Structure of the Rho transcription terminator: mechanism of mRNA recognition and helicase loading

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