Fluorescence study of the RecA‐dependent proteolysis of LexA, the represser of the SOS system in Escherichia coli

FEBS Letters

Schnarr, Manfred¹  Daune, Michel¹  Takahashi, Masayuki¹ 

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

关键词: RecA protein LexA repressor SOS system Fluorescence Proteolysis Kinetics;   

DOI  :  10.1016/0014-5793(86)80249-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The fluorescence of the LexA protein, the common repressor of the SOS system in Escherichia coli decreases by about 30% upon incubation with the Ree A protein, and its cofactors ATP [or its non-hydroly sable analogue adenosine-5'-O-(3-thiotriphosphate), ATPγS] Mg²⁺ and single-stranded DNA. In the absence of any one of these elements required for the RecA-dependent proteolysis of LexA, this fluorescence change was not observed. The final fluorescence change depends only upon the concentration of LexA regardless of that of RecA. The time course of the fluorescence decrease corresponds well with the kinetics of the decrease of intact LexA protein and the increase of its 2 proteolytic fragments as determined by SDS-polyacrylamide gel electrophoresis. These results allow us to use the fluorescence change as a signal for a detailed kinetic analysis. The velocity of the proteolysis (d[LexA]/dt) is proportional to the concentration of LexA and RecA indicating that the formation of the LexA-RecA complex is the limiting step.

【 授权许可】

Unknown