The biochemical basis of antimicrobial responses in Manduca sexta  

作　　者：Haobo Jiang 

机构地区：[1]Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, 74078, USA

出　　处：《Insect Science》2008年第1期53-66,共14页昆虫科学（英文版）

摘　　要：Innate immunity is essential for the wellbeing of vertebrates and invertebrates. Key components of this defense system include pattern recognition receptors that bind to infectious agents, extra-and intra-cellular proteins that relay signals, as well as molecules and cells that eliminate pathogens. We have been studying the defense mechanisms in a biochemical model insect, Manduca sexta. In this insect, hemolin, peptidoglycan recognition proteins, β-1,3-glucan recognition proteins and C-type lectins detect microbial surface molecules and induce immune responses such as phagocytosis, nodulation, encapsulation, melanization and production of antimicrobial peptides. Some of these responses are mediated by extracellular serine proteinase pathways. The proteolytic activation of prophenoloxidase （proPO） yields active phenoloxidase （PO） which catalyzes the formation of quinones and melanin for wound healing and microbe killing. M. sexta hemolymph proteinase 14 （HP 14） precursor interacts with peptidoglycan or β-1,3-glucan, autoactivates, and leads to the activation of other HPs including HP21 and proPO-activating proteinases （PAPs）. PAP-1, -2 and -3 cut proPO to generate active PO in the presence of two serine proteinase homologs. Inhibition of the proteinases by serpins and association of the proteinase homologs with bacteria ensure a localized defense reaction. M. sexta HP1, HP6, HP8, HP17 and other proteinases may also participate in proPO activation or processing of spatzle and plasmatocyte spreading peptide.Innate immunity is essential for the wellbeing of vertebrates and invertebrates. Key components of this defense system include pattern recognition receptors that bind to infectious agents, extra-and intra-cellular proteins that relay signals, as well as molecules and cells that eliminate pathogens. We have been studying the defense mechanisms in a biochemical model insect, Manduca sexta. In this insect, hemolin, peptidoglycan recognition proteins, β-1,3-glucan recognition proteins and C-type lectins detect microbial surface molecules and induce immune responses such as phagocytosis, nodulation, encapsulation, melanization and production of antimicrobial peptides. Some of these responses are mediated by extracellular serine proteinase pathways. The proteolytic activation of prophenoloxidase （proPO） yields active phenoloxidase （PO） which catalyzes the formation of quinones and melanin for wound healing and microbe killing. M. sexta hemolymph proteinase 14 （HP 14） precursor interacts with peptidoglycan or β-1,3-glucan, autoactivates, and leads to the activation of other HPs including HP21 and proPO-activating proteinases （PAPs）. PAP-1, -2 and -3 cut proPO to generate active PO in the presence of two serine proteinase homologs. Inhibition of the proteinases by serpins and association of the proteinase homologs with bacteria ensure a localized defense reaction. M. sexta HP1, HP6, HP8, HP17 and other proteinases may also participate in proPO activation or processing of spatzle and plasmatocyte spreading peptide.

关 键 词：insect immunity hemolymph protein MELANIZATION clip domain serine proteinase cascade SERPIN spatzle Toll pathway PLASMATOCYTE tobacco homworm 

分 类 号：Q965[生物学—昆虫学]