Analysis of a novel existence region of Sir3p in S. cerevisiae

In the budding yeast, HMR, HML, telomere and rDNA domain are known as a silencing region. Sir2 need to make it at rDNA and, HMR, HML and the telomere need to Sir2, Sir3, Sir4 complex to control internal gene repression. In this report, we found a newly Sir3 binding domain, CN domain (Chromosome New region) 1~14, by the ChIP on chip analysis on S.cerevisiae chromosome. In addition, we also performed ChIP on chip analysis with anti-Sir3 antibody using G1 phase synchronized cell to find Sir3 distribution difference of stage of cell cycle and we found CN15~CN25 which was G1 phase specific Sir3 binding region. Furthermore, we analyzed difference of gene expression at CN region in sir3 strain, and some regions did not change level of gene expression. In the conventional report, Sir3 had recruited by Sir2 and Sir4 on chromosome, but recruit of Sir3 was independent on Sir2 and Sir4 at some CN regions. These data suggested that we found a newly Sir3 function and Sir3 recruited system on chromosome. Distribution of Sir3 on chromosomes during log phase or G1 phase. In the both cases, hybridization data for ChIP fraction was compared with Input (whole cell extract fraction). Several binding signals were confirmed by quantitative real time PCR.