| Autor: |
McRae, Ewan K. S., Wan, Christopher J. K., Kristoffersen, Emil L., Hansen, Kalinka, Gianni, Edoardo, Gallego, Isaac, Curran, Joseph F., Attwater, James, Holliger, Philipp, Andersen, Ebbe S. |
| Předmět: |
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| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; 1/16/2024, Vol. 121 Issue 3, p1-11, 70p |
| Abstrakt: |
The emergence of an RNA replicase capable of self-replication is considered an important stage in the origin of life. RNA polymerase ribozymes (PR) -including a variant that uses trinucleotide triphosphates (triplets) as substrates -have been created by in vitro evolution and are the closest functional analogues of the replicase, but the structural basis for their function is poorly understood. Here we use single-particle cryogenic electron microscopy (cryo-EM) and high-throughput mutation analysis to obtain the structure of a triplet polymerase ribozyme (TPR) apoenzyme and map its functional landscape. The cryo-EM structure at 5-Å resolution reveals the TPR as an RNA heterodimer comprising a catalytic subunit and a noncatalytic, auxiliary subunit, resembling the shape of a left hand with thumb and fingers at a 70° angle. The two subunits are connected by two distinct kissing-loop (KL) interactions that are essential for polymerase function. Our combined structural and functional data suggest a model for templated RNA synthesis by the TPR holoenzyme, whereby heterodimer formation and KL interactions preorganize the TPR for optimal primer-template duplex binding, triplet substrate discrimination, and templated RNA synthesis. These results provide a better understanding of TPR structure and function and should aid the engineering of more efficient PRs. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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