Functional and structural features of γ-zeathionins, a new class of sodium channel blockers

• Published in: FEBS letters 1998-12, Vol.440 (3), p.302-306
• Main Authors: Kushmerick, Christopher, de Souza Castro, Mariana, Santos Cruz, Jáder, Bloch, Carlos, Beirão, Paulo S.L.
• Format: Article
• Language: English
• Subjects: 2D NMR, two-dimensional nuclear magnetic resonance spectroscopy; Amino Acid Sequence; Animals; Antimicrobial Cationic Peptides; Cell Line; Defensins; Dose-Response Relationship, Drug; Electrophysiology; GH3 cell line; Molecular Sequence Data; Patch clamp; Plant defensin; Plant Proteins - chemistry; Plant Proteins - pharmacology; Proteins - chemistry; Proteins - pharmacology; Rats; RP-HPLC, reverse-phase high-performance liquid chromatography; Sequence Homology, Amino Acid; Sodium channel; Sodium Channel Blockers; Sodium Channels - metabolism; STX, saxitoxin; TTX, tetrodotoxin; Zea mays; γ-Thionin; γ1-Z and γ2-Z, γ1- and γ2-zeathionins; μ-Conotoxin
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(98)01480-X

γ1- and γ2-zeathionins (γ1-Z and γ2-Z) are members of a family of small and basic peptides involved in plant protection. These plant defensins exhibit remarkable structural similarity to scorpion neurotoxins and insect defensins. In the present report, we used the whole-cell patch clamp technique to investigate the inhibition of the sodium current ( I Na) by γ1-Z and γ2-Z in the GH3 cell line. Both γ1-Z and γ2-Z rapidly and reversibly inhibited I Na without changing the kinetics or voltage dependence of activation or inactivation. To our knowledge, this is the first example of a plant protein that inhibits the sodium channel. From structural comparisons with the μ-conotoxins, a family of peptides that block the sodium channel, we detected some similar features that could provide the basis of inhibition of sodium channels by γ-zeathionins.