4RKD: Psychrophilic Aromatic Amino Acids Aminotransferase From Psychrobacter Sp. B6 Cocrystalized With Aspartic Acid

Citation:
Abstract
Aminotransferases (ATs) are enzymes that are commonly used in the chemical and pharmaceutical industries for the synthesis of natural and non-natural amino acids by transamination reactions. Currently, the easily accessible enzymes from mesophilic organisms are most commonly used; however, for economical and ecological reasons the utilization of aminotransferases from psychrophiles would be more advantageous, as their optimum reaction temperature is usually significantly lower than for the mesophilic ATs. Here, gene isolation, protein expression, purification, enzymatic properties and structural studies are reported for the cold-active aromatic amino-acid aminotransferase (PsyArAT) from Psychrobacter sp. B6, a psychrotrophic, Gram-negative strain from Antarctic soil. Preliminary computational analysis indicated dual functionality of the enzyme through the ability to utilize both aromatic amino acids and aspartate as substrates. This postulation was confirmed by enzymatic activity tests, which showed that it belonged to the class EC 2.6.1.57. The first crystal structures of a psychrophilic aromatic amino-acid aminotransferase have been determined at resolutions of 2.19 A for the native enzyme (PsyArAT) and 2.76 A for its complex with aspartic acid (PsyArAT/D). Both types of crystals grew in the monoclinic space group P21 under slightly different crystallization conditions. The PsyArAT crystals contained a dimer (90 kDa) in the asymmetric unit, which corresponds to the active form of this enzyme, whereas the crystals of the PsyArAT/D complex included four dimers showing different stages of the transamination reaction.
PDB ID: 4RKDDownload
MMDB ID: 127671
PDB Deposition Date: 2014/10/12
Updated in MMDB: 2015/04
Experimental Method:
x-ray diffraction
Resolution: 2.76  Å
Source Organism:
Similar Structures:
Biological Unit for 4RKD: dimeric; determined by author and by software (PISA)
Molecular Components in 4RKD
Label Count Molecule
Proteins (2 molecules)
2
Aromatic Amino Acid Aminotransferase
Molecule annotation
Chemicals (4 molecules)
1
1
2
2
3
1
* Click molecule labels to explore molecular sequence information.

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