期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1999
卷号：96
期号：8
页码：4279-4284
DOI：10.1073/pnas.96.8.4279
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The {beta} protein of bacteriophage {lambda} acts in homologous genetic recombination by catalyzing the annealing of complementary single-stranded DNA produced by the {lambda} exonuclease. It has been shown that the {beta} protein binds to the products of the annealing reaction more tightly than to the initial substrates. We find that {beta} protein exists in three structural states. In the absence of DNA, {beta} protein forms inactive rings with {approx}12 subunits. The active form of the {beta} protein in the presence of oligonucleotides or single-stranded DNA is a ring, composed of {approx}15-18 subunits. The double-stranded products of the annealing reaction catalyzed by the rings are bound by {beta} protein in a left-handed helical structure, which protects the products from nucleolytic degradation. These observations suggest structural homology for a family of proteins, including the phage P22 erf, the bacterial RecT, and the eukaryotic Rad52 proteins, all of which are involved in homologous recombination.
