Genetic and enzymatic analysis of a gene controlling UV sensitivity in Neurospora crassa

Abstract

The upr-I gene controlling UV sensitivity in Neurospora crassa has been transferred from a microconidial strain into a macroconidial strain. The properties of the strain with respect to UV sensitivity and photoreactivation (PR) have been modified in the macroconidial background leading to an enhancement of resistance to UV by a factor of about 2 and some suggestion of enzymatic PR. The upr-I gene confers sensitivity to nitrous acid to about the same degree as that for UV. However, inactivation of strains carrying the upr-I gene by white light in the presence of photosensitizing dyes is equivalent to that of strains exhibiting normal sensitivity to UV. Although in vivo enzymatic PR in strains carrying the upr-I gene is impaired, enzymatic analysis with the Hemophilus influenzae transformation systems in vitro reveals that strains carrying the upr-I gene possess a functional PR enzyme. It is suggested that the upr-I gene may control nuclease(s) which compete with the PR enzyme for substrate. The upr-I gene has been located on linkage group IL about 1.6 map units proximal to mating type. The gene has been shown to be without effect on ascus and ascospore development and to have no significant effect on crossing-over.