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spinqualitylabelsall models PDB ID 1qz9 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 1.85Å
Ligands:	, and
Activity:	Kynureninase, with EC number 3.7.1.3
Coordinates:	save as pdb, mmCIF, xml

The Three Dimensional Structure of Kynureninase from Pseudomonas fluorescens

Overview

Kynureninase [E.C. 3.7.1.3] is a pyridoxal-5'-phosphate (PLP)-dependent enzyme that catalyzes the hydrolytic cleavage of l-kynurenine to anthranilic acid and l-alanine. Sequence alignment with other PLP-dependent enzymes indicated that kynureninase is in subgroup IVa of the aminotransferases, along with nifS, CsdB, and serine-pyruvate aminotransferase, which suggests that kynureninase has an aminotransferase fold. Crystals of Pseudomonas fluorescens kynureninase were obtained, and the structure was solved by molecular replacement using the CsdB coordinates combined with multiple isomorphous heavy atom replacement. The coordinates were deposited in the PDB (ID code 1QZ9). The structure, refined to an R factor of 15.5% to 1.85 A resolution, is dimeric and has the aminotransferase fold. The structure also confirms the prediction from sequence alignment that Lys-227 is the PLP-binding residue in P. fluorescens kynureninase. The conserved Asp-201, expected for an aminotransferase fold, is located near the PLP nitrogen, but Asp-132 is also strictly conserved and at a similar distance from the pyridinium nitrogen. Mutagenesis of both conserved aspartic acids shows that both contribute equally to PLP binding, but Asp-201 has a greater role in catalysis. The structure shows that Tyr-226 donates a hydrogen bond to the phosphate of PLP. Unusual among PLP-dependent enzymes, Trp-256, which is also strictly conserved in kynureninases from bacteria to humans, donates a hydrogen bond to the phosphate through the indole N1-hydrogen.

About this Structure

1QZ9 is a Single protein structure of sequence from Pseudomonas fluorescens. Full crystallographic information is available from OCA.

Reference

Three-dimensional structure of kynureninase from Pseudomonas fluorescens., Momany C, Levdikov V, Blagova L, Lima S, Phillips RS, Biochemistry. 2004 Feb 10;43(5):1193-203. PMID:14756555

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