Phage Mu Gam protein promotes NHEJ in concert with Escherichia coli ligase.

ABSTRACT: The Gam protein of transposable phage Mu is an ortholog of eukaryotic and bacterial Ku proteins, which carry out nonhomologous DNA end joining (NHEJ) with the help of dedicated ATP-dependent ligases. Many bacteria carry Gam homologs associated with either complete or defective Mu-like prophages, but the role of Gam in the life cycle of Mu or in bacteria is unknown. Here, we show that MuGam is part of a two-component bacterial NHEJ DNA repair system. Ensemble and single-molecule experiments reveal that MuGam binds to DNA ends, slows the progress of RecBCD exonuclease, promotes binding of NAD⁺-dependent Escherichia coli ligase A, and stimulates ligation. In vivo, Gam equally promotes both precise and imprecise joining of restriction enzyme-digested linear plasmid DNA, as we

SUBMITTER: Bhattacharyya S 

PROVIDER: S-EPMC6294893 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature