Transcription Termination Factor Rho

Transcription termination factor Rho is a ring-shaped RNA-DNA helicase that induces release of transcription complexes at specific loci of bacterial genomes. Several structures of Rho in various liganded states haven been solved by X-ray crystallography by the J. M. Berger lab (Berkeley): 1a8v, 1pv4, 1pvo, 1xpr, 1xpu, 2a8v, and 2ht1.

The asymmetric unit solved as 2ht1 contains only two chains, so it represents only one third of the Biological unit, which is a homo-hexamer.

Here is one representation showing the Rho hexamer in a closed state and with RNA fragments occupying both its primary and secondary binding sites. <applet load='Rho1.pdb' size='300' frame='true' align='right' scene='Transcription_Termination_Factor_Rho/Rho_closed_1/3'>