title: The first gene-encoded amphibian neurotoxin.
abstract: Many gene-encoded neurotoxins with various functions have been discovered in fish, reptiles, and mammals. A novel 60-residue neurotoxin peptide (anntoxin) that inhibited tetrodotoxin-sensitive (TTX-S) voltage-gated sodium channel (VGSC) was purified and characterized from the skin secretions of the tree frog Hyla annectans (Jerdon). This is the first gene-encoded neurotoxin found in amphibians. The IC50 of anntoxin for the TTX-S channel was about 3.4 microM. Anntoxin shares sequence homology with Kunitz-type toxins but contains only two of three highly conserved cysteine bridges, which are typically found in these small, basic neurotoxin modules, i.e. snake dendrotoxins. Anntoxin showed an inhibitory ability against trypsin with an inhibitory constant (Ki) of 0.025 microM. Anntoxin was distributed in skin, brain, stomach, and liver with a concentration of 25, 7, 3, and 2 microg/g wet tissue, respectively. H. annectans lives on trees or other plants for its entire life cycle, and its skin contains the largest amount of anntoxin, which possibly helps defend against various aggressors or predators. A low dose of anntoxin was found to induce lethal toxicity for several potential predators, including the insect, snake, bird, and mouse. The tissue distribution and functional properties of the current toxin may provide insights into the ecological adaptation of tree-living amphibians.
authors.affiliation: Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan; Graduate School of the Chinese Academy of Sciences, Beijing 100009, China.
authors.forename: Dewen
authors.initials: D
authors.lastname: You
authors.affiliation: Graduate School of the Chinese Academy of Sciences, Beijing 100009, China; Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203.
authors.forename: Jing
authors.initials: J
authors.lastname: Hong
authors.affiliation: The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081.
authors.forename: Mingqiang
authors.initials: M
authors.lastname: Rong
authors.affiliation: College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, Hebei.
authors.forename: Haining
authors.initials: H
authors.lastname: Yu
authors.affiliation: The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081.
authors.forename: Songping
authors.initials: S
authors.lastname: Liang
authors.affiliation: Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan; Graduate School of the Chinese Academy of Sciences, Beijing 100009, China.
authors.forename: Yufang
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan; Graduate School of the Chinese Academy of Sciences, Beijing 100009, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Yang
authors.affiliation: Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan; Graduate School of the Chinese Academy of Sciences, Beijing 100009, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203.
authors.forename: Donghai
authors.initials: D
authors.lastname: Lin
authors.affiliation: Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan.
authors.forename: Ren
authors.initials: R
authors.lastname: Lai
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry*; D000818:Animals; D003001:Cloning, Molecular; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005786:Gene Expression Regulation; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000378:metabolism*; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D012867:Skin / Q000378:metabolism
chemical_list: D029845:Amphibian Proteins; D009498:Neurotoxins; C543423:anntoxin, Hyla annectans