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. Author manuscript; available in PMC: 2016 Oct 10.
Published in final edited form as: Biochem Cell Biol. 2016 Mar 31;94(5):407–418. doi: 10.1139/bcb-2016-0012

Figure 4.

Figure 4

Hypothetical models for how the yeast Rad51 paralogues could associate with the Rad51-Rad52-RPA filament during HR [adapted from (Gibb et al. 2014)]. A DSB is recognized and resected to generate 3′ ssDNA overhangs, which are immediately coated by the ssDNA binding complex RPA. Rad52 then binds the RPA-coated ssDNA and stabilizes a patch of RPA on the ssDNA. Next, the Rad51 paralogues, Rad55-Rad57, form a higher order ensemble with Rad52 and the Shu complex to stimulate Rad51 filament formation. Although filaments of Rad52-RPA coat the Rad51 nucleoprotein filament, whether Rad55-Rad57 and the Shu complex exhibit similar interactions with the Rad51 nucleoprotein filament remains unknown. Three hypothetical models for how the Rad51 paralogues and the Shu complex may interact with the Rad52-RPA-Rad51 nucleoprotein filament are shown. On the left, Rad55-Rad57 and the Shu complex are released after Rad51 filaments form and are not associated with the Rad52-RPA-Rad51 filament. In the middle model, Rad55-Rad57 and the Shu complex are integrated into the Rad51 nucleoprotein filament but have no additional interactions with Rad52-RPA. On the right, Rad55-Rad57 and the Shu complex interact with Rad52-RPA and together coat the Rad51 filament as a co-filament. Importantly, the middle and right-hand models are not mutually exclusive, and Rad55-Rad57 and the Shu complex could both integrate into the Rad51 filament as well as form a co-filament with Rad52-RPA.