8.B.26 The Scorpion Toxin, Scoloptoxin (Scoloptoxin) Familly  

The Scoloptoxin family includes a number of peptide/protein toxins of vaious sized that bind to and inhibit various Na+ and K+ channels of the VIC superfamily (1.A.1).  For example, κ-scoloptoxin, Ssm1a, inhibits voltage-gated potassium channel currents in DRG neurons with an IC50 of 44.2 nM and shows signs of neurotoxicity including twitching, paralysis, and body contractions (Yang et al. 2012), and the 47 aa centipede toxin, Ssd609, inhibits K+ currents by binding to KCNE1 (8.A.10.1.1), a single-span transmembrane auxiliary protein that modulates the voltage-gated potassium channel KCNQ1 (TC# 1.A.1.15.1 and 1.A.1.15.6). The KCNQ1/KCNE1 complex in cardiomyocytes exhibited slow activated potassium (Iks) currents (Sun et al. 2015). Another centipede toxin, SsmTx-I acts as a simple inhibitor or channel blocker rather than a gating modifier of at least 9 channels including Kv2.1 (TC# 1.A.1.2.11) (Chen et al. 2014). The high resolution structures of several of these toxins are known.



This family belongs to the .

 

References:

Chen, M., J. Li, F. Zhang, and Z. Liu. (2014). Isolation and characterization of SsmTx-I, a Specific Kv2.1 blocker from the venom of the centipede Scolopendra Subspinipes Mutilans L. Koch. J Pept Sci 20: 159-164.

Sun, P., F. Wu, M. Wen, X. Yang, C. Wang, Y. Li, S. He, L. Zhang, Y. Zhang, and C. Tian. (2015). A distinct three-helix centipede toxin SSD609 inhibits Iks channels by interacting with the KCNE1 auxiliary subunit. Sci Rep 5: 13399.

Yang, S., Z. Liu, Y. Xiao, Y. Li, M. Rong, S. Liang, Z. Zhang, H. Yu, G.F. King, and R. Lai. (2012). Chemical punch packed in venoms makes centipedes excellent predators. Mol. Cell Proteomics 11: 640-650.

Examples:

TC#NameOrganismal TypeExample
8.B.26.1.1

κ-scoloptoxin of 74 aas.  Inhibits K+ currents selectively (Yang et al. 2012).

κ-Scoloptoxin of Scolopendra mutilans (Chinese red-headed centipede) (Scolopendra subspinipes mutilans)

 
8.B.26.1.2

Kappa-SLPTX-Ssm1c toxin of 73 aas that inhibits voltage-gated potassium channels.

kappa toxin Ssm1c of Scolopendra mutilans (Chinese red-headed centipede) (Scolopendra subspinipes mutilans)

 
8.B.26.1.3

Mu-SLPTx3-ssm6a of 46 aas (short version).  The solution structure is available (PDB# 2MUN)

SSM61 of Scolopendra mutilans

 
8.B.26.1.4

Mu-SLPTx3-Ssm6a of 112 aas (full length version).

SSM61 of Scolopendra mutilans

 
8.B.26.1.6

Kappa-scoloptoxin-Ssm1d; Short=Kappa-SLPTX-Ssm1d of 75 aas

Ssm1d of Scolopendra mutilans

κ-scoloptonxin of Scolopendra mutilans (Chinese red-headed centipede)