Immulectin‐4 from the tobacco hornworm Manduca sexta binds to lipopolysaccharide and lipoteichoic acid

Abstract

Insect C-type lectins function as pattern recognition receptors in innate immunity. In the tobacco hornworm Manduca sexta, we have previously isolated three C-type lectins named immulectins, which are involved in innate immune responses. Here, we report a new member of the immulectin family, immulectin-4 (IML-4). IML-4 mRNA was detected in the fat body of control larvae and was induced in the fat body when larvae were injected with bacteria. Recombinant IML-4 bound to bacterial lipopolysaccharide (LPS) and lipoteichoic acid (LTA), and the binding activity was not affected by addition of calcium or EGTA. IML-4 agglutinated bacteria and yeast, and agglutination of Escherichia coli by IML-4 was concentration- and calcium-dependent. IML-4 also enhanced haemocyte encapsulation and melanization.

High Innate Immune Specificity through Diversified C-Type Lectin-Like Domain Proteins in Invertebrates

“…They bind to microbe-associated molecular patterns (MAMPs) [30] with different affinities and specificities in vitro. While immulectin-1, -3 and -4 bind to a broad range of MAMPs, immulectin-2 specifically binds to lipopolysaccharide [28,29,31] .…”

“…The expression of the four characterized M. sexta CTLD proteins immulectin-1 to -4 is induced upon bacterial exposure in the fat body. Immulectin-1 and -2 function in activation of the prophenoloxidase [27] and immulectin-3 and -4 act in enhancing encapsulation and melanization [28,29] . They bind to microbe-associated molecular patterns (MAMPs) [30] with different affinities and specificities in vitro.…”

Pattern Recognition Protein Binds to Lipopolysaccharide and β-1,3-Glucan and Activates Shrimp Prophenoloxidase System

“…To date, various types of PRPs in the proPO system have been reported such as peptidoglycan recognition proteins (2,(13)(14)(15)(16)(17)(18)(19)(20), C-type lectins (21,22), ␤-glucan-binding proteins (bGBPs) (23,24) and LPSand ␤-1,3-glucan binding proteins (LGBPs) (25)(26)(27). In crustaceans, the binding of LGBP to LPS or ␤-1,3-glucan has been documented to activate the proPO system of the freshwater crayfish, Pacifastacus leniusculus (27).…”

Molecular cloning, characterization and expression analysis of a C-type lectin (Ec-CTL) in orange-spotted grouper, Epinephelus coioides

“…OLABL, a C-type lectin from the eggs of shishamo smelt, Osmerus (Spirinchus) lanceolatus do not require Ca 2þ to function [39]. Several C-type lectins also do not require calcium for their binding activity, but require calcium for agglutinating activity [40,41]. AmphiCTL1, from Amphioxus, requires Ca 2þ for the hemagglutinating and microbial aggregation activities, but not for the microbial binding and growth suppression activities [42].…”