1pv4

Publication Abstract from PubMed

In bacteria, one of the major transcriptional termination mechanisms requires a RNA/DNA helicase known as the Rho factor. We have determined two structures of Rho complexed with nucleic acid recognition site mimics in both free and nucleotide bound states to 3.0 A resolution. Both structures show that Rho forms a hexameric ring in which two RNA binding sites--a primary one responsible for target mRNA recognition and a secondary one required for mRNA translocation and unwinding--point toward the center of the ring. Rather than forming a closed ring, the Rho hexamer is split open, resembling a "lock washer" in its global architecture. The distance between subunits at the opening is sufficiently wide (12 A) to accommodate single-stranded RNA. This open configuration most likely resembles a state poised to load onto mRNA and suggests how related ring-shaped enzymes may be breached to bind nucleic acids.

Structure of the Rho transcription terminator: mechanism of mRNA recognition and helicase loading.,Skordalakes E, Berger JM Cell. 2003 Jul 11;114(1):135-46. PMID:12859904^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.