Article

Leureptin: A soluble, extracellular leucine-rich repeat protein from Manduca sexta that binds lipopolysaccharide

Department of Biochemistry, Kansas State University, 141 Chalmers Hall, Manhattan, KS 66506, USA.
Insect biochemistry and molecular biology (Impact Factor: 3.42). 10/2010; 40(10):713-22. DOI: 10.1016/j.ibmb.2010.07.002
Source: PubMed

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.

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    • "Leureptin is constitutively expressed in M. sexta larvae; its amounts in haemolymph decrease continuously after infection as it binds to haemocytes and accumulates in the fat body (Zhu et al., 2010). In contrast, IRP30 was neither constitutively expressed nor could its expression be induced by infection during larval development (Figs. "
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    • "), LPS-binding leureptin (contig 15857, RA IH/CH : 10.7) (Zhu et al., 2010), Ig domain-containing hemicentin-1 (contig 00131, RA IF/CF : 6.4) and -2 (contig 14278, RA IF/CF : 8.7) (Vogel and Hedgecock, 2001). Therefore, expression profiling and sequence similarity together provided a powerful tool to discover process-related genes without a priori genome sequence. "
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