Characterization and regulation of expression of an antifungal peptide from hemolymph of an insect, Manduca sexta.

摘要: Insects secrete antimicrobial peptides as part of the innate immune response. Most from insects have antibacterial but not antifungal activity. We characterized an peptide, diapausin-1 hemolymph a lepidopteran insect, Manduca sexta (tobacco hornworm). Diapausin-1 was isolated by size exclusion chromatography plasma larvae that were previously injected with yeast, Saccharomyces cerevisiae. Fractions containing activity against S. cerevisiae analyzed SDS-PAGE and MALDI-TOF MS/MS found to contain 45-residue peptide encoded sequences identified in M. sexta transcriptome genome databases. A cDNA for cloned prepared fat body RNA. is member diapausin family peptides, which includes members known The contains 14 genes high similarity diapausin-1, each 6 conserved Cys residues. produced recombinant protein Escherichia coli. Purified active S. cerevisiae, IC50 12 μM, had no detectable bacteria. Spores some plant fungal pathogens treated curled germination tubes or reduced branched hyphal growth. mRNA level strongly increased after yeast Micrococcus luteus. In addition, levels midgut at wandering larval stage prior pupation, suggesting developmental regulation gene. Our results indicate synthesis response infection M. sexta.