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A DEAD-Box Protein Alone Promotes Group II Intron Splicing and Reverse Splicing by Acting as an RNA Chaperone
Sabine Mohr, Manabu Matsuura, Philip S. Perlman and Alan M. Lambowitz
Proceedings of the National Academy of Sciences of the United States of America
Vol. 103, No. 10 (Mar. 7, 2006), pp. 3569-3574
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/30048628
Page Count: 6
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Group II intron RNAs self-splice in vitro but only at high salt and/or Mg²⁺ concentrations and have been thought to require proteins to stabilize their active structure for efficient splicing in vivo. Here, we show that a DEAD-box protein, CYT-19, can by itself promote the splicing and reverse splicing of the yeast al5γ and bll group II introns under near-physiological conditions by acting as an ATPdependent RNA chaperone, whose continued presence is not required after RNA folding. Our results suggest that the folding of some group II introns may be limited by kinetic traps and that their active structures, once formed, do not require proteins or high Mg²⁺ concentrations for structural stabilization. Thus, during evolution, group II introns could have spliced and transposed by reverse splicing by using ubiquitous RNA chaperones before acquiring more specific protein partners to promote their splicing and mobility. More generally, our results provide additional evidence for the widespread role of RNA chaperones in folding cellular RNAs.
Proceedings of the National Academy of Sciences of the United States of America © 2006 National Academy of Sciences