title: Lysozyme and defense peptides as suppressors of phenoloxidase activity in Galleria mellonella.
abstract: The prophenoloxidase (proPO) cascade supplies quinones and other reactive compounds for melanin formation, protein cross-linking, hemolymph coagulation, and killing of microbial invaders as well as parasites. The high cytotoxicity of the generated compounds requires a strict control of the activation of the proPO system and phenoloxidase (PO) activity to minimize damage to host tissues and cells. The PO activity in hemolymph of Escherichia coli challenged Galleria mellonella larvae increased, with a temporal drop 1 h after the challenge, reaching the highest level 24 h after the challenge. In the present study, a potential role of G. mellonella defense peptides and lysozyme in controlling the proPO system was investigated. The effects of purified defense peptides (anionic peptides 1 and 2, cecropin D-like peptide, Galleria defensin, proline-rich peptides 1 and 2) and lysozyme were analyzed. Four compounds, namely lysozyme, Galleria defensin, proline-rich peptide 1, and anionic peptide 2, decreased the hemolymph PO activity considerably, whereas the others did not affect the enzyme activity level. Our results indicate that these hemolymph factors could play multiple and distinct roles in the insect immune response.
authors.affiliation: Department of Immunobiology, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Sklodowska University, Lublin, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Zdybicka-Barabas
authors.forename: Paweł
authors.initials: P
authors.lastname: Mak
authors.forename: Teresa
authors.initials: T
authors.lastname: Jakubowicz
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Cytryńska
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000276:immunology / Q000302:isolation & purification; D023082:Defensins / Q000276:immunology / Q000302:isolation & purification; D004792:Enzyme Precursors / Q000276:immunology / Q000302:isolation & purification; D004927:Escherichia coli Infections; D006458:Hemolymph / Q000201:enzymology* / Q000276:immunology*; D007814:Larva / Q000201:enzymology* / Q000276:immunology*; D016982:Micrococcus luteus; D014442:Monophenol Monooxygenase / Q000276:immunology / Q000302:isolation & purification; D009036:Moths / Q000201:enzymology* / Q000276:immunology*; D009113:Muramidase / Q000276:immunology / Q000302:isolation & purification; D010455:Peptides / Q000276:immunology / Q000302:isolation & purification
chemical_list: D023082:Defensins; D004792:Enzyme Precursors; D010455:Peptides; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D009113:Muramidase
keywords: Galleria mellonella; defense peptides; lysozyme; phenoloxidase