2vka

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spinqualitylabelsall models 2vka, resolution 2.000Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

SITE-DIRECTED MUTAGENESIS OF THE CATALYTIC TRYPTOPHAN ENVIRONMENT IN PLEUROTUS ERYNGII VERSATILE PEROXIDASE

Overview

Lignin degradation by fungal peroxidases is initiated by one-electron, transfer to an exposed tryptophan radical, a reaction mediated by veratryl, alcohol (VA) in lignin peroxidase (LiP). Versatile peroxidase (VP) differs, not only in its oxidation of Mn2+ at a second catalytic site but also in, its ability to directly oxidize different aromatic compounds. The, catalytic tryptophan environment was compared in LiP and VP crystal, structures, and six residues near VP Trp164 were modified by site-directed, mutagenesis. Oxidation of Mn2+ was practically unaffected. However, several mutations modified the oxidation kinetics of the, high-redox-potential substrates VA and Reactive Black 5 (RB5), demonstrating that other residues contribute to substrate oxidation by the, Trp164 radical. Introducing acidic residues at the tryptophan environment, did not increase the efficiency of VP oxidizing VA. On the contrary, all, variants harboring the R257D mutation lost their activity on RB5., Interestingly, this activity was restored when VA was added as a mediator, revealing the LiP-type behavior of this variant. Moreover, combination of, the A260F and R257A mutations strongly increased (20-50-fold) the apparent, second-order rate constants for reduction of VP compounds I and II by VA, to values similar to those found in LiP. Dissociation of the, enzyme-product complex seemed to be the limiting step in the turnover of, this improved variant. Nonexposed residues in the vicinity of Trp164 can, also affect VP activity, as found with the M247F mutation. This was a, direct effect since no modification of the surrounding residues was found, in the crystal structure of this variant.

About this Structure

2VKA is a Single protein structure of sequence from Pleurotus eryngii with , , and as ligands. Known structural/functional Sites: , , , and . Full crystallographic information is available from OCA.

Reference

Site-Directed Mutagenesis of the Catalytic Tryptophan Environment in Pleurotus eryngii Versatile Peroxidase(,)., Ruiz-Duenas FJ, Morales M, Mate MJ, Romero A, Martinez MJ, Smith AT, Martinez AT, Biochemistry. 2008 Jan 18;. PMID:18201105

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