Cryo-EM structure of the Arabidopsis thaliana ribosome in translating and non-translating states

Translational control of mRNA expression underpins much of post-transcriptional gene expression driving developmental processes in eukaryotes. How ribosomal mRNA translation is executed in plants may be especially important for adapting to an ever-changing environment. Arabidopsis thaliana is the main genetic model organism in plant science, yet structural insights into developmental processes where ribosomal gene expression plays important roles currently remain lacking. Here, we present cryoelectron microscopy (cryo-EM) structures of the Arabidopsis cytosolic ribosome in both translating and non-translating states, which together provide new structural details into how translation of cytosolic mRNAs is coordinated. Our structures reveal detailed information on the interactions of tRNAs, mRNA, and the nascent polypeptide with subunits of the actively translating 80S ribosome and the role of ribosomal RNA methylation in stabilizing ribosomal subunits. The structures provide a foundation for interpreting the functional effects of many mutations of ribosomal proteins affecting phenotypic effects for plant tissue development.