3CMQ: Crystal Structure of Human Mitochondrial Phenylalanine tRNA Synthetase

All class II aminoacyl-tRNA synthetases (aaRSs) are known to be active as functional homodimers, homotetramers, or heterotetramers. However, multimeric organization is not a prerequisite for phenylalanylation activity, as monomeric mitochondrial phenylalanyl-tRNA synthetase (PheRS) is also active. We herein report the structure, at 2.2 A resolution, of a human monomeric mitPheRS complexed with Phe-AMP. The smallest known aaRS, which is, in fact, 1/5 of a cytoplasmic analog, is a chimera of the catalytic module of the alpha and anticodon binding domain (ABD) of the bacterial beta subunit of (alphabeta)2 PheRS. We demonstrate that the ABD located at the C terminus of mitPheRS overlaps with the acceptor stem of phenylalanine transfer RNA (tRNAPhe) if the substrate is positioned in a manner similar to that seen in the binary Thermus thermophilus complex. Thus, formation of the PheRS-tRNAPhe complex in human mitochondria must be accompanied by considerable rearrangement (hinge-type rotation through approximately 160 degrees) of the ABD upon tRNA binding.
PDB ID: 3CMQDownload
MMDB ID: 65260
PDB Deposition Date: 2008/3/24
Updated in MMDB: 2008/12 
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 3CMQ: monomeric; determined by author and by software (PISA)
Molecular Components in 3CMQ
Label Count Molecule
Protein (1 molecule)
Phenylalanyl-trna Synthetase, Mitochondrial(Gene symbol: FARS2)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB