Chorion peroxidase-mediated NADH/O2 oxidoreduction cooperated by chorion malate dehydrogenase-catalyzed NADH production: a feasible pathway leading to H2O2 formation during chorion hardening in Aedes aegypti mosquitoes

Abstract

A specific chorion peroxidase is present in Aedes aegypti and this enzyme is responsible for catalyzing chorion protein cross-linking through dityrosine formation during chorion hardening. Peroxidase-mediated dityrosine cross-linking requires H 2 O 2 , and this study discusses the possible involvement of the chorion peroxidase in H 2 O 2 formation by mediating NADH/O 2 oxidoreduction during chorion hardening in A. aegypti eggs. Our data show that mosquito chorion peroxidase is able to catalyze pH-dependent NADH oxidation, which is enhanced in the presence of Mn 2+ . Molecular oxygen is the electron acceptor during peroxidase-catalyzed NADH oxidation, and reduction of O 2 leads to the production of H 2 O 2 , demonstrated by the formation of dityrosine in a NADH/peroxidase reaction mixture following addition of tyrosine. An oxidoreductase capable of catalyzing malate/NAD + oxidoreduction is also present in the egg chorion of A. aegypti. The cooperative roles of chorion malate/NAD + oxidoreductase and chorion peroxidase on generating H 2 O 2 with NAD + and malate as initial substrates were demonstrated by the production of dityrosine after addition of tyrosine to a reaction mixture containing NAD + and malate in the presence of both malate dehydrogenase fractions and purified chorion peroxidase. Data suggest that chorion peroxidase-mediated NADH/O 2 oxidoreduction may contribute to the formation of the H 2 O 2 required for chorion protein cross-linking mediated by the same peroxidase, and that the chorion associated malate dehydrogenase may be responsible for the supply of NADH for the H 2 O 2 production.

Minor proteins and enzymes of the Drosophila eggshell matrix

“…Thus it is possible that CG12398 could produce the hydrogen peroxide necessary for tyrosine cross-linking, especially of the vitelline membrane where no source of hydrogen peroxide has been found. A similar mechanism of hydrogen peroxide production has been postulated for hardening of the Aedes aegypti chorion, involving a malate dehydrogenase activity that has not been cloned (Han et al, 2000).…”

Integrated proteomic and transcriptomic analysis of the Aedes aegyptieggshell

“…Peroxidases, phenoloxidases, laccases, dopachrome-conversion enzymes, and transglutaminases are enzymes present in the eggshell samples (Figure 3 , Additional files 1 , 2 and 3 ). Peroxidase-catalyzed chorion protein crosslinking is a phenomenon documented previously in insect eggshell formation [ 45 ] with AAEL004386-PA, HPX8C, identified in the proteome, having been characterized previously as an Ae. aegypti chorion peroxidase (CPO) [ 18 ].…”

Inheritance of chorionic malformations and insecticide resistance by Spodoptera exigua

“…This process strengthens and hardens the structure of the chorion by catalysing protein cross‐linking. The process involves hydrogen peroxide, which is one of the most important reactive oxygen species ( Han et al., 2000a,b). Hence, the process can be disturbed by pesticides resulting in the weakened, soft eggshell.…”