7zhg
From Proteopedia
High-resolution cryo-EM structure of Pyrococcus abyssi 30S ribosomal subunit bound to mRNA and initiator tRNA anticodon stem-loop
Structural highlights
Function[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. [RS19E_PYRAB] May be involved in maturation of the 30S ribosomal subunit. [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. [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. [RS3_PYRAB] Binds the lower part of the 30S subunit head. [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. [RS11_PYRAB] Located on the platform of the 30S subunit (By similarity). [RS12_PYRAB] With S4 and S5 plays an important role in translational accuracy. Located at the interface of the 30S and 50S subunits. [RS17_PYRAB] One of the primary rRNA binding proteins, it binds specifically to the 5'-end of 16S ribosomal RNA.[HAMAP-Rule:MF_01345] [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. [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 PubMedIn eukaryotes and in archaea late steps of translation initiation involve the two initiation factors e/aIF5B and e/aIF1A. In eukaryotes, the role of eIF5B in ribosomal subunit joining is established and structural data showing eIF5B bound to the full ribosome were obtained. To achieve its function, eIF5B collaborates with eIF1A. However, structural data illustrating how these two factors interact on the small ribosomal subunit have long been awaited. The role of the archaeal counterparts, aIF5B and aIF1A, remains to be extensively addressed. Here, we study the late steps of Pyrococcus abyssi translation initiation. Using in vitro reconstituted initiation complexes and light scattering, we show that aIF5B bound to GTP accelerates subunit joining without the need for GTP hydrolysis. We report the crystallographic structures of aIF5B bound to GDP and GTP and analyze domain movements associated to these two nucleotide states. Finally, we present the cryo-EM structure of an initiation complex containing 30S bound to mRNA, Met-tRNAiMet, aIF5B and aIF1A at 2.7 A resolution. Structural data shows how archaeal 5B and 1A factors cooperate to induce a conformation of the initiator tRNA favorable to subunit joining. Archaeal and eukaryotic features of late steps of translation initiation are discussed. Role of aIF5B in archaeal translation initiation.,Kazan R, Bourgeois G, Lazennec-Schurdevin C, Larquet E, Mechulam Y, Coureux PD, Schmitt E Nucleic Acids Res. 2022 Jun 24;50(11):6532-6548. doi: 10.1093/nar/gkac490. PMID:35694843[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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