6sw9
From Proteopedia
IC2A model of cryo-EM structure of a full archaeal ribosomal translation initiation complex devoid of aIF1 in P. abyssi
Structural highlights
Function[IF2G_SACS2] eIF-2 functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA.[HAMAP-Rule:MF_00119] [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. [RS5_PYRAB] With S4 and S12 plays an important role in translational accuracy. [RS14Z_PYRAB] Binds 16S rRNA, required for the assembly of 30S particles. [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. [RS3_PYRAB] Binds the lower part of the 30S subunit head. [RS11_PYRAB] Located on the platform of the 30S subunit (By similarity). [RS8_PYRAB] One of the primary rRNA binding proteins, it binds directly to 16S rRNA central domain where it helps coordinate assembly of the platform of the 30S subunit. [IF2A_SACS2] eIF-2 functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA.[HAMAP-Rule:MF_00231] [RS19E_PYRAB] May be involved in maturation of the 30S ribosomal subunit. [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. [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. [RS12_PYRAB] With S4 and S5 plays an important role in translational accuracy. Located at the interface of the 30S and 50S subunits. [IF2B_SACS2] eIF-2 functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA.[HAMAP-Rule:MF_00232] [RS17_PYRAB] One of the primary rRNA binding proteins, it binds specifically to the 5'-end of 16S ribosomal RNA.[HAMAP-Rule:MF_01345] [RS4_PYRAB] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the body of the 30S subunit. With S5 and S12 plays an important role in translational accuracy. 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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