Natural Sciences and Engineering Research Council (NSERC, Canada)
532417
カナダ
The Carlsberg Foundation
CF20-0635
デンマーク
Lundbeckfonden
R250-2017-1502
デンマーク
UK Research and Innovation (UKRI)
MC_U105178804
英国
EIPOD fellowship under Marie Sklodowska-Curie Actions COFUND
H2020-MSCA-IF-2018-845303
ドイツ
The Carlsberg Foundation
CF17-0809
デンマーク
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2024 タイトル: Cryo-EM structure and functional landscape of an RNA polymerase ribozyme. 著者: Ewan K S McRae / Christopher J K Wan / Emil L Kristoffersen / Kalinka Hansen / Edoardo Gianni / Isaac Gallego / Joseph F Curran / James Attwater / Philipp Holliger / Ebbe S Andersen / 要旨: 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 ...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.