Dynamics of uS19 C-Terminal Tail during the Translation Elongation Cycle in Human Ribosomes

Abstract

Ribosomes undergo multiple conformational transitions during translation elongation. Here, we report the high-resolution cryoelectron microscopy (cryo-EM) structure of the human 80S ribosome in the post-decoding pre-translocation state (classical-PRE) at 3.3-Å resolution along with the rotated (hybrid-PRE) and the post-translocation states (POST). The classical-PRE state ribosome structure reveals a previously unobserved interaction between the C-terminal region of the conserved ribosomal protein uS19 and the A-and P-site tRNAs and the mRNA in the decoding site. In addition to changes in the inter-subunit bridges, analysis of different ribosomal conformations reveals the dynamic nature of this domain and suggests a role in tRNA accommodation and translocation during elongation. Furthermore, we show that diseaseassociated mutations in uS19 result in increased frameshifting. Together, this structure-function analysis provides mechanistic insights into the role of the uS19 C-terminal tail in the context of mammalian ribosomes.

Recent Advances in Archaeal Translation Initiation

“…Consistent with the archaeal case, the tails of uS13 and uS19 were recently observed in contact with the anticodon stem of the initiator tRNA in a mammalian late-stage initiation complex (Simonetti et al, 2020). On another hand, uS13 and uS19 are also involved in translation elongation, as observed recently in a mammalian elongation complex (Bhaskar et al, 2020) and during the translocation step in bacteria (Zhou et al, 2013).…”

“…Notably, the core domains of uS13 and uS19, located on the SSU head, are involved in the B1a and B1b/c bridges with the large ribosomal subunit (LSU). Several studies in yeast identified allosteric information pathways connecting functional centers in the LSU to the decoding center in the SSU through these bridges (Ben-Shem et al, 2011;Rhodin and Dinman, 2011;Bowen et al, 2015;Bhaskar et al, 2020). Interestingly, archaeal and eukaryotic uS13 and uS19 have sequence insertions in their core domains as compared to the bacterial proteins.…”

“…The view is a composite using the SSU from PDB 6SWC (Coureux et al, 2020) and the LSU from PDB 4V6U (Armache et al, 2013). (B) Structure of human ribosome from PDB 6Y0G (Bhaskar et al, 2020). (C) Structure of Escherichia coli ribosome from PDB 5AFI (Fischer et al, 2015).…”

Structural basis for translational shutdown and immune evasion by the Nsp1 protein of SARS-CoV-2

“…( D ) Cross-section of the 40S highlighting the central position of Nsp1 within the mRNA tunnel. The putative position of the N-terminal domain of Nsp1 is schematically indicated [models based on PDB-2HSX ( 21 ) and PDB-6Y0G ( 47 )]. ( E ) SDS-PAGE analysis of Nsp1-ribosomal complexes affinity purified from HEK293T cells.…”

“…( D ) mRNA entry channel, 40S head is removed. Nsp1-C occupies the mRNA path [mRNA based on PDB-6Y0G ( 47 )]. ( E ) K164 and H165 of Nsp1 bind to a pocket on h18.…”