Organization and expression of the immunoresponsive lysozyme gene in the giant silk moth, Hyalophora cecropia

Abstract

Lysozyme is one of the antibacterial proteins that are produced by the giant silk moth Hyalophora cecropia in response to bacterial infection or injury. As an essential step toward the understanding of the mechanisms involved in the immune response, we have isolated and characterized the lysozyme gene from Cecropia. The complete nucleotide sequence of the gene as well as the immediate flanking sequences have been determined. The gene includes three exons. Its first intron contains a repetitive sequence. In the evolutionary aspect, the Cecropia lysozyme gene and two vertebrate lysozyme genes have been found to maintain a similar organization pattern of exons. The lysozyme gene has been found to be strongly induced by lipopolysaccharides and a phorbol ester as well as bacteria. In the induction by bacteria, the lysozyme transcript appears at about 2 h, reaches to the maximum level at about 24 h, and then declines. Comparison of the 5'-flanking sequences with several other genes involved in the immune response of H. cecropia and Drosophila melanogaster revealed a kappa B-like consensus sequence. This sequence is specifically recognized by a nuclear protein from the induced pupa.