4RRR: K121M mutant of N-terminal editing domain of threonyl-tRNA synthetase from Pyrococcus abyssi with L-Thr3AA

Proofreading modules of aminoacyl-tRNA synthetases are responsible for enforcing a high fidelity during translation of the genetic code. They use strategically positioned side chains for specifically targeting incorrect aminoacyl-tRNAs. Here, we show that a unique proofreading module possessing a D-aminoacyl-tRNA deacylase fold does not use side chains for imparting specificity or for catalysis, the two hallmark activities of enzymes. We show, using three distinct archaea, that a side-chain-stripped recognition site is fully capable of solving a subtle discrimination problem. While biochemical probing establishes that RNA plays the catalytic role, mechanistic insights from multiple high-resolution snapshots reveal that differential remodelling of the catalytic core at the RNA-peptide interface provides the determinants for correct proofreading activity. The functional crosstalk between RNA and protein elucidated here suggests how primordial enzyme functions could have emerged on RNA-peptide scaffolds before recruitment of specific side chains.
PDB ID: 4RRRDownload
MMDB ID: 130843
PDB Deposition Date: 2014/11/6
Updated in MMDB: 2017/12
Experimental Method:
x-ray diffraction
Resolution: 1.86  Å
Source Organism:
Similar Structures:
Biological Unit for 4RRR: dimeric; determined by author and by software (PISA)
Molecular Components in 4RRR
Label Count Molecule
Proteins (2 molecules)
Threonine--trna Ligase(Gene symbol: PAB_RS07200)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB