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From Proteopedia
THE CRYSTAL STRUCTURE OF THE 50S LARGE RIBOSOMAL SUBUNIT FROM DEINOCOCCUS RADIODURANS COMPLEXED WITH TROLEANDOMYCIN MACROLIDE ANTIBIOTIC
Structural highlights
FunctionRL22_DEIRA This protein binds specifically to 23S rRNA; its binding is stimulated by other ribosomal proteins, e.g. L4, L17, and L20. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome (By similarity).[HAMAP-Rule:MF_01331_B] The globular domain of the protein is located by the polypeptide exit tunnel on the outside of the subunit while an extended beta-hairpin forms part of the wall of the tunnel. Forms a pair of "tweezers" with L32 that hold together two different domains of the 23S rRNA. Interacts with the tunnel-blocking modified macrolide azithromycin. Upon binding of the macrolide troleadomycin to the ribosome, the tip of the beta-hairpin is displaced, which severely restricts the tunnel. This and experiments in E.coli have led to the suggestion that it is part of the gating mechanism involved in translation arrest in the absence of the protein export system.[HAMAP-Rule:MF_01331_B] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedNascent proteins emerge out of ribosomes through an exit tunnel, which was assumed to be a firmly built passive path. Recent biochemical results, however, indicate that the tunnel plays an active role in sequence-specific gating of nascent chains and in responding to cellular signals. Consistently, modulation of the tunnel shape, caused by the binding of the semi-synthetic macrolide troleandomycin to the large ribosomal subunit from Deinococcus radiodurans, was revealed crystallographically. The results provide insights into the tunnel dynamics at high resolution. Here we show that, in addition to the typical steric blockage of the ribosomal tunnel by macrolides, troleandomycin induces a conformational rearrangement in a wall constituent, protein L22, flipping the tip of its highly conserved beta-hairpin across the tunnel. On the basis of mutations that alleviate elongation arrest, the tunnel motion could be correlated with sequence discrimination and gating, suggesting that specific arrest motifs within nascent chain sequences may induce a similar gating mechanism. Structural insight into the role of the ribosomal tunnel in cellular regulation.,Berisio R, Schluenzen F, Harms J, Bashan A, Auerbach T, Baram D, Yonath A Nat Struct Biol. 2003 May;10(5):366-70. PMID:12665853[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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