Functional characterization of short-type peptidoglycan recognition proteins (PGRPs) from silkworm Bombyx mori in innate immunity

• Published in: Developmental and comparative immunology 2019-06, Vol.95, p.59-67
• Main Authors: Zhang, Ruo-Nan, Li, Cai-ting, Ren, Fei-fei, Ye, Ming-Qiang, Deng, Xiao-juan, Yi, Hui-Yu, Cao, Yang, Yang, Wan-Ying
• Format: Article
• Language: English
• Subjects: Agglutination; Amidase; Bacteria; Bombyx mori; Cell walls; E coli; Fruit flies; Hemocytes; Immune clearance; Immune response; Immune system; Immunity; Immunoregulation; Innate immunity; Insects; Larvae; Pattern recognition; Pattern recognition receptors; Peptidoglycan recognition protein; Peptidoglycan recognition proteins; Phagocytosis; Proteins; Receptors; Short-type; Silkworms
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2019.01.015

Peptidoglycan recognition proteins (PGRPs) are members of an important class of pattern recognition receptors in insects that can specifically recognize peptidoglycan (PGN) in bacterial cell walls and participate in immune regulation and bacterial clearance. Although the role of PGRPs in regulating the innate immune response in Drosophila melanogaster has been studied, little is known regarding PGRPs in Lepidoptera species. In this study, five short (S)-type Bombyx mori PGRPs (BmPGRPs) were cloned, expressed, and evaluated for their function in innate immunity. B. mori larvae that were injected with the gram-positive bacterium Bacillus megaterium or the gram-negative bacterium Escherichia coli exhibited a rapid and significant upregulation in S-type BmPGRP expression. The results showed that the five evaluated BmPGRPs have significant agglutination activity toward E. coli and B. megaterium and more notable amidase activity toward meso-diaminopimelic acid peptidoglycan (DAP-PGN). Furthermore, only in the presence of BmPGRP-S5 did B. mori larval hemocytes exhibit significant phagocytosis against E. coli and B. megaterium. [Display omitted] Peptidoglycan recognition proteins (PGRPs), as a very important class of pattern recognition receptors, can specifically recognize peptidoglycan (PGN) in the bacterial cell wall and participate in insect immune regulation. The function of PGRPs in Drosophila has been studied. In this study, five short (S)-type BmPGRPs in Bombyx mori were cloned and expressed. The five S-type BmPGRPs have significant agglutination effects on E. coli and B. megaterium but have more obvious amidase activity on me-so-diaminopimelic acid peptidoglycan (DAP-PGN). Only in the presence of BmPGRP-S5 did the hemocytes of the B. mori larvae have significant phagocytosis effects against E. coli and B. megaterium. •There are five S-type BmPGRPs in silkworm and could be rapidly up-regulated expression by E. coli and B. megaterium.•The five S-type BmPGRPs have significant agglutination effects on E. coli and B. megaterium but have more obvious amidase activity on DAP-PGN.•Only in the presence of BmPGRP-S5 did the hemocytes of the B. mori larvae have significant phagocytosis effects against E. coli and B. megaterium.