Research Publications (Food Safety)

The Agr-like quorum sensing (QS) system of Clostridium perfringens controls production of many toxins, including beta toxin (CPB). We previously showed (Vidal et al. Mol Microbiol. 2012, 83 (1): 179-194) that an eight amino acid, AgrD-derived peptide named 8-R upregulates CPB production by this QS system. The current study synthesized a series of small signaling peptides corresponding to sequences within the C. perfringens AgrD polypeptide to investigate the C.

The gram-negative curved bacillus Vibrio cholerae causes the severe diarrheal illness cholera. During host infection, a complex regulatory cascade results in production of ToxT, a DNA-binding protein that activates the transcription of major virulence genes that encode cholera toxin (CT) and toxin-coregulated pilus (TCP).

Cyclic β-1,2-glucans (CβG) are periplasmic homopolysaccharides that play an important role in the virulence and interaction of Brucella with the host. Once synthesized in the cytoplasm by the CβG synthase (Cgs), CβG are transported to the periplasm by the CβG transporter (Cgt) and succinylated by the CβG modifier enzyme (Cgm).

Metal homeostasis in bacterial cells is a highly regulated process requiring intricately coordinated import and export, as well as precise sensing of intracellular metal concentrations. The uptake of zinc (Zn) has been linked to the virulence of Brucella abortus; however, the capacity of Brucella strains to sense Zn levels and subsequently coordinate Zn homeostasis has not been described.

Campylobacter jejuni is a leading cause of bacterial diarrheal disease and a frequent commensal of the intestinal tract of poultry and other animals. For optimal growth and colonization of hosts, C. jejuni employs two-component regulatory systems (TCSs) to monitor environmental conditions and promote proper expression of specific genes. We analyzed the potential of C.

MerR metalloregulators alleviate toxicity caused by the excess of metal ions such copper, zinc, mercury, lead, cadmium, silver or gold by triggering the expression of specific efflux or detoxification systems upon metal detection. The sensor protein binds the inducer metal ion using two conserved cysteine residues at the C-terminal metal-binding loop (MBL).

Listeriae take up glucose and mannose predominantly through a mannose-class PEP:carbohydrate phosphotransferase system (PTSMan), whose three components are encoded by the manLMN genes. Expression of these genes is controlled by ManR, a LevR-type transcription activator containing two PTS regulation domains (PRDs) and two PTS-like domains (EIIAMan- and EIIBGat-like). We demonstrate here that in L.

The Gram-negative enteric bacterium Citrobacter rodentium is a natural mouse pathogen that has been extensively used as a surrogate model for studying the human pathogens enteropathogenic and enterohemorrhagic Escherichia coli. All three pathogens produce similar attaching and effacing (A/E) lesions in the intestinal epithelium. During infection these bacteria employ surface structures called fimbriae to adhere and colonize the host intestinal epithelium. For C.

Coenzyme A (CoA) is a ubiquitous coenzyme involved in fundamental metabolic processes. CoA is synthesized from pantothenic acid by a pathway that is largely conserved among bacteria and eukaryotes, and consists of five enzymatic steps. While higher organisms, including humans, must scavenge pantothenate from the environment, most bacteria and plants are capable of de novo pantothenate biosynthesis.

The type III protein secretion system (T3SS) encoded by the locus of enterocyte effacement (LEE) is essential for the pathogenesis of attaching/effacing bacterial pathogens, including enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC), and Citrobacter rodentium.

The ability to form biofilms is critical for environmental survival and transmission of Vibrio cholerae, a facultative human pathogen responsible for the disease cholera. Biofilm formation is controlled by several transcriptional regulators and alternative sigma factors. In this study, we report that the two main positive regulators of biofilm formation, VpsR and VpsT bind to non-overlapping target sequences in the regulatory region of vpsL in vitro.

Vibrio cholerae is autochthonous to various aquatic niches and the etiological agent of the life-threatening diarrheal disease, cholera. The persistence of V. cholerae in natural habitats is a crucial factor in the epidemiology of cholera. In contrast to the well studied V. cholerae-chitin connection, scarce information is available about the factors employed by the bacteria for the interaction with collagens.

Catalase enzymes detoxify H2O2 by the dismutation of H2O2 into O2 and H2O through the use of hemin cofactors. While the structure and biochemical properties of catalase enzymes have been well characterized over many decades of research, it remained unclear how catalases acquire hemin. We have previously reported that Cj1386 is essential for ensuring proper hemin content in Campylobacter jejuni catalase (KatA).

Fosfomycin resurfaced in particular interest because it is a great beneficial antibiotic for refractory infectious diseases caused by pathogens that are resistant to other commonly used antibiotics. Cells that are resistant to fosfomycin by chromosomal mutation have a high biological cost. We previously found that a bacterial two-component system, CpxAR induces fosfomycin tolerance of enterohaemorrhagic E. coli (EHEC) O157:H7.

The bulk of bacterial protein secretion occurs through the conserved SecY translocation channel that is powered by SecA-dependent ATP-hydrolysis. Many Gram-positive bacteria including the human pathogen Listeria monocytogenes, possess an additional non-essential specialized ATPase, SecA2. SecA2-dependent secretion is required for normal cell morphology and virulence in L. monocytogenes, however the mechanism of export via this pathway is poorly understood. L.

The anaerobic pathogen Clostridium perfringens encodes either toxin genes or antibiotic resistance determinants on a unique family of conjugative plasmids that have a novel conjugation region, the tcp locus. Studies on the paradigm conjugative plasmid from C. perfringens, the 47-kb tetracycline resistance plasmid pCW3, have identified several tcp-encoded proteins that are involved in conjugative transfer and form part of the transfer apparatus.

When exposed to nutrient or non-nutrient germinants, individual Bacillus spores can return to life through germination followed by outgrowth. Laser tweezers Raman spectroscopy, and either differential interference contrast or phase contrast microscopy were used to analyze the slow dipicolinic acid (DPA) leakage (normally ~20% of spore DPA) from individual spores that takes place prior to the lag time, Tlag, when spores begin rapid release of remaining DPA.