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Targeted Delivery of Cyclotides via Conjugation to a Nanobody.
- Source :
-
ACS chemical biology [ACS Chem Biol] 2018 Oct 19; Vol. 13 (10), pp. 2973-2980. Date of Electronic Publication: 2018 Oct 05. - Publication Year :
- 2018
-
Abstract
- Many naturally occurring peptides have poor proteolytic stability, which limits their therapeutic applications. Cyclotides are plant-derived cyclic peptides that resist proteolysis due to their highly constrained structure, comprising a head-to-tail cyclic backbone and three disulfide bonds that form a cystine-knotted core. This structure makes them useful as scaffolds onto which peptide sequences (epitopes) can be grafted. In this study, VHH7, an alpaca-derived nanobody that targets murine class II MHC molecules, was used for the targeted delivery of cyclotides to antigen-presenting cells (APCs). The cyclotides MCoTI-I, and MCoTI-I with a HA-tag (YPYDVPDYA) grafted into loop 6 (MCoTI-HA), were tested for immunogenic properties. To produce the requisite VHH7-peptide conjugates, a site-specific sortase A-catalyzed reaction in combination with a copper-free strain-promoted cycloaddition reaction was used. MCoTI-I alone did not display any obvious antibody response, thus showing the capacity of cyclotides as immunologically silent scaffolds. By contrast, MCoTI-I conjugated to VHH7 elicited antibodies against cyclic or linear MCoTI-I, thus suggesting a simple and robust approach for targeting cyclotides to APCs, and potentially to other cell types. A similar antibody response was observed when MCoTI-HA was conjugated to VHH7, but there was no reactivity toward a linear HA-tag itself, suggesting differences in conformational constraint between cyclotide-presented and linear epitopes. Studies of commercially available HA antibodies applied to MCoTI-HA confirmed that the conformation of peptide immunogens affects their reactivity. Thus, the production of antibodies that recognize constrained epitopes may benefit from engraftment onto scaffolds such as cyclotides. More broadly, this study validates that a prototypic cyclotide, a member of a peptide family that has proven to be useful as drug design scaffolds in many other studies, can efficiently reach a specific target in vivo.
- Subjects :
- Amino Acid Sequence
Animals
Camelids, New World
Cyclotides blood
Cyclotides chemistry
Epitopes immunology
Humans
Mice
Plant Proteins blood
Plant Proteins chemistry
Protein Stability
Single-Domain Antibodies blood
Single-Domain Antibodies chemistry
Cyclotides immunology
Plant Proteins immunology
Single-Domain Antibodies immunology
Subjects
Details
- Language :
- English
- ISSN :
- 1554-8937
- Volume :
- 13
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- ACS chemical biology
- Publication Type :
- Academic Journal
- Accession number :
- 30248263
- Full Text :
- https://doi.org/10.1021/acschembio.8b00653