Research Paper Volume 4, Issue 11 pp 790—802

The helicase and ATPase activities of RECQL4 are compromised by mutations reported in three human patients

Martin Borch Jensen1, *,, Christopher A. Dunn1, *,, Guido Keijzers1, , Tomasz Kulikowicz2, , Lene Juel Rasmussen1, , Deborah L. Croteau2, , Vilhelm A. Bohr1,2, ,

  • 1 Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
  • 2 Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
* Equal contribution

Received: November 1, 2012       Accepted: December 1, 2012       Published: December 4, 2012      

https://doi.org/10.18632/aging.100506
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Abstract

RECQL4 is one of five members of the human RecQ helicase family, and is implicated in three syndromes displaying accelerating aging, developmental abnormalities and a predisposition to cancer. In this study, we purified three variants of RECQL4 carrying previously reported patient mutations. These three mutant proteins were analyzed for the known biochemical activities of RECQL4: DNA binding, unwinding of duplex DNA, ATP hydrolysis and annealing of simplex DNA. Further, the mutant proteins were evaluated for stability and recruitment to sites of laser-induced DNA damage. One mutant was helicase-dead, had marginal ATPase activity and may be structurally compromised, while the other two showed greatly reduced helicase and ATPase activities. The remaining biochemical activities and ability to recruit to damage sites were not significantly impaired for any of the mutants. Our findings demonstrate a consistent pattern of functional deficiency and provide further support for a helicase-dependent cellular function of RECQL4 in addition to its Nterminus-dependent role in initiation of replication, a function that may underlie the phenotype of RECQL4-linked disease.

Abbreviations

BGS: Baller-Gerold syndrome; BLM: Bloom syndrome protein; HRDC: Helicase/RNAse D C-terminal; RQC: RecQ C-terminal; RTS: Rothmund-Thomson syndrome; WRN: Werner syndrome ATP-dependent helicase.