TY - JOUR
T1 - Evolutionary changes of the flhDC flagellar master operon in Shigella strains
AU - Tominaga, Akira
AU - Lan, Ruiting
AU - Reeves, Peter R.
PY - 2005/6
Y1 - 2005/6
N2 - 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 Escherichla 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.
AB - 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 Escherichla 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.
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U2 - 10.1128/JB.187.12.4295-4302.2005
DO - 10.1128/JB.187.12.4295-4302.2005
M3 - Article
C2 - 15937193
AN - SCOPUS:20444505242
VL - 187
SP - 4295
EP - 4302
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 12
ER -