Sequence characterization of an unusual lysozyme gene expressed in the intestinal tract of the reduviid bug Triatoma infestans (Insecta).

Antibacterial proteins like lysozyme are important components of the insect non-specific immune response against bacteria. The complementary deoxyribonucleic acid (cDNA) encoding a new lysozyme from Triatoma infestans, named lysozyme2, has been amplified by polymerase chain reaction and the rapid amplification of cDNA ends technique. The gene is expressed in the small intestine of the insect. The deduced protein sequence shows up to 70% similarity to lysozymes from other species. Furthermore, the protein exhibits significant structural concordance to other insect lysozymes. A striking feature of the lysozyme2 protein is the replacement of the conserved amino acid residues of the active site of classical c-type lysozymes, glutamate and aspartate, by valine and tyrosine.