Analysis of the G-overhang structures on plant telomeres: evidence for two distinct telomere architectures

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Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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ŘÍHA Karel MCKNIGHT Thomas FAJKUS Jiří VYSKOT Boris SHIPPEN Dorothy E.

Rok publikování 2000
Druh Článek v odborném periodiku
Časopis / Zdroj The Plant Journal
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Obor Genetika a molekulární biologie
Klíčová slova telomere; telomerase; Silene latifolia; Arabidopsis thaliana; DNA replication
Popis Telomeres are highly conserved structures essential for maintaining the integrity of eukaryotic genomes. In yeast, ciliates and mammals, the G-rich strand of the telomere forms a 3' overhang on the chromosome terminus. Here we investigate the architecture of telomeres in the dicot plants Silene latifolia and Arabidopsis thaliana using the PENT (primer extension/nick translation) assay. We show that both Arabidopsis and Silene telomeres carry G-overhangs longer than 20-30 nucleotides. However, in contrast to yeast and ciliate telomeres, only half of the telomeres in Silene seedlings possess detectable G-overhangs. PENT reactions using a variety of primers and reaction conditions revealed that the remaining fraction of Silene telomeres carries either no overhangs or overhangs less than 12 nucleotides in length. G-overhangs were observed in Silene seeds and leaves, tissues that lack telomerase activity. These findings suggest that incomplete DNA replication of the lagging strand, rather than synthesis by telomerase, is the primary mechanism for G-overhang synthesis in plants. Unexpectedly, we found that the fraction of telomeres with detectable G-overhangs decreased from 50% in seedlings to 35% in leaves. The difference may reflect increased susceptibility of the G-overhangs to nuclease attack in adult leaves, an event that could act as a precursor for the catabolic processes accompanying leaf senescence
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