Affiliation:
1. School of Molecular and Microbial Biosciences (GO8), The University of Sydney, Sydney, NSW 2006, Australia
2. School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
Abstract
ABSTRACT
Shigella
strains are nonmotile. The master operon of flagellar synthesis,
flhDC
, was analyzed for genetic damage in 46
Shigella
strains representing all known serotypes. In 11 strains (B1, B3, B6, B8, B10, B18, D5, F1B, D10, F3A, and F3C) the
flhDC
operon was completely deleted. PCR and sequence analysis of the
flhDC
region of the remaining 35 strains revealed many insertions or deletions associated with insertion sequences, and the majority of the strains were found to be defective in their
flhDC
genes. As these genes also play a role in regulation of nonflagellar genes, the loss may have other consequences or be driven by selection pressures other than those against flagellar motility. It has been suggested that
Shigella
strains fall mostly into three clusters within
Escherichia coli
, with five outlier strains, four of which are also within
E. coli
(G. M. Pupo, R. Lan, and P. R. Reeves, Proc. Natl. Acad. Sci. USA 97:10567-10572, 2000). The distribution of genetic changes in the
flhDC
region correlated very well with the three clusters and outlier strains found using housekeeping gene DNA sequences, enabling us to follow the sequence of mutational change in the
flhDC
locus. Two cluster 2 strains were found to have unique
flhDC
sequences, which are most probably due to recombination during the exchange of the adjacent O-antigen gene clusters.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
24 articles.
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