Kelly Rice
Assistant Professor
Department of Microbiology and Cell Science, University of Florida
Ph.D. (2001) University of Toronto, Toronto, ON, Canada
Post-doctoral training (2001-2005) University of Idaho, Moscow, ID
Instructor (2005-2008) University of Nebraska Medical Center, Omaha, NE
Teaching Interest
Molecular Microbiology, Undergraduate Research
Description of Research
Bacterial cell death and lysis is a highly-regulated and important component of bacterial physiology. It is required for complex developmental processes such as mother cell lysis during sporulation, release of DNA during development of genetic competence, and growth of bacteria as a multicellular biofilm. Dr. Rice’s research has been focused on studying the Staphylococcus aureus cid and lrg operons that encode regulators of cell death and lysis in this important pathogen. CidA and LrgA appear to be structurally and functionally analogous to bacteriophage-encoded holins, which regulate host cell lysis during the lytic cycle of infection. The ubiquitous distribution of cid and lrg homologs among different bacteria suggests that they play an important and conserved role in bacterial physiology.
CidA-mediated cell lysis is critical for S. aureus biofilm development, and the released genomic DNA is an important structural component of the biofilm matrix. However, the specific metabolic and environmental cues that regulate cid and lrg-mediated cell death and lysis within the context of the biofilm remain ill-defined. Nitric oxide (NO) has been implicated as a regulator of cell death in other single-celled organisms, but the molecular mechanisms involved are not well understood. Addition of NO to S. aureus culture is a potent signal that regulates expression of cid and lrg, and genes involved in the nitrosative stress response and NO metabolism are associated with the lrg operon. It is hypothesized that NO is an important signal in the control of Cid/Lrg-mediated cell death and lysis during biofilm development. This hypothesis will be tested by a detailed examination of the effect of NO on cid and lrg expression, characterizing the effect of NO and NO-related genes on cell death and lysis during biofilm development, and identifying NO-dependent regulators of cid and lrg expression.
A second research project in Dr. Rice’s lab focuses on characterizing the Cid/Lrg system in Streptococcus mutans, the primary causative agent of dental caries. This bacterium can also cause potentially lethal infective endocarditis (IE) in at-risk patients. In both diseases, S. mutans virulence is intimately related to its ability to form biofilm. It is hypothesized that cell death and lysis is regulated by the Cid/Lrg system in S. mutans, and contributes to its ability to establish biofilm. There appear to be distinct differences in the organization and regulation of the S. mutans cid and lrg genes compared to what is known about these genes in S. aureus. Therefore characterization of the Cid/Lrg system in S. mutans has the potential to uncover previously unrecognized aspects of its regulation and/or function. The long-term goal of this research is to define the molecular mechanisms that control cell death and autolysis in S. mutans, and how these processes contribute to their ability to grow and survive as biofilm in the oral cavity as well as on heart valve vegetations during IE.
Selected Publications
1. Rice, K.C., and K.W. Bayles. 2008. Molecular control of bacterial death and lysis (review). MMBR. 72: 85-109.
2. Rice, K.C., Mann, E.E., Endres, J.L., Weiss, E.C., Cassat, J.E., Smeltzer, M.S., and K.W. Bayles. 2007. The cidA murein hydrolase regulator contributes to DNA release and biofilm development in Staphylococcus aureus. PNAS. 104: 8113-8118.
3. Nelson, J.L., Rice, K.C., Slater, S.L., Fox, P.M., Archer, G.L., Bayles, K.W., Fey, P.D., Kreiswith, B.N., and G.A. Somerville. 2007. Vancomycin Intermediate Staphylococcus aureus have impaired acetate catabolism: implications for polysaccharide adhesin synthesis and autolysis. Antimicrobial Agents and Chemotherapy. 51: 616-622.
4. Cassat, J., Dunman, P.M., Murphy, E.J., Projan, S.J., Beenken, K.E., Palm, K.J., Yang, S.J., Rice, K.C., Bayles, K.W., and M.S. Smeltzer. 2006. Transcriptional profiling of a Staphylococcus aureus clinical isolate and its isogenic agr and sarA mutants reveals global differences in comparison to the laboratory strain RN6390. Microbiol. 152: 3075-3090.
5. Yang, S-J., Rice, K.C., Brown, R.J., Patton, T.G., Liou, L.E., Park, Y.H., and K.W. Bayles. 2005. A LysR-type regulator, CidR, is required for the induction of the Staphylococcus aureus cidABC operon. J. Bacteriol. 187: 5893-5900.
6. Patton, T.G., Rice, K.C., Foster, M.K., and K.W. Bayles. 2005. The Staphylococcus aureus cidC gene encodes a pyruvate oxidase that affects acetate metabolism and cell death in stationary phase. Mol. Microbiol. 56: 1664-1674.
7. Rice, K.C., Nelson, J.B., Patton, T.G., Yang, S.J., and K.W. Bayles. 2005. Acetic acid induces expression of the Staphylococcus aureus cidABC and lrgAB murein hydrolase regulator operons. J. Bacteriol. 187: 813-821.
8. Rice, K.C., Patton, T.G., Yang, S-J., Dumoulin, A., Bischoff, M., and K.W. Bayles. 2004. Transcription of the Staphylococcus aureus cid and lrg murein hydrolase regulators is affected by Sigma Factor B. J. Bacteriol. 186: 3029-3037.
9. Rice, K.C., and K.W. Bayles. 2003. Death’s toolbox: examining the molecular components of bacterial programmed cell death (review). Mol. Microbiol. 50: 729-738.
10. Rice, K.C., Firek, B.A., Nelson, J.B., Yang, S.J., Patton, T.G., and K.W. Bayles. 2003. The Staphylococcus aureus cidAB operon: evaluation of its role in regulation of murein hydrolase activity and penicillin tolerance. J. Bacteriol. 185: 2635-2643.
11. Massimi, I., Park, E., Rice, K., Muller-Esterl, W., Sauder, D.N., and M.J. McGavin. 2002. Identification of a novel maturation mechanism and restricted substrate specificity for the SspB cysteine protease of Staphylococcus aureus. J. Biol. Chem. 277: 41770-41777.
12. Rice, K., Huesca, M., Vaz, D., and M.J. McGavin. 2001. Variance in fibronectin-binding and fnb gene locus polymorphisms in Staphylococcus aureus: Identification of antigenic variation in a fibronectin-binding protein adhesin of the epidemic CMRSA-1 strain of methicillin resistant S. aureus. Infect. Immun. 69: 3791-3799.
13. Rice, K., Peralta, R., Bast, D., de Azavedo, J., and M.J. McGavin. 2001. Description of the staphylococcus serine protease (ssp) operon in Staphylococcus aureus, and non-polar inactivation of the sspA serine protease. Infect. Immun. 69: 159-169.
14. McGavin, M.J., Zahradka, C., Rice, K., and J.E. Scott. 1997. Modification of the Staphylococcus aureus fibronectin-binding phenotype by V8 protease. Infect. Immun. 65: 2621-2628.
Address
Department of Microbiology and Cell Science
P.O. Box 110700
University of Florida
Gainesville, FL 32611-0700
Office Location - Room 1147
Telephone
352 -392 1192
Fax
352 392 5922