RecA protein-dependent proteolysis of bacteriophage lambda repressor Characterization of the reaction and stimulation by DNA-binding proteins.
1981; Elsevier BV; Volume: 256; Issue: 21 Linguagem: Inglês
10.1016/s0021-9258(19)68527-3
ISSN1083-351X
AutoresGeorge M. Weinstock, Kathleen Mc Entee,
Tópico(s)Bacteriophages and microbial interactions
ResumoRecA protein (the wild type form of the protein, Le. the product of the mcA+ gene), purified to homogeneity by a novel ATP elution step (Cox, M. M., McEntee, K., and Lehman, I. R. (1981) J. BioL Chem 266,4676-4678), cleaves bacteriophage X repressor in a reaction requiring a nucleoside triphosphate, single-stranded polynucleotide and divalent cation.(d,r)ATP, (d,r)UTP, rATP[yS], rUTP[yS], and rGTP[yS] serve as cofactors for recA protease activity, whereas (r,d)GTP, (r,d)CTP, and d'ITP do not.The reaction is inhibited by ADP, UDP, and dITP, all of which bind to recA protein.In the presence of ATP or other hydrolyzable nucleoside triphosphates, the rate of repressor cleavage is greatly enhanced by substituting Mn" ion for M&+, an effect which is correlated with a reduction in ATP hydrolysis.The polynucleotide requirement is satisfied by +X114 DNA, poly(dT), poly(dU), and poly(dC).Polyribonucleotides and oligodeoxynucleotides are significantly less effective and duplex DNA inhibits the cleavage of X repressor in the presence of single-stranded DNA.A ratio of 2-3 single-stranded nucleotides/recA protein monomer is optimal for proteolysis and the reaction is inhibited at higher ratios.Single-stranded DNA binding protein of Escherichia coli and gene 32 protein of bacteriophage T4 prevent the inhibition of proteolysis by excess single-stranded DNA.However, a defective single-stranded DNA binding protein isolated from a Z e x C mutant of E. coli does not reverse this inhibition by excess polynucleotide.These results provide evidence for a role of single strand DNA-binding protein in the mechanism of bacteriophage X induction in vivo.The SOS response, a complex and coordinate alteration of metabolic processes in the bacterium Escherichia coli, is elicited when DNA is damaged or its replication is blocked (1, 2) and involves induction of the synthesis of several gene products (3), including the recA protein.'At least some of
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