Document Type
Thesis - University Access Only
Award Date
2008
Degree Name
Master of Science (MS)
Department / School
Biology and Microbiology
Abstract
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) employ a Type Three Secretion System (T3SS) to translocate bacterial encoded proteins (effectors) into host cells to promote increased bacterial adherence and subversion of host cell processes. In each pathogen, the T3SS is located on a 35 kbp pathogenicity island termed the locus of enterocyte effacement (LEE). In addition to the T3SS, the LEE encodes transcriptional regulatory molecules, effectors and their chaperones, the adhesin molecules intimin and the translocated intimin receptor, Tir. Recent studies have shown that EPEC and EHEC contain numerous effectors not encoded by the LEE (Non-LEE ~encoded effectors or Nles). We present a preliminary characterization of NleF. We show that NleF is secreted and translocated by the T3SS. The N-terminal 40 amino acids of NleF are sufficient for translocation. Phenotypic characterization of EHEC !inleF shows that it is not distinguishable from wt EHEC in an in vitro model of infection. Despite the lack of an in vitro phenotype, the !inleF mutant was deficient in its ability to colonize the gnotobiotic piglet colon and rectoanal junction. Our study of the NleF trans location domain led us to investigate the translocation domain of EspG. Preliminary experiments are presented that suggest the translocation domain of EspG is not within the N terminus, an observation that has not been documented with effectors. These data led us to the study of translocation domains in the EspG homo logs, EspG2 and VirA. While sequence alignments suggested EspG may be a cysteine protease, we were unable to detect a- or P-tubulin degradation with an in vitro infection model or purified EspG.
Library of Congress Subject Headings
Escherichia coli infections
Intestines -- Infections -- Pathogenesis
Bacterial proteins
Format
application/pdf
Number of Pages
99
Publisher
South Dakota State University
Recommended Citation
Echtenkamp, Frank, "Bacterial Subversion of Host Cells: A Study of The Type Three Secreted Effectors NleF and EspG" (2008). Electronic Theses and Dissertations. 1436.
https://openprairie.sdstate.edu/etd2/1436
