Interactions of Disulfide-deficient Selenocysteine Analogues of µ-BuIIIB with the Voltage-Gated Sodium Channel Na<sub>V</sub>1.3 — ASN Events
  1. Schedule
  2. Session 10: Poster Session C
  3. Interactions of Disulfide-deficient Selenocysteine Analogues of µ-BuIIIB with the Voltage-Gated Sodium Channel NaV1.3

Interactions of Disulfide-deficient Selenocysteine Analogues of µ-BuIIIB with the Voltage-Gated Sodium Channel NaV1.3 (#332)

Brad R Green 1 , Min-Min Zhang 2 , Sandeep Chhabra 1 , Samuel D Robinson 1 , Baldomero M Olivera 2 , Grzegorz Bulaj 3 , Raymond S Norton 1
  1. Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
  2. Department of Biology, University of Utah, Salt Lake City, Utah, USA
  3. Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, Utah, USA

Nine voltage-gated sodium channel subtypes (NaV1.1 - NaV1.9) have been described to date in mammals.  Of these, three have been clearly identified as important for the transmission of pain signals from the central or peripheral nervous systems to the brain (NaV1.7, NaV1.8 and NaV1.9).  Less clear has been the role of the NaV1.3 subtype in pain signaling. This subtype is prevalent in the embryonic nervous system; but, largely absent in the adult nervous system.  Hains and co-workers showed the up-regulated expression of NaV1.3 in the spinal cord and thalamus following spinal cord injury, suggesting a role in neuropathic pain (1).  Unfortunately, molecular tools to discover the role of NaV1.3 in neuropathic pain have been lacking.    Members of the μ-conotoxin family from the venoms of fish hunting marine gastropods have shown potential as potent inhibitors of voltage-gated sodium channels.  The majority of these target either skeletal (NaV1.4) or neuronal (NaV1.2) subtypes.  However, the sequential similarities between subtypes often result in lesser block of the remaining subtypes (2).  The recently identified μ-conotoxin BuIIIB from Conus bullatus was shown to preferentially block NaV1.4. However, it also blocked NaV1.3 with low micromolar potency (Kd = 0.2 μM) (2, 3). 

Efforts to describe the molecular interactions between μ-BuIIIB and NaV1.3 have been largely unsuccessful due to the synthetic inaccessibility of this peptide which has precluded detailed structure-activity (SAR) studies.  To circumvent these issues, we employed a strategy of disulfide-bridge depletion, in combination with diselenide-bridge incorporation, to simplify the oxidative folding pathway and reduce the number of potential folding isoforms.  This resulted in a synthetically available analogue of μ-BuIIIB which retained all non-cysteine residues and exhibited 'native-like' potency for NaV1.3, namely BuIIIB[C5U,C17U,C6A,C23A].  This scaffold was used to identify important interactions between the peptide and NaV1.3.   SAR studies revealed an important substitution near the N-terminus which resulted in increased NaV1.3 potency.  The solution structure of the peptide scaffold revealed significant structural differences compared to the native peptide, despite its potent neuroactivity.  Herein, we report the discovery of a new peptide blocker of NaV1.3 which may prove useful as a tool to better understand the role of this subtype in neuropathic pain.    

  1. Hains, B. C., Klein, J. P., Saab, C. Y., Craner, M. J., Black, J. A. and Waxman, S. G. (2003) J. Neurosci. 23(26), 8881-92.
  2. Wilson, M. J., Yoshikami, D., Azam, L., Gajewiak, J., Olivera, B. M., Bulaj, G. and Zhang, M. M. (2011) Proc. Natl. Acad. Sci. USA. 108(25), 10302-07.
  3. Kuang, Z., Zhang, M. M., Gupta, K., Gajewiak, J., Gulyas, J., Balaram, P., Rivier, J. E., Olivera, B. M., Yoshikami, D., Bulaj, G. and Norton, R. S. (2013) ACS Chem. Biol. 8, 1344-51.