title: From crystal structure of α-conotoxin GIC in complex with Ac-AChBP to molecular determinants of its high selectivity for α3β2 nAChR.
abstract: Acetylcholine binding proteins (AChBPs) are unique spatial homologs of the ligand-binding domains of nicotinic acetylcholine receptors (nAChRs), and they reproduce some pharmacological properties of nAChRs. X-ray crystal structures of AСhBP in complex with α-conotoxins provide important insights into the interactions of α-conotoxins with distinct nAChR subtypes. Although considerable efforts have been made to understand why α-conotoxin GIC is strongly selective for α3β2 nAChR, this question has not yet been solved. Here we present the structure of α-conotoxin GIC in complex with Aplysia californica AChBP (Ac-AChBP) at a resolution of 2.1 Å. Based on this co-crystal structure complemented with molecular docking data, we suggest the key residues of GIC in determining its high affinity and selectivity for human α3β2 vs α3β4 nAChRs. These suggestions were checked by radioligand and electrophysiology experiments, which confirmed the functional role of detected contacts for GIC interactions with Ac-AChBP and α3β2 nAChR subtypes. While GIC elements responsible for its high affinity binding with Ac-AChBP and α3β2 nAChR were identified, our study also showed the limitations of computer modelling in extending the data from the X-ray structures of the AChBP complexes to all nAChR subtypes.
authors.affiliation: Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou Hainan 570228, P. R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Lin
authors.affiliation: Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, P. R. China.
authors.forename: Manyu
authors.initials: M
authors.lastname: Xu
authors.affiliation: Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou Hainan 570228, P. R. China.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou Hainan 570228, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, P. R. China.
authors.forename: Xi
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou Hainan 570228, P. R. China.
authors.forename: Dongting
authors.initials: D
authors.lastname: Zhangsun
authors.affiliation: Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou Hainan 570228, P. R. China.
authors.forename: Yuanyan
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Nebraska Centre for Virology, School of Veterinary Medicine and Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
authors.forename: Shi-Hua
authors.initials: SH
authors.lastname: Xiang
authors.affiliation: Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10 Moscow 117997, Russia.
authors.forename: Igor E
authors.initials: IE
authors.lastname: Kasheverov
authors.affiliation: Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10 Moscow 117997, Russia.
authors.forename: Victor I
authors.initials: VI
authors.lastname: Tsetlin
authors.affiliation: Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, P. R. China.
authors.forename: Xinquan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Lab for Marine Drugs of Haikou, Hainan University, Haikou Hainan 570228, P. R. China.
authors.forename: Sulan
authors.initials: S
authors.lastname: Luo
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D020916:Conotoxins / Q000378:metabolism*; D018360:Crystallography, X-Ray; D062105:Molecular Docking Simulation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011978:Receptors, Nicotinic / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D020916:Conotoxins; D011978:Receptors, Nicotinic; C419362:nicotinic receptor alpha3beta2; C403530:nicotinic receptor alpha3beta4; D000109:Acetylcholine