9Q2H

Rad55-Rad57-SHU homologous recombination complex

Summary for 9Q2H

• Entry DOI: 10.2210/pdb9q2h/pdb
• EMDB information: 72165
• Descriptor: Methylated-DNA--protein-cysteine methyltransferase,DNA repair protein RAD55, DNA repair protein RAD57, Chromosome segregation in meiosis protein 2, ... (9 entities in total)
• Functional Keywords: homologous recombination complex, rad51 paralog complex, dna binding protein, dna binding protein-transferase complex, dna binding protein/transferase
• Biological source: Saccharomyces cerevisiae (brewer's yeast); More
• Total number of polymer chains: 6
• Total formula weight: 227756.13

Authors

Yatskevich, S.,Koo, C.W.,Ciferri, C. (deposition date: 2025-08-15, release date: 2026-07-29, Last modification date: 2026-09-30)

Primary citation

Koo, C.W.,Gore, S.K.,Ro, S.Y.,Liu, J.,Yu, C.,Azumaya, C.M.,Brillantes, B.,Zilberleyb, I.,Chen, H.,Rafiqzada, M.B.,Garcia Sanchez, L.,Heyer, W.D.,Ciferri, C.,Yatskevich, S.
Yeast Rad55-Rad57-SHU paralog complex dynamically promotes Rad51 filament formation.
Mol.Cell, 86:3639-, 2026

PubMed Abstract: Homologous recombination (HR) is an important DNA repair pathway that safeguards genome integrity. During HR, the Rad51 nucleoprotein filaments catalyze strand invasion into a homologous duplex DNA. Filament formation requires a conserved family of Rad51 paralogs that act as tumor suppressors in humans. By capturing six distinct states using cryo-electron microscopy, we reveal that the Saccharomyces cerevisiae Rad51 paralog complex, composed of the Rad55-Rad57 heterodimer and the SHU (Psy3-Csm2-Shu1-Shu2) complex, selectively brings Rad51 to single-stranded DNA to seed filament formation. Rad51 itself is a transient yet integral component of this machinery which binds along the Rad57 subunit to complete a high-affinity DNA-binding site. We also uncover a dual-nucleotide regulatory mechanism: a structural ADP molecule stabilizes the complex, while a second, catalytic ATPase site at the Rad57-Rad51 interface promotes the release of the paralog complex. These structural and mechanistic features provide a blueprint for understanding the function of Rad51 paralogs across eukaryotes.

PubMed: 42480524
DOI: 10.1016/j.molcel.2026.06.045

Experimental method

ELECTRON MICROSCOPY (2.74 Å)