Rotary motion of Rho hexameric helicase elucidated

UC Berkeley researchers, James Berger and Nathan Thomsen, used the SIBYLS beamline to solve the structure of a hexameric helicase, the Rho transcription termination factor (from E. coli), bound to both ATP mimics and an RNA substrate. The results showed that Rho functions like a rotary engine: as the motor spins, it pulls RNA strands through it’s interior. The rotary firing order of the motor is biased so that the Rho protein can walk in only one direction along the RNA chain. The results were [published](http://dx.doi.org/10.1016/j.cell.2009.08.043) in the Oct 30th issue of Cell, and have recently been [written up](http://www.als.lbl.gov/als/science/sci_archive/206hexhelicase.html) as an ALS scientific highlight.