The RecQ helicase Sgs1 drives ATP-dependent disruption of Rad51 filaments

Nucleic Acids Res. 2019 May 21;47(9):4694-4706. doi: 10.1093/nar/gkz186.

Abstract

DNA helicases of the RecQ family are conserved among the three domains of life and play essential roles in genome maintenance. Mutations in several human RecQ helicases lead to diseases that are marked by cancer predisposition. The Saccharomyces cerevisiae RecQ helicase Sgs1 is orthologous to human BLM, defects in which cause the cancer-prone Bloom's Syndrome. Here, we use single-molecule imaging to provide a quantitative mechanistic understanding of Sgs1 activities on single stranded DNA (ssDNA), which is a central intermediate in all aspects of DNA metabolism. We show that Sgs1 acts upon ssDNA bound by either replication protein A (RPA) or the recombinase Rad51. Surprisingly, we find that Sgs1 utilizes a novel motor mechanism for disrupting ssDNA intermediates bound by the recombinase protein Rad51. The ability of Sgs1 to disrupt Rad51-ssDNA filaments may explain some of the defects engendered by RECQ helicase deficiencies in human cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / genetics
  • Bloom Syndrome / genetics
  • Bloom Syndrome / pathology
  • DNA Repair / genetics
  • DNA, Single-Stranded
  • Humans
  • Mutation / genetics
  • Rad51 Recombinase / genetics*
  • RecQ Helicases / genetics*
  • Recombination, Genetic*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / genetics*

Substances

  • DNA, Single-Stranded
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphate
  • RAD51 protein, S cerevisiae
  • RAD51 protein, human
  • Rad51 Recombinase
  • Bloom syndrome protein
  • SGS1 protein, S cerevisiae
  • RecQ Helicases