Plasmid-Encoded MCP Is Involved in Virulence, Motility, and Biofilm Formation of Cronobacter sakazakiiATCC 29544

ABSTRACTThe aim of this study was to elucidate the function of the plasmid-borne mcp(methyl-accepting chemotaxis protein) gene, which plays pleiotropic roles in Cronobacter sakazakiiATCC 29544. By searching for virulence factors using a random transposon insertion mutant library, we identified and sequenced a new plasmid, pCSA2, in C. sakazakiiATCC 29544. An in silicoanalysis of pCSA2 revealed that it included six putative open reading frames, and one of them was mcp. The mcpmutant was defective for invasion into and adhesion to epithelial cells, and the virulence of the mcpmutant was attenuated in rat pups. In addition, we demonstrated that putative MCP regulates the motility of C. sakazakii, and the expression of the flagellar genes was enhanced in the absence of a functional mcpgene. Furthermore, a lack of the mcpgene also impaired the ability of C. sakazakiito form a biofilm. Our results demonstrate a regulatory role for MCP in diverse biological processes, including the virulence of C. sakazakiiATCC 29544. To the best of our knowledge, this study is the first to elucidate a potential function of a plasmid-encoded MCP homolog in the C. sakazakiisequence type 8 (ST8) lineage.