PROTEUS-MIRABILIS AMBIENT-TEMPERATURE FIMBRIAE - CLONING AND NUCLEOTIDE-SEQUENCE OF THE ATF GENE-CLUSTER

Uropathogenic Proteus mirabilis produces at least four types of fimbri ae. Amino acid sequences from two peptides, derived by tryptic digesti on of the structural subunit of one type of these fimbriae, the ambien t-temperature fimbriae, were determined: NVVPGQPSSTQ and LIEGENQLNYNA. PCR primers, based on these sequences and that of the N terminus, wer e used to amplify a 359-bp fragment. A cosmid clone, isolated from a P . mirabilis genomic library by hybridization with the 359-bp PCR produ ct, was used to determine the nucleotide sequence of the atf gene clus ter. A 3,903-bp region encodes three polypeptides: AtfA, the structura l subunit; AtfB, the chaperone; and AtfC, the outer membrane molecular usher. No fimbria-related genes are evident either 5' or 3' to the th ree contiguous genes. AtfA demonstrates significant amino acid sequenc e identity with type 1 major fimbrial subunits of several enteric spec ies. The 359-bp PCR product hybridized strongly with all Proteus isola tes (n = 9) and 25% of 355 Escherichia coli isolates but failed to hyb ridize with any of 26 isolates among nine other uropathogenic species. Ambient-temperature fimbriae of P. mirabilis may represent a novel ty pe of fimbriae of enteric species.