G-overhang dynamics at Tetrahymena telomeres

被引:53
作者
Jacob, NK
Skopp, R
Price, CM
机构
[1] Univ Cincinnati, Sch Med, Dept Mol Genet Biochem & Microbiol, Cincinnati, OH 45267 USA
[2] Univ Nebraska, Dept Vet Sci, Lincoln, NE 68588 USA
关键词
DNA replication; telomerase; telomere; tetrahymena;
D O I
10.1093/emboj/20.15.4299
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
To learn more about the structure of the DNA terminus at Tetrahymena thermophila telomeres, we have devised a ligation-mediated primer extension protocol to accurately measure the length of the G-strand overhang. We show that overhang length and the identity of the 3'-terminal nucleotide are tightly regulated. The majority of overhangs terminate in the sequence 5'-TTGGGGT and >80% are either 14-15 or 20-21 nucleotides in length. No significant changes in overhang length were detected as cells traversed the cell cycle. However, changes in length distribution were observed when cells exited the cell cycle, indicating an altered balance between DNA synthesis and degradation or end protection. We also provide evidence that rDNA molecules have overhangs on both telomeres. Full-length rDNA could be cloned by a strategy that depends on overhangs being present at both ends. Moreover, analysis of leading strand telomeres revealed that a significant fraction have overhangs greater than or equal to5 nucleotides. Our results indicate that generation of the terminal telomeric DNA structure is highly regulated and requires several distinct DNA-processing events.
引用
收藏
页码:4299 / 4308
页数:10
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