Disome-seq reveals widespread ribosome collisions that promote cotranslational protein folding

• Published in: Genome Biology Vol. 22; no. 1; p. 16
• Main Authors: Zhao, Taolan, Chen, Yan-Ming, Li, Yu, Wang, Jia, Chen, Siyu, Gao, Ning, Qian, Wenfeng
• Format: Journal Article
• Language: English
• Published: England BioMed Central 05.01.2021; BMC
• Subjects: Asparagine; Chaperones; Codons; cryo-electron microscopy; cysteine; Disome-seq; Electron microscopy; Genes; Glycine; Homeostasis; mRNA; Peptides; Polylysine; Proline; Protein folding; protein value; Quality control; Ribosome collision; Ribosome release; Ribosome-associated chaperones; Ribosomes; stop codon; Translation; Translation elongation; Translational pause; Yeast; Cotranslational protein folding; Translational pause; Disome structure; Translation elongation; Protein homeostasis; Ribosome collision; Ribosome-associated chaperones; Ribosome release; Disome-seq
• ISSN: 1474-760X; 1474-7596; 1474-760X
• DOI: 10.1186/s13059-020-02256-0

The folding of proteins is challenging in the highly crowded and sticky environment of a cell. Regulation of translation elongation may play a crucial role in ensuring the correct folding of proteins. Much of our knowledge regarding translation elongation comes from the sequencing of mRNA fragments protected by single ribosomes by ribo-seq. However, larger protected mRNA fragments have been observed, suggesting the existence of an alternative and previously hidden layer of regulation. In this study, we performed disome-seq to sequence mRNA fragments protected by two stacked ribosomes, a product of translational pauses during which the 5'-elongating ribosome collides with the 3'-paused one. We detected widespread ribosome collisions that are related to slow ribosome release when stop codons are at the A-site, slow peptide bond formation from proline, glycine, asparagine, and cysteine when they are at the P-site, and slow leaving of polylysine from the exit tunnel of ribosomes. The structure of disomes obtained by cryo-electron microscopy suggests a different conformation from the substrate of the ribosome-associated protein quality control pathway. Collisions occurred more frequently in the gap regions between α-helices, where a translational pause can prevent the folding interference from the downstream peptides. Paused or collided ribosomes are associated with specific chaperones, which can aid in the cotranslational folding of the nascent peptides. Therefore, cells use regulated ribosome collisions to ensure protein homeostasis.