PDBsum entry 2hzp

Hydrolase

PDB id: 2hzp

Contents

Protein chain

447 a.a. *

Ligands

PLP

Waters ×540

* Residue conservation analysis

PDB id:

2hzp

Name:

Hydrolase

Title:

Crystal structure of homo sapiens kynureninase

Structure:

Kynureninase. Chain: a. Synonym: l-kynurenine hydrolase. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: kynu. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.00Å R-factor: 0.152 R-free: 0.195

Authors:

S.Lima,R.Khristoforov,C.Momany,R.S.Phillips

Key ref:

S.Lima et al. (2007). Crystal structure of Homo sapiens kynureninase. Biochemistry, 46, 2735-2744. PubMed id: 17300176 DOI: 10.1021/bi0616697

Date:

09-Aug-06 Release date: 07-Nov-06

Protein chain

Q16719  (KYNU_HUMAN) -  Kynureninase from Homo sapiens

Seq: 465 a.a.

Struc: 447 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.3.7.1.3 - kynureninase.
• Pathway: Tryptophan Catabolism
• Reaction: L-kynurenine + H2O = anthranilate + L-alanine + H⁺
• Cofactor: Pyridoxal 5'-phosphate

Pyridoxal 5'-phosphate (Bound ligand (Het Group name = PLP) matches with 93.75% similarity)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/bi0616697

Biochemistry 46:2735-2744 (2007)

PubMed id: 17300176

Crystal structure of Homo sapiens kynureninase.

S.Lima, R.Khristoforov, C.Momany, R.S.Phillips.

ABSTRACT

Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.