6swe | pdb_00006swe
IC2 head of cryo-EM structure of a full archaeal ribosomal translation initiation complex devoid of aIF1 in P. abyssi
Structural highlights
Function[RS14Z_PYRAB] Binds 16S rRNA, required for the assembly of 30S particles. [RS19E_PYRAB] May be involved in maturation of the 30S ribosomal subunit. [RS7_PYRAB] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the head domain of the 30S subunit. Is located at the subunit interface close to the decoding center. [RS3_PYRAB] Binds the lower part of the 30S subunit head. [IF1A_PYRAB] Seems to be required for maximal rate of protein biosynthesis. Enhances ribosome dissociation into subunits and stabilizes the binding of the initiator Met-tRNA(I) to 40 S ribosomal subunits (By similarity). [RS19_PYRAB] Protein S19 forms a complex with S13 that binds strongly to the 16S ribosomal RNA. [RS10_PYRAB] Involved in the binding of tRNA to the ribosomes. [RL7A_PYRAB] Multifunctional RNA-binding protein that recognizes the K-turn motif in ribosomal RNA, the RNA component of RNase P, box H/ACA, box C/D and box C'/D' sRNAs. [RS13_PYRAB] Located at the top of the head of the 30S subunit, it contacts several helices of the 16S rRNA. In the 70S ribosome it contacts the 23S rRNA (bridge B1a) and protein L5 of the 50S subunit (bridge B1b), connecting the 2 subunits; these bridges are implicated in subunit movement. Publication Abstract from PubMedArchaeal translation initiation occurs within a macromolecular complex containing the small ribosomal subunit (30S) bound to mRNA, initiation factors aIF1, aIF1A and the ternary complex aIF2:GDPNP:Met-tRNAi(Met). Here, we determine the cryo-EM structure of a 30S:mRNA:aIF1A:aIF2:GTP:Met-tRNAi(Met) complex from Pyrococcus abyssi at 3.2 A resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N(4)-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without aIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life. Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation.,Coureux PD, Lazennec-Schurdevin C, Bourcier S, Mechulam Y, Schmitt E Commun Biol. 2020 Feb 6;3(1):58. doi: 10.1038/s42003-020-0780-0. PMID:32029867[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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