Characterization of TioF, a tryptophan 2,3-dioxygenase involved in 3-hydroxyquinaldic acid formation during thiocoraline biosynthesis?

Molecular BioSystems Pub Date: 2008-04-04 DOI: 10.1039/B801391H

Abstract

Thiocoraline is a thiodepsipeptide antitumor agent that belongs to the family of bisintercalator natural products that bind duplex DNA through their two planar intercalating moieties. In thiocoraline, the 3-hydroxyquinaldic acid (3HQA) chromophores required for intercalation are derived from L-Trp. We have expressed the Micromonospora sp. ML1 tryptophan 2,3-dioxygenase (TDO) TioF, purified it from E. coli, and confirmed its role in the irreversible oxidation of L-Trp to N-formylkynurenine, the proposed first step during 3HQA biosynthesis. We have established that TioF is a catalyst with broader specificity than other TDOs, but that is less promiscuous than indoleamine 2,3-dioxygenases. TioF was found to display activity with various L-Trp analogs (serotonin, D-Trp, and indole). The TioF reaction products generated during this study will be used as substrates for subsequent analysis of the other enzymes involved in 3HQA biosynthesis.

Graphical abstract: Characterization of TioF, a tryptophan 2,3-dioxygenase involved in 3-hydroxyquinaldic acid formation during thiocoraline biosynthesis
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