1GC4: Thermus Thermophilus Aspartate Aminotransferase Tetra Mutant 2 Complexed With Aspartate

Citation:
Abstract
Aspartate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus HB8 (ttAspAT), has been believed to be specific for an acidic substrate. However, stepwise introduction of mutations in the active-site residues finally changed its substrate specificity to that of a dual-substrate enzyme. The final mutant, [S15D, T17V, K109S, S292R] ttAspAT, is active toward both acidic and hydrophobic substrates. During the course of stepwise mutation, the activities toward acidic and hydrophobic substrates changed independently. The introduction of a mobile Arg292* residue into ttAspAT was the key step in the change to a "dual-substrate" enzyme. The substrate recognition mechanism of this thermostable "dual-substrate" enzyme was confirmed by X-ray crystallography. This work together with previous studies on various enzymes suggest that this unique "dual-substrate recognition" mechanism is a feature of not only aminotransferases but also other enzymes.
PDB ID: 1GC4Download
MMDB ID: 17040
PDB Deposition Date: 2000/7/19
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 3.3  Å
Source Organism:
Similar Structures:
Biological Unit for 1GC4: dimeric; determined by author and by software (PISA)
Molecular Components in 1GC4
Label Count Molecule
Proteins (2 molecules)
2
Aspartate Aminotransferase(Gene symbol: TTHA0046)
Molecule annotation
Chemicals (4 molecules)
1
2
2
2
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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