Human Rad54 protein stimulates human Mus81-Eme1 endonuclease.
Rad54, a key protein of homologous recombination, physically interacts with a DNA structure-specific endonuclease, Mus81-Eme1. Genetic data indicate that Mus81-Eme1 and Rad54 might function together in the repair of damaged DNA. In vitro, Rad54 promotes branch migration of Holliday junctions, whereas the Mus81-Eme1 complex resolves DNA junctions by endonucleolytic cleavage. Here, we show that human Rad54 stimulates Mus81-Eme1 endonuclease activity on various Holliday junction-like intermediates. This stimulation is the product of specific interactions between the human Rad54 (hRad54) and Mus81 proteins, considering that Saccharomyces cerevisiae Rad54 protein does not stimulate human Mus81-Eme1 endonuclease activity. Stimulation of Mus81-Eme1 cleavage activity depends on formation of specific Rad54 complexes on DNA substrates occurring in the presence of ATP and, to a smaller extent, of other nucleotide cofactors. Thus, our results demonstrate a functional link between the branch migration activity of hRad54 and the structure-specific endonuclease activity of hMus81-Eme1, suggesting that the Rad54 and Mus81-Eme1 proteins may cooperate in the processing of Holliday junction-like intermediates during homologous recombination or DNA repair.
Mazina
Olga M
OM
Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102-1192, USA.
Mazin
Alexander V
AV
D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D009687:Nuclear Proteins / Q000502:physiology*; D011995:Recombination, Genetic; D013379:Substrate Specificity
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D004247:DNA; C507947:Eme1 protein, human; D004706:Endodeoxyribonucleases; D004720:Endonucleases; C498772:MUS81 protein, human; D004265:DNA Helicases; C103532:RAD54L protein, human