Genetic variation of dTDP-L-rhamnose pathway genes in Salmonella enterica

被引:50
作者
Li, Q [1 ]
Reeves, PR [1 ]
机构
[1] Univ Sydney, Dept Microbiol G08, Sydney, NSW 2006, Australia
来源
MICROBIOLOGY-UK | 2000年 / 146卷
关键词
rml genes; rhamnose pathway; Salmonella enterica; lateral gene transfer;
D O I
10.1099/00221287-146-9-2291
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
The genetic variation in the dTDP-L-rhamnose pathway gene set (rmlB, rmlD, rmlA, rmlC) in Salmonella enterica was examined after sequencing the four genes from 11 rml-containing gene clusters encoding seven O antigens. and a 903 bp rmlB segment from another 23 strains representing the seven subspecies. There was considerable sequence variation and strong polarity in the nature and level of variation among rml genes, the 5' end of the rml gene set, including rmlB, rmlD and most of rmlA. is in general subspecies specific. In contrast, the 3' end, including part of rmlA and all of rmlC, is O antigen specific. The G + C content of the 3' end is lower than that of the 5' end. The variation in the 3' end of the gene set is much greater than that of the 5' end. It is apparent that the rml gene set of S. enterica includes genes with two different evolutionary histories. In addition, there has been extensive recombination in the gene set, probably related to O antigen transfer between subspecies. These findings provide evidence for the lateral transfer of O antigen genes between species and among subspecies of S. enterica. The results have also shown that conserved genes at the end of an O antigen gene cluster play a major role in mediating exchange of the central serogroup-specific regions.
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页码:2291 / 2307
页数:17
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