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Kunitz-type protease inhibitor BmSPI51 plays an antifungal role in the silkworm cocoon.
Kunitz-type protease inhibitor BmSPI51 plays an antifungal role in the silkworm cocoon.
- Source :
-
Insect biochemistry and molecular biology [Insect Biochem Mol Biol] 2020 Jan; Vol. 116, pp. 103258. Date of Electronic Publication: 2019 Oct 31. - Publication Year :
- 2020
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Abstract
- The protease inhibitors found in silkworm cocoons can be divided into several families, a majority of which contain serpin, TIL, or Kunitz domains. Previously, it has been reported that TIL-type protease inhibitors have antimicrobial activity. To date, however, it has not been determined whether the Kunitz-type protease inhibitor BmSPI51, the most abundant of cocoon protease inhibitors, plays an antimicrobial role. Thus, in this study, we sought to determine the biological role of BmSPI51 in silkworm cocoons. Our results obtained from real-time quantitative reverse transcription PCR and immunofluorescence analyses indicate that BmSPI51 is expressed exclusively in the silk glands during the larval fifth instar stage and is subsequently secreted into cocoon silk. Moreover, at a molar ratio of 1:1, BmSPI51 produced via prokaryotic expression exhibited inhibitory activity against trypsin and also proved to be highly stable over wide ranges of temperature and pH values. The expression of BmSPI51 was also found to be significantly upregulated in the larval fat body after infection with three species of fungi, namely, Candida albicans, Beauveria bassiana, and Saccharomyces cerevisiae. In vitro inhibition tests revealed that BmSPI51 significantly inhibited the sporular growth of all three of these fungal species. Further, results obtained from a binding assay showed that BmSPI51 binds to β-d-glucan and mannan on the surface of fungal cells. In this study, we, thus, revealed the antimicrobial activity of BmSPI51 and its underlying mechanism in silkworm, thereby contributing to our present understanding of defense mechanisms in silkworm cocoons.<br /> (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Subjects :
- Animals
Antifungal Agents metabolism
Beauveria physiology
Bombyx growth & development
Candida albicans physiology
Fat Body chemistry
Insect Proteins metabolism
Larva growth & development
Larva metabolism
Larva microbiology
Saccharomyces cerevisiae physiology
Serine Proteinase Inhibitors metabolism
Bombyx metabolism
Bombyx microbiology
Insect Proteins genetics
Serine Proteinase Inhibitors genetics
Subjects
Details
- Language :
- English
- ISSN :
- 1879-0240
- Volume :
- 116
- Database :
- MEDLINE
- Journal :
- Insect biochemistry and molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 31678582
- Full Text :
- https://doi.org/10.1016/j.ibmb.2019.103258