Molecular cloning and characterization of chromosomal virulence region kcpA of Shigella flexneri

Abstract

In Shigella flexneri, in addition to several well‐recognized plasmid‐borne virulence loci, at least three genetic loci implicated in pathogenesis have been recognized on the chromosome. To understand more about the pathogenesis of bacillary dysentery at a molecular level, the genetically recognized but previously unidentified KcpA region (one of the chromosomal regions near purE) was cloned and sequenced. A single translatable open reading frame encoding a 12310 Dalton protein corresponding to the minicell product was found. Immunofluorescence microscopy, as well as optical and electron microscopic comparison of tissue‐cultured cells and guinea‐pigs’eyes infected with wild‐type or kcpA mutant bacteria, revealed that the kcpA product is required by invading bacteria for spread into adjacent cells.