Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q9UIJ5 (Rec)
 58,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When Escherichia coli K12(lambda) lysogens are infected with heteroimmune lambda phage, which are unable to replicate, general recombination between phage and prophage depends on the bacterial recF gene. It has been shown that in E. coli K12 postconjugational recombination, the RecF pathway only works with full efficiency if exonuclease I is absent (Clark 1973). However, results presented in this paper indicate that under conditions in which lambda replication is blocked, the recombination pathway dependent on the recF gene is fully active in producing viral recombinants even, if the phage is Red+, in the presence of exonuclease I. In contrast, removal of lambda exonuclease and beta protein requires elimination of exonuclease I for an efficient RecF pathway. It is concluded that the Red system cooperates with the RecF pathway and that this cooperation involves overcoming the inhibitor effects of exonuclease I. In the absence of lambda exonuclease, beta protein stimulates recF-dependent recombination but does not suffice to prevent the negative effect of exonuclease I. In the presence of beta protein, full efficiency of the RecF pathway can be obtained either via cooperation with lambda exonuclease I or, if the viral exonuclease is defective, via inactivation of exonuclease I. Since activity of lambda exonuclease appears necessary to overcome the inhibitory effects of exonuclease I, it is proposed here that lambda exonuclease diverts material from the RecF pathway in a shunt reaction which allows completion of recF-initiated recombinational intermediates via a mechanism insensitive to exonuclease I. When lambda replication is allowed, the Rec system produces viral recombinants mainly via a recF-independent mechanism. However, a major contribution to the RecF pathway to lambda recombination is observed after removal of the Red system and exonuclease.
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PMID:Role of the recF gene of Escherichia coli K-12 in lambda recombination. 626 23

Recent studies have generated interest in the use of the homologous recombination system of bacteriophage lambda for genetic engineering. The system, called Red, consists primarily of three proteins: lambda exonuclease, which processively digests the 5'-ended strand of a dsDNA end; beta protein, which binds to ssDNA and promotes strand annealing; and gamma protein, which binds to the bacterial RecBCD enzyme and inhibits its activities. These proteins induce a 'hyper-rec' state in Escherichia coli and other bacteria, in which recombination events between DNA species with as little as 40 bp of shared sequence occur at high frequency. Red-mediated recombination in the hyper-rec bacterium proceeds via a number of different pathways, and with the involvement of different sets of bacterial proteins, depending in part on the nature of the recombining DNA species. The role of high-frequency double-strand break repair/recombination in the life cycle of the lambdoid phages is discussed.
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PMID:What makes the bacteriophage lambda Red system useful for genetic engineering: molecular mechanism and biological function. 1144 60