title: Fusion of Ssm6a with a protein scaffold retains selectivity on NaV1.7 and improves its therapeutic potential against chronic pain.
abstract: Voltage-gated sodium channel NaV1.7 serves as an attractive target for chronic pain treatment. Several venom peptides were found to selectively inhibit NaV1.7 but with intrinsic problems. Among them, Ssm6a, a recently discovered centipede venom peptide, shows the greatest selectivity against NaV1.7, but dissociates from the target too fast and loses bioactivity in synthetic forms. As a disulfide-rich venom peptide, it is difficult to optimize Ssm6a by artificial mutagenesis and produce the peptide with common industrial manufacturing methods. Here, we developed a novel protein scaffold fusion strategy to address these concerns. Instead of directly mutating Ssm6a, we genetically fused Ssm6a with a protein scaffold engineered from human muscle fatty acid-binding protein. The resultant fusion protein, SP-TOX, maintained the selectivity and potency of Ssm6a upon NaV1.7 but dissociated from target at least 10 times more slowly. SP-TOX dramatically reduced inflammatory pain in a rat model through DRG-targeted delivery. Importantly, SP-TOX can be expressed cytosolically in Escherichia coli and purified in a cost-effective way. In summary, our study provided the first example of cytosolically expressed fusion protein with high potency and selectivity on NaV1.7. Our protein scaffold fusion approach may have its broad application in optimizing disulfide-rich venom peptides for therapeutic usage.
authors.affiliation: Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.
authors.forename: Chuan
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Pharmacy, The Fourth Hospital of Hebei Medical University, Shijiazhuang, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Shan
authors.affiliation: Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Neurobiology, Beijing Institute for Brain Disorders, Beijing Center of Neural Regeneration and Repair, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Capital Medical University, Beijing, China.
authors.forename: Qunyuan
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.
authors.forename: Hailin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Neurobiology, Beijing Institute for Brain Disorders, Beijing Center of Neural Regeneration and Repair, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Capital Medical University, Beijing, China.
authors.forename: Huimeng
authors.identifier: 0000-0003-2404-203X
authors.initials: H
authors.lastname: Lei
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001180:Arthropod Venoms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D059350:Chronic Pain / Q000628:therapy*; D004195:Disease Models, Animal; D055808:Drug Discovery; D050556:Fatty Acid-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000188:drug therapy; D062556:NAV1.7 Voltage-Gated Sodium Channel / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000627:therapeutic use*
chemical_list: D001180:Arthropod Venoms; D050556:Fatty Acid-Binding Proteins; D062556:NAV1.7 Voltage-Gated Sodium Channel; D010455:Peptides; D011993:Recombinant Fusion Proteins
keywords: NaV1.7 inhibitor; Ssm6a; chronic pain; drug discovery; sodium channel; venom