High impact information on SAN1

• We show here that one of the suppressor genes is the previously reported SAN1 gene; san1 mutations were originally identified as suppressors of a sir4 mutation, implicated in the chromatin-mediated transcriptional silencing of the two mating-type loci HML and HMR [1].
• Our findings suggest that the San1 protein antagonizes the transcriptional activator function of the Cdc68 protein [1].
• Consistent with the idea that San1 participates as an accessory factor to regulate silent chromatin, including the silent mating-type loci, microarray analysis defined a small but statistically significant role for San1 in transcription of several mating pheromone-responsive genes [2].
• Sir Antagonist 1 (San1) is a ubiquitin ligase [2].
• These suppressor mutations, which define at least three new genes, SAN1, SAN2 and SAN3, arose at the frequency expected for loss-of-function mutations following mutagenesis [3].

Biological context of SAN1

• Each san1 mutation, including a san1 null allele, reversed all aspects of the cdc68 mutant phenotype [1].

Regulatory relationships of SAN1

• SAN1 may act posttranslationally to control the stability or activity of the SIR4 protein [3].
• Mutations in Sir Antagonist 1 (SAN1) suppress defects in SIR4 and SPT16 in Saccharomyces cerevisiae [2].

Other interactions of SAN1

• Consistent with this idea, mutant sir4 and spt16 proteins are unstable in SAN1 cells but are stabilized in san1Delta cells [2].

References