2i46

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Revision as of 20:34, 12 November 2007

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spinqualitylabelsall models 2i46, resolution 2.7Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of human TPP1

Overview

Telomeres were originally defined as chromosome caps that prevent the, natural ends of linear chromosomes from undergoing deleterious degradation, and fusion events. POT1 (protection of telomeres) protein binds the, single-stranded G-rich DNA overhangs at human chromosome ends and, suppresses unwanted DNA repair activities. TPP1 is a previously identified, binding partner of POT1 that has been proposed to form part of a, six-protein shelterin complex at telomeres. Here, the crystal structure of, a domain of human TPP1 reveals an oligonucleotide/oligosaccharide-binding, fold that is structurally similar to the beta-subunit of the telomere, end-binding protein of a ciliated protozoan, suggesting that TPP1 is the, missing beta-subunit of human POT1 protein. Telomeric DNA end-binding, proteins have generally been found to inhibit rather than stimulate the, action of the chromosome end-replicating enzyme, telomerase. In contrast, we find that TPP1 and POT1 form a complex with telomeric DNA that, increases the activity and processivity of the human telomerase core, enzyme. We propose that POT1-TPP1 switches from inhibiting telomerase, access to the telomere, as a component of shelterin, to serving as a, processivity factor for telomerase during telomere extension.

About this Structure

2I46 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

The POT1-TPP1 telomere complex is a telomerase processivity factor., Wang F, Podell ER, Zaug AJ, Yang Y, Baciu P, Cech TR, Lei M, Nature. 2007 Feb 1;445(7127):506-10. Epub 2007 Jan 21. PMID:17237768

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