Research Publications (Food Safety)

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.

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.

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 translocation between cells containing identical or highly similar plasmids.

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, the Psp response in V. cholerae has remained completely uncharacterized.

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) Escherichia coli.

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.

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. Accordingly, B.

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.

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.

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. Recently, two novel GT-42 genes, cstIV and cstV, have been identified in C. coli.

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 prokaryotic lag.

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 transition from rod to hook polymerization occurs.

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.

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.

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 lysine, arginine, ornithine, respectively.

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.

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, which inhibited linearization of c-di-GMP.

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 via putative STAC and PAS domains.

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 cognate bEBP for the 54-dependent promoter of the rsr-yrlBA-rtcBA operon is RtcR.

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.

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 the growth media and to induced oxidative stress.

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 serpentine movement of the cell bodies through tissues.

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.

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 appreciated to play a central role in bacterial pathogenesis.

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.