Dataset Information

The OB-fold domain 1 of human POT1 recognizes both telomeric and non-telomeric DNA motifs.

ABSTRACT: The POT1 protein plays a critical role in telomere protection and telomerase regulation. POT1 binds single-stranded 5'-TTAGGGTTAG-3' and forms a dimer with the TPP1 protein. The dimer is recruited to telomeres, either directly or as part of the Shelterin complex. Human POT1 contains two Oligonucleotide/Oligosaccharide Binding (OB) fold domains, OB1 and OB2, which make physical contact with the DNA. OB1 recognizes 5'-TTAGGG whereas OB2 binds to the downstream TTAG-3'. Studies of POT1 proteins from other species have shown that some of these proteins are able to recognize a broader variety of DNA ligands than expected. To explore this possibility in humans, we have used SELEX to reexamine the sequence-specificity of the protein. Using human POT1 as a selection matrix, high-affinity DNA ligands were selected from a pool of randomized single-stranded oligonucleotides. After six successive rounds of selection, two classes of high-affinity targets were obtained. The first class was composed of oligonucleotides containing a cognate POT1 binding sites (5'-TTAGGGTTAG-3'). The second and more abundant class was made of molecules that carried a novel non-telomeric consensus: 5'-TNCANNAGKKKTTAGG-3' (where K = G/T and N = any base). Binding studies showed that these non-telomeric sites were made of an OB1-binding motif (TTAGG) and a non-telomeric motif (NT motif), with the two motifs recognized by distinct regions of the OB1 domain. POT1 interacted with these non-telomeric binding sites with high affinity and specificity, even when bound to its dimerization partner TPP1. This intrinsic ability of POT1 to recognize NT motifs raises the possibility that the protein may fulfill additional functions at certain non-telomeric locations of the genome, in perhaps gene transcription, replication, or repair.

SUBMITTER: Choi KH

PROVIDER: S-EPMC4500675 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The OB-fold domain 1 of human POT1 recognizes both telomeric and non-telomeric DNA motifs.

Choi Kyung H KH Lakamp-Hawley Amanda S AS Kolar Carol C Yan Ying Y Borgstahl Gloria E O GEO Ouellette Michel M MM

Biochimie 20150428

The POT1 protein plays a critical role in telomere protection and telomerase regulation. POT1 binds single-stranded 5'-TTAGGGTTAG-3' and forms a dimer with the TPP1 protein. The dimer is recruited to telomeres, either directly or as part of the Shelterin complex. Human POT1 contains two Oligonucleotide/Oligosaccharide Binding (OB) fold domains, OB1 and OB2, which make physical contact with the DNA. OB1 recognizes 5'-TTAGGG whereas OB2 binds to the downstream TTAG-3'. Studies of POT1 proteins fro ...[more]

PMID: 25934589

Similar Datasets

Project description:BACKGROUND: Cellular senescence is a state reached by normal mammalian cells after a finite number of cell divisions and is characterized by morphological and physiological changes including terminal cell-cycle arrest. The limits on cell division imposed by senescence may play an important role in both organismal aging and in preventing tumorigenesis. Cellular senescence and organismal aging are both accompanied by increased DNA damage, seen as the formation of gamma-H2AX foci (gamma-foci), which may be found on uncapped telomeres or at non-telomeric sites of DNA damage. However, the relative importance of telomere- and non-telomere-associated DNA damage to inducing senescence has never been demonstrated. Here we present a new approach to determine accurately the chromosomal location of gamma-foci and quantify the number of telomeric versus non-telomeric gamma-foci associated with senescence in both human and mouse cells. This approach enables researchers to obtain accurate values and to avoid various possible misestimates inherent in earlier methods. RESULTS: Using combined immunofluorescence and telomere fluorescence in situ hybridization on metaphase chromosomes, we show that human cellular senescence is not solely determined by telomeric DNA damage. In addition, mouse cellular senescence is not solely determined by non-telomeric DNA damage. By comparing cells from different generations of telomerase-null mice with human cells, we show that cells from late generation telomerase-null mice, which have substantially short telomeres, contain mostly telomeric gamma-foci. Most notably, we report that, as human and mouse cells approach senescence, all cells exhibit similar numbers of total gamma-foci per cell, irrespective of chromosomal locations. CONCLUSION: Our results suggest that the chromosome location of senescence-related gamma-foci is determined by the telomere length rather than species differences per se. In addition, our data indicate that both telomeric and non-telomeric DNA damage responses play equivalent roles in signaling the initiation of cellular senescence and organismal aging. These data have important implications in the study of mechanisms to induce or delay cellular senescence in different species.

Dataset Information

The OB-fold domain 1 of human POT1 recognizes both telomeric and non-telomeric DNA motifs.

Publications

The OB-fold domain 1 of human POT1 recognizes both telomeric and non-telomeric DNA motifs.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets