DNA rotation by a coordinated conformational change of RecA filaments

RecA protein forms two types of filament structures in the presence or absence of nucleotide cofactors. We recently constructed two molecular models of the DNA structure, the unwound form (N-type structure) and the twisted form (S-type structure), which correspond to the helical pitches of the extended form (ATP form) and compressed form (non-nucleotide form) of the RecA filament, respectively. If ATP hydrolysis is unidirectional and cooperative, and if the extended and compressed forms of RecA filament are interconvertible, the coordinated conformational change travels along the filament. While the RecA filament undergoes this worm-like motion, the wave of conformational change between the unwound and the twisted forms of DNA travels as ATP hydrolyzes, which makes the DNA strands rotate.