Laccases are copper-containing oxidases with broad substrate specificity. They have been implicated in a variety of physiological processes in plants and fungi, including lignin synthesis and degradation, morphogenesis, pigmentation, detoxification, and virulence. Related multicopper oxidases are involved in protection against metal toxicity in bacteria and fungi. Whether laccases have similar functions in insects is unknown, as laccases have not previously been investigated in insects in detail. The one identified role of insect laccases is in catalyzing cuticle tanning and sclerotization reactions, but preliminary results suggest that some insect laccase genes may have other functions. The long term goals of this research are to determine the function of six putative laccases in the mosquito, Anopheles garnbiae, to increase our understanding of laccase-substrate interactions, and eventually to use this information to develop strategies to reduce disease transmission by mosquitoes. This project has three specific aims designed to test hypotheses regarding potential functions for laccases in mosquito physiology and to investigate laccase inhibitors for use in biochemical analyses of laccase function and for testing whether laccases may be a potentially useful new target for chemical control of mosquitoes. 1) Investigate the role of laccases in cuticle sclerotization, pigmentation, wound healing, and egg shell tanning. 2) Determine whether laccases have a role in protecting insects from toxic substances such as phenolic compounds in the larval environment or iron in the blood meal. 3) Design, synthesize, and test inhibitors of Anopheles laccases for exploring the laccase active site and for tests of the inhibitors'effects on mosquito development and survival. Relevance: Because they are vectors of human diseases, mosquitoes have a tremendous human health impact, and Anopheles gambiae is particularly important as the major vector of malaria in Africa. Studies of mosquito laccases will increase our understanding of fundamental processes in mosquito biology and may provide knowledge regarding how these insects transmit diseases or how they tolerate toxic chemicals. Disrupting laccase function may provide a new mechanism for controlling mosquito populations.
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