NDLI: Substitutions in the Domain III Voltage-sensing Module Enhance the Sensitivity of an Insect Sodium Channel to a Scorpion β-Toxin*

Content Provider	PubMed Central
Author	Song, Weizhong Du, Yuzhe Liu, Zhiqi Luo, Ningguang Turkov, Michael Gordon, Dalia Michael, Gurevitz Goldin, Alan L. Dong, Ke
Copyright Year	2011
Abstract	Scorpion β-toxins bind to the extracellular regions of the voltage-sensing module of domain II and to the pore module of domain III in voltage-gated sodium channels and enhance channel activation by trapping and stabilizing the voltage sensor of domain II in its activated state. We investigated the interaction of a highly potent insect-selective scorpion depressant β-toxin, Lqh-dprIT3, from Leiurus quinquestriatus hebraeus with insect sodium channels from Blattella germanica (BgNav). Like other scorpion β-toxins, Lqh-dprIT3 shifts the voltage dependence of activation of BgNav channels expressed in Xenopus oocytes to more negative membrane potentials but only after strong depolarizing prepulses. Notably, among 10 BgNav splice variants tested for their sensitivity to the toxin, only BgNav1-1 was hypersensitive due to an L1285P substitution in IIIS1 resulting from a U-to-C RNA-editing event. Furthermore, charge reversal of a negatively charged residue (E1290K) at the extracellular end of IIIS1 and the two innermost positively charged residues (R4E and R5E) in IIIS4 also increased the channel sensitivity to Lqh-dprIT3. Besides enhancement of toxin sensitivity, the R4E substitution caused an additional 20-mV negative shift in the voltage dependence of activation of toxin-modified channels, inducing a unique toxin-modified state. Our findings provide the first direct evidence for the involvement of the domain III voltage-sensing module in the action of scorpion β-toxins. This hypersensitivity most likely reflects an increase in IIS4 trapping via allosteric mechanisms, suggesting coupling between the voltage sensors in neighboring domains during channel activation.
Related Links	http://dx.doi.org/10.1074/jbc.m110.217000
Ending Page	15788
Page Count	8
Starting Page	15781
File Format	PDF
ISSN	00219258
e-ISSN	1083351X
Journal	The Journal of Biological Chemistry
Issue Number	18
Volume Number	286
Language	English
Publisher	American Society for Biochemistry and Molecular Biology
Publisher Date	2011-05-06
Access Restriction	Open
Rights Holder	American Society for Biochemistry and Molecular Biology
Subject Keyword	Cell Biology Biochemistry Molecular Biology Research in Higher Education
Content Type	Text
Resource Type	Article
Subject	Cell Biology Biochemistry Molecular Biology

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Substitutions in the Domain III Voltage-sensing Module Enhance the Sensitivity of an Insect Sodium Channel to a Scorpion β-Toxin

Mapping the Interaction Site for a β-Scorpion Toxin in the Pore Module of Domain III of Voltage-gated Na+ Channels

Mapping the Interaction Site for a β-Scorpion Toxin in the Pore Module of Domain III of Voltage-gated Na+ Channels*

Structure-Function Map of the Receptor Site for β-Scorpion Toxins in Domain II of Voltage-gated Sodium Channels

Structure and Function of the Voltage Sensor of Sodium Channels Probed by a β-Scorpion Toxin* S

Neutralization of Gating Charges in Domain II of the Sodium Channel α Subunit Enhances Voltage-Sensor Trapping by a β-Scorpion Toxin

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Elucidation of the Molecular Basis of Selective Recognition Uncovers the Interaction Site for the Core Domain of Scorpion α-Toxins on Sodium Channels

Substitutions in the Domain III Voltage-sensing Module Enhance the Sensitivity of an Insect Sodium Channel to a Scorpion β-Toxin*

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