Cohn M, Blackburn E H
Department of Microbiology and Immunology, University of California, San Francisco 94143-0414, USA.
Science. 1995 Jul 21;269(5222):396-400. doi: 10.1126/science.7618104.
The ribonucleoprotein enzyme telomerase synthesizes telomeric DNA by copying an internal RNA template sequence. The telomerase activities of the yeasts Saccharomyces castellii and Saccharomyces cerevisiae--with regular and irregular telomeric sequences, respectively--have now been identified and characterized. The S. cerevisiae activity required the telomerase RNA gene TLC1 but not the EST1 gene, both of which are required for normal telomere maintenance in vivo. This activity exhibited low processivity and produced no regularly repeated products. An inherently high stalling frequency of the S. cerevisiae telomerase may account for its in vitro properties and for the irregular telomeric sequences of this yeast.
核糖核蛋白酶端粒酶通过复制内部RNA模板序列来合成端粒DNA。现已鉴定并表征了分别具有规则和不规则端粒序列的酿酒酵母和卡氏酵母的端粒酶活性。酿酒酵母的活性需要端粒酶RNA基因TLC1，但不需要EST1基因，而这两个基因在体内正常端粒维持中都是必需的。这种活性表现出低持续性，并且不产生规则重复的产物。酿酒酵母端粒酶固有的高停顿频率可能解释了其体外特性以及该酵母不规则的端粒序列。
