Campus Units

Zoology

Document Type

Article

Publication Version

Published Version

Publication Date

3-1995

Journal or Book Title

Molecular and Cellular Biology

Volume

15

Issue

3

First Page

1144

Last Page

1153

DOI

10.1128/MCB.15.3.1144

Abstract

Telomeric DNA of Tetrahymena thermophila consists of a long stretch of (TTGGGG)n double-stranded repeats with a single-stranded (TTGGGG)2 3' overhang at the end of the chromosome. We have identified and characterized a protein that specifically binds to a synthetic telomeric substrate consisting of duplex DNA and the 3' telomeric repeat overhang. This protein is called TEP (telomere end-binding protein). A change from G to A in the third position of the TTGGGG overhang repeat converts the substrate to a human telomere analog and reduces the binding affinity approximately threefold. Changing two G's to C's in the TTGGGG repeats totally abolishes binding. However, permutation of the Tetrahymena repeat sequence has only a minor effect on binding. A duplex structure adjacent to the 3' overhang is required for binding, although the duplex need not contain telomeric repeats. TEP does not bind to G-quartet DNA, which is formed by many G-rich sequences. TEP has a greatly reduced affinity for RNA substrates. The copy number of TEP is at least 2 x 10(4) per cell, and it is present under different conditions of cell growth and development, although its level varies. UV cross-linking experiments show that TEP has an apparent molecular mass of approximately 65 kDa. Unlike other telomere end-binding proteins, TEP is sensitive to high salt concentrations.

Comments

This article is from Molecular and Cellular Biology 15 (1995): 1144, doi: 10.1128/MCB.15.3.1144. Posted with permission.

Copyright Owner

American Society for Microbiology

Language

en

File Format

application/pdf

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