Multiple POT1-TPP1 Proteins Coat and Compact Long Telomeric Single-Stranded DNA

JOURNAL OF MOLECULAR BIOLOGY

卷:410

Article

Taylor, Derek J.^1,2  Podell, Elaine R.^2,3  Taatjes, Dylan J.²  Cech, Thomas R.^2,3 

[1] Case Western Reserve Univ, Dept Pharmacol, Cleveland, OH 44106 USA

[2] Univ Colorado, Dept Chem & Biochem, Boulder, CO 80309 USA

[3] Howard Hughes Med Inst, Chevy Chase, MD USA

关键词: telomeres;    telomerase;    POT1;    TPP1;   

DOI  :  10.1016/j.jmb.2011.04.049

来源: Elsevier

【 摘 要 】

Telomeres are nucleoprotein complexes that cap and protect the ends of linear chromosomes. In humans, telomeres end in 50-300 nt of G-rich single-stranded DNA (ssDNA) overhangs. Protection of telomeres 1 (POT1) binds with nanomolar affinity to the ssDNA overhangs and forms a dimer with another telomere-end binding protein called TPP1. Whereas most previous studies utilized telomeric oligonucleotides comprising single POT1-TPP1 binding sites, here, we examined 72- to 144-nt tracts of telomeric DNA containing 6-12 POT1-TPP1 binding sites. Using electrophoretic mobility gel shift assays, size-exclusion chromatography, and electron microscopy, we analyzed telomeric nucleoprotein complexes containing POT1 alone, POT1-TPP1, and a truncated version of POT1 (POT1-N) that maintains its DNA-binding domain. The results revealed that POT1-N and POT1-TPP1 can completely coat long telomeric ssDNA substrates. Furthermore, we show that ssDNA coated with human POT1-TPP1 heterodimers forms compact, potentially ordered structures. (C) 2011 Elsevier Ltd. All rights reserved.

【 授权许可】

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