| Budget Amount *help |
¥18,590,000 (Direct Cost: ¥14,300,000、Indirect Cost: ¥4,290,000)
Fiscal Year 2012: ¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000)
Fiscal Year 2011: ¥5,590,000 (Direct Cost: ¥4,300,000、Indirect Cost: ¥1,290,000)
Fiscal Year 2010: ¥7,670,000 (Direct Cost: ¥5,900,000、Indirect Cost: ¥1,770,000)
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| Research Abstract |
Rad51 has a central role in recombination, assembling onto single-stranded DNA as a nucleoprotein filament and catalyzing the invasion and exchange of homologous DNA sequences. Generally, Rad51 requires the assistance of mediators to overcome the inhibition by RPA. The Swi5-Sfr1 complex has been identified as a mediator, and recent studies have shown that it can activate recombinases directly, and thus this complex is the first molecule for the recombinase activator.We describe the crystal structure of the C-terminal half of Sfr1 in complex with Swi5 from S. pombe. Swi5 and Sfr1 form a parallel coiled-coil heterodimer, joined firmly together by formation of two newly identified leucine-zipper motifs and a bundle. Remarkably, the coiled-coil is sharply kinked, generating an elongated and curved shape. This molecular shape is suitable for binding within the reconstituted helical groove of the Rad51 filament, causing the activation of Rad51 filament by stabilizing it as an active form with a longer helical pitch. Biochemical analysis shows that the C-terminal region of Sfr1 complexed with Swi5 possesses the essential function of Swi5-Sfr1 for a recombination activator, while the N-terminal region of Sfr1 plays a role for the efficient recruitment of the Swi5-Sfr1 complex. Swi5-Sfr1 is conserved from yeast to humans, and therefore the phenomena presented here would be prevalent among all eukaryotic organisms.
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