3DEG: Complex Of Elongating Escherichia Coli 70s Ribosome And Ef4(lepa)- Gmppnp

Citation:
Abstract
EF4 (LepA) is an almost universally conserved translational GTPase in eubacteria. It seems to be essential under environmental stress conditions and has previously been shown to back-translocate the tRNAs on the ribosome, thereby reverting the canonical translocation reaction. In the current work, EF4 was directly visualized in the process of back-translocating tRNAs by single-particle cryo-EM. Using flexible fitting methods, we built a model of ribosome-bound EF4 based on the cryo-EM map and a recently published unbound EF4 X-ray structure. The cryo-EM map establishes EF4 as a noncanonical elongation factor that interacts not only with the elongating ribosome, but also with the back-translocated tRNA in the A-site region, which is present in a previously unseen, intermediate state and deviates markedly from the position of a canonical A-tRNA. Our results, therefore, provide insight into the underlying structural principles governing back-translocation.
PDB ID: 3DEGDownload
MMDB ID: 66179
PDB Deposition Date: 2008/6/10
Updated in MMDB: 2008/08
Experimental Method:
electron microscopy
Resolution: 10.9  Å
Source Organism:
Escherichia coli K-12
Similar Structures:
Biological Unit for 3DEG: undecameric; determined by author
Molecular Components in 3DEG
Label Count Molecule
Proteins (3 molecules)
1
Gtp-binding Protein Lepa(Gene symbol: lepA)
Molecule annotation
1
30S Ribosomal Protein S12(Gene symbol: rpsL)
Molecule annotation
1
50S Ribosomal Protein L11(Gene symbol: rplK)
Molecule annotation
Nucleotides(8 molecules)
1
A/l-trna
Molecule annotation
1
P-trna
Molecule annotation
1
30S RNA Helix 8
Molecule annotation
1
30S RNA Helix 14
Molecule annotation
1
50S RNA Helix 42-44
Molecule annotation
1
50S RNA Helix 95
Molecule annotation
1
50S RNA Helix 71
Molecule annotation
1
50S RNA Helix 92
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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