A ring ATPase from a bacteriophage, ϕ29, helps load the dsDNA genome into the viral shell. It is shown that this motor packages the DNA in 10 base pair (bp) bursts, which are composed of four individual 2.5 bp steps, each representing hydrolysis of a single ATP. Such a non-integral step size is unexpected, and raises intriguing mechanistic questions about ATP hydrolysis within rings.
- Jeffrey R. Moffitt
- Yann R. Chemla
- Carlos Bustamante