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Biochem Pharmacol. 2014 May 15;89(2):276-86. doi: 10.1016/j.bcp.2014.02.008. Epub 2014 Feb 19.

Isolation, synthesis and characterization of ω-TRTX-Cc1a, a novel tarantula venom peptide that selectively targets L-type Cav channels.

Author information

1
Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: j.klint@imb.uq.edu.au.
2
Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia. Electronic address: geza.berecki@rmit.edu.au.
3
Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: t.durek@imb.uq.edu.au.
4
Centre for Advanced Imaging, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: m.mobli@uq.edu.au.
5
Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia. Electronic address: knapplowitsch@yahoo.de.
6
Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: g.king2@uq.edu.au.
7
Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia. Electronic address: david.adams@rmit.edu.au.
8
Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: P.Alewood@imb.uq.edu.au.
9
Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: l.rash@uq.edu.au.

Abstract

Spider venoms are replete with peptidic ion channel modulators, often with novel subtype selectivity, making them a rich source of pharmacological tools and drug leads. In a search for subtype-selective blockers of voltage-gated calcium (CaV) channels, we isolated and characterized a novel 39-residue peptide, ω-TRTX-Cc1a (Cc1a), from the venom of the tarantula Citharischius crawshayi (now Pelinobius muticus). Cc1a is 67% identical to the spider toxin ω-TRTX-Hg1a, an inhibitor of CaV2.3 channels. We assembled Cc1a using a combination of Boc solid-phase peptide synthesis and native chemical ligation. Oxidative folding yielded two stable, slowly interconverting isomers. Cc1a preferentially inhibited Ba(2+) currents (IBa) mediated by L-type (CaV1.2 and CaV1.3) CaV channels heterologously expressed in Xenopus oocytes, with half-maximal inhibitory concentration (IC50) values of 825nM and 2.24μM, respectively. In rat dorsal root ganglion neurons, Cc1a inhibited IBa mediated by high voltage-activated CaV channels but did not affect low voltage-activated T-type CaV channels. Cc1a exhibited weak activity at NaV1.5 and NaV1.7 voltage-gated sodium (NaV) channels stably expressed in mammalian HEK or CHO cells, respectively. Experiments with modified Cc1a peptides, truncated at the N-terminus (ΔG1-E5) or C-terminus (ΔW35-V39), demonstrated that the N- and C-termini are important for voltage-gated ion channel modulation. We conclude that Cc1a represents a novel pharmacological tool for probing the structure and function of L-type CaV channels.

KEYWORDS:

Citharischius crawshayi; Peptide isomer; Tarantula; Venom-peptide; Voltage-gated calcium channel; Voltage-gated sodium channel

PMID:
24561180
DOI:
10.1016/j.bcp.2014.02.008
[Indexed for MEDLINE]

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