Molecular characterization of a defensin gene from the mosquito, Aedes aegypti.

Insect immune proteins, defensins, are inducible anti-Gram-positive bacterial peptides. We report here the identification of two defensin genes from the mosquito, Aedes aegypti, which encode a large 541 bp transcript (AaDef Ala) and a small 473 bp transcript (AaDef Asm). The cDNA corresponding to AaDef Ala was cloned, sequenced, and compared with the previously reported AaDef Asm cDNA. The AaDef Ala gene was isolated through genomic library screening and characterized. It putative regulatory region contains a 64 bp intron, a TATA box and a putative arthropod initiator. Two 150 bp long direct and several palindromic repeats are present in this sequence. Similar to other insect immune peptide genes, the AaDef Ala gene contains numerous putative regulatory motifs with impressive similarity to elements of vertebrate acute phase response protein genes.