We further characterize a novel plasmid function preventing SOS induction called Psi (Plasmid SOS Inhibition). We show that Psi function is expressed by psiB, a gene located at coordinate 54.9 of plasmid R6-5 and near oriT, the origin of conjugal transfer. Deletions and amber mutations of the psiB g
A temperature sensitive RecA protein of Escherichia coli
β Scribed by Hickson, Ian D. ;Gordon, Robert L. ;Tomkinson, Alan E. ;Emmerson, Peter T.
- Publisher
- Springer
- Year
- 1981
- Tongue
- English
- Weight
- 470 KB
- Volume
- 184
- Category
- Article
- ISSN
- 0026-8925
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β¦ Synopsis
The temperature sensitive allele recA200 has been cloned into the multiple copy number plasmid pBR322 and the gene product isolated. The purified RecA200 protein is temperature sensitive in ability to cleave the phage lambda and LexA repressors in vitro and also in ability to promote a successful search for homology between single stranded DNA and a homologous duplex leading to D-loop formation. However, at the non-permissive temperature the RecA200 protein has approximately wild type single stranded DNA dependent ATPase activity and ability to promote pairing between homologous single DNA strands. The demonstration that the temperature sensitivity in vivo can be correlated with the temperature sensitive cleavage of the lambda and LexA repressors in vitro and also with D-loop formation shows that these in vitro reactions, which require large amounts of RecA protein, are not carried out by trace amounts of contaminating proteins.
π SIMILAR VOLUMES
The tif-1 mutation has been shown to affect protein synthesis in vitro by increasing translational ambiguity (Ephrati-Elizur, Luther-Davies and Hayes, 1976). It is demonstrated here that some recA mutations confer similar abnormality. By comparing suitable combinations of ribosomes and soluble prote