The Biological Activity of the Prototypic Cyclotide Kalata B1 Is Modulated by the Formation of Multimeric Pores

Huang, Y. H., Colgrave, M. L., Daly, N. L., Keleshian, A, Martinac, B and Craik, D. J. (2009) The Biological Activity of the Prototypic Cyclotide Kalata B1 Is Modulated by the Formation of Multimeric Pores. Journal of Biological Chemistry, 284 31: 20699-20707. doi:10.1074/jbc.M109.003384

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Author Huang, Y. H.
Colgrave, M. L.
Daly, N. L.
Keleshian, A
Martinac, B
Craik, D. J.
Title The Biological Activity of the Prototypic Cyclotide Kalata B1 Is Modulated by the Formation of Multimeric Pores
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
Publication date 2009-07-01
Year available 2009
Sub-type Article (original research)
DOI 10.1074/jbc.M109.003384
Open Access Status File (Publisher version)
Volume 284
Issue 31
Start page 20699
End page 20707
Total pages 9
Editor Herbert Tabor
Place of publication Bethesda Maryland USA
Publisher American Society for Biochemistry and Molecular Biology
Language eng
Subject C1
970106 Expanding Knowledge in the Biological Sciences
060199 Biochemistry and Cell Biology not elsewhere classified
Abstract The cyclotides are a large family of circular mini-proteins containing a cystine knot motif. They are expressed in plants as defense-related proteins, with insecticidal activity. Here we investigate their role in membrane interaction and disruption. Kalata B1, a prototypic cyclotide, was found to induce leakage of the self-quenching fluorophore, carboxyfluorescein, from phospholipid vesicles. Alanine-scanning mutagenesis of kalata B1 showed that residues essential for lytic activity are clustered, forming a bioactive face. Kalata B1 was sequestered at the membrane surface and showed slow dissociation from vesicles. Electrophysiological experiments showed that conductive pores were induced in liposome patches on incubation with kalata B1. The conductance calculated from the current-voltage relationship indicated that the diameter of the pores formed in the bilayer patches is 41-47 angstrom. Collectively, the findings provide a mechanistic explanation for the diversity of biological functions ascribed to this fascinating family of ultrastable macrocyclic peptides.
Keyword MECHANOSENSITIVE ION-CHANNEL
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Thu, 03 Sep 2009, 17:45:42 EST by Mr Andrew Martlew on behalf of Institute for Molecular Bioscience