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Schwartz, A ; Walmacq, C ; Rahmouni, AR ; Boudvillain, M

Noncanonical interactions in the management of RNA structural blocks by the transcription termination Rho helicase

Biochemistry 46 (33) 9366-9379

par Administrateur - publié le

Abstract :

To trigger transcription termination, the ring-shaped RNA-DNA helicase Rho from Escherichia coli chases the RNA polymerase along the nascent transcript, starting from a single-stranded C-rich Rut (Rho utilization) loading site. In some instances, a small hairpin structure divides harmlessly the C-rich loading region into two smaller Rut subsites, best exemplified by the tR1 terminator from phage lambda. Here, we show that the Rho helicase can also elude a RNA structural block located far downstream from the single-stranded C-rich region but upstream from a reporter RNA-DNA hybrid. In this process, Rho hexamers do not melt the intervening RNA motif but require single-stranded RNA segments on both of its sides.