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Walmacq, C ; Rahmouni, AR ; Boudvillain, M

Influence of substrate composition on the helicase activity of transcription termination factor Rho : Reduced processivity of unwinding of RNA-DNA Rho hexamers during hybrid regions

Journal of Molecular Biology 342 (2) 403-420

par Administrateur - publié le

Abstract :

Transcription termination factor Rho forms ring-shaped hexameric structures that load onto segments of the nascent RNA transcript that are C-rich and mostly single-stranded. This interaction converts Rho hexamers into active molecular motors that use the energy resulting from their ATP hydrolase activity to move towards the transcript 3’-end. Upon translocation along the RNA chain, Rho can displace physical roadblocks, such as those formed by RNA-DNA helices, a feature that is likely central to the transcription termination mechanism. To study this translocase (helicase) activity, we have designed a collection of Rho substrate chimeras containing an RNA-DNA helix located at various positions with respect to a short (47 nucleotides) artificial loading site.