Molecular cloning of RAD16, a gene involved in differential repair in Saccharomyces cerevisiae

We have cloned the RAD16 gene of Saccharomyces cerevisiae and determined its nucleotide sequence. The gene complements the UV sensitivity of a rad16 mutant and restores the ability to repair the transcriptionally inactive HML-alpha locus that is absent in this mutant. Disruption mutants that were constructed using the cloned gene are viable and UV sensitive and show no detectable growth defect. Moreover, such a mutant is deficient for repair of the HML-alpha locus. The nucleotide sequence shows that the gene codes for a protein of 790 amino acids that has two potential zinc binding domains and shares homology with two other yeast proteins: the RAD54 gene product involved in recombinational repair and SNF2, a transcription factor that possibly functions in transcription activation through an interaction with chromatin components that allows access of other factors involved in transcription. The role of RAD16 in the repair of HML-alpha might be to change the chromatin structure of silenced genes to provide access for excision repair enzymes.