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Cryo-EM structure and functional landscape of an RNA polymerase ribozyme.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America . 1/16/2024, Vol. 121 Issue 3, p1-11. 70p. - Publication Year :
- 2024
-
Abstract
- 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]
- Subjects :
- *NON-coding RNA
*RNA polymerases
*RNA replicase
*RNA synthesis
*HETERODIMERS
Subjects
Details
- Language :
- English
- ISSN :
- 00278424
- Volume :
- 121
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 175225319
- Full Text :
- https://doi.org/10.1073/pnas.2313332121