title: Structural and functional characterization of ryanodine receptor-natrin toxin interaction.
abstract: Cysteine-rich secretory proteins (CRISPs) are widely distributed, and notably occur in the mammalian reproductive tract and in the salivary glands of venomous reptiles. Most CRISPs can inhibit ion channels, such as the cyclic nucleotide-gated ion channel, potassium channel, and calcium channel. Natrin is a CRISP that has been purified from snake venom. Its targets include the calcium-activated potassium channel, the voltage-gated potassium channel, and the calcium release channel/ryanodine receptor (RyR). Immunoprecipitation experiments showed that natrin binds specifically to type 1 RyR (RyR1) from skeletal muscle. Natrin was found to inhibit both the binding of ryanodine to RyR1, and the calcium-channel activity of RyR1. Cryo-electron microscopy and single-particle image reconstruction analysis revealed that natrin binds to the clamp domains of RyR1. Docking of the crystal structure of natrin into our cryo-electron microscopy density map of the RyR1 + natrin complex suggests that natrin inhibits RyR1 by stabilizing a domain-domain interaction, and that the cysteine-rich domain of natrin is crucial for binding. These findings help reveal how natrin toxin inhibits the RyR calcium release channel, and they allow us to posit a generalized mechanism that governs the interaction between CRISPs and ion channels.
authors.affiliation: Department of Biological Sciences and Biotechnology, State-Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhou
authors.forename: Qiong-Ling
authors.initials: QL
authors.lastname: Wang
authors.forename: Xing
authors.initials: X
authors.lastname: Meng
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Shu
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Terence
authors.initials: T
authors.lastname: Wagenknecht
authors.forename: Chang-Cheng
authors.initials: CC
authors.lastname: Yin
authors.forename: Sen-Fang
authors.initials: SF
authors.lastname: Sui
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D015220:Calcium Channels / Q000378:metabolism; D020134:Catalytic Domain; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D003545:Cysteine; D004546:Elapid Venoms / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D008958:Models, Molecular; D008968:Molecular Conformation; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004546:Elapid Venoms; D019837:Ryanodine Receptor Calcium Release Channel; C495581:natrin protein, Naja atra; D012433:Ryanodine; D003545:Cysteine