title: Characterization of two virulence proteins secreted by rabbit enteropathogenic Escherichia coli, EspA and EspB, whose maximal expression is sensitive to host body temperature.
abstract: Enteropathogenic Escherichia coli (EPEC) and rabbit EPEC (RDEC-1) cause unique histopathological features on intestinal mucosa, including attaching/effacing (A/E) lesions. Due to the human specificity of EPEC, RDEC-1 has been used as an animal model to study EPEC pathogenesis. At least two of the previously identified EPEC-secreted proteins, EspA and EspB, are required for triggering host epithelial signal transduction pathways, intimate adherence, and A/E lesions. However, the functions of these secreted proteins and their roles in pathogenesis have not been characterized. To investigate the function of EspA and EspB in RDEC-1, the espA and espB genes were cloned and their sequences were compared to that of EPEC O127. The EspA proteins showed high similarity (88.5% identity), while EspB was heterogeneous in internal regions (69.8% identity). However, RDEC-1 EspB was identical to that of enterohemorrhagic E. coli serotype O26. Mutations in RDEC-1 espA and espB revealed that the corresponding RDEC-1 gene products are essential for triggering of host signal transduction pathways and invasion into HeLa cells. Complementation with plasmids containing EPEC espA or/and espB genes into RDEC-1 mutant strains demonstrated that they were functionally interchangeable, although the EPEC proteins mediated higher levels of invasion. Furthermore, maximal expression of RDEC-1 and EPEC-secreted proteins occurred at their respective host body temperatures, which may contribute to the lack of EPEC infectivity in rabbits.
authors.affiliation: Biotechnology Laboratory, University of British Columbia, Vancouver, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Abe
authors.forename: B
authors.initials: B
authors.lastname: Kenny
authors.forename: M
authors.initials: M
authors.lastname: Stein
authors.forename: B B
authors.initials: BB
authors.lastname: Finlay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004848:Epithelium / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D007410:Intestinal Diseases / Q000382:microbiology*; D008969:Molecular Sequence Data; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013696:Temperature
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C087863:EaeB protein, E coli; D029968:Escherichia coli Proteins; C102051:EspA protein, E coli