Novel Colicin F Y of Yersinia frederiksenii Inhibits Pathogenic Yersinia Strains via YiuR-Mediated Reception, TonB Import, and Cell Membrane Pore Formation

Abstract

ABSTRACT A novel colicin type, designated colicin F Y , was found to be encoded and produced by the strain Yersinia frederiksenii Y27601. Colicin F Y was active against both pathogenic and nonpathogenic strains of the genus Yersinia . Plasmid YF27601 (5,574 bp) of Y. frederiksenii Y27601 was completely sequenced. The colicin F Y activity gene ( cfyA ) and the colicin F Y immunity gene ( cfyI ) were identified. The deduced amino acid sequence of colicin F Y was very similar in its C-terminal pore-forming domain to colicin Ib (69% identity in the last 178 amino acid residues), indicating pore forming as its lethal mode of action. Transposon mutagenesis of the colicin F Y -susceptible strain Yersinia kristensenii Y276 revealed the yiuR gene (ykris001_4440), which encodes the YiuR outer membrane protein with unknown function, as the colicin F Y receptor molecule. Introduction of the yiuR gene into the colicin F Y -resistant strain Y. kristensenii Y104 restored its susceptibility to colicin F Y . In contrast, the colicin F Y -resistant strain Escherichia coli TOP10F′ acquired susceptibility to colicin F Y only when both the yiuR and tonB genes from Y. kristensenii Y276 were introduced. Similarities between colicins F Y and Ib, similarities between the Cir and YiuR receptors, and the detected partial cross-immunity of colicin F Y and colicin Ib producers suggest a common evolutionary origin of the colicin F Y -YiuR and colicin Ib-Cir systems.