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PMID:17237767

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Citation

Xin, H, Liu, D, Wan, M, Safari, A, Kim, H, Sun, W, O'Connor, MS and Songyang, Z (2007) TPP1 is a homologue of ciliate TEBP-beta and interacts with POT1 to recruit telomerase. Nature 445:559-62

Abstract

Telomere dysfunction may result in chromosomal abnormalities, DNA damage responses, and even cancer. Early studies in lower organisms have helped to establish the crucial role of telomerase and telomeric proteins in maintaining telomere length and protecting telomere ends. In Oxytricha nova, telomere G-overhangs are protected by the TEBP-alpha/beta heterodimer. Human telomeres contain duplex telomeric repeats with 3' single-stranded G-overhangs, and may fold into a t-loop structure that helps to shield them from being recognized as DNA breaks. Additionally, the TEBP-alpha homologue, POT1, which binds telomeric single-stranded DNA (ssDNA), associates with multiple telomeric proteins (for example, TPP1, TIN2, TRF1, TRF2 and RAP1) to form the six-protein telosome/shelterin and other subcomplexes. These telomeric protein complexes in turn interact with diverse pathways to form the telomere interactome for telomere maintenance. However, the mechanisms by which the POT1-containing telosome communicates with telomerase to regulate telomeres remain to be elucidated. Here we demonstrate that TPP1 is a putative mammalian homologue of TEBP-beta and contains a predicted amino-terminal oligonucleotide/oligosaccharide binding (OB) fold. TPP1-POT1 association enhanced POT1 affinity for telomeric ssDNA. In addition, the TPP1 OB fold, as well as POT1-TPP1 binding, seemed critical for POT1-mediated telomere-length control and telomere-end protection in human cells. Disruption of POT1-TPP1 interaction by dominant negative TPP1 expression or RNA interference (RNAi) resulted in telomere-length alteration and DNA damage responses. Furthermore, we offer evidence that TPP1 associates with the telomerase in a TPP1-OB-fold-dependent manner, providing a physical link between telomerase and the telosome/shelterin complex. Our findings highlight the critical role of TPP1 in telomere maintenance, and support a yin-yang model in which TPP1 and POT1 function as a unit to protect human telomeres, by both positively and negatively regulating telomerase access to telomere DNA.

Links

PubMed Online version:10.1038/nature05469

Keywords

Animals; Cell Line; Crystallography, X-Ray; DNA, Single-Stranded/chemistry; DNA, Single-Stranded/genetics; DNA, Single-Stranded/metabolism; Humans; Multiprotein Complexes/chemistry; Multiprotein Complexes/metabolism; Oxytricha/chemistry; Protein Binding; Protein Conformation; Protein Subunits/chemistry; Protein Subunits/metabolism; Sequence Homology, Amino Acid; Telomerase/metabolism; Telomere/enzymology; Telomere/genetics; Telomere/metabolism; Telomere-Binding Proteins/chemistry; Telomere-Binding Proteins/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

HUMAN:TERT

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:O14773-1

F

Seeded From UniProt

complete

HUMAN:TERT

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q96AP0

F

Seeded From UniProt

complete

HUMAN:TPP1

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:O14746

F

Seeded From UniProt

complete

HUMAN:ACD

involved_in

GO:0016233: telomere capping

ECO:0000303: author statement without traceable support used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ACD

involved_in

GO:0060381: positive regulation of single-stranded telomeric DNA binding

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ACD

enables

GO:0070182: DNA polymerase binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:O14746

F

Seeded From UniProt

complete

HUMAN:POTE1

enables

GO:0043047: single-stranded telomeric DNA binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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