Right or left turn? RecA family protein filaments promote homologous recombination through clockwise axial rotation.
The RecA family proteins mediate homologous recombination, a ubiquitous mechanism for repairing DNA double-strand breaks (DSBs) and stalled replication forks. Members of this family include bacterial RecA, archaeal RadA and Rad51, and eukaryotic Rad51 and Dmc1. These proteins bind to single-stranded DNA at a DSB site to form a presynaptic nucleoprotein filament, align this presynaptic filament with homologous sequences in another double-stranded DNA segment, promote DNA strand exchange and then dissociate. It was generally accepted that RecA family proteins function throughout their catalytic cycles as right-handed helical filaments with six protomers per helical turn. However, we recently reported that archaeal RadA proteins can also form an extended right-handed filament with three monomers per helical turn and a left-handed protein filament with four monomers per helical turn. Subsequent structural and functional analyses suggest that RecA family protein filaments, similar to the F1-ATPase rotary motor, perform ATP-dependent clockwise axial rotation during their catalytic cycles. This new hypothesis has opened a new avenue for understanding the molecular mechanism of RecA family proteins in homologous recombination.
Wang
Ting-Fang
TF
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan. tfwang@gate.sinica.edu.tw
Chen
Li-Tzu
LT
Wang
Andrew H-J
AH
D000818:Animals; D002384:Catalysis; D003599:Cytoskeleton / Q000737:chemistry / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D008958:Models, Molecular; D005810:Multigene Family / Q000502:physiology; D020836:Protein Structure, Quaternary; D011938:Rec A Recombinases / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D011995:Recombination, Genetic / Q000502:physiology*; D012399:Rotation
D011938:Rec A Recombinases