PSY3 is one of the components of the yeast Shu complex that maintains genomic stability during replication. Psy3 complexes first with Cms2, and their L2 loops confer the DNA-binding activity to the Shu complex [1,2]. The Shu complex binds to recombination sites and is required for Rad51 assembly and function during meiosis. The heterodimer of Psy3-Csm2 stabilises the Rad51-single-stranded DNA complex independently of nucleotide cofactor because Psy3-Csm2 is a structural mimic of the Rad51-dimer [3].

1: Structural analysis of Shu proteins reveals a DNA binding role essential for resisting damage. Tao Y, Li X, Liu Y, Ruan J, Qi S, Niu L, Teng M; J Biol Chem. 2012;287:20231-20239. PMID:22465956

2: Structural and SAXS analysis of the budding yeast SHU-complex proteins. She Z, Gao ZQ, Liu Y, Wang WJ, Liu GF, Shtykova EV, Xu JH, Dong YH; FEBS Lett. 2012;586:2306-2312. PMID:22749910

3: A new protein complex promoting the assembly of Rad51 filaments. Sasanuma H, Tawaramoto MS, Lao JP, Hosaka H, Sanda E, Suzuki M, Yamashita E, Hunter N, Shinohara M, Nakagawa A, Shinohara A; Nat Commun. 2013;4:1676. PMID:23575680