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4v6g

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Initiation complex of 70S ribosome with two tRNAs and mRNA.

Structural highlights

4v6g is a 20 chain structure with sequence from Thermus thermophilus HB8. This structure supersedes the now removed PDB entries 3i9b, 3i9c, 3i9d and 3i9e. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 3.5Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

RL20_THET8 Binds directly to 23S ribosomal RNA and is necessary for the in vitro assembly process of the 50S ribosomal subunit. It is not involved in the protein synthesizing functions of that subunit (By similarity).[HAMAP-Rule:MF_00382]

Publication Abstract from PubMed

One key question in protein biosynthesis is how the ribosome couples mRNA and tRNA movements to prevent disruption of weak codon-anticodon interactions and loss of the translational reading frame during translocation. Here we report the complete path of mRNA on the 70S ribosome at the atomic level (3.1-A resolution), and we show that one of the conformational rearrangements that occurs upon transition from initiation to elongation is a narrowing of the downstream mRNA tunnel. This rearrangement triggers formation of a network of interactions between the mRNA downstream of the A-site codon and the elongating ribosome. Our data elucidate the mechanism by which hypermodified nucleoside 2-methylthio-N6 isopentenyl adenosine at position 37 (ms(2)i(6)A37) in tRNA(Phe)(GAA) stabilizes mRNA-tRNA interactions in all three tRNA binding sites. Another network of contacts is formed between this tRNA modification and ribosomal elements surrounding the mRNA E/P kink, resulting in the anchoring of P-site tRNA. These data allow rationalization of how modification deficiencies of ms(2)i(6)A37 in tRNAs may lead to shifts of the translational reading frame.

Structural aspects of messenger RNA reading frame maintenance by the ribosome.,Jenner LB, Demeshkina N, Yusupova G, Yusupov M Nat Struct Mol Biol. 2010 May;17(5):555-60. Epub 2010 Apr 18. PMID:20400952^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Jenner LB, Demeshkina N, Yusupova G, Yusupov M. Structural aspects of messenger RNA reading frame maintenance by the ribosome. Nat Struct Mol Biol. 2010 May;17(5):555-60. Epub 2010 Apr 18. PMID:20400952 doi:10.1038/nsmb.1790