Molecular basis of toxicity of N-type calcium channel inhibitor MVIIA.
MVIIA (ziconotide) is a specific inhibitor of N-type calcium channel, Cav2.2. It is derived from Cone snail and currently used for the treatment of severe chronic pains in patients unresponsive to opioid therapy. However, MVIIA produces severe side-effects, including dizziness, nystagmus, somnolence, abnormal gait, and ataxia, that limit its wider application. We previously identified a novel inhibitor of Cav2.2, ω-conopeptide SO-3, which possesses similar structure and analgesic activity to MVIIA's. To investigate the key residues for MVIIA toxicity, MVIIA/SO-3 hybrids and MVIIA variants carrying mutations in its loop 2 were synthesized. The substitution of MVIIA's loop 1 with the loop 1 of SO-3 resulted in significantly reduced Cav2.2 binding activity in vitro; the replacement of MVIIA loop 2 by the loop 2 of SO-3 not only enhanced the peptide/Cav2.2 binding but also decreased its toxicity on goldfish, attenuated mouse tremor symptom, spontaneous locomotor activity, and coordinated locomotion function. Further mutation analysis and molecular calculation revealed that the toxicity of MVIIA mainly arose from Met(12) in the loop 2, and this residue inserts into a hydrophobic hole (Ile(300), Phe(302) and Leu(305)) located between repeats II and III of Cav2.2. The combinative mutations of the loop 2 of MVIIA or other ω-conopeptides may be used for future development of more effective Cav2.2 inhibitors with lower side effects.
Beijing Institute of Biotechnology, Beijing 100071, China.
Fei
F
Wang
Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
Zhenzhen
Z
Yan
Beijing Institute of Biotechnology, Beijing 100071, China.
Zhuguo
Z
Liu
Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
Sheng
S
Wang
Beijing Institute of Biotechnology, Beijing 100071, China.
Qiaoling
Q
Wu
Beijing Institute of Biotechnology, Beijing 100071, China.
Shuo
S
Yu
Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China. Electronic address: jpding@mail.hust.edu.cn.
Jiuping
J
Ding
Beijing Institute of Biotechnology, Beijing 100071, China. Electronic address: qy_dai@yahoo.com.
Qiuyun
Q
Dai
D000818:Animals; D002121:Calcium Channel Blockers / Q000378:metabolism / Q000633:toxicity*; D020864:Calcium Channels, N-Type / Q000235:genetics / Q000378:metabolism*; D006054:Goldfish; D057809:HEK293 Cells; D006801:Humans; D008124:Locomotion / Q000187:drug effects / Q000235:genetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008815:Mice, Inbred Strains; D000068079:Motor Disorders / Q000188:drug therapy / Q000235:genetics; D009154:Mutation; D009437:Neuralgia / Q000188:drug therapy / Q000209:etiology; D010455:Peptides / Q000494:pharmacology; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D017386:Sequence Homology, Amino Acid; D014202:Tremor / Q000139:chemically induced; D020960:omega-Conotoxins / Q000737:chemistry / Q000633:toxicity*
D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D010455:Peptides; D020960:omega-Conotoxins; C500963:Cacna1b protein, mouse; C482173:SO-3 conopeptide, Conus striatus; C078452:ziconotide
MVIIA; N-type-calcium channel inhibitor; SO-3; Toxicity; ω-conotoxins