Engineering Stabilized Vascular Endothelial Growth Factor-A Antagonists: Synthesis, Structural Characterization, and Bioactivity of Grafted Analogues of Cyclotides

Gunasekera, Sunithi; Foley, Fiona; Clark, Richard J.; Sando, Lillian; Fabri, Louis; Craik, David J.; Daly, Norelle L.

doi:10.1021/jm800704e

Cited by 179 publications

(179 citation statements)

References 52 publications

Supporting

Mentioning

175

Contrasting

Order By: Relevance

“…These activities reflect the ability of cyclotides to target cells of different compositions. More than 150 cyclotides have been characterized (10), and their diverse sequences, remarkable stability, and various bioactivities suggest that they have exciting potential as molecular frameworks in drug design (11).…”

mentioning

confidence: 99%

Decoding the Membrane Activity of the Cyclotide Kalata B1

Henriques

Huang

Rosengren

et al. 2011

Journal of Biological Chemistry

Self Cite

162

116

View full text Add to dashboard Cite

Cyclotides, a large family of cyclic peptides from plants, have a broad range of biological activities, including insecticidal, cytotoxic, and anti-HIV activities. In all of these activities, cell membranes seem likely to be the primary target for cyclotides. However, the mechanistic role of lipid membranes in the activity of cyclotides remains unclear. To determine the role of lipid organization in the activity of the prototypic cyclotide, kalata B1 (kB1), and synthetic analogs, their bioactivities and affinities for model membranes were evaluated. We found that the bioactivity of kB1 is dependent on the lipid composition of target cell membranes. In particular, the activity of kB1 requires specific interactions with phospholipids containing phosphatidylethanolamine (PE) headgroups but is further modulated by nonspecific peptide-lipid hydrophobic interactions, which are favored in raft-like membranes. Negatively charged phospholipids do not favor high kB1 affinity. This lipid selectivity explains trends in antimicrobial and hemolytic activities of kB1; it does not target bacterial cell walls, which are negatively charged and lacking PE-phospholipids but can insert in the membranes of red blood cells, which have a low PE content and raft domains in their outer layer. We further show that the anti-HIV activity of kB1 is the result of its ability to target and disrupt the membranes of HIV particles, which are raft-like membranes very rich in PE-phospholipids.Cyclotides are plant-derived peptides characterized by a cyclic backbone and three disulfide bonds forming a cystine knot motif (1) (Fig. 1) that confers them with exceptional stability (2). Their natural function appears to be as host defense insecticidal agents (3), but many other activities have also been reported, including uterotonic (4), anti-HIV (5), hemolytic (6), antibacterial (7), anti-cancer (8), and pesticidal action (9). These activities reflect the ability of cyclotides to target cells of different compositions. More than 150 cyclotides have been characterized (10), and their diverse sequences, remarkable stability, and various bioactivities suggest that they have exciting potential as molecular frameworks in drug design (11).It is believed that the activity of cyclotides is mediated by their ability to target and disrupt cell membranes. Such a mechanism of action is consistent with their hemolytic properties (6) and ability to disrupt gut epithelial cells in lepidopteron larvae (3) and is further supported by a range of biophysical studies (12-15). The prototypic cyclotide kalata B1 (kB1) 7 is the most well studied cyclotide, and it has been shown to bind to (12) and disrupt phospholipid bilayers by a pore-forming mechanism (15). Furthermore, in a previous study we showed that the all-D enantiomer (D-kB1) is bioactive, suggesting that activity does not require recognition by a chiral protein receptor (9). In combination, these reports suggest that cyclotides target cell membranes by interacting directly with lipids.Differences in bioactivity are...

show abstract

mentioning

confidence: 99%

Decoding the Membrane Activity of the Cyclotide Kalata B1

Henriques

Huang

Rosengren

et al. 2011

Journal of Biological Chemistry

Self Cite

162

116

View full text Add to dashboard Cite

show abstract

“…As another example, it may be possible to optimise the membrane-permeabilizing ability of cyclotides through scaffold modification to efficiently synergise the action of established anticancer drugs, as described above for cliotide CT2 and paclitaxel [68]. Proof-of-concept for such work was recently demonstrated when a grafted cyclotide, showed activity against growth factors involved in angiogenesis [101]; it is well-established that tumor growth is usually associated with unregulated angiogenesis [102]. As further proof-of-concept, more recently, work, which was patented [103], demonstrated that engineered cyclotides were cytotoxic to cancer cells through activation of the p53 tumor suppressor pathway, which is commonly inactivated by these cells to promote survival [104].…”

