4TMT: Translation Initiation Factor Eif5b (517-858) Mutant D533a From C. Thermophilum, Bound To Gtpgammas

Citation:
Abstract
Translational GTPases are universally conserved GTP hydrolyzing enzymes, critical for fidelity and speed of ribosomal protein biosynthesis. Despite their central roles, the mechanisms of GTP-dependent conformational switching and GTP hydrolysis that govern the function of trGTPases remain poorly understood. Here, we provide biochemical and high-resolution structural evidence that eIF5B and aEF1A/EF-Tu bound to GTP or GTPgammaS coordinate a monovalent cation (M(+)) in their active site. Our data reveal that M(+) ions form constitutive components of the catalytic machinery in trGTPases acting as structural cofactor to stabilize the GTP-bound "on" state. Additionally, the M(+) ion provides a positive charge into the active site analogous to the arginine-finger in the Ras-RasGAP system indicating a similar role as catalytic element that stabilizes the transition state of the hydrolysis reaction. In sequence and structure, the coordination shell for the M(+) ion is, with exception of eIF2gamma, highly conserved among trGTPases from bacteria to human. We therefore propose a universal mechanism of M(+)-dependent conformational switching and GTP hydrolysis among trGTPases with important consequences for the interpretation of available biochemical and structural data.
PDB ID: 4TMTDownload
MMDB ID: 123464
PDB Deposition Date: 2014/6/2
Updated in MMDB: 2014/11
Experimental Method:
x-ray diffraction
Resolution: 1.58  Å
Source Organism:
Similar Structures:
Biological Unit for 4TMT: monomeric; determined by author
Molecular Components in 4TMT
Label Count Molecule
Protein (1 molecule)
1
Eif5b
Molecule annotation
Chemicals (9 molecules)
1
1
2
1
3
5
4
1
5
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.