Gotta M, Strahl-Bolsinger S, Renauld H, Laroche T, Kennedy B K, Grunstein M, Gasser S M
Swiss Institute for Experimental Cancer Research, Chemin des Boveresses, Epalinges/Lausanne, Switzerland.
EMBO J. 1997 Jun 2;16(11):3243-55. doi: 10.1093/emboj/16.11.3243.
In wild-type budding yeast strains, the proteins encoded by SIR3, SIR4 and RAP1 co-localize with telomeric DNA in a limited number of foci in interphase nuclei. Immunostaining of Sir2p shows that in addition to a punctate staining that coincides with Rap1 foci, Sir2p localizes to a subdomain of the nucleolus. The presence of Sir2p at both the spacer of the rDNA repeat and at telomeres is confirmed by formaldehyde cross-linking and immunoprecipitation with anti-Sir2p antibodies. In strains lacking Sir4p, Sir3p becomes concentrated in the nucleolus, by a pathway requiring SIR2 and UTH4, a gene that regulates life span in yeast. The unexpected nucleolar localization of Sir2p and Sir3p correlates with observed effects of sir mutations on rDNA stability and yeast longevity, defining a new site of action for silent information regulatory factors.
在野生型芽殖酵母菌株中，SIR3、SIR4和RAP1编码的蛋白质在间期核中与端粒DNA共定位于有限数量的位点。对Sir2p的免疫染色显示，除了与Rap1位点一致的点状染色外，Sir2p还定位于核仁的一个亚结构域。通过甲醛交联和抗Sir2p抗体免疫沉淀，证实了Sir2p在rDNA重复序列间隔区和端粒处均存在。在缺乏Sir4p的菌株中，Sir3p通过一种需要SIR2和UTH4（一个调节酵母寿命的基因）的途径，集中在核仁中。Sir2p和Sir3p意外的核仁定位与观察到的sir突变对rDNA稳定性和酵母寿命的影响相关，确定了沉默信息调节因子的一个新作用位点。
