6s05
From Proteopedia
Cryo-EM structures of Lsg1-TAP pre-60S ribosomal particles
Structural highlights
Function[REH1_YEAST] Pre-60S-associated cytoplasmic factor involved in the cytoplasmic maturation of the 60S subunit. May act redundantly with REI1 to directly promote a stabilizing structural rearrangement in cytoplasmic 60S subunit maturation independent on the REI1-specific ARX1 recycling.[1] [RL25_YEAST] This protein binds to a specific region on the 26S rRNA. [IF6_YEAST] Binds to the 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit to form the 80S initiation complex in the cytoplasm. Is also involved in ribosome biogenesis. Associates with pre-60S subunits in the nucleus and is involved in its nuclear export. Cytoplasmic release of TIF6 from 60S subunits and nuclear relocalization is promoted by the GTPase RIA1/EFL1 and by SDO1. Also required for pre-rRNA processing.[2] [3] [4] [5] [6] [7] [RL16B_YEAST] Component of the ribosome, a large ribonucleoprotein complex responsible for the synthesis of proteins in the cell. The small ribosomal subunit (SSU) binds messenger RNAs (mRNAs) and translates the encoded message by selecting cognate aminoacyl-transfer RNA (tRNA) molecules. The large subunit (LSU) contains the ribosomal catalytic site termed the peptidyl transferase center (PTC), which catalyzes the formation of peptide bonds, thereby polymerizing the amino acids delivered by tRNAs into a polypeptide chain. The nascent polypeptides leave the ribosome through a tunnel in the LSU and interact with protein factors that function in enzymatic processing, targeting, and the membrane insertion of nascent chains at the exit of the ribosomal tunnel.[8] [NMD3_YEAST] Acts as an adapter for the XPO1/CRM1-mediated export of the 60S ribosomal subunit. Unlikely to play a significant role in nonsense-mediated mRNA decay (NMD).[9] [RL5_YEAST] Binds 5S RNA and is required for 60S subunit assembly. [RL4A_YEAST] Participates in the regulation of the accumulation of its own mRNA.[10] [RL37A_YEAST] Binds to the 23S rRNA (By similarity). [PVH1_YEAST] May be directly involved in signal transduction and/or cell cycle regulation. It is necessary for maintaining growth rate or spore germination. Could show both activity toward tyrosine-protein phosphate as well as with serine-protein phosphate. [LSG1_YEAST] GTPase required for the nuclear export of the 60S ribosomal subunit. Acts by mediating the release of NMD3 from the 60S ribosomal subunit after export into the cytoplasm.[11] [12] [13] [14] [RL11A_YEAST] Binds to 5S ribosomal RNA. Publication Abstract from PubMedDuring their final maturation in the cytoplasm, pre-60S ribosomal particles are converted to translation-competent large ribosomal subunits. Here, we present the mechanism of peptidyltransferase centre (PTC) completion that explains how integration of the last ribosomal proteins is coupled to release of the nuclear export adaptor Nmd3. Single-particle cryo-EM reveals that eL40 recruitment stabilises helix 89 to form the uL16 binding site. The loading of uL16 unhooks helix 38 from Nmd3 to adopt its mature conformation. In turn, partial retraction of the L1 stalk is coupled to a conformational switch in Nmd3 that allows the uL16 P-site loop to fully accommodate into the PTC where it competes with Nmd3 for an overlapping binding site (base A2971). Our data reveal how the central functional site of the ribosome is sculpted and suggest how the formation of translation-competent 60S subunits is disrupted in leukaemia-associated ribosomopathies. Mechanism of completion of peptidyltransferase centre assembly in eukaryotes.,Kargas V, Castro-Hartmann P, Escudero-Urquijo N, Dent K, Hilcenko C, Sailer C, Zisser G, Marques-Carvalho MJ, Pellegrino S, Wawiorka L, Freund SM, Wagstaff JL, Andreeva A, Faille A, Chen E, Stengel F, Bergler H, Warren AJ Elife. 2019 May 22;8. pii: 44904. doi: 10.7554/eLife.44904. PMID:31115337[15] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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