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Updated: Aug 29, 2026

High Sensitivity Measurement of Transcription Factor-DNA Binding Affinities by Competitive Titration Using Fluorescence Microscopy
Published on: February 7, 2019
DNA binding features of human POT1: a nonamer 5'-TAGGGTTAG-3' minimal binding site, sequence specificity, and
Diego Loayza1, Heather Parsons, Jill Donigian
1Laboratory for Cell Biology and Genetics, The Rockefeller University, 1320 York Avenue, New York, NY 10021, USA.
Abstract:
The human telomeric protein POT1 is known to bind single-stranded telomeric DNA in vitro and to participate in the regulation of telomere maintenance by telomerase in vivo. We examined the in vitro DNA binding features of POT1. We report that deleting the oligosaccharide/oligonucleotide-binding fold of POT1 abrogates its DNA binding activity. The minimal binding site (MBS) for POT1 was found to be the telomeric nonamer 5'-TAGGGTTAG-3', and the optimal substrate is [TTAGGG](n (n > or = 2)). POT1 displays exceptional sequence specificity when binding to MBS, tolerating changes only at position 7 (T7A). Whereas POT1 binding to MBS or [TTAGGG](2) was enhanced by the proximity of a 3' end, POT1 was able to bind to a [TTAGGG](5) array when positioned internally. These data indicate that POT1 has a strong sequence preference for the human telomeric repeat tract and predict that POT1 can bind both the 3' telomeric overhang and the displaced TTAGGG repeats at the base of the t-loop.
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