Molecular cloning of the trypsin inhibitor from the skin secretion of the Madagascan Tomato Frog, Dyscophus guineti (Microhylidae), and insights into its potential defensive role

Enrico Konig, Christina Wesse, Anna C. Murphy, Mei Zhou, Lei Wang, Tianbao Chen, Chris Shaw, Olaf R. P. Bininda-Emonds

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

In this study, we investigate the skin secretion of the Madagascan Tomato Frog, Dyscophus guineti, which is characterized by its peculiarly adhesive and viscous nature, with a view toward the function of the member of the Kunitz/bovine pancreatic trypsin inhibitor family (BPTI) it is known to contain. Using “shotgun” cloning of a skin secretion-derived cDNA library, we obtained the full-length sequence of the respective precursor that encodes this trypsin inhibitor. Furthermore, we demonstrated that this enzyme has inhibitory activity against trypsin, but not against thrombin, and also has no antimicrobial activity. Moreover, we confirm that it appears to be the only bioactive peptide in the skin secretion of this species. Using these observations, we attempt to posit a role for this inhibitor. In particular, we hypothesize that the trypsin inhibitor in D. guineti (and possibly other microhylid frogs) maintains the soluble state of the skin secretion during storage in the glands. Upon discharge of the secretion, the trypsin inhibitor, which occurs in low concentrations, can no longer prevent the polymerisation process of other yet unidentified skin proteins, thereby resulting in the conversion of the secretion to its final glue-like state. Thus, the major defensive value of the skin secretion appears to be mechanical, impeding ingestion through a combination of adhesion and the body inflation typical for some microhylid frogs rather than chemical through antimicrobial activity or toxicity.
Original languageEnglish
Pages (from-to)453-461
JournalOrganisms Diversity & Evolution
Volume13
Issue number3
Early online date10 Feb 2013
DOIs
Publication statusPublished - Sep 2013

Keywords

  • Amphibian skin . Host-defence; Protease inhibitors; Adhesive secretion; cDNA

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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