Solution Structure of Peptide Toxins That Block Mechanosensitive Ion Channels

Abstract

Mechanosensitive channels (MSCs) play key roles in sensory processing and have been implicated as primary transducers for a variety of cellular responses ranging from osmosensing to gene expression. This paper presents the first structures of any kind known to interact specifically with MSCs. GsMTx-4 and GsMtx-2 are inhibitor cysteine knot peptides isolated from venom of the tarantula, Grammostola spatulata (Suchyna, T.

A Novel Family of Insect-Selective Peptide Neurotoxins Targeting Insect Large-Conductance Calcium-Activated K+ Channels Isolated from the Venom of the Theraphosid Spider Eucratoscelus constrictus

“…This mode of action is similar to that reported for the insect-selective neurotoxin -HXTX-Hv1c, from the venom of the hexathelid spider H. versuta, that also inhibits BK Ca channels (Gunning et al, 2008). Homology modeling of -TRTX-Ec2 toxins on the known structure of -TRTX-Gr2a (formerly GsMTx-2, Oswald et al, 2002;Protein Data Bank ID 1LUP), revealed several pairs of basic and aromatic residues that could satisfy the requirements of a functional dyad (Fig. 8).…”

“…Percentage identity (%I) is relative to -TRTX-Ec2a, whereas percentage homology (%H) includes conservatively substituted residues. The disulfide bonding pattern for the strictly conserved cysteine residues determined for -TRTX-Gr2a (Oswald et al, 2002) and -TRTX-Ps2a (Diochot et al, 1999) is indicated above the sequences; it is assumed that the -TRTX-Ec2 toxins share the same disulfide bonding pattern. The known mammalian targets (unless otherwise indicated) of these spider toxins are identified on the right, with channels identified in brackets indicating only weak affinity.…”

Mechanosensitive ion channels and the peptide inhibitor GsMTx-4: History, properties, mechanisms and pharmacology

“…GsMTx4 follows the Inhibitory Cysteine Knot (ICK) motif with six cysteines (Pallaghy et al, 1994;Oswald et al, 2002), and as with similar neuroactive peptides, it is amphipathic ( Figure 5). The hydrophobic face is in green and the charged residues in red (negative) and blue (positive).…”

“…Using this sequence, we chemically synthesized GsMTx4 with a phenylalanine-amide at the C-terminal and determined the conditions for folding (Ostrow et al, 2003;Oswald et al, 2002). The synthetic peptide appeared indistinguishable from wild type peptide in all physicalchemical properties.…”

The slow force response to stretch in atrial and ventricular myocardium from human heart: Functional relevance and subcellular mechanisms

“…The following drugs were used (source): BQ123 (Calbiochem or Sigma), candesartan or CV11974 (generous gift of AstraZeneca, Mölndal, Sweden), cariporide or HOE642 (generous gift of Aventis Pharma, Frankfurt, Germany), GF203109X (Calbiochem), GsMtx-4 (prepared as described before (Ostrow et al, 2003;Oswald et al, 2002)), KB-R7943 (Tocris), L-NAME (Sigma), ML-7 (Calbiochem), PD145065 (Sigma), streptomycin (Sigma), wortmannin (Calbiochem).…”