1. Ctp1 protein-DNA filaments promote DNA bridging and DNA double-strand break repair.
- Author
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Andres, Sara N., Li, Zimeng M., Erie, Dorothy A., and Williams, R. Scott
- Subjects
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DNA-binding proteins , *NUCLEOTIDE sequencing , *SCHIZOSACCHAROMYCES , *TETRAMERS (Oligomers) , *DOUBLE-strand DNA breaks - Abstract
The Ctp1 protein in Schizosaccharomyces pombe is essential for DNA double-strand break (DSB) repair by homologous recombination. Fission yeast Ctp1 and its budding yeast (Sae2) and human (CtIP) homologs control Mre11-Rad50-Nbs1 nuclease complex activity and harbor DNA-binding and -bridging activities. However, the molecular basis for Ctp1-DNA transactions remains undefined. Here, we report atomic force microscopy (AFM) imaging of S. pombe Ctp1-DNA complexes revealing that Ctp1 polymerizes ondsDNAmolecules and forms synaptic filaments that bridge two dsDNA strands.Weobserved that Ctp1 DNA filaments are typified by an average filament length of ~180 bp of dsDNA and a Ctp1 tetramer footprint of ~15 bp. Biochemical results characterizing Ctp1 variants with impaired DNA-binding or -bridging properties were consistent with Ctp1-mediatedDNAbridging requiring the intact and correctly folded Ctp1 tetramer. Furthermore, mutations altering Ctp1 oligomerization and DNA bridging in vitro conferred cell sensitivity to DSB-producing agents. Together, these results support an important role for Ctp1-regulatedDNAstrand coordination required for DNA DSB repair in S. pombe. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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