Open AccessThe Telomerase-Specific T Motif Is a Restrictive Determinant of Repetitive Reverse Transcription by Human Telomerase
Author(s) -
William C. Drosopoulos,
Vinayaka R. Prasad
Publication year - 2010
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00853-09
Subject(s) - telomerase , biology , retrotransposon , reverse transcriptase , protein subunit , processivity , rna , primer (cosmetics) , telomere , primer extension , sequence motif , telomerase rna component , telomerase reverse transcriptase , microbiology and biotechnology , genetics , dna , dna replication , gene , mutant , transposable element , chemistry , organic chemistry
The central hallmark of telomerases is repetitive copying of a short, defined sequence within its integral RNA subunit. We sought to identify structural determinants of this unique activity in the catalytic protein subunit telomerase reverse transcriptase (TERT) of telomerase. Residues within the highly conserved telomerase-specific T motif of human TERT were mutationally probed, leading to variant telomerases with increased repeat extension rates and wild-type processivity. The extension rate increases were independent of template sequence composition and only moderately correlated to telomerase RNA (TR) binding. Importantly, analysis of substrate primer elongation showed that the extension rate increases primarily resulted from increases in the repeat (type II) translocation rate. Our findings indicate a participatory role for the T motif in repeat translocation, an obligatory event for repetitive telomeric DNA synthesis. Thus, the T motif serves as a restrictive determinant of repetitive reverse transcription.