DNA twist, flexibility and transcription of the osmoregulated proU promoter of Salmonella typhimurium.
AUTOR(ES)
Jordi, B J
RESUMO
Transcription from many bacterial promoters is sensitive to the level of DNA supercoiling. We have investigated the mechanism by which environmentally induced changes in DNA supercoiling might regulate transcription. For the proU promoter of Salmonella typhimurium, osmotically induced changes in DNA topology appear to play a primary regulatory role. Changes in DNA supercoiling (linking number; delta Lk) are partitioned into changes in the winding of the strands of the double helix about themselves (twist; delta Tw) and/or elastic deformations or flexibility of the DNA helix (writhe; delta Wr). Mutations of the proU promoter were isolated in vivo, or generated in vitro, which altered the spacing between the -10 and -35 motifs. Studies on these mutant promoters, both in vivo and in vitro, exclude models in which changes in DNA twist play a regulatory role. Instead, our data suggest that increased DNA flexibility, reflecting the osmotically induced increase in negative supercoiling of DNA, is required for promoter activation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=394684Documentos Relacionados
- Site-directed mutational analysis of the osmotically regulated proU promoter of Salmonella typhimurium.
- A transcriptional silencer downstream of the promoter in the osmotically controlled proU operon of Salmonella typhimurium.
- Evidence for transcription attenuation rendering cryptic a sigmaS-dependent promoter of the osmotically regulated proU operon of Salmonella typhimurium.
- Fine-structure deletion analysis of the transcriptional silencer of the proU operon of Salmonella typhimurium.
- Selection of mutations that alter the osmotic control of transcription of the Salmonella typhimurium proU operon.