Excision Repair in the Yeast, Saccharomyces Cerevisiae

1987 Journal of Cell Science  
cdc9 mutants of yeast lack detectable DN A ligase activity at restrictive temperatures. They also appear to be more sensitive than wild-type cells to ultraviolet (u.v.) radiation and it has been assumed that this is because the CDC9 ligase is needed for the final ligation step in excision repair. The fact that single-strand breaks have been demonstrated in u.v.-irradiated cdc9 mutants has been regarded as evidence for this interpretation. However, the kinetics of appearance of nicks in the D N
more » ... f nicks in the D N A do not support this since maximal levels of strand breaks appear almost immediately after exposure to u.v. light and not progressively as repair events are initiated. We believe, therefore, that these strand breaks are connected with a u.v.-dependent preincision event, possibly connected with reorganization of chromatin. MATERIALS AND METHODS These are essentially as described by Resnick et al. (1981) and McCready & Cox (1980). Brief outlines of the methods are given in Figs 1 and 2.
doi:10.1242/jcs.1984.supplement_6.2 fatcat:u2jkmy2uizhldlm4yctg2ex6eu