FUNCTIONAL CONSERVATION OF THE SALMONELLA AND SHIGELLA EFFECTORS OF ENTRY INTO EPITHELIAL-CELLS

A Salmonella typhi chromosomal locus composed of five adjacent genes, designated sipEBCDA, was identified by transposon mutagenesis as being essential for cell invasion. Products of the sip genes exhibit. exten sive sequence similarities to the effecters of Shigella entry into epi thelial cells encoded by the virulence plasmid-borne ipa operon. Expre ssion of sipE and sipB in a Shigella non-invasive ipaB mutant restored the ability to invade epithelial cells. The structural and functional conservation of the Sip and Ipa proteins suggests that Salmonella and Shigella entry processes are promoted by similar effecters.