The 987P fimbrial gene cluster of enterotoxigenic Escherichia coli is plasmid encoded.
A clone containing the 987P fimbrial gene cluster was selected from a cosmid library of total DNA of the prototype Escherichia coli strain 987 by using 987P-specific antiserum. A subclone of 12 kilobases containing all of the genes required for fimbrial expression on a nonfimbriated K-12 strain of E. coli and a DNA fragment internal to the fimbrial subunit gene were used to probe the prototype strain and various isolates of 987P-fimbriated enterotoxigenic E. coli. All strains had several plasmids, as shown by agarose gel electrophoresis, and each of five strains which expressed 987P fimbriae showed a plasmid of 35 to 40 megadaltons (MDa) hybridizing to both 987P-specific probes. Hybridization to restricted DNA of strain 987 supported a plasmid origin for the cloned 987P gene cluster. Moreover, an isogenic strain which had lost its 35-MDa plasmid was no longer capable of synthesizing fimbrial subunits, but regained fimbrial expression after reintroduction of the TnphoA (Tn5 IS50L::phoA)-tagged 35-MDa plasmid. Absence of fimbrial subunit synthesis in K-12 strains transformed with the 35-MDa plasmid alone suggested the requirement of regulatory elements existing in strain 987 but missing in K-12 strains. A probe for the heat-stable enterotoxin STIa hybridized in each of the 987P-fimbriated strains to the plasmid containing the 987P genes and in most of these strains to an additional plasmid which contained the gene for the heat-stable enterotoxin STII. Occurrence of the 987P and STIa genes on the same replicon correlates with epidemiological observations, STIa being the most prevalent toxin produced by 987P-fimbriated E. coli.
Schifferli
D M
DM
Department of Microbiology and Immunology, University of Tennessee Center for the Health Sciences, Memphis.
Beachey
E H
EH
Taylor
R K
RK
D001427:Bacterial Toxins / Q000235:genetics; D015153:Blotting, Western; D004269:DNA, Bacterial / Q000235:genetics; D004768:Enterotoxins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial; D005798:Genes, Bacterial; D010957:Plasmids
D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli)