Structural and sequence diversity of the pathogenicity island of uropathogenic Escherichia coli which encodes the USP protein

A total of 321 uropathogenic Escherichia coli (UPEC) strains and 12 strains of E. coli isolated from stool samples of healthy individuals, which were previously shown to be positive in colony hybridization test using the usp (encoding for the uropathogenic-specific protein) DNA probe. were examined by PCR amplification to determine the size of the usp gene and the pathogen icity island (PI). Three types of size variation were observed for the usp gene and four types for the PI. Sequencing analysis of the Pls from seven r epresentative strains (six UPEC and one from a normal healthy individual) r evealed that the usp genes can be classified into two groups, each having d ifferent sequences in the 3'-terminal region. The peptides encoded by the t hree open reading frames (ORFs) downstream of usp had identical 23 amino ac id residues in the C-terminal region. The subregion encoding these small OR Fs has a mosaic structure constituted of six segments. The positions of the se segments vary from strain to strain. and in some strains, two to four se gments are deleted. This indicates that rearrangements occur frequently in this region and the mosaic arrangement apparently contributes to the size v ariation observed in the PCR examination of the usp genes and Pls. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Sc ience B.V. All rights reserved.