Research Interests

Our research focuses on the cellular, molecular, and ultrastructural aspects of the interaction of pathogenic bacteria with host cells. Specifically, we study structure-function mechanisms of novel adherence factors that mediate the adherence of pathogenic E. coli strains including, enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroaggregative (EAEC), enterohemorrhagic (EHEC), and uropathogenic (UPEC) E. coli to host epithelial cells. We have recently identified 3 new pili types in EHEC O157:H7 and defining their role in human and bovine colonization is the central objective of our research. The new pili include the E. coli common pilus (ECP), a type IV pilus called hemorrhagic coli pilus (HCP) and the E. coli laminin-binding fimbriae (ELF). We are interested in understanding how these new pili are synchronized during human or bovine colonization, how they are regulated and if their expression if coupled to expression of other virulence factors.

Of interest as well, is to study the molecular mechanisms of pili biogenesis. Recent outbreaks of intestinal disease in the USA associated to consumption of tainted spinach stimulated us to study the interaction of leafy greens with E. coli O157:H7. We have found that this human pathogen establishes a niche on the produce leaves where they can survive in the environment and gain access to the human host.

We also expand our study to other human and animal pathogenic bacteria such as Shigella, Vibrio cholera, Klebsiella pneumoniae, Brucella, and Mycobacterium tuberculosis.

We have studied the adherence properties of Brucella spp., a human and animal pathogenic microorganism classified as a potential bioterrorism agent and we are interested in pursuing the study of the role of surface proteins as adhesins in this organism. Recently, we discovered that M. tuberculosis is capable of assembling pili structures and their role in the pathogenesis scheme of this organism remains elusive. Future studies will aim at determine the biological and immunological relevance of pili in the mycobacteria.

An exciting and innovative aspect of our research is the relationship between the assembly machineries of type 3 secretion systems, flagella, and type IV pili. We hope to provide useful information regarding their coordinate regulation and function within the context of the interaction of the pathogen with host cells.

Our long-term goal is the understanding of how bacterial pathogens interact with host epithelial cells aiming at proposing new strategies for prevention of infectious diseases.

 

Recent Peer-Reviewed Publications

1.       Castañeda-Roldán, E., Ouahrani-Bettache, S., Avelino, F., Rendón, M., Dornand, J., and Girón, J. A. 2006. Characterization of SP41, a surface protein of Brucella associated with adherence and invasion of host epithelial cells. Cell. Microbiol. 8(12) 1877-87.

2.       Xicohtencatl-Cortes, J., Lyons, S., Chaparro, A.P., Hernández, D.R., Saldaña, Z., Ledesma, M.A., Rendón, M. A., Gewirtz, A.T., Klose, K.E., and Girón, J.A. 2006. Identification of proinflammatory flagellin proteins in supernatants of Vibrio cholerae O1 by proteomics analysis. Mol. Cell Proteomics 5(12) 2374-83.

3.       Alteri, C., Hess, S., Caballero, G., Girón, JA, and Friedman, RL. 2007. Mycobacterium tuberculosis produces pili during human infection. Proc. Natl. Acad. Sci. USA 104 (12) 5145-50.

4.       Rendón, MA, Saldaña, Z, Monteiro-Neto, V, Erdem, AL, Vázquez, A, Kaper, JB, Puente, JL, and Girón, JA. 2007. Commensal and pathogenic Escherichia coli use a common adherence factor for epithelial cell colonization. Proc. Natl. Acad. Sci. USA. 104:10637-10642. This paper was highlighted in Nature and Nature Microbiological Reviews.

5.       Erdem, A.L.P., Avelino, F., Juan Xicohtencatl, and Girón, J.A. 2007. Host protein binding and adhesive properties of H6 and H7 flagella of attaching and effacing Escherichia coli. J. Bacteriol. 189: 7426-7435.

6.       Xicohtencatl-Cortes, Z, Monteiro-Neto, V, Francetic, O, Rendón, MA, Ledesma, MA, Kaper, JA, Puente, JL, and Girón, JA. 2007. Intestinal adherence associated with type IV pili of enterohemorrhagic Escherichia coli O157:H7. J. Clin Invest. 117(11): 3519–3529.

7.       Gomez-Duarte, O.G., Chattopadhyay, S., Weissman, S.J., Giron, J.A., Kaper, J.B., and Sokurenko, E.V. 2007. Genetic and evolutionary analysis of the operon encoding Longus, a type IV pilus of enterotoxigenic Escherichia coli. J. Bacteriol. 189:9145-9149.

8.       Xicohtencatl-Cortes, Z, Monteiro-Neto, V, Saldana, Z., Ledesma, MA, Puente, JL, and Girón, JA. 2009. The type 4 pili of enterohemorrhagic Escherichia coli O157:H7 are multipurpose structures with pathogenic attributes. J. Bacteriol. 191:411-421.

9.       Schuller S., Lucas M., Kaper, JB, Giron JA, and Phillips AD. 2008. The ex vivo response of human intestinal mucosa to enteropathogenic Escherichia coli infection. Cell. Microbiol. Dec 30 Epub.

10.    Saldaña, S., Xicohtencatl-Cortes, J., Avelino, F., Phillips, AD., Kaper, JB, Puente, JL, and Girón, JA. 2009. Synergistic role of curli and cellulose in cell adherence and biofilm formation of attaching and effacing Escherichia coli and identification of Fis as a negative regulator of curli. Environ. Microbiol. E pub.

 

 

Jorge A. Girón

Associate Professor

Jorge A. Girón

Associate Professor Department of Molecular Genetics and Microbiology;
And Emerging Pathogens Institute

Post Doctoral Fellowships, Bacterial Pathogenesis-Stanford University, University of Maryland

Ph. D. Microbiology-National Polytechnique Institute, Mexico City

B.S. Clinical Chemistry and Pharmacy-National Authonomous University of Mexico, Mexico City.

Awards, Professional Service:

Editorial Board- Infection and Immunity

Research Awards from the NIAID-NIH, Arizona Disease Control Research Commission, and Fresh Express produce

Award from the Svensk Institutet, Stockholm, Sweden