PROTEIN-PURIFICATION AND NUCLEOTIDE-SEQUENCE OF A LYSOZYME FROM THE BACTERIA-INDUCED LARVAE OF THE FALL WEBWORM, HYPHANTRIA-CUNEA

A protein with lytic activity against Micrococcus luteus was purified from the hemolymph of the fall webworm, Hyphantria cunea, larvae chall enged with live E. coli. A bacteriolytic protein of about 14,000 dalto ns in mass was purified by cation exchange chromatography and reverse- phased HPLC. The optimum pH and optimum temperature range for activity were around pH 6.2 and 50 degrees C, respectively, in a 100 mM phosph ate buffer. The amino-terminal amino acid sequence of this protein was determined and the corresponding cDNA was isolated and analyzed. The deduced protein of 142 amino acid residues was composed of a putative leader sequence of 20 residues and the mature enzyme of 122 residues. The cloned lysozyme gene was strongly induced in response to bacterial injection, implying that the enzyme is a part of the immune response of H. cunea. Comparison with other known lysozyme sequences shows that our lysozyme belongs to the chicken lysozyme. (C) 1997 Wiley-Liss, In c.