An Insect Multiligand Recognition Protein Functions as an Opsonin for the Phagocytosis of Microorganisms

From the Department of Biotechnology, Hoseo University, Asan City, Chungnam 336-795, South Korea.
Journal of Biological Chemistry (Impact Factor: 4.57). 08/2010; 285(33):25243-50. DOI: 10.1074/jbc.M110.134940
Source: PubMed


We characterize a novel pathogen recognition protein obtained from the lepidopteran Galleria mellonella. This protein recognizes Escherichia coli, Micrococcus luteus, and Candida albicans via specific binding to lipopolysaccharides, lipoteichoic acid, and beta-1,3-glucan, respectively. As a multiligand receptor capable of coping with a broad variety of invading pathogens, it is constitutively produced in the fat body, midgut, and integument but not in the hemocytes and is secreted into the hemolymph. The protein was confirmed to be relevant to cellular immune response and to further function as an opsonin that promotes the uptake of invading microorganisms into hemocytes. Our data reveal that the mechanism by which a multiligand receptor recognizes microorganisms contributes substantially to their phagocytosis by hemocytes. A better understanding of an opsonin with the required repertoire for detecting diverse invaders might provide us with critical insights into the mechanisms underlying insect phagocytosis.

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    • "Such a coating of BmTCTP on the surface of bacteria leads to an enhanced ingestion of bacteria as shown in phagocytosis assay. Another multi-ligand recognition protein, cationic protein 8 (CP8), was identified in Galleria mellonella [53]. This protein recognizes E. coli, Micrococcus luteus and Candida albicans via specific binding to LPS, lipoteichoic acid (LTA) and β-1,3-glucan and acts as an opsonin. "
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