Abstract:
:The virulent phenotype of Shigella requires loci on the chromosome as well as on the large virulence plasmid, and is regulated via a complex web of interactions amongst various chromosomal and large plasmid genes. To further investigate the role of chromosomal loci in virulence, we performed random Tn10 mutagenesis in Shigella flexneri YSH6000T, and isolated an avirulent mutant (V3404) incapable of spreading throughout an epithelial cell monolayer. Although V3404 initially spread intercellularly at the same rate as the wild-type, it gradually slowed down and ceased spreading as a result of increasing defects in cell division, leading to the formation of long filamentous bacteria lacking septa, trapped within cells. In addition, the mutation affected the ability of V3404 to polymerize actin, a prerequisite for intra- and inter-cellular spreading ability. Sequencing of Tn10-flanking DNA revealed that the mutated gene, designated ispA (intracellular septation), was equivalent to a previously sequenced but uncharacterised gene of Escherichia coli located between trp and tonB. Using E. coli sequence data, we cloned the ispA gene from the YSH6000T chromosome and found that it complemented the V3404 mutation. Nucleotide sequencing and in vitro expression experiments revealed that ispA coded for a small (21 kDa), very hydrophobic protein. These results thus show that ispA is an essential virulence gene affecting several functions of the virulence process.
journal_name
Mol Microbioljournal_title
Molecular microbiologyauthors
Mac Síomóin RA,Nakata N,Murai T,Yoshikawa M,Tsuji H,Sasakawa Cdoi
10.1046/j.1365-2958.1996.405941.xsubject
Has Abstractpub_date
1996-02-01 00:00:00pages
599-609issue
3eissn
0950-382Xissn
1365-2958journal_volume
19pub_type
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