Summary information and primary citation
- PDB-id
-
3deg;
DSSR-derived features in text and
JSON formats
- Class
- ribosome
- Method
- cryo-EM (10.9 Å)
- Summary
- Complex of elongating escherichia coli 70s ribosome and
ef4(lepa)-gmppnp
- Reference
-
Connell SR, Topf M, Qin Y, Wilson DN, Mielke T, Fucini P,
Nierhaus KH, Spahn CMT (2008): "A new tRNA
intermediate revealed on the ribosome during EF4-mediated
back-translocation." Nat.Struct.Mol.Biol.,
15, 910-915. doi: 10.1038/nsmb.1469.
- 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.
