Open AccessThe rad51-K191R ATPase-Defective Mutant Is Impaired forPresynaptic Filament Formation
Author(s) -
Cindy W. Fung,
Gary S Fortin,
Shaun Peterson,
Lorraine S. Symington
Publication year - 2006
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00599-06
Subject(s) - rad51 , biology , atp hydrolysis , microbiology and biotechnology , homologous recombination , protein filament , helicase , dna , atpase , biochemistry , enzyme , gene , rna
Thenucleoprotein filament formed by Rad51 polymerization onsingle-stranded DNA is essential for homologous pairing and strandexchange. ATP binding is required for Rad51 nucleoprotein filamentformation and strand exchange, but ATP hydrolysis is not required forthese functions in vitro. Previous studies have shown that a yeaststrain expressing therad51-K191R allele is sensitive toionizing radiation, suggesting an important role for ATP hydrolysis invivo. The recruitment of Rad51-K191R to double-strand breaks isdefective in vivo, and this phenotype can be suppressed by eliminationof the Srs2 helicase, an antagonist of Rad51 filament formation. Thephenotype of therad51-K191R strain is also suppressed byoverexpression of Rad54. In vitro, the Rad51-K191R protein exhibits aslight decrease in binding to DNA, consistent with the defect inpresynaptic filament formation. However, therad51-K191R mutation is dominant in heterozygous diploids, indicating that thedefect is not due simply to reduced affinity for DNA. We suggest theRad51-K191R protein either forms an altered filament or is defective inturnover, resulting in a reduced pool of free protein available for DNAbinding.