3UZK: Crystal Structure Analysis Of Ribosomal Decoding

Citation:
Abstract
During protein synthesis, the ribosome accurately selects transfer RNAs (tRNAs) in accordance with the messenger RNA (mRNA) triplet in the decoding centre. tRNA selection is initiated by elongation factor Tu, which delivers tRNA to the aminoacyl tRNA-binding site (A site) and hydrolyses GTP upon establishing codon-anticodon interactions in the decoding centre. At the following proofreading step the ribosome re-examines the tRNA and rejects it if it does not match the A codon. It was suggested that universally conserved G530, A1492 and A1493 of 16S ribosomal RNA, critical for tRNA binding in the A site, actively monitor cognate tRNA, and that recognition of the correct codon-anticodon duplex induces an overall ribosome conformational change (domain closure). Here we propose an integrated mechanism for decoding based on six X-ray structures of the 70S ribosome determined at 3.1-3.4 A resolution, modelling cognate or near-cognate states of the decoding centre at the proofreading step. We show that the 30S subunit undergoes an identical domain closure upon binding of either cognate or near-cognate tRNA. This conformational change of the 30S subunit forms a decoding centre that constrains the mRNA in such a way that the first two nucleotides of the A codon are limited to form Watson-Crick base pairs. When U.G and G.U mismatches, generally considered to form wobble base pairs, are at the first or second codon-anticodon position, the decoding centre forces this pair to adopt the geometry close to that of a canonical C.G pair. This by itself, or with distortions in the codon-anticodon mini-helix and the anticodon loop, causes the near-cognate tRNA to dissociate from the ribosome.
MMDB ID: 99565
PDB Deposition Date: 2011/12/7
Updated in MMDB: 2012/08
Experimental Method:
x-ray diffraction
Resolution: 3.3  Å
Source Organism:
Escherichia coli APEC O78
Similar Structures:
Merged PDB IDs:3UZK 3UZL 3UZM 3UZN
Asymmetric Unit for 3UZK: 110-meric
Molecular Components in 3UZK
Label Count Molecule
Proteins (96 molecules)
2
50S Ribosomal Protein L2
Molecule annotation
2
50S Ribosomal Protein L3
Molecule annotation
2
50S Ribosomal Protein L4
Molecule annotation
2
50S Ribosomal Protein L5
Molecule annotation
2
50S Ribosomal Protein L6
Molecule annotation
2
50S Ribosomal Protein L9
Molecule annotation
2
50S Ribosomal Protein L13
Molecule annotation
2
50S Ribosomal Protein L14
Molecule annotation
2
50S Ribosomal Protein L15
Molecule annotation
2
50S Ribosomal Protein L16
Molecule annotation
2
50S Ribosomal Protein L17
Molecule annotation
2
50S Ribosomal Protein L18
Molecule annotation
2
50S Ribosomal Protein L19
Molecule annotation
2
50S Ribosomal Protein L20
Molecule annotation
2
50S Ribosomal Protein L21
Molecule annotation
2
50S Ribosomal Protein L22
Molecule annotation
2
50S Ribosomal Protein L23
Molecule annotation
2
50S Ribosomal Protein L24
Molecule annotation
2
50S Ribosomal Protein L25
Molecule annotation
2
50S Ribosomal Protein L27
Molecule annotation
2
50S Ribosomal Protein L28
Molecule annotation
2
50S Ribosomal Protein L29
Molecule annotation
2
50S Ribosomal Protein L30
Molecule annotation
2
50S Ribosomal Protein L31
Molecule annotation
2
50S Ribosomal Protein L32
Molecule annotation
2
50S Ribosomal Protein L33
Molecule annotation
2
50S Ribosomal Protein L34
Molecule annotation
2
50S Ribosomal Protein L35
Molecule annotation
2
30S Ribosomal Protein S2
Molecule annotation
2
30S Ribosomal Protein S3
Molecule annotation
2
30S Ribosomal Protein S4
Molecule annotation
2
30S Ribosomal Protein S5
Molecule annotation
2
30S Ribosomal Protein S6
Molecule annotation
2
30S Ribosomal Protein S7
Molecule annotation
2
30S Ribosomal Protein S8
Molecule annotation
2
30S Ribosomal Protein S9
Molecule annotation
2
30S Ribosomal Protein S10
Molecule annotation
2
30S Ribosomal Protein S11
Molecule annotation
2
30S Ribosomal Protein S12
Molecule annotation
2
30S Ribosomal Protein S13
Molecule annotation
2
30S Ribosomal Protein S14
Molecule annotation
2
30S Ribosomal Protein S15
Molecule annotation
2
30S Ribosomal Protein S16
Molecule annotation
2
30S Ribosomal Protein S17
Molecule annotation
2
30S Ribosomal Protein S18
Molecule annotation
2
30S Ribosomal Protein S19
Molecule annotation
2
30S Ribosomal Protein S20
Molecule annotation
2
30S Ribosomal Protein THX
Molecule annotation
Nucleotides(7 molecules)
1
RNA (2912-mer)
Molecule annotation
2
5S Ribosomal RNA
Molecule annotation
2
16S Ribosomal RNA
Molecule annotation
4
tRNA-tyr
Molecule annotation
2
tRNA-fmet
Molecule annotation
2
mRNA
Molecule annotation
1
23S Ribosomal RNA
Molecule annotation
Chemicals (1619 molecules)
1
903
2
710
3
4
4
2
* Click molecule labels to explore molecular sequence information.

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