Structure-activity relationships of ω-Agatoxin IVA in lipid membranes

• Published in: Biochemical and biophysical research communications Vol. 482; no. 1; pp. 170 - 175
• Main Authors: Ryu, Jae Ha, Jung, Hoi Jong, Konishi, Shiro, Kim, Ha Hyung, Park, Zee-Yong, Kim, Jae Il
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-01-2017
• Subjects: 60 APPLIED LIFE SCIENCES; Animals; Binding Sites; Calcium Channels, N-Type - chemistry; Calcium Channels, N-Type - ultrastructure; Cav2.1; Cell Membrane - chemistry; Gating modifier toxin; Lipid Bilayers - chemistry; MATHEMATICAL SOLUTIONS; MEMBRANES; Molecular Conformation; NITROGEN 15; NUCLEAR MAGNETIC RESONANCE; omega-Agatoxin IVA - chemistry; Protein Binding; Purkinje Cells - chemistry; Rats; Rats, Wistar; Structure-Activity Relationship; STRUCTURE-ACTIVITY RELATIONSHIPS; TOXINS; ω-Agatoxin IVA; ω-Aga IVA; CD; CSP; NMR; Gating modifier toxin; DPC; ω-Agatoxin IVA; Cav2.1; HSQC
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2016.11.025

To analyze structural features of ω-Aga IVA, a gating modifier toxin from spider venom, we here investigated the NMR solution structure of ω-Aga IVA within DPC micelles. Under those conditions, the Cys-rich central region of ω-Aga IVA still retains the inhibitor Cys knot motif with three short antiparallel β-strands seen in water. However, 15N HSQC spectra of ω-Aga IVA within micelles revealed that there are radical changes to the toxin's C-terminal tail and several loops upon binding to micelles. The C-terminal tail of ω-Aga IVA appears to assume a β-turn like conformation within micelles, though it is disordered in water. Whole-cell patch clamp studies with several ω-Aga IVA analogs indicate that both the hydrophobic C-terminal tail and an Arg patch in the core region of ω-Aga IVA are critical for Cav2.1 blockade. These results suggest that the membrane environment stabilizes the structure of the toxin, enabling it to act in a manner similar to other gating modifier toxins, though its mode of interaction with the membrane and the channel is unique.
•The NMR structure of ω-Aga IVA in DPC micelles is determined.•ω-Aga IVA stabilized its C-terminal tail with a β-turn structure within micelles.•Both the C-terminal tail and Arg patch play a crucial role for blocking Cav2.1.