Plasmid-encoded MCP is involved in virulence, motility, and biofilm formation of Cronobacter sakazakii ATCC 29544

Abstract

The aim of this study was to elucidate the function of the plasmid-encoded mcp (methyl-accepting chemotaxis protein) gene that plays pleiotropic roles in C. sakazakii ATCC 29544. By searching for virulence factors using a random transposon insertion mutant library, I identified and sequenced a new plasmid, pCSA2, in C. sakazakii ATCC 29544. In silico analysis of pCSA2 revealed that it encoded 6 open reading frames, and one of them was mcp. The mcp mutant was defective for invasion into and adhesion to epithelial cells, and the virulence of the mcp mutant was attenuated in rat pups. In addition, I showed that putative MCP regulates the motility of C. sakazakii ATCC 29544 and the expression of the flagellar genes was enhanced in the absence of a functional mcp gene. Furthermore, lack of the mcp gene also impaired the ability of C. sakazakii to form biofilm. Our results demonstrate a regulatory role for MCP in diverse biological processes including virulence of C. sakazakii ATCC 29544. To the best of our knowledge, this study is the first to elucidate a potential function of a plasmid-encoded MCP homolog in C. sakazakii ST8.