A comparison of the self-association behavior of the plant cyclotides kalata B1 and kalata B2 via analytical ultracentrifugation

Nourse, A., Trabi, M., Daly, N. L. and Craik, D. J. (2004) A comparison of the self-association behavior of the plant cyclotides kalata B1 and kalata B2 via analytical ultracentrifugation. Journal of Biological Chemistry, 279 1: 562-570.


Author Nourse, A.
Trabi, M.
Daly, N. L.
Craik, D. J.
Title A comparison of the self-association behavior of the plant cyclotides kalata B1 and kalata B2 via analytical ultracentrifugation
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
1083-351X
Publication date 2004-01-02
Year available 2003
Sub-type Article (original research)
DOI 10.1074/jbc.M306826200
Volume 279
Issue 1
Start page 562
End page 570
Total pages 9
Place of publication Bethesda
Publisher American Society for Biochemistry and Molecular Biology
Collection year 2004
Language eng
Subject 0601 Biochemistry and Cell Biology
Abstract The recently discovered cyclotides kalata B1 and kalata B2 are miniproteins containing a head-to-tail cyclized backbone and a cystine knot motif, in which disulfide bonds and the connecting backbone segments form a ring that is penetrated by the third disulfide bond. This arrangement renders the cyclotides extremely stable against thermal and enzymatic decay, making them a possible template onto which functionalities can be grafted.We have compared the hydrodynamic properties of two prototypic cyclotides, kalata B1 and kalata B2, using analytical ultracentrifugation techniques. Direct evidence for oligomerization of kalata B2 was shown by sedimentation velocity experiments in which a method for determining size distribution of polydisperse molecules in solution was employed. The shape of the oligomers appears to be spherical. Both sedimentation velocity and equilibrium experiments indicate that in phosphate buffer kalata B1 exists mainly as a monomer, even at millimolar concentrations. In contrast, at 1.6 mM, kalata B2 exists as an equilibrium mixture of monomer (30%), tetramer (42%), octamer (25%), and possibly a small proportion of higher oligomers. The results from the sedimentation equilibrium experiments show that this self-association is concentration dependent and reversible. We link our findings to the three-dimensional structures of both cyclotides, and propose two putative interaction interfaces on opposite sides of the kalata B2 molecule, one involving a hydrophobic interaction with the Phe(6), and the second involving a charge-charge interaction with the Asp(25) residue. An understanding of the factors affecting solution aggregation is of vital importance for future pharmaceutical application of these molecules.
Keyword Biochemistry & Molecular Biology
Size-distribution Analysis
Macrocyclic Peptides
Structural Motif
Knotted Proteins
Lamm Equation
Drug Design
Sedimentation
Macromolecules
Systems
Solutes
Q-Index Code C1

 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 44 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 44 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Access Statistics: 88 Abstract Views  -  Detailed Statistics
Created: Mon, 13 Aug 2007, 14:02:31 EST