title: Leureptin: a soluble, extracellular leucine-rich repeat protein from Manduca sexta that binds lipopolysaccharide.
abstract: Leucine-rich repeat containing proteins are involved in immune response in many capacities. In insects, these include Toll-like receptors and the Anopheles gambiae proteins APL1 and LRIM1. Here we describe the identification and characterization of leureptin, a novel extracellular protein with 13 leucine-rich repeats from hemolymph of the insect Manduca sexta. After injection of bacteria, leureptin mRNA level increased in fat body, but protein levels in plasma decreased, an indication that leureptin is consumed during the immune response. Leureptin bound to bacterial lipopolysaccharide (LPS). Microscopy using leureptin antiserum showed that leureptin associates with hemocytes after injection of bacteria, an indication that leureptin is involved in hemocyte responses to bacterial infection. Sequence database searches suggest similar proteins are present in other Lepidopteran species.
authors.affiliation: Department of Biochemistry, Kansas State University, 141 Chalmers Hall, Manhattan, KS 66506, USA.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Zhu
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Ragan
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kanost
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D005110:Extracellular Space / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006434:Hemocytes / Q000737:chemistry / Q000378:metabolism; D006458:Hemolymph / Q000737:chemistry / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000090263:Leucine-Rich Repeat Proteins; D008070:Lipopolysaccharides / Q000378:metabolism*; D018402:Manduca / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D012995:Solubility
chemical_list: D019476:Insect Proteins; D000090263:Leucine-Rich Repeat Proteins; D008070:Lipopolysaccharides; D011506:Proteins