Concerted folding of a Candida ribozyme into the catalytically active structure posterior to a rapid RNA compaction |
| |
Authors: | Xiao Mu Leibowitz Michael J Zhang Yi |
| |
Institution: | Department of Biotechnology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China. |
| |
Abstract: | Folding of the major population of Tetrahymena intron RNA into the catalytically active structure is trapped in a slow pathway. In this report, folding of Candida albicans intron was investigated using the trans-acting Ca.L-11 ribozyme as a model. We demonstrated that both the catalytic activity (kobs) and compact folding equilibrium of Ca.L-11 are strongly dependent on Mg2+ at physiological concentrations, with both showing an Mg2+ Hill coefficient of 3. Formation of the compact structure of Ca.L-11 is shown to occur very rapidly, on a subsecond time scale similar to that of RNase T1 cleavage. Most of the ribozyme RNA population folds into the catalytically active structure with a rate constant of 2 min–1 at 10 mM Mg2+; neither slower kinetics nor obvious Mg2+ inhibition is observed. These results suggest that folding of the Ca.L-11 ribozyme is initiated by a rapid magnesium-dependent RNA compaction, which is followed by a slower searching for the native contacts to form the catalytically active structure without interference from the long-lived trapped states. This model thus provides an ideal system to address a range of interesting aspects of RNA folding, such as conformational searching, ion binding and the role of productive intermediates. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|