Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
Naturally occurring as well as ‘designer’ cyclic peptides offer great potential as leads for drug design or crop protection agents in agriculture. This talk will focus on one class of cyclic peptides known as cyclotides, which are topologically unique in that they have a head-to-tail cyclized peptide backbone and a cystine knotted arrangement of three conserved disulfide bonds. This makes cyclotides exceptionally resistant to chemical, thermal or enzymatic degradation and, indeed, cyclotides are amongst nature’s most stable proteins. They occur in plants from the Rubiaceae (coffee), Violaceae (violet), Solanaceae (nightshade), Fabaceae (legume) and Cucurbitaceae (cucumber) families of plants where their natural function is presumed to be in host defence. This presentation will describe the membrane binding properties of cyclotides and how the delineation of these properties by NMR and other biophysical techniques has assisted in the understanding of their natural defense functions and pharmaceutical applications. In particular, solid phase synthesis has allowed us to make a range of modified cyclotides to probe structure-activity relationships. A cyclotide-containing product was recently approved for insect control in cotton and macadamia nut crops, marking the first commercial application of cyclotides in agriculture, and there are more than two dozen published examples of cyclotide-based drug leads.
Acknowledgments: Work in our laboratory is supported by the Australian Research Council and the National Health & Medical Research Council