4AOA image
Entry Detail
PDB ID:
4AOA
Keywords:
Title:
Biochemical properties and crystal structure of a novel beta- phenylalanine aminotransferase from Variovorax paradoxus
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2012-03-25
Release Date:
2012-10-24
Method Details:
Experimental Method:
Resolution:
2.28 Å
R-Value Free:
0.22
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:BETA-PHENYLALANINE AMINOTRANSFERASE
Chain IDs:A, B
Chain Length:454
Number of Molecules:2
Biological Source:VARIOVORAX PARADOXUS
Primary Citation
Biochemical Properties and Crystal Structure of a Beta-Phenylalanine Aminotransferase from Variovorax Paradoxus.
Appl.Environ.Microbiol. 79 185 ? (2013)
PMID: 23087034 DOI: 10.1128/AEM.02525-12

Abstact

By selective enrichment, we isolated a bacterium that can use β-phenylalanine as a sole nitrogen source. It was identified by 16S rRNA gene sequencing as a strain of Variovorax paradoxus. Enzyme assays revealed an aminotransferase activity. Partial genome sequencing and screening of a cosmid DNA library resulted in the identification of a 1,302-bp aminotransferase gene, which encodes a 46,416-Da protein. The gene was cloned and overexpressed in Escherichia coli. The recombinant enzyme was purified and showed a specific activity of 17.5 U mg(-1) for (S)-β-phenylalanine at 30°C and 33 U mg(-1) at the optimum temperature of 55°C. The β-specific aminotransferase exhibits a broad substrate range, accepting ortho-, meta-, and para-substituted β-phenylalanine derivatives as amino donors and 2-oxoglutarate and pyruvate as amino acceptors. The enzyme is highly enantioselective toward (S)-β-phenylalanine (enantioselectivity [E], >100) and derivatives thereof with different substituents on the phenyl ring, allowing the kinetic resolution of various racemic β-amino acids to yield (R)-β-amino acids with >95% enantiomeric excess (ee). The crystal structures of the holoenzyme and of the enzyme in complex with the inhibitor 2-aminooxyacetate revealed structural similarity to the β-phenylalanine aminotransferase from Mesorhizobium sp. strain LUK. The crystal structure was used to rationalize the stereo- and regioselectivity of V. paradoxus aminotransferase and to define a sequence motif with which new aromatic β-amino acid-converting aminotransferases may be identified.

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