PNAS reveals the topological intersection center of the misfolded tetrahymbranenuclease

The thermophila type I self-splicing introns are the first pure RNA system

On September 6, 2022, Zhang Kaiming of the University of Science and Technology of China and professors Rhiju Das and Wah Chiu of Stanford University cooperated to publish important research results

Using the advantages of cryo-EM to resolve highly heterogeneous and flexible sample structures, the researchers resolved the misfolded structure

Figure 1: The M and N topologies are different

This topological difference between M-isomorphism and N explains the failure of the 5'-splicing site substrate docking in M, supports the "topological isomer" model of slow refolding of M-toN due to trapped chain crossing, and proposes a pathway for M-to-N to refold (Figure 2

The intersection of J7/3 and J8/7 makes the direct transition from M to N chemically impossible during the transition from M to N ((1)).

Figure 2: A possible M-to-N refolding pathway

Overall, in this work, the researchers confirmed the topological differences between M and N and identified intersections involving the J7/3 and J8/7 core chains

The research has received strong support

Original link:of Life Sciences and Medicine, Key Laboratory of Cell Dynamics, Cryo-EM Platform, Scientific Research Department)