Section: Discussionmentioning

confidence: 99%

Anionic Host Defence Peptides from the Plant Kingdom: Their Anticancer Activity and Mechanisms of Action

Harris¹,

Prabhu²,

Dennison³

et al. 2016

PPL

View full text Add to dashboard Cite

Abstract:It is becoming increasingly clear that plants ranging across the plant kingdom produce anionic host defence peptides (AHDPs) with potent activity against a wide variety of human cancers cells. In general, this activity involves membrane partitioning by AHDPs, which leads to membranolysis and / or internalization to attack intracellular targets such as DNA. Several models have been proposed to describe these events including: the toroidal pore and Shai-Matsuzaki-Huang mechanisms but, in general, the mechanisms underpinning the membrane interactions and anticancer activity of these peptides are poorly understood. Plant AHDPs with anticancer activity can be conveniently discussed with reference to two groups: cyclotides, which possess cyclic molecules stabilized by cysteine knot motifs, and other ADHPs that adopt extended andhelical conformations. Here, we review research into the anticancer action of these two groups of peptides along with current understanding of the mechanisms underpinning this action.

show abstract

“…Despite the minimal changes introduced in kB1 by SrtA cyclization, no correctly folded peptide was produced when oxidation occurred after cyclization. Small changes in the amino acid composition of cyclotides can have profound effects on the refolding of synthetic forms (6,20), and it is possible that the introduction of the TGGG amino acid sequence in loop 6 of kB1 had a negative effect on the oxidative refolding of the cyclic form. The proximity of the cyclization point to Cys I ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…5), the loss of hemolytic activity is presumably due to the effects of the residues introduced into loop 6 upon cyclization. Previous grafting experiments utilizing kB1 have also shown the abrogation of hemolytic activity after relatively minor changes to the primary sequence; for example, the grafting of the vascular endothelial growth factor sequence (RRKRRR) into loop 2, 3, 5, or 6 significantly reduced the hemolytic activity of kB1 (20). The effects of single point mutations on the hemolytic activity of kB1 have also been extensively studied (73).…”

Section: Discussionmentioning

confidence: 99%

“…This tolerance to sequence substitutions makes them ideal scaffolds for the development of stable peptide-based drugs incorporating epitopes of therapeutic value. For example, a kB1 hybrid, with an anti-angiogenic epitope incorporated into loop 3, combined anti-angiogenic activity with the native stability of kB1 (20). Likewise, molecules possessing activity against foot-andmouth disease (21), inhibitory activity against ␤-tryptase and human leukocyte elastase (22), angiogenic activity (23), and the ability to antagonize intracellular p53 degradation (24) have also been achieved by grafting relevant bioactive epitopes into the cyclotide MCoTI-I or MCoTI-II.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Semienzymatic Cyclization of Disulfide-rich Peptides Using Sortase A

Jia

Kwon

Wang

et al. 2014

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Background: Sortase A (SrtA) is a transpeptidase capable of catalyzing the formation of amide bonds. Results: SrtA was used to backbone-cyclize disulfide-rich peptides, including kalata B1, ␣-conotoxin Vc1.1, and SFTI-1. Conclusion: SrtA-mediated cyclization is applicable to small disulfide-rich peptides. Significance: SrtA-mediated cyclization is an alternative to native chemical ligation for the cyclization of small peptides of therapeutic interest.

show abstract

Engineering Stabilized Vascular Endothelial Growth Factor-A Antagonists: Synthesis, Structural Characterization, and Bioactivity of Grafted Analogues of Cyclotides

Cited by 179 publications

References 52 publications

Decoding the Membrane Activity of the Cyclotide Kalata B1

Decoding the Membrane Activity of the Cyclotide Kalata B1

Anionic Host Defence Peptides from the Plant Kingdom: Their Anticancer Activity and Mechanisms of Action

Semienzymatic Cyclization of Disulfide-rich Peptides Using Sortase A

Contact Info

Product

Resources

About