Immulectin-2, a lipopolysaccharide-specific lectin from an insect, Manduca sexta, is induced in response to gram-negative bacteria.

Abstract

A lipopolysaccharide-specific lectin, immulectin-2, was isolated from plasma of the tobacco hornworm, Manduca sexta. Immulectin-2 has specificity for xylose, glucose, lipopolysaccharide, and mannan. A cDNA clone encoding immulectin-2 was isolated from an Escherichia coli-induced M. sexta larval fat body cDNA library. The cDNA is 1253 base pairs long, with an open reading frame of 981 base pairs, encoding a 327-residue polypeptide. Immulectin-2 is a member of the C-type lectin superfamily. It consists of two carbohydrate recognition domains, which is similar to the organization of M. sexta immulectin-1. Immulectin-2 was present at a constitutively low level in plasma of control larvae and increased 3-4-fold after injection of Gram-negative bacteria or lipopolysaccharide. Immulectin-2 mRNA was detected in fat body of control larvae, and its level increased dramatically after injection of E. coli. The concentration of immulectin-2 in plasma did not change significantly after injection of Gram-positive bacteria or yeast, even though its mRNA level was increased by these treatments. Compared with immulectin-1, immulectin-2 has a more restricted specificity for binding to Gram-negative bacteria. Immulectin-2 at low physiological concentrations agglutinated E. coli in a calcium-dependent manner. It also bound to immobilized lipopolysaccharide from E. coli. Binding of immulectin-2 to lipopolysaccharide stimulated phenol oxidase activation in plasma. The properties of immulectin-2 are consistent with its function as a pattern recognition receptor for detection and defense against Gram-negative bacterial infection in M. sexta.

• Authors: X Q Yu, M R Kanost
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 275 Issue 48 Pg. 37373-81 (Dec 01 2000) ISSN: 0021-9258 [Print] United States
• PMID: 10954704 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA, Complementary
• Insect Proteins
• Lectins
• Lectins, C-Type
• Ligands
• Lipopolysaccharides
• immulectin-2 protein, Manduca sexta

Topics

• Agglutination Tests
• Amino Acid Sequence
• Animals
• Base Sequence
• DNA, Complementary
• Electrophoresis, Polyacrylamide Gel
• Escherichia coli (physiology)
• Insect Proteins
• Lectins (biosynthesis, genetics, isolation & purification, metabolism)
• Lectins, C-Type
• Ligands
• Lipopolysaccharides (pharmacology)
• Manduca (metabolism, microbiology)
• Molecular Sequence Data
• Protein Binding
• Reverse Transcriptase Polymerase Chain Reaction
• Sequence Homology, Amino Acid