A stepwise 2 '-hydroxyl activation mechanism for the bacterial transcription termination factor Rho helicase

Abstract : The bacterial Rho factor is a ring-shaped ATP-dependent helicase that tracks along RNA transcripts and disrupts RNA-DNA duplexes and transcription complexes in its path. Using combinatorial nucleotide analog interference mapping (NAIM), we explore the topology and dynamics of functional Rho-RNA complexes and reveal the RNA-dependent stepping mechanism of Rho helicase. Periodic Gaussian distributions of NAIM signals show that Rho forms uneven productive interactions with the track nucleotides and disrupts RNA-DNA duplexes in a succession of large(similar to 7-nucleotide-long) discrete steps triggered by 2'-hydroxyl activation events. This periodic 2'-OH-dependent activation does not depend on the RNA-DNA pairing energy but is finely tuned by sequence-dependent interactions with the RNA track. These features explain the strict RNA specificity and contextual efficiency of the enzyme and provide a new paradigm for conditional tracking by a helicase ring.
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Submitted on : Monday, October 11, 2010 - 4:11:59 PM
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Annie Schwartz, Makhlouf Rabhi, Frederique Jacquinot, Emmanuel Margeat, A. Rachid Rahmouni, et al.. A stepwise 2 '-hydroxyl activation mechanism for the bacterial transcription termination factor Rho helicase. Nature Structural and Molecular Biology, Nature Publishing Group, 2009, 16 (12), pp.1309-1316. ⟨10.1038/nsmb.1711⟩. ⟨hal-00525325⟩

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