A junction branch point adjacent to a DNA backbone nick directs substrate cleavage by Saccharomyces cerevisiae Mus81-Mms4.

ABSTRACT: The DNA structure-selective endonuclease Mus81-Mms4/Eme1 incises a number of nicked joint molecule substrates in vitro. 3'-flaps are an excellent in vitro substrate for Mus81-Mms4/Eme1. Mutants in MUS81 are synthetically lethal with mutations in the 5'-flap endonuclease FEN1/Rad27 in Saccharomyces cerevisiae and Schizosaccharomyces pombe. Considering the possibility for isoenergetic interconversion between 3'- and 5'- flaps, these data are consistent with the hypothesis that Mus81-Mms4/Eme1 acts on 3'-flaps in vivo. FEN1/Rad27 prefers dually flapped substrates and cleaves in a way that allows direct ligation of the resulting nick in the product duplex. Here we test the activity of Mus81-Mms4 on dually flapped substrates and find that in contrast to FEN1/Rad27, Mus81-Mms4 activity is impair

SUBMITTER: Ehmsen KT 

PROVIDER: S-EPMC2665226 | biostudies-literature | 2009 Apr

REPOSITORIES: biostudies-literature