A GENETIC-LOCUS INVOLVED IN IRON UTILIZATION UNIQUE TO SOME CAMPYLOBACTER STRAINS

Two genes involved in iron utilization in Campylobacter coli VC167 T1 have been characterized. The cfrA gene encodes a protein with a predic ted M-r of 77,653 which, after processing of the leader sequence, has a predicted M-r of 75,635, This protein has significant sequence ident ity to siderophore receptors of several bacteria, and site-specific mu tants defective in cfrA do not synthesize one of two major iron-repres sible outer membrane proteins. An adjacent gene encodes a TonB-like pr otein; a mutant in this gene lost the ability to utilize hemin, ferric hrome, and enterochelin as iron sources. The cfrA and tonB genes of VC 167 T1 hybridized to all strains of C. coli and most strains of C. jej uni examined but did not hybridize to several other strains of C. jeju ni, suggesting that the thermophilic campylobacters can be separated i nto two categories based on the presence of these two iron utilization genes.