Research Interests
E. coli S. typhimurium E. sakazakii
Signal Recognition Particle of Escherichia coli
The signal recognition particle (SRP) is an RNA/protein complex that is highly conserved throughout all living systems, including bacteria. In E. coli, as in other cellular systems, the SRP functions in the targeting and translocation of protein across the cytoplasmic membrane. One of our approaches to understand SRP function is the isolation and characterization of new ffh mutants. The ffh (fifty four homologue) gene encodes the protein component of the E. coli SRP. A temperature-sensitive ffh mutant that is rapidly inactivated upon shift to the nonpermissive temperature has been especially valuable to identify proteins that are dependent on the SRP for localization. To better understand how the structure of the SRP contributes to its function, we are also exploring the function of 4.5S, the RNA component of the SRP. Interestingly, in addition to its role as a component of the SRP, 4.5S RNA also appears to play an essential role in protein synthesis. We are exploring the role of the RNA in cellular function by isolating and characterizing ffs mutants that are altered in highly conserved bases.
Antibiotic Tolerance of Salmonella enterica Ser Typhimurium
Subpopulations of many bacteria are able to enter into a quiescent, non-growing state that can survive a number of environmental conditions that is lethal for the majority of the cells. These so-called persistent bacteria could negatively impact food safety at a number of levels. Because of the potential importance of bacterial persistence in food safety, we are studying the mechanisms by which subpopulations of Salmonella enterica ser. Typhimurium survive lethal environmental conditions, including exposure to antibiotics.
Characterization of Enterobacter sakazakii-an emerging foodborne pathogen
Enterobacter sakazakii is an emerging foodborne pathogen that can cause several serious diseases in newborn infants resulting in high mortality. Little is known about the molecular biology of this pathogen, however, including the nature of virulence factors. To study E. sakazakii we have used transposon mutagenesis to isolate mutants that are altered in virulence properties and pigment production. Shown are some “hyperpigmented” mutants, i.e., mutants whose pigment production was elevated. Further characterization of these mutants, as well as generation of new mutants, should prove useful to understand virulence and pigment production of E. sakazakii. We have also developed a C. elegans model to further study the pathogenicity of E. sakazakii.
