National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
P41GM103832
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01GM079429
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
U24GM129541
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R35GM122579
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R21 AI145647
米国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2022 タイトル: Topological crossing in the misfolded ribozyme resolved by cryo-EM. 著者: Shanshan Li / Michael Z Palo / Grigore Pintilie / Xiaojing Zhang / Zhaoming Su / Kalli Kappel / Wah Chiu / Kaiming Zhang / Rhiju Das / 要旨: The group I intron has been a key system in the understanding of RNA folding and misfolding. The molecule folds into a long-lived misfolded intermediate (M) , which has been known to form extensive ...The group I intron has been a key system in the understanding of RNA folding and misfolding. The molecule folds into a long-lived misfolded intermediate (M) , which has been known to form extensive native-like secondary and tertiary structures but is separated by an unknown kinetic barrier from the native state (N). Here, we used cryogenic electron microscopy (cryo-EM) to resolve misfolded structures of the L-21 ScaI ribozyme. Maps of three M substates (M1, M2, M3) and one N state were achieved from a single specimen with overall resolutions of 3.5 Å, 3.8 Å, 4.0 Å, and 3.0 Å, respectively. Comparisons of the structures reveal that all the M substates are highly similar to N, except for rotation of a core helix P7 that harbors the ribozyme's guanosine binding site and the crossing of the strands J7/3 and J8/7 that connect P7 to the other elements in the ribozyme core. This topological difference between the M substates and N state explains the failure of 5'-splice site substrate docking in M, supports a topological isomer model for the slow refolding of M to N due to a trapped strand crossing, and suggests pathways for M-to-N refolding.