Interaction of a Saccharomyces cerevisiae strand exchange stimulatory factor with DNA

Publisher Website
Google Scholar
Abstract
In the preceding paper (Norris and Kolodner, 1990), we discribed the purification of a Mr 33,000 polypeptide which dramatically stimulated the activity of SEP1, the yeast mitotic strand exchange protein. In this paper, we characterized this new protein, which was designated SF1, in the absence of SEP1. SF1 had a sedimentation coefficient of 1.7 S and a Stokes radius of 30 .ANG., which was consistent with a calculated native molecular weight of 31,000, indicating that SF1 existed in solution as a monomer. Filter binding assays showed that SF1 bound perferentially to single-stranded rather than double-stranded DNA. Fluorescence spectroscopy analysis indicated that SF1 occluded approximately eight nucleotides when bound to single-stranded DNA and exhibited a dissociation constant, KD, of 2.83 .times. 10-6 M. The binding of SF1 to single-stranded DNA was noncooperative and appeared to involve at least one tyrosine residue. SF1, in the absence of SEP1, stimulated the renaturation of homologous single-stranded DNA, suggesting that it might act directly in some phase of the strand exchange reaction.

This publication has 25 references indexed in Scilit: