Localization of recombination proteins and Srs2 reveals anti-recombinase function in vivo
| Authors | |
|---|---|
| Year of publication | 2009 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Cell Biology |
| MU Faculty or unit | |
| Citation | |
| Field | Genetics and molecular biology |
| Keywords | Homologous recombination; Srs2 anti-recombinase; Rad51 filaments; Rad54; Rad52; Replication fork |
| Description | Homologous recombination (HR), while an important DNA repair mechanism, is dangerous to the cell if improperly regulated. The Srs2 anti-recombinase restricts HR by disassembling the Rad51 nucleoprotein filament, an intermediate in homology search and exchange of homologous DNA strands. Here, through characterization of Srs2 function in vivo, we describe a novel mechanism for regulating the initiation of HR. We find that Srs2 is recruited separately to replication and repair centers, and describe the genetic requirements for its recruitment. In the absence of Srs2 activity, Rad51 foci accumulate, and surprisingly, these foci form in the absence of Rad52 mediation. However, these Rad51 foci do not represent repair proficient filaments as determined by recombination assays. Such antagonistic roles for Rad52 and Srs2 in Rad51 filament formation are also observed in vitro. Furthermore, we provide evidence that Srs2 removes Rad51 indiscriminately from DNA, while other HR proteins, particularly Rad52, coordinates appropriate filament reformation. This constant breakdown and rebuilding of filaments may act as a stringent quality control mechanism during HR. |
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