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Investigation of an antifungal peptide, Diapausin, from Manduca sexta
Author(s) -
Li Miao,
Al Souhail Qasim,
Veerapandian Raja,
Vediyappan Govindsamy,
Kanost Michael
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.800.2
Subject(s) - manduca sexta , biology , microbiology and biotechnology , candida albicans , hemolymph , antimicrobial , yeast , biochemistry , saccharomyces cerevisiae , antimicrobial peptides , botany , insect
Antimicrobial peptides, a first line of defenses against the infectious microbes, are present in bacterial, fungal, plant and animal kingdoms. They are typically cationic and are less than 50 amino acid residues long. Most known insect antimicrobial peptides are bactericidal, and a few target both bacteria and fungi with relatively broad spectrum, but only a small group is specifically active against fungi. Manduca sexta , the tobacco hornworm, is an established model for biochemical studies of insect immunity. Eighty‐six antimicrobial peptide genes from 12 families were identified in the M. sexta genome. We recently discovered diapausins as a family of antifungal peptides in M. sexta hemolymph, active against Saccharomyces cerevisi ae and some ascomycete fungi. Diapausin concentration increases in hemolymph after injecting the larvae with yeast or bacteria. Purified diapausin‐1 and ‐2 recombinant proteins expressed in E. coli block growth of S. cerevisiae with IC 50 of 30uM and 60uM, respectively. Diapausin‐1 and ‐2 disrupt daughter cell separation after cell division, resulting in cell clusters. Diapausin‐1 is active against the human fungal pathogen Candida genus as well. The growth of Candida albicans and Candida krusei is inhibited by diapausin‐1, with IC 50 of 60uM and 20uM respectively, and diapausin‐1 treatment alters the morphology of these fungi. Diapausin‐1 impairs the germination of spores and hyphal growth of Beauveria bassiana , an insect pathogenic fungus. FITC‐labeled diapausin‐1 binds to the surface of S. cerevisiae , and pull‐down experiments show that diapausin‐1 binds to □‐1,3‐glucan, a component of fungal cell walls. We are investigating the mechanisms of diapausin action using □‐1,3‐glucan synthase (FKS1) mutants from S. cerevisiae and C. albicans . Diapausin‐1 may disrupt fungal growth by binding to □‐1,3‐glucan and/or impairing □‐1,3‐glucan synthesis. This study advances our understanding of an insect immune response to fungal infections and may contribute to the identification of new targets for the development of antifungal drugs. Support or Funding Information NIH grants GM041247, Kansas State University Division of Biology's startup funds, AHA grants 4SDG18910036 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .