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- Title
A stepwise 2′-hydroxyl activation mechanism for the bacterial transcription termination factor Rho helicase.
- Authors
Schwartz, Annie; Rabhi, Makhlouf; Jacquinot, Frédérique; Margeat, Emmanuel; Rahmouni, A Rachid; Boudvillain, Marc
- 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 (∼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.
- Subjects
GENES; GAUSSIAN distribution; RIBOSOMAL DNA; DNA helicases; NUCLEOTIDES; HYDROXYL group; ENZYMES
- Publication
Nature Structural & Molecular Biology, 2009, Vol 16, Issue 12, p1309
- ISSN
1545-9993
- Publication type
Article
- DOI
10.1038/nsmb.1711