Journal of Bacteriology

The Research Publications track research that is published across national and international peer-reviewed journals. The most recent articles are available ahead of print and searchable by Journal Title, Subject, USDA Grant Funding Agencies or FDA Grant Funding Agencies. The research publications are tracked across five subject areas: Bacterial Pathogens, Chemical Contaminants, Natural Toxins, Parasites, and Viruses.

Tue, 02/11/2020 - 03:25
Salmonella enterica serovar Typhimurium colonizes and invades host intestinal epithelial cells using the Type Three Secretion System (T3SS) encoded on Salmonella Pathogenicity Island 1 (SPI1). The level of SPI1 T3SS gene expression is controlled by the transcriptional activator HilA, encoded on SPI1. Expression of hilA is positively regulated by three homologous transcriptional regulators, HilD,...
Tue, 01/28/2020 - 03:26
The physiological relevance of bacterial iron efflux has only recently been appreciated. The Bacillus subtilis P1B4-type ATPase PfeT (peroxide-induced ferrous efflux transporter) was one of the first iron efflux pumps to be characterized, and cells lacking pfeT accumulate high levels of intracellular iron. The pfeT promoter region has binding sites for both PerR, a peroxide sensing Fur-family...
Tue, 01/28/2020 - 03:26
Exoelectrogens are able to transfer electrons extracellularly, enabling them to respire on insoluble terminal electron acceptors. Extensively studied exoelectrogens like Geobacter sulfurreducens and Shewanella oneindensis are Gram-negative, but more recently it has been reported that Gram-positive bacteria like Listeria monocytogenes and Enterococcus faecalis also exhibit the ability to transfer...
Wed, 01/22/2020 - 03:24
Listeria monocytogenes is a Gram-positive Firmicute that causes food-borne infections, in part due to its ability to use multiple strategies, including biofilm formation, to survive adverse growth conditions. As a potential way to screen for genes required for biofilm formation we harnessed the ability of bacteria to accumulate mutations in the genome over time, diverging the properties of...
Wed, 01/22/2020 - 03:24
Transition metals are essential for life, but are toxic when in excess. Metal ion intoxication may result from the mismetallation of essential metal-dependent enzymes with a non-cognate metal. To begin to identify enzymes and processes that are susceptible to mismetallation, we have selected for strains with increased resistance to Mn(II) and Co(II). In Bacillus subtilis, cells lacking the MntR...
Tue, 01/14/2020 - 03:23
Campylobacter jejuni causes acute gastroenteritis world-wide and is transmitted primarily through poultry, in which it is often a commensal member of the intestinal microbiota. Previous RNASeq experiments showed that transcripts from an operon encoding a high affinity phosphate transporter (PstSCAB) of C. jejuni were among the most abundant when grown in chickens. Elevated levels of the pstSCAB...
Tue, 01/14/2020 - 03:23
Enterococcus faecalis cells are known to have ferric reductase activity and the ability to transfer electrons generated in metabolism to the external environment. We have isolated mutants defective in ferric reductase activity and studied their electron transfer properties to electrodes mediated by ferric ions and an osmium complex modified redox polymer (OsRP), respectively. Electron transfer...
Tue, 01/14/2020 - 03:23
The marine bacterium and human pathogen Vibrio parahaemolyticus rapidly colonizes surfaces by using swarming motility and forming robust biofilms. Entering either colonization program, swarming motility or sessility, involves differential regulation of many genes resulting in a dramatic shift in physiology and behavior. V. parahaemolyticus has evolved complex regulation to control these two...
Tue, 12/24/2019 - 03:23
Quorum Sensing (QS) are mechanisms of synthesis and detection of signaling molecules to regulate gene expression and coordinate behaviors in bacterial populations. In Bacillus subtilis (Bs), multiple paralog Rap-Phr QS systems (receptor-signaling peptide) are highly redundant and multifunctional, interconnecting the regulation of differentiation processes such as sporulation and competence....
Tue, 12/24/2019 - 03:23
The intrinsic resistance of Pseudomonas aeruginosa to many antibiotics limits treatment options for pseudomonal infections. P. aeruginosa's outer membrane is highly impermeable and decreases antibiotic entry into the cell. We used an unbiased, high-throughput approach to examine mechanisms underlying outer membrane-mediated antibiotic exclusion. Insertion Sequencing (INSeq) identified genes that...
Tue, 12/03/2019 - 03:45
Bacterial lipopolysaccharides are major components and contributors to the integrity of Gram-negative outer membranes. The more conserved lipid A-core part of this complex glycolipid is synthesized separately from the hypervariable O-antigenic polysaccharide (OPS) part and they are joined in the periplasm prior to translocation to the outer membrane. Three different biosynthesis strategies are...
Wed, 11/13/2019 - 03:24
The Na+ - ion translocating NADH:quinone oxidoreductase (NQR) from Vibrio cholerae is a membrane bound respiratory enzyme which harbors flavins and Fe-S clusters as redox centers. The NQR is the main producer of sodium motive force (SMF) and drives energy-dissipating processes such as flagellar rotation, substrate uptake, ATP synthesis and cation-proton antiport. The NQR requires for its...
Tue, 10/29/2019 - 03:26
Cytochrome bd quinol oxidases, which have greater affinity for oxygen than heme-copper cytochrome oxidases (HCOs), promote bacterial respiration and fitness in low-oxygen environments such as host tissues. Here, we show that in addition to the CydA and CydB subunits, the small protein CydX is required for the assembly and function of the cytochrome bd complex in the enteric pathogen Salmonella...
