Fast abortive initiation of uvrA promoter in a supercoiled plasmid studied by stopped‐flow techniques

FEBS Letters

Pouyet, J.¹  Lefèvre, J.F.¹  Daune, M.¹  Ling, C.¹  Schnarr, M.¹  Bertrand-Burggraf, E.¹ 

[1] Institut de Biologie Moléculaire et Cellulaire du CNRS, Laboratoire de Biophysique, 15 rue René-Descartes, 67084 Strasbourg Cédex, France

关键词: Regulation;    Transcription initiation;    RNA polymerase;    Supercoiling;    Fluorescence;    Stopped-flow;   

DOI  :  10.1016/0014-5793(87)80118-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In order to follow the fast kinetics of abortive initiation (lag time from 1 ms to 10 s), we have built a stopped-flow apparatus equipped for fluorescence detection. The small volume used for each assay (35 μl), and the short dead time (∼0.5 ms) are the essential advantages of this apparatus. Supercoiling of DNA affects considerably the initiation of transcription from the uvrA promoter. It decreases the lag time due to the isomerisation process 3-fold. Nevertheless, it does not change significantly the product K _B k ₂, which is indicative of promoter strength and shows that uvrA is an ‘association-limited’ promoter. The presence of the LexA repressor increases the lag time considerably. At least for small RNA polymerase concentrations this increase is stronger for supercoiled than for linearized DNA.

【 授权许可】

Unknown