The venom of the male Australian duck-billed platypus contains a family of four polypeptides of appox. 5 kDa, which are referred to as defensin-like peptides (DLPs). They are unique in that their amino acid sequences have no significant similarities to those of any known peptides; however, the tertiary structure of one of them, DLP-1, has recently been shown to be similar to β-defensin-12 and to the sodium neurotoxin peptide ShI (Stichodactyla helianthus neurotoxin I). Although DLPs are the major peptides in the platypus venom, little is known about their biological roles. In this study, we determined the three-dimensional structure of DLP-2 by NMR spectroscopy, with the aim of gaining insights into the natural function of the DLPs in platypus venom. The DLP-2 structure was found to incorporate a short helix that spans residues 9-12, and an antiparallel β-sheet defined by residues 15-18 and 37-40. The overall fold and cysteine-pairing pattern of DLP-2 were found to be similar to those of DLP-1, and hence β-defensin-12; however, the sequence similarities between the three molecules are relatively small. The distinct structural fold of the DLP-1, DLP-2, and β-defensin-12 is based upon several key residues that include six cysteines. DLP-3 and DLP-4 are also likely to be folded similarly since they have high sequence similarity with DLP-2. The DLPs, and β-defensin-12 may thus be grouped together into a class of polypeptide molecules which have a common or very similar global fold. The fact that the DLPs did not display antimicrobial, myotoxic, or cell-growth-promoting activities implies that the nature of the side chains in this group of peptides is likely to play an important role in defining the biological function(s).
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June 2000
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Research Article|
June 07 2000
Defensin-like peptide-2 from platypus venom: member of a class of peptides with a distinct structural fold
Allan M. TORRES;
Allan M. TORRES
*Department of Biochemistry, University of Sydney, NSW 2006, Australia
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Greg M. DE PLATER;
Greg M. DE PLATER
†Centre for Molecular Structure and Function, The John Curtin School of Medical Research, Australian National University, Canberra ACT 2601, Australia
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Magnus DOVERSKOG;
Magnus DOVERSKOG
‡Department of Biotechnology, KTH, S-100 44, Stockholm, Sweden
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Liesl C. BIRINYI-STRACHAN;
Liesl C. BIRINYI-STRACHAN
§Department of Health Sciences, University of Technology, Sydney NSW 2007, Australia
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Graham M. NICHOLSON;
Graham M. NICHOLSON
§Department of Health Sciences, University of Technology, Sydney NSW 2007, Australia
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Clifford H. GALLAGHER;
Clifford H. GALLAGHER
ǁTaronga Zoo, Mosman, NSW 2088, Australia
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Philip W. KUCHEL
Philip W. KUCHEL
1
*Department of Biochemistry, University of Sydney, NSW 2006, Australia
1To whom correspondence should be addressed (e-mail: p.kuchel@;biochem.usyd.edu.au).
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Publisher: Portland Press Ltd
Received:
February 07 2000
Revision Received:
March 24 2000
Accepted:
April 11 2000
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 2000
2000
Biochem J (2000) 348 (3): 649–656.
Article history
Received:
February 07 2000
Revision Received:
March 24 2000
Accepted:
April 11 2000
Citation
Allan M. TORRES, Greg M. DE PLATER, Magnus DOVERSKOG, Liesl C. BIRINYI-STRACHAN, Graham M. NICHOLSON, Clifford H. GALLAGHER, Philip W. KUCHEL; Defensin-like peptide-2 from platypus venom: member of a class of peptides with a distinct structural fold. Biochem J 15 June 2000; 348 (3): 649–656. doi: https://doi.org/10.1042/bj3480649
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