The Vibrio Pathogenicity Island of Epidemic Vibrio cholerae Forms Precise Extrachromosomal Circular Excision Products
AUTOR(ES)
Rajanna, C.
FONTE
American Society for Microbiology
RESUMO
The Vibrio pathogenicity island (VPI) in epidemic Vibrio cholerae is an essential virulence gene cluster. Like many pathogenicity islands, the VPI has at its termini a phage-like integrase gene (int), a transposase-like gene (vpiT), and phage-like attachment (att) sites, and is inserted at a tRNA-like locus (ssrA). We report that the VPI precisely excises from the chromosome and that its left and right ends join to form an extrachromosomal circular excision product (pVPI). Two-stage nested PCR analysis and DNA sequencing confirmed the int-att-vpiT junction and that the core attP of pVPI is identical to the chromosomal VPI attR site. Excision was independent of toxR and toxT. Excision was independent of recA, suggesting that it is mediated by site-specific recombination. Interestingly, while excision was detected in int and vpiT mutants, excision was abolished in a double (int vpiT) mutant and was restored by plasmids containing genes for either recombinase. Excision results in deletion of A361 in the ssrA locus, which flanks the right junction of the VPI. Since A361 encodes U70 in the critical G · U base pair in the acceptor stem of the ssrA RNA that is the determinant for aminoacylation with alanine, this deletion might have deleterious effects on ssrA function. Also, vpiT may have undergone interchromosomal translocation or may represent an independent integration event, as it was found downstream of hutA in some isolates. Our results provide new insight into the molecular biology of the VPI, and we propose that the process of excision and circularization is important in the emergence, pathogenesis, and persistence of epidemic V. cholerae.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=262723Documentos Relacionados
- The Vibrio Pathogenicity Island-Encoded Mop Protein Modulates the Pathogenesis and Reactogenicity of Epidemic Vibrio cholerae
- A Vibrio cholerae pathogenicity island associated with epidemic and pandemic strains
- Precise Excision of the Large Pathogenicity Island, SPI7, in Salmonella enterica Serovar Typhi
- Characterization of VPI Pathogenicity Island and CTXφ Prophage in Environmental Strains of Vibrio cholerae
- Comparative Genomic Analyses of the Vibrio Pathogenicity Island and Cholera Toxin Prophage Regions in Nonepidemic Serogroup Strains of Vibrio cholerae