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Identification and biochemical characterization of the Anopheles gambiae 3‐hydroxykynurenine transaminase
Author(s) -
Rossi Franca,
Lombardo Fabrizio,
Paglino Alessandra,
Cassani Camilla,
Miglio Gianluca,
Arcà Bruno,
Rizzi Menico
Publication year - 2005
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2005.04961.x
Subject(s) - xanthurenic acid , biology , anopheles gambiae , anopheles stephensi , biochemistry , transaminase , enzyme , anopheles , metabolic pathway , malaria , aedes aegypti , tryptophan , amino acid , botany , larva , immunology
Spontaneous oxidation of 3‐hydroxykynureine (3‐HK), a metabolic intermediate of the tryptophan degradation pathway, elicits a remarkable oxidative stress response in animal tissues. In the yellow fever mosquito Aedes aegypti the excess of this toxic metabolic intermediate is efficiently removed by a specific 3‐HK transaminase, which converts 3‐HK into the more stable compound xanthurenic acid. In anopheline mosquitoes transmitting malaria, xanthurenic acid plays an important role in Plasmodium gametocyte maturation and fertility. Using the sequence information provided by the Anopheles gambiae genome and available ESTs, we adopted a PCR‐based approach to isolate a 3‐HK transaminase coding sequence from the main human malaria vector A. gambiae . Tissue and developmental expression analysis revealed an almost ubiquitary profile, which is in agreement with the physiological role of the enzyme in mosquito development and 3‐HK detoxification. A high yield procedure for the expression and purification of a fully active recombinant version of the protein has been developed. Recombinant A. gambiae 3‐HK transaminase is a dimeric pyridoxal 5′‐phosphate dependent enzyme , showing an optimum pH of 7.8 and a comparable catalytic efficiency for both 3‐HK and its immediate catabolic precursor kynurenine. This study may be useful for the identification of 3‐HK transaminase inhibitors of potential interest as malaria transmission‐blocking drugs or effective insecticides.