1MF1: Structure Of The Recombinant Mouse-muscle Adenylosuccinate Synthetase Complexed With Amp

Adenylosuccinate synthetase governs the committed step of AMP biosynthesis, the generation of 6-phosphoryl-IMP from GTP and IMP followed by the formation of adenylosuccinate from 6-phosphoryl-IMP and l-aspartate. The enzyme is subject to feedback inhibition by AMP and adenylosuccinate, but crystallographic complexes of the mouse muscle synthetase presented here infer mechanisms of inhibition that involve potentially synergistic ligand combinations. AMP alone adopts the productive binding mode of IMP and yet stabilizes the active site in a conformation that favors the binding of Mg(2+)-IMP to the GTP pocket. On the other hand, AMP, in the presence of GDP, orthophosphate, and Mg(2+), adopts the binding mode of adenylosuccinate. Depending on circumstances then, AMP behaves as an analogue of IMP or as an analogue of adenylosuccinate. The complex of adenylosuccinate.GDP.Mg(2+).sulfate, the first structure of an adenylosuccinate-bound synthetase, reveals significant geometric distortions and tight nonbonded contacts relevant to the proposed catalytic mechanism. Adenylosuccinate forms from 6-phosphoryl-IMP and l-aspartate by the movement of the purine ring into the alpha-amino group of l-aspartate.
PDB ID: 1MF1Download
MMDB ID: 20980
PDB Deposition Date: 2002/8/9
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.7  Å
Source Organism:
Similar Structures:
Biological Unit for 1MF1: dimeric; determined by author and by software (PISA,PQS)
Molecular Components in 1MF1
Label Count Molecule
Proteins (2 molecules)
Adenylosuccinate Synthetase(Gene symbol: Adssl1)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

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