HST1, A NEW MEMBER OF THE SIR2 FAMILY OF GENES

A novel Saccharomyces cerevisiae gene, HST1, was identified from among anonymous cDNAs and the complete corresponding genomic clone was isol ated and sequenced. HST1 is very closely related to SIR2, showing 71% sequence identity over 84% of its length. Polymerase chain reaction wi th degenerate primers on S. cerevisiae DNA identified three additional SIR2-related genes designated HST2, HST3 and HST4. The sequences of H ST2, HST3 and HST4 correspond to sequences previously released by the S. cerevisiae genome sequencing project as U33335, NCBI gi:965078; X87 331, NCBI gi:829135; and Z48784, YD9346.03, respectively. Disruption o f HST1 has shown no phenotype with respect to mechanisms in which SIR2 has a role, namely, regional silencing of HML alpha, or in rDNA recom bination. The sequence of HST1 has been deposited in the DDBJ, EMBL an d GenBank at NCBI database under Accession Number L47120.