Discovery of plant proteins and protein scaffolds

Ribosomally produced proteins and peptides represent a class of natural products that still is vastly underexplored. Our research is focused on discovery and applications of novel proteins and protein scaffolds, and in particular, on the family of cyclic and cystine knotted plant proteins known as cyclotides.^1,2 This peptide family defines an ultra-stable peptide scaffold that may be considered ideal for peptide engineering. Currently, we are exploring the antimicrobial activity of cyclotides and their mechanism of action. We have recently shown that specific cyclotides have potent effect against gram-negative bacteria,³ and that they act by membrane thinning.⁴ However, recent results demonstrate that the membrane is not the only target of these peptides. At sub-cytotoxic concentrations, cyclotides demonstrate a different mode of action: they also cross over the cell membrane.

1. Göransson U, Burman R, Gunasekera S, Strömstedt AA, Rosengren KJ (2012)J Biol Chem, In press. 2. Craik DJ, Daly NL, Bond T, Waine C (1999)J Mol Biol, 294:1327. 3. Pränting M, Lööv C, Burman R, Göransson U, Andersson DI (2010)J Antimicrob Chemother. 65:1964. 4. Burman R, Strömstedt AA, Malmsten M, Göransson U (2011) BBA-Biomembranes, 1808:2665.