Chronic pain is a major worldwide health issue, with patients often receiving inadequate treatment. The voltage-gated sodium (NaV) channel, NaV1.7 is a promising target for development of analgesics to treat chronic pain since loss-of-function mutations in this channel lead to a congenital indifference to all forms of pain. Thus, blockers of Nav1.7 are likely to be useful analgesics for treating a wide range of pain disorders. However, it is critical to ensure that such drugs do not inhibit other NaV subtypes with essential physiological functions, such as NaV1.5 that is critical for the cardiac action potential.
Venom-based drug discovery is emerging as a promising source of novel pharmaceutical lead compounds. Using a proprietary in-house screen, we identified a large number of spider-venom peptides that block the human NaV1.7 channel. A number of these peptides, along with a subset of previously published spider-venom peptides, fall into a single structural family. Systematic structural and functional analysis of these peptides should enable us to determine the primary epitopes that govern their affinity and selectivity for various NaV channel subtypes, and thus engineer peptides with improved potency and subtype selectivity.
To facilitate this goal, we developed a recombinant expression system for production of uniformly 15N/13C-labelled peptide for structure determination using the high-throughput ASAP-NMR pipeline developed at The University of Queensland. NMR spectra are obtained by non-uniform sampling and processed using maximum entropy reconstruction, an approach that provides both significant time savings and enhanced spectral resolution. The availability of a recombinant expression system and a high-throughput structure determination platform is allowing us to probe the structural epitopes that mediate the interaction of these venom peptides with NaV channels, and to design peptides with improved therapeutic properties.