2n8e
Three-dimensional structure of cyclic PVIIA
Structural highlights
FunctionO17A_CONPU Kappa-conotoxins bind and inhibit voltage-gated potassium channels (Kv). This toxin inhibits the drosophila Shaker channel (IC(50)=57-80 nM) (PubMed:12074021, PubMed:10818087, PubMed:27093300). In vivo, when tested in fish, this toxin induces hyperactivity, followed by continuous contraction and extension of major fins, without immobilization or death (PubMed:9417043, PubMed:12074021). Injection of this peptide together with the delta-conotoxin PVIA causes the sudden tetanus of prey (STOP) syndrome, which is a single, lethal 'fin-pop' in envenomed fish (PubMed:9417043, PubMed:12074021). When tested in mice, induces hyperactivity (PubMed:9417043).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedDisulfide-rich peptides isolated from cone snails are of great interest as drug leads due to their high specificity and potency toward therapeutically relevant ion channels and receptors. They commonly contain the inhibitor cystine knot (ICK) motif comprising three disulfide bonds forming a knotted core. Here we report the successful enzymatic backbone cyclization of an ICK-containing peptide kappa-PVIIA, a 27-amino acid conopeptide from Conus purpurascens, using a mutated version of the bacterial transpeptidase, sortase A. Although a slight loss of activity was observed compared to native kappa-PVIIA, cyclic kappa-PVIIA is a functional peptide that inhibits the Shaker voltage-gated potassium (Kv) channel. Molecular modeling suggests that the decrease in potency may be related to the loss of crucial, but previously unidentified electrostatic interactions between the N-terminus of the peptide and the Shaker channel. This hypothesis was confirmed by testing an N-terminally acetylated kappa-PVIIA, which shows a similar decrease in activity. We also investigated the conformational dynamics and hydrogen bond network of cyc-PVIIA, both of which are important factors to be considered for successful cyclization of peptides. We found that cyc-PVIIA has the same conformational dynamics, but different hydrogen bond network compared to those of kappa-PVIIA. The ability to efficiently cyclize ICK peptides using sortase A will enable future protein engineering for this class of peptides and may help in the development of novel therapeutic molecules. Biotechnol. Bioeng. 2016;113: 2202-2212. (c) 2016 Wiley Periodicals, Inc. Efficient enzymatic cyclization of an inhibitory cystine knot-containing peptide.,Kwon S, Bosmans F, Kaas Q, Cheneval O, Conibear AC, Rosengren KJ, Wang CK, Schroeder CI, Craik DJ Biotechnol Bioeng. 2016 Oct;113(10):2202-12. doi: 10.1002/bit.25993. Epub 2016, Aug 9. PMID:27093300[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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