Hydrolysis of b-alanyl derivatives of neurotransmitters in insects

BADARACCO A; PEREZ M.M; QUESADA-ALLUE L.A.

San Miguel de Tucuman/Tucuman/ Argentina

Congreso; 45th Annual Meeting-Argentine Society for Biochemistry and Molecular Biology Research/XLV Reunión anual-Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2009

Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular

We study the metabolism of â-alanyl derivatives of neurotransmitters in insects. The best known of these are N-â-alanyldopamine (NBAD), the main sclerotization precursor of insect brown cuticles, and carcinine (N-â-alanylhistamine), an essential compound of the visual system. In Drosophila melanogaster, the gene tan codifies the NBAD-Hydrolase (NBAD-H), the enzyme responsible for the hydrolysis of these conjugates. Our aim was to study the biochemical characteristics of the NBAD-H protein in epidermal and nervous tissue: pH dependence, substrate specificity, life cycle dependent expression, etc. We found that the NBAD-H is active in a constitutive manner. Using in vitro assays and HPLC, we demonstrated that this enzyme is able to hydrolyze other â-alanyl derivatives. Brain confocal images revealed that the NBAD-H is mainly expressed in the optic lobes. We studied tan1 and tan3 mutants and found (by western blots) that tan1 cannot process the precursor protein. Our results also showed that tan3 is a complex mutant, with different phenotypes in epidermal and nervous tissues. The NBAD-H, along with the NBAD-synthase, the DDC enzyme and others, are reused in different occasions depending on the life cycle and the physiological requirements.