Solution structure of a novel α-conotoxin with a distinctive loop spacing pattern
- 214 Downloads
α-Pharmacological conotoxins are among the most selective ligands of nicotinic acetylcholine receptors with typical cysteine frameworks. They are characterized by the intercysteine loop and classified into various subfamilies, such as α3/5 and α4/7 conotoxins. A novel α-conotoxin, Pu14a (DCPPHPVPGMHKCVCLKTC), with a distinct loop spacing pattern between cysteines was reported recently. Pu14a belongs to the Cys framework 14 (–C–C–C–C) family containing four proline residues in the loop 1 region. Similar to another framework 14 conotoxin Lt14a (MCPPLCKPSCTNC-NH2), Pu14a has C1–C3/C2–C4 disulfide linkage, and can inhibit some subtypes of nicotinic acetylcholine receptors. In this study, the solution structure of Pu14a was investigated using 1H nuclear magnetic resonance spectroscopy to understand the structure-activity relationship of this conotoxin. 20 converged structures of this conopeptide, with RMSD value of 0.77 Å, were obtained based on distance constraints, dihedral angles and disulfide bond constraints. The three-dimensional structure of Pu14a showed remarkable difference from typical α-conotoxins because of a large intercysteine loop between C2 and C13, as well as a 310-helix near the C-terminal. Furthermore, four proline residues in Pu14a adopted the trans conformation that may correlate with the large loop configuration and the biological activity of this conopeptide. The distinct structural characteristics of Pu14a will be very useful for studying the structure-activity relationship of α-conotoxins.
Keywordsα-Conotoxin Pu14a Solution structure Proline
We thank Prof. Chunguang Wang and Prof. Chengwu Chi from Tongji University for supplying the sample of Pu14a friendly. This work was supported by the National Basic Research Program (No. 2011CB808503), and the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China (No. 10XNJ011).
Conflict of interest
- Koradi R, Billeter M, Wüthrich K (1996) MOLMOL: a program for display and analysis of macromolecular structures. J Mol Graph 14(51–55):29–32Google Scholar
- Lopez-Vera1 E, Aguilar MB, Schiavon E, Marinzi C, Ortiz E, Cassulini RR, Batista CVF, Possani LD, de la Cotera EPH, Peri F, Becerril B, Wanke E (2007) Novel α-conotoxins from conus spurius and theα-conotoxin EI share high-affinity potentiation and low-affinity inhibition of nicotinic acetylcholine receptors. FEBS J 274:3972–3985Google Scholar
- Luo SL, Akondi KB, Zhangsun D, Wu Y, Zhu XP, Hu YY, Christensen S, Dowell C, Daly NL, Craik DJ, Wang CA, Lewis RJ, Alewood PF, McIntosh JM (2010) A typical α-conotoxin ltIA from conus litteratus targets a novel microsite of the α3β2 nicotinic receptor. J Biol Chem 285:12355–12366PubMedCrossRefGoogle Scholar
- McIntosh JM, Cruz LJ, Hunkapiller MW, Gray WR, Olivera BM (1982) Isolation and structure of a peptide toxin from the marine snail Conusmagus. Arch Biochem Biophys 5:280–292Google Scholar
- Wuthrich K (1986) NMR of proteins and nucleic acids. Wiley, New YorkGoogle Scholar