The RAD6 gene of yeast: a link between DNA repair, chromosome structure and protein degradation?

Among the DNA repair mutants of the yeast Saccharomyces cerevisiae, the rad6 mutants are characterized by a highly pleiotropic phenotype. Most remarkably, these mutants are sensitive towards a variety of DNA-damaging agents and deficient in mutation induction. The RAD6 gene has been cloned and most recently, ubiquitin-conjugating activity of the Rad6 protein has been demonstrated. In this brief review, the properties of rad6 mutants are discussed in the light of these new findings. The available data hint at a connection between DNA repair, mutagenesis, chromosome structure and protein degradation.