Peptidoglycan recognition proteins involved in 1,3-beta-D-glucan-dependent prophenoloxidase activation system of insect.
The prophenoloxidase (proPO) cascade is a major innate immune response in invertebrates, which is triggered into its active form by elicitors, such as lipopolysaccharide, peptidoglycan, and 1,3-beta-D-glucan. A key question of the proPO system is how pattern recognition proteins recognize pathogenic microbes and subsequently activate the system. To investigate the biological function of 1,3-beta-D-glucan pattern recognition protein in the proPO cascade system, we isolated eight different 1,3-beta-D-glucan-binding proteins from the hemolymph of large beetle (Holotrichia diomphalia) larvae by using 1,3-beta-D-glucan immobilized column. Among them, a 20- and 17-kDa protein (referred to as Hd-PGRP-1 and Hd-PGRP-2) show high sequence identity with the short forms of peptidoglycan recognition proteins (PGRPs-S) from human and Drosophila melanogaster. To be able to characterize the biochemical properties of these two proteins, we expressed them in Drosophila S2 cells. Hd-PGRP-1 and Hd-PGRP-2 were found to specifically bind both 1,3-beta-D-glucan and peptidoglycan. By BIAcore analysis, the minimal 1,3-beta-D-glucan structure required for binding to Hd-PGRP-1 was found to be laminaritetraose. Hd-PGRP-1 increased serine protease activity upon binding to 1,3-beta-D-glucan and subsequently induced the phenoloxidase activity in the presence of both 1,3-beta-D-glucan and Ca(2+), but no phenoloxidase activity was elicited under the same conditions in the presence of peptidoglycan and Ca(2+). These results demonstrate that Hd-PGRP-1 can serve as a receptor for 1,3-beta-D-glucan in the insect proPO activation system.
College of Pharmacy, Pusan National University, Jangjeon Dong, Kumjeong Ku, Busan 609-735, Korea.
Mi Hee
MH
Lee
Tsukasa
T
Osaki
Joo Young
JY
Lee
Min Ji
MJ
Baek
Rong
R
Zhang
Ji Won
JW
Park
Shun-ichiro
S
Kawabata
Kenneth
K
Söderhäll
Bok Luel
BL
Lee
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D004156:Catechol Oxidase / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004331:Drosophila melanogaster; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D015723:Gene Library; D005936:Glucans / Q000737:chemistry*; D006458:Hemolymph / Q000737:chemistry; D006801:Humans; D015151:Immunoblotting; D007313:Insecta; D008024:Ligands; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000737:chemistry; D010457:Peptidoglycan / Q000737:chemistry*; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry; D013997:Time Factors; D047071:beta-Glucans
D002352:Carrier Proteins; D018076:DNA, Complementary; D004792:Enzyme Precursors; D005936:Glucans; D008024:Ligands; D010457:Peptidoglycan; D011994:Recombinant Proteins; D047071:beta-Glucans; C118897:peptidoglycan recognition protein; C033363:beta-1,3-glucan; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D012697:Serine Endopeptidases