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Modeling and structure function analysis of the putative anchor site of yeast telomerase
Telomerase is a ribonucleoprotein reverse transcriptase responsible for extending one strand of the telomere terminal repeats. Unique among reverse transcriptases, telomerase is thought to possess a DNA-binding domain (known as anchor site) that allows the enzyme to add telomere repeats processively...
Autores principales: | , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
Oxford University Press
2007
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1976438/ https://www.ncbi.nlm.nih.gov/pubmed/17670795 http://dx.doi.org/10.1093/nar/gkm531 |
Sumario: | Telomerase is a ribonucleoprotein reverse transcriptase responsible for extending one strand of the telomere terminal repeats. Unique among reverse transcriptases, telomerase is thought to possess a DNA-binding domain (known as anchor site) that allows the enzyme to add telomere repeats processively. Previous crosslinking and mutagenesis studies have mapped the anchor site to an N-terminal region of TERT, and the structure of this region of Tetrahymena TERT was recently determined at atomic resolutions. Here we use a combination of homology modeling, electrostatic calculation and site-specific mutagenesis analysis to identify a positively charged, functionally important surface patch on yeast TERT. This patch is lined by both conserved and non-conserved residues, which when mutated, caused loss of telomerase processivity in vitro and telomere shortening in vivo. In addition, we demonstrate that a point mutation in this domain of yeast TERT simultaneously enhanced the repeat addition processivity of telomerase and caused telomere elongation. Our data argue that telomerase anchor site has evolved species-specific residues to interact with species-specific telomere repeats. The data also reinforce the importance of telomerase processivity in regulating telomere length. |
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