1ykj

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spinqualitylabelsall models 1ykj, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

A45G p-hydroxybenzoate hydroxylase with p-hydroxybenzoate bound

Overview

p-Hydroxybenzoate hydroxylase (PHBH) is a homodimeric flavoprotein, monooxygenase that catalyzes the hydroxylation of p-hydroxybenzoate to, form 3,4-dihydroxybenzoate. Controlled catalysis is achieved by movement, of the flavin and protein between three conformations, in, out, and open, [Entsch, B., et al. (2005) Arch. Biochem. Biophys. 433, 297-311]. The open, conformation is important for substrate binding and product release, the, in conformation for reaction with oxygen and hydroxylation, and the out, conformation for the reduction of FAD by NADPH. The open conformation is, similar to the structure of Arg220Gln-PHBH in which the backbone peptide, loop of residues 43-46, located on the si side of the flavin, is rotated., In this paper, we examine the structure and properties of the, Ala45Gly-PHBH mutant enzyme. The crystal structure of the Ala45Gly enzyme, is an asymmetric dimer, with one monomer similar (but not identical) to, wild-type PHBH, while the other monomer has His72 flipped into solvent and, replaced with Glu73 as one of several changes in the structure. The two, structures correlate with evidence from kinetic studies for two forms of, Ala45Gly-PHBH. One form of the enzyme dominates turnover and hydroxylates, while the other contributes little to turnover and fails to hydroxylate., Ala45Gly-PHBH favors the in conformation over alternative conformations., The effect of this mutation on the structure and function of PHBH, illustrates the importance of the si side loop in the conformational state, of PHBH and, consequently, the function of the enzyme. This work, demonstrates some general principles of how enzymes use conformational, movements to allow both access and egress of substrates and product, while, restricting access to the solvent at a critical stage in catalysis.

About this Structure

1YKJ is a Single protein structure of sequence from Pseudomonas aeruginosa with SO4, FAD, PHB and PSL as ligands. Active as 4-hydroxybenzoate 3-monooxygenase, with EC number 1.14.13.2 Full crystallographic information is available from OCA.

Reference

Removal of a methyl group causes global changes in p-hydroxybenzoate hydroxylase., Cole LJ, Gatti DL, Entsch B, Ballou DP, Biochemistry. 2005 Jun 7;44(22):8047-58. PMID:15924424

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