Tue, 10/22/2019 - 03:28
Background: Mycobacterium tuberculosis nicotinamidase/pyrazinamidase (PZAse) is a metalloenzyme that catalyzes conversion of nicotinamide/pyrazinamide to nicotinic acid/pyrazinoic acid. This study investigated whether a metallochaperone is required for optimal PZAse activity.Methods: M. tuberculosis and E.coli PZAses (PZAse-MT and PZAse-EC respectively) were inactivated by metal depletion (giving...
Tue, 10/15/2019 - 03:33
Escherichia coli O157:H7 is a foodborne pathogen, implicated in various multi-state outbreaks. It encodes Shiga toxin on a prophage, and Shiga toxin production is linked to phage induction. An E. coli strain, designated 0.1229, was identified that amplified Stx2a production when co-cultured with E. coli O157:H7 strain PA2. Growth of PA2 in 0.1229 cell-free supernatants had a similar effect, even...
Tue, 10/08/2019 - 03:28
The gene designated BAB_RS23470 in the Brucella abortus 2308 genome encodes an ortholog of the cation diffusion facilitator family protein EmfA which has been linked to resistance to Mn toxicity in Rhizobium etli. A B. abortus emfA null mutant derived from strain 2308 displays increased sensitivity to elevated levels of Mn in the growth medium compared to the parent strain, but wild-type...
Tue, 09/24/2019 - 03:27
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...
Tue, 09/24/2019 - 03:27
Brucella are intracellular pathogens that cause a disease known as brucellosis. Though the genus is highly monomorphic at the genetic level, species have animal host preferences and some defining physiologic characteristics. Of note is the requirement for CO2 supplementation to cultivate particular species, which confounded early efforts to isolate B. abortus from diseased cattle. Differences in...
Tue, 09/24/2019 - 03:27
Colicin U is a protein produced by the bacterium Shigella boydii (serovars 1 and 8). It exerts antibacterial activity against strains of the enterobacterial genera Shigella and Escherichia. Here we report that colicin U forms voltage-dependent pores in planar lipid membranes; its single-pore conductance was found to be about 22 pS in 1M KCl, at pH 6 under 80 mV in asolectin bilayers. In agreement...
Sun, 09/22/2019 - 03:22
Germination of Bacillus spores is triggered by the binding of specific nutrients to germinant receptors (GRs) located in the spore's inner membrane. The GRs typically consist of A, B and C subunits, encoded by tricistronic ger operons. The Bacillus licheniformis genome contains the gerA family operons gerA, ynd and gerK. In contrast to the ABC (D) organization that characterizes gerA operons of...
Sun, 09/22/2019 - 03:22
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...
Sun, 09/22/2019 - 03:22
Production of flagella is costly and subject to global, multi-layered regulation. This is reflected in the hierarchical control of flagellar production in many bacterial species. For Salmonella enterica serovar Typhimurium and its relatives, global regulation of flagellar production primarily occurs through control of flhDC transcription and mRNA translation. In this study, the role of the...
Sun, 09/22/2019 - 03:22
Coxiella burnetii is an obligate intracellular gammaproteobacterium and zoonotic agent of Q fever. We previously identified 15 small non-coding RNAs (sRNAs) of C. burnetii. One of them, CbsR12 (Coxiella b urnetii small RNA 12), is highly transcribed during axenic growth and becomes more prominent during infection of cultured mammalian cells. Secondary structure predictions of CbsR12 revealed four...
Sun, 09/22/2019 - 03:22
Macrophage parasitism by Coxiella burnetii, the cause of human Q fever, requires translocation of proteins with effector functions directly into the host cell cytosol via a Dot/Icm type 4B secretion system (T4BSS). Secretion by the analogous Legionella pneumophila T4BSS involves signal sequences within C-terminal and internal domains of effector proteins. The cytoplasmic chaperone pair IcmSW...
Mon, 09/09/2019 - 11:22
Production of flagella is costly and subject to global, multi-layered regulation. This is reflected in the hierarchical control of flagellar production in many bacterial species. For Salmonella enterica serovar Typhimurium and its relatives, global regulation of flagellar production primarily occurs through control of flhDC transcription and mRNA translation. In this study, the role of the...
Mon, 09/09/2019 - 11:22
Macrophage parasitism by Coxiella burnetii, the cause of human Q fever, requires translocation of proteins with effector functions directly into the host cell cytosol via a Dot/Icm type 4B secretion system (T4BSS). Secretion by the analogous Legionella pneumophila T4BSS involves signal sequences within C-terminal and internal domains of effector proteins. The cytoplasmic chaperone pair IcmSW...
Tue, 09/03/2019 - 11:50
Brucella are intracellular pathogens that cause a disease known as brucellosis. Though the genus is highly monomorphic at the genetic level, species have animal host preferences and some defining physiologic characteristics. Of note is the requirement for CO2 supplementation to cultivate particular species, which confounded early efforts to isolate B. abortus from diseased cattle. Differences in...
Mon, 08/26/2019 - 12:33
Coxiella burnetii is an obligate intracellular gammaproteobacterium and zoonotic agent of Q fever. We previously identified 15 small non-coding RNAs (sRNAs) of C. burnetii. One of them, CbsR12 (Coxiella b urnetii small RNA 12), is highly transcribed during axenic growth and becomes more prominent during infection of cultured mammalian cells. Secondary structure predictions of CbsR12 revealed four...
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...

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