Genetic relationship of putative colonization factor O166 to colonization factor antigen I and coli surface antigen 4 of enterotoxigenic Escherichia coli.
Plasmid DNA from two strains of enterotoxigenic Escherichia coli harboring genes encoding coli surface antigen 4 (CS4) and from seven Indian enterotoxigenic E. coli isolates cross-hybridized at low stringency but not at high stringency with two polynucleotide probes derived from the colonization factor antigen I (CFA/I) operon. Low-stringency Southern blot hybridization of PstI-digested plasmid DNA from the seven Indian isolates yielded characteristic restriction fragment patterns, distinct from those of CS4- and CFA/I-associated plasmid DNA. Two of the Indian strains were transformed with a recombinant plasmid harboring the cfaD gene, which encodes a positive regulator of CFA/I and CS4 genes. The cfaD transformants produced large amounts of putative colonization factor O166 (PCFO166) irrespective of whether the nutrient agar contained bile salts, a growth factor otherwise required for adequate PCFO166 expression. A considerable interstrain variation in the level of PCFO166 production could be explained by differences in the proportion of bacteria that were fimbriated, as visualized by electron microscopy. The N-terminal amino acid sequence of PCFO166 fimbrial protein showed a high degree of homology with the corresponding sequences of CFA/I and CS4.
Sommerfelt
H
H
Centre for International Health, University of Bergen, Haukeland Hospital, Norway.
Grewal
H M
HM
Svennerholm
A M
AM
Gaastra
W
W
Flood
P R
PR
Viboud
G
G
Bhan
M K
MK
D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics*; D015139:Blotting, Southern; D004926:Escherichia coli / Q000235:genetics*; D005260:Female; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data
D000942:Antigens, Bacterial; D000954:Antigens, Surface; C022924:colonization factor antigens; D036781:Fimbriae Proteins