Fimbrial phase variation in Bordetella pertussis: a novel mechanism for transcriptional regulation.
AUTOR(ES)
Willems, R
RESUMO
Fimbriae belong to a class of extracellular filamentous proteins which are involved in the attachment of bacteria to host tissues. Bordetella pertussis, the etiological agent of whooping cough, produces two serologically distinct fimbriae. We show that, like a number of other B. pertussis virulence genes, transcription of the fimbrial subunit genes (fim) is positively controlled by trans-acting polypeptides encoded by the bvg locus. In addition to this coordinate control, transcription of the fim genes is regulated at an individual level by phase variation. This process is characterized by a switching between a high and low level of expression of a particular fim gene. We have identified a conserved DNA region, located close to the start of the fim genes, which is likely to be involved in both positive regulation by the bvg locus, and phase variation. This promoter region contains a stretch of approximately 15 C residues and it appears that phase transitions occur by small insertions or deletions in this C-rich region. We propose that these mutations affect transcription of the fim genes by varying the distance between the binding site for an activator and the -10 box. The fim promoter shows homology with the pertussis toxin promoter, which is also positively regulated by the bvg locus.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=551991Documentos Relacionados
- Phase-variation of pyelonephritis-associated pili in Escherichia coli: evidence for transcriptional regulation.
- Polymerase chain reaction assay for pertussis: simultaneous detection and discrimination of Bordetella pertussis and Bordetella parapertussis.
- Spontaneous phase variation in Bordetella pertussis is a multistep non-random process.
- Plasmid transfer to Bordetella pertussis: conjugation and transformation.
- Humoral Immunity against Bordetella pertussis: Antibodies or B Cells?