bfpH | GeneID:6382177 | Escherichia coli

ABG29516   CAA92335   S70975   YP_001965388  

1. [ ] Brinkley C, et al. (2006) "Nucleotide sequence analysis of the enteropathogenic Escherichia coli adherence factor plasmid pMAR7." Infect Immun. 74(9):5408-5413. PMID:16926437

The complete nucleotide sequence was determined for pMAR7, an enteropathogenic Escherichia coli (EPEC) adherence factor (EAF) plasmid that contains genes encoding a type IV attachment pilus (Bfp) and the global virulence regulator per. Prototypic EAF plasmid pMAR7 is self-transmissible, unlike the smaller EAF plasmid pB171, which has no genes encoding conjugative functions. The tra locus, a highly conserved 33-kb segment found in pMAR7, is similar to the tra (conjugation) region of the F plasmid. ISEc13 copies flanking the pMAR7 tra region could potentially mobilize or delete the tra genes. Hybridization of 134 EPEC strains showed that a complete tra region is present only in strains of the EPEC1 clonal group. This study confirms EPEC's potential for dissemination of virulence attributes by horizontal transfer of the EAF plasmid.

2. [ ] Stone KD, et al. (1996) "A cluster of fourteen genes from enteropathogenic Escherichia coli is sufficient for the biogenesis of a type IV pilus." Mol Microbiol. 20(2):325-337. PMID:8733231

Enteropathogenic Escherichia coli (EPEC) adhere to epithelial cells in microcolonies, a pattern termed localized adherence (LA). LA is dependent upon the presence of 50-70 MDa plasmids, termed EPEC adherence factor (EAF) plasmids. Expression of an EAF plasmid-encoded type IV fimbria, the bundle-forming pilus (BFP), is associated with the LA phenotype. TnphoA insertions in bfpA, the gene encoding the major structural subunit of the BFP, abolish LA. While bfpA::TnphoA mutants cannot be complemented for LA by plasmids carrying the bfpA gene alone in trans, this work shows that they can be complemented by plasmids carrying the bfpA gene, as well as approximately 10 kb of downstream sequence, suggesting that such mutations have polar effects on downstream genes. The identification and characterization of a cluster of 13 genes immediately downstream of bfpA are described. The introduction into a laboratory Escherichia coli strain of a plasmid containing these 14 bfp gene cluster genes, along with pJPN14, a plasmid containing another fragment derived from the EAF plasmid, confers LA ability and BFP biogenesis. However, when a mutation is introduced into the last gene of the bfp cluster, neither LA nor BFP biogenesis is conferred. This work also provides evidence to show that the fragment cloned in pJPN14 encodes a factor(s) which results in increased levels of the pilin protein. Finally, it is shown that expression of the 14 genes in the bfp cluster from an IPTG-inducible promoter, in the absence of pJPN14, is sufficient to reconstitute BFP biogenesis in a laboratory E. coli strain, but is insufficient for LA. This is the first report demonstrating the reconstitution of a type IV pilus in a laboratory E. coli strain with a defined set of genes. The BFP system should prove to be a useful model for studying the molecular mechanisms of type IV pilus biogenesis.

3. [ ] Zhang HZ, et al. (1994) "A plasmid-encoded prepilin peptidase gene from enteropathogenic Escherichia coli." J Bacteriol. 176(22):6885-6891. PMID:7961448

Enteropathogenic Escherichia coli, a leading agent of infantile diarrhea worldwide, adheres to tissue culture cells in a pattern called "localized adherence." Localized adherence is associated with bundle-forming pili encoded by the plasmid bfpA gene, the product of which is homologous with the major structural subunit proteins of type IV fimbriae in other bacteria. Several of these proteins have been shown to be processed from a precursor by a specific prepilin peptidase. We cloned restriction fragments downstream of the bfpA gene into an E. coli-Pseudomonas aeruginosa shuttle vector and mobilized them into a P. aeruginosa prepilin peptidase (pilD) mutant. A plasmid containing a 1.3-kb PstI-BamHI fragment was able to complement the pilD mutation, as demonstrated by restoration of sensitivity to the pilus-specific bacteriophage PO4. The DNA sequence of this fragment revealed an open reading frame, designated bfpP, the predicted product of which is homologous to other prepilin peptidases, including TcpJ of Vibrio cholerae (30% identical amino acids), PulO of Klebsiella oxytoca (29%), and PilD of P. aeruginosa (28%). A bfpA::TnphoA mutant complemented with a bfpA-containing DNA fragment only partially processes the BfpA protein. When complemented with a larger fragment containing bfpP as well as bfpA, the mutant expresses the fully processed BfpA protein. P. aeruginosa PAK, but not a pilD mutant of PAK, expresses mature BfpA protein when the bfpA gene is mobilized into this strain. Thus, as in other type IV fimbria systems, enteropathogenic E. coli utilizes a specific prepilin peptidase to process the major subunit of the bundle-forming pilus. This prepilin petidase contains sequence and reciprocal functional homologies with the PilD protein of P. aeruginosa.