Affiliation:
1. Ralph H. Johnson V. A. Medical Center and Infectious Diseases Division, Medical University of South Carolina, Charleston, South Carolina 29425,1 and
2. Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington 981952
Abstract
ABSTRACT
We isolated the genetic determinant of AF/R1 pilus production in attaching/effacing
Escherichia coli
RDEC-1 and identified seven genes required for pilus expression and function. DNA sequence analysis of the structural subunit gene
afrA
corrected an error in the published sequence and extended homology with the F18 pilus subunit of pig edema
E. coli
strains. AfrB and AfrC, encoded downstream from AfrA, were required for pilus expression. AfrB was related to the usher protein PefC of
Salmonella typhimurium
plasmid-encoded fimbriae, and AfrC was related to PefD, a chaperone protein. AfrD and AfrE, encoded downstream from AfrC, were not necessary for the expression of AF/R1 pili but were required for ileal adherence as assayed by ileal brush border aggregation. Thus, the adhesive subunit of the AF/R1 pilus is distinct from the structural subunit, as is the case for Pap pili and type 1 pili. AfrD was related to FedE of the F18 fimbrial operon of the
E. coli
strain that causes edema disease in pigs. AfrE was a novel protein. AfrR and AfrS are encoded upstream from AfrA, in the opposite orientation. AfrR is related to the AraC family of transcriptional regulators, and AfrR and AfrS interact to function in a novel mode of transcriptional activation of
afrA
. AF/R1 pili mediate the adherence to Peyer’s patch M cells, ileal mucosa, and colonic mucosa in a rabbit model of diarrhea caused by enteropathogenic
E. coli
. Our observations will facilitate the further study of the phenomena of M-cell adherence.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
21 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献