期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2008
卷号：105
期号：37
页码：13853-13858
DOI：10.1073/pnas.0804034105
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Group II intron ribozymes fold into their native structure by a unique stepwise process that involves an initial slow compaction followed by fast formation of the native state in a Mg2+-dependent manner. Single-molecule fluorescence reveals three distinct on-pathway conformations in dynamic equilibrium connected by relatively small activation barriers. From a most stable near-native state, the unobserved catalytically active conformer is reached. This most compact conformer occurs only transiently above 20 mM Mg2+ and is stabilized by substrate binding, which together explain the slow cleavage of the ribozyme. Structural dynamics increase with increasing Mg2+ concentrations, enabling the enzyme to reach its active state.
关键词：multidomain RNA folding ; single-molecule Förster resonance energy transfer ; splicing ; structural dynamics ; metal ions
