Manduca sexta lipopolysaccharide-specific immulectin-2 protects larvae from bacterial infection.
We previously reported the isolation of a lipopolysaccharide (LPS)-specific immulectin-2 from the tobacco hornworm, Manduca sexta [J. Biol. Chem. 275 (2000) 37373]. Immulectin-2 is a C-type lectin that is present at a constitutively low level in hemolymph of naive larvae, and its synthesis is induced after injection of Gram-negative bacteria or LPS. Immulectin-2 contains two carbohydrate recognition domains. It binds to LPS and stimulates prophenoloxidase activation in plasma. In this paper, we focus on properties of carbohydrate recognition domain-2 of immulectin-2 and the biological functions of immulectin-2 in immune responses. The carboxyl-terminal carbohydrate recognition domain (CRD2) of immulectin-2 was able to bind bacterial LPS. Binding of recombinant CRD2 to LPS stimulated activation of prophenoloxidase in plasma. Injection of antiserum against immulectin-2 into M. sexta larvae inhibited clearance of a Gram-negative bacterial pathogen, Serratia marcescens, and decreased survival of infection. These results suggest that immulectin-2 plays an important role in the immune system of M. sexta, and helps to protect the animal from Gram-negative bacterial infections.
Yu
Xiao-Qiang
XQ
Department of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA.
Kanost
Michael R
MR
D000818:Animals; D004156:Catechol Oxidase / Q000378:metabolism; D004198:Disease Susceptibility; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism; D016905:Gram-Negative Bacterial Infections / Q000276:immunology*; D019476:Insect Proteins / Q000502:physiology*; D007814:Larva / Q000276:immunology; D037181:Lectins, C-Type / Q000502:physiology*; D008070:Lipopolysaccharides / Q000378:metabolism*; D018402:Manduca / Q000276:immunology* / Q000382:microbiology; D010587:Phagocytosis; D011817:Rabbits
D004792:Enzyme Precursors; D019476:Insect Proteins; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; C417733:immulectin-2 protein, Manduca sexta; C038451:pro-phenoloxidase; D004156:Catechol Oxidase