Evolution of Arabidopsis protection of telomeres 1 alters nucleic acid recognition and telomerase regulation
AffiliationUniv Arizona, Sch Plant Sci
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PublisherOXFORD UNIV PRESS
CitationEvolution of Arabidopsis protection of telomeres 1 alters nucleic acid recognition and telomerase regulation 2016:gkw807 Nucleic Acids Research
JournalNucleic Acids Research
RightsThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc/4.0/).
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AbstractProtection of telomeres (POT1) binds chromosome ends, recognizing single-strand telomeric DNA via two oligonucleotide/oligosaccharide binding folds (OB-folds). The Arabidopsis thaliana POT1a and POT1b paralogs are atypical: they do not exhibit telomeric DNA binding, and they have opposing roles in regulating telomerase activity. AtPOT1a stimulates repeat addition processivity of the canonical telomerase enzyme, while AtPOT1b interacts with a regulatory lncRNA that represses telomerase activity. Here, we show that OB1 of POT1a, but not POT1b, has an intrinsic affinity for telomeric DNA. DNA binding was dependent upon a highly conserved Phe residue (F65) that in human POT1 directly contacts telomeric DNA. F65Amutation of POT1aOB1 abolished DNA binding and diminished telomerase repeat addition processivity. Conversely, AtPOT1b and other POT1b homologs from Brassicaceae and its sister family, Cleomaceae, naturally bear a non-aromatic amino acid at this position. By swapping Val (V63) with Phe, AtPOT1bOB1 gained the capacity to bind telomeric DNA and to stimulate telomerase repeat addition processivity. We conclude that, in the context of DNA binding, variation at a single amino acid position promotes divergence of the AtPOT1b paralog from the ancestral POT1 protein.
NoteOpen Access Journal.
VersionFinal published version
SponsorsNIH [R01 GM065383]; NSF [MCB 1540273]