Telomerase-associated protein 1, HSP90, and topoisomerase IIα associate directly with the BLM helicase in immortalized cells using ALT and modulate its helicase activity using telomeric DNA substrates

Saumitri Bhattacharyya, Jeremy Keirsey, Beatriz Russell, Jurai Kavecansky, Kate Lillard-Wetherell, Kambiz Tahmaseb, John Turchi, Joanna Groden

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Abstract

The BLM helicase associates with the telomere structural proteins TRF1 and TRF2 in immortalized cells using the alternative lengthening of telomere (ALT) pathways. This work focuses on identifying protein partners of BLM in cells using ALT. Mass spectrometry and immunoprecipitation techniques have identified three proteins that bind directly to BLM and TRF2 in ALT cells: telomerase-associated protein 1 (TEP1), heat shock protein 90 (HSP90), and topoisomerase IIα (TOPOIIα). BLM predominantly co-localizes with these proteins in foci actively synthesizing DNA during late S and G2/M phases of the cell cycle when ALT is thought to occur. Immunoprecipitation studies also indicate that only HSP90 and TOPOIIα are components of a specific complex containing BLM, TRF1, and TRF2 but that this complex does not include TEP1. TEP1, TOPOIIα, and HSP90 interact directly with BLM in vitro and modulate its helicase activity on telomere-like DNA substrates but not on non-telomeric substrates. Initial studies suggest that knockdown of BLM in ALT cells reduces average telomere length but does not do so in cells using telomerase.

Original languageEnglish
Pages (from-to)14966-14977
Number of pages12
JournalJournal of Biological Chemistry
Volume284
Issue number22
DOIs
StatePublished - May 29 2009

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Telomere Homeostasis
HSP90 Heat-Shock Proteins
Type II DNA Topoisomerase
Telomerase
Telomere
DNA
Substrates
Proteins
Immunoprecipitation
Telomeric Repeat Binding Protein 2
Telomeric Repeat Binding Protein 1
G2 Phase
Cell Division
Mass Spectrometry
Cell Cycle
Mass spectrometry
Cells

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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Telomerase-associated protein 1, HSP90, and topoisomerase IIα associate directly with the BLM helicase in immortalized cells using ALT and modulate its helicase activity using telomeric DNA substrates. / Bhattacharyya, Saumitri; Keirsey, Jeremy; Russell, Beatriz; Kavecansky, Jurai; Lillard-Wetherell, Kate; Tahmaseb, Kambiz; Turchi, John; Groden, Joanna.

In: Journal of Biological Chemistry, Vol. 284, No. 22, 29.05.2009, p. 14966-14977.

Research output: Contribution to journalArticle

Bhattacharyya, Saumitri ; Keirsey, Jeremy ; Russell, Beatriz ; Kavecansky, Jurai ; Lillard-Wetherell, Kate ; Tahmaseb, Kambiz ; Turchi, John ; Groden, Joanna. / Telomerase-associated protein 1, HSP90, and topoisomerase IIα associate directly with the BLM helicase in immortalized cells using ALT and modulate its helicase activity using telomeric DNA substrates. In: Journal of Biological Chemistry. 2009 ; Vol. 284, No. 22. pp. 14966-14977.
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