates the consumption of acetate, which in turn, alters the relative virulence of interactions with arthropods, including Drosophila melanogaster. CrbS is a histidine kinase that links a transporter-like domain to its signaling apparatus...
Mon, 09/10/2018 - 11:28
The 54 regulon in Salmonella enterica serovar Typhimurium includes a predicted RNA repair operon, encoding homologs of the metazoan Ro60 protein (Rsr), Y RNAs (YrlBA), RNA ligase (RtcB), and RNA 3'-phosphate cyclase (RtcA). Transcription from 54-dependent promoters requires that a cognate bacterial enhancer binding protein (bEBP) be activated by a specific environmental or cellular signal; the...
Tue, 09/04/2018 - 11:23
The Rid protein superfamily (YjgF/YER057c/UK114) is found in all domains of life. The archetypal protein, RidA from Salmonella enterica, is a deaminase that quenches the reactive metabolite 2-aminoacrylate (2AA). 2AA deaminase activity is conserved in RidA proteins from humans, plants, yeast, archaea and bacteria. Mutants of Salmonella enterica, Escherichia coli, and Saccharomyces cerevisiae that...
Mon, 08/27/2018 - 11:24
Copper is both a required micronutrient and a source of toxicity in most organisms, including Campylobacter jejuni. Two proteins expressed in C. jejuni (termed CopA and CueO) have been shown to be a copper transporter and multicopper oxidase, respectively. We have isolated strains with mutations in these genes and here we report that they were more susceptible to both the addition of copper in...
Mon, 08/13/2018 - 11:10
The bacterial flagellum has evolved as one of the most remarkable nanomachines in nature. It provides swimming and swarming motilities that are often essential for bacterial life cycle and for pathogenesis. Many bacteria such as Salmonella and Vibrio species use flagella as an external propeller to move to favorable environments, while spirochetes utilize internal periplasmic flagella to drive a...
Mon, 07/02/2018 - 11:27
Elucidating the function of proteins less 50 amino acids in length is no small task. Nevertheless, small proteins can play vital roles in the lifestyle of bacteria and influence the virulence of pathogens; thus, the investigation of the small proteome is warranted. Recently our group identified the Brucella abortus protein VtlR as a transcriptional activator of four genes, one of which is the...
Mon, 07/02/2018 - 11:27
To adapt to ever-changing environments, pathogens quickly alter gene expression. This can occur through transcriptional, post-transcriptional, or post-translational regulation. Historically, transcriptional regulation has been thoroughly studied to understand pathogen niche adaptation, whereas post-transcriptional and post-translational gene regulation have only been relatively recently...
Mon, 06/18/2018 - 11:37
YbeY is a highly conserved, multifunctional endoribonuclease that plays a significant role in ribosome biogenesis and has several additional roles. Here, we show in Escherichia coli that overexpressing the conserved GTPase, Era, partially suppresses the growth defect of a ybeY strain while improving 16S rRNA processing and 70S ribosome assembly. This suppression requires both Era's ability to...
Mon, 06/04/2018 - 12:26
Yersinia enterocolitica is a pathogen that causes gastroenteritis in humans. Because of its low temperature-dependent insecticidal activity, it can oscillate between invertebrates and mammals as host organisms. The insecticidal activity of strain W22703 is associated with a pathogenicity island of 19 kb (Tc-PAIYe), which carries regulators and genes encoding the toxin complex (Tc). The island...
Mon, 05/14/2018 - 11:29
Germination of Clostridium difficile spores is a crucial early requirement for colonization of the gastrointestinal tract. Likewise, C. difficile cannot cause disease pathologies unless their spores germinate into metabolically active, toxin-producing cells. Recent advances in our understanding of C. difficile spore germination mechanisms indicate that this process is both complex and unique....
Mon, 05/14/2018 - 11:29
Mycobacterium tuberculosis is a global pathogen of significant medical importance. A key aspect of its lifecycle is the ability to enter into an altered physiological state of non-replicating persistence during latency and resist elimination by the host immune system. One mechanism by which M. tuberculosis facilitates its survival during latency is by producing and metabolizing intracytoplasmic...
Mon, 05/07/2018 - 11:46
The biofilm growth mode is important in both the intestinal and environmental phases of Vibrio cholerae's life cycle. Regulation of biofilm formation involves several transcriptional regulators and alternative sigma factors. One such factor is the alternative sigma factor, RpoN, which positively regulates biofilm formation. RpoN requires bacterial enhancer-binding proteins (bEBPs) to initiate...
Mon, 05/07/2018 - 11:46
The electrogenic, sodium ion translocating NADH:quinone oxidoreductase (NQR) from Vibrio cholerae is frequent in pathogenic bacteria and a potential target for antibiotics. NQR couples the oxidation of NADH to the formation of a sodium motive force (SMF) and therefore drives important processes such as flagellar rotation, substrate uptake, and energy-dissipating cation-proton antiport. We...
Mon, 04/30/2018 - 11:07
In Staphylococcus aureus, the global transcriptional regulator CodY modulates the expression of hundreds of genes in response to the availability of GTP and the branched-chain amino acids isoleucine, leucine, and valine (ILV). CodY DNA-binding activity is high when GTP and ILV are abundant. When GTP and ILV are limited, CodY's affinity for DNA drops, altering expression of CodY regulated targets...
Mon, 04/16/2018 - 11:28
Listeria monocytogenes is a food pathogen capable of growing at a broad temperature range from 50°C to refrigerator temperatures. A key requirement for bacterial activity and growth at low temperatures is the ability to adjust membrane lipid composition to maintain cytoplasma membrane fluidity. In this study we confirmed earlier findings that the extent of fatty acid profile adaptation...

Pages