The role of N-b-alanyldopamine synthase in the innate immune response of insects

MARTÍN M. PÉREZ; LUCÍA TURDERA; JULIETA SCHACHTER; CLAUDIA LOPEZ LASTRA; LUIS A. QUESADA-ALLUÉ

Mar del Plata

Congreso; 51 Annual Meeting Argentine Society for Biochemistry and Molecular Biology- LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Insects trigger a multifaceted innate immune response to fight microbial infections. The first line of response to microbial entry is mediated by the rapid action of phenoloxidases present in the integument and in the hemolymph which generate quinones that lead to localized melanization and cross-linking, eventually encapsulating invaders. We ascertained if N--alanyldopamine (NBAD), which is the main sclerotization precursor of insect brown cuticles is involved in the innate immune response. Insects were injected with microorganisms (bacteria, yeast), polysaccharides or spores of the entomopathogenic fungus Beauveria bassiana and the activation of NBAD-synthase was assessed. Antimicrobial properties of NBAD were also determined. We show that septic injures induce, in Tenebrio molitor and Ceratitis capitata, the synthesis of NBAD. We demonstrated in cell-free extracts that NBAD synthase is induced in the epidermis and exhibit the same properties of the ecdysone-induced enzyme expressed only at the time of cuticle molt. Significantly, NBAD showed antimicrobial properties in vitro. These results indicate, for the first time, that synthesis of NBAD is a novel aspect of the overall innate immune response in insects, which likely reinforces the action of the well-known antibacterial peptides.