Homologs of the Shigella IpaB and IpaC invasins are required for Salmonella typhimurium entry into cultured epithelial cells.

AUTOR(ES)

Kaniga, K

RESUMO

Entry into host cells is an essential feature in the pathogenicity of Salmonella spp. The inv locus of Salmonella typhimurium encodes several proteins which are components of a type III protein secretion system required for these organisms to gain access to host cells. We report here the identification of several proteins whose secretion into the culture supernatant of S. typhimurium is dependent on the function of the inv-encoded translocation apparatus. Nucleotide sequence analysis of the genes encoding two of these secreted proteins, SipB and SipC, indicated that they are homologous to the Shigella sp. invasins IpaB and IpaC, respectively. An additional gene was identified, sicA, which encodes a protein homologous to IpgC, a Shigella protein that serves as a molecular chaperone for the invasins IpaB and IpaC. Nonpolar mutations in sicA, sipB, and sipC rendered S. typhimurium unable to enter cultured epithelial cells, indicating that these genes are required for bacterial internalization.

Documentos Relacionados

• Nonpolar mutagenesis of the ipa genes defines IpaB, IpaC, and IpaD as effectors of Shigella flexneri entry into epithelial cells.
• Induction of Necrosis in Human Neutrophils by Shigella flexneri Requires Type III Secretion, IpaB and IpaC Invasins, and Actin Polymerization
• IpaB of Shigella flexneri causes entry into epithelial cells and escape from the phagocytic vacuole.
• The secretion of the Shigella flexneri Ipa invasins is activated by epithelial cells and controlled by IpaB and IpaD.
• Secretion of Shigella flexneri Ipa invasins on contact with epithelial cells and subsequent entry of the bacterium into cells are growth stage dependent.