Cryo-EM strucutre of human acid-sensing ion channel 1a at pH 8.0

N-acetyl-beta-D-glucosamine; 2-acetamido-2-deoxy-beta-D-glucose; 2-acetamido-2-deoxy-D-glucose; 2-acetamido-2-deoxy-glucose; N-ACETYL-D-GLUCOSAMINE

Structural insights into human acid-sensing ion channel 1a inhibition by snake toxin mambalgin1.

The optimized coding DNAs for human hASIC1a (Uniprot: P78348) was synthesized by GeneScript. The truncated hASIC1a (with the carboxyl terminal 60 residues removed, named as hASIC1a-DeltaC) was cloned into the pFastBac1 vector (Invitrogen) with 8-His tag at the amino terminus. Baculovirus-infected Sf9 cells (Thermo Fisher) were used for overexpression and were grown at 300K in serum-free SIM SF medium (Sino Biological Inc.).

Grids were transferred to a Titan Krios electron microscope (FEI) operated at 300 kV equipped with a Gatan K2 Summit direct detection camera. Images of hASIC1a was collected using the automated image acquisition software SerialEM in counting mode with 29,000x magnification yielding a pixel size of 1.014 A. The total dose of 50 e-/A2 was fractionated to 40 frames with 0.2 s per frame. Nominal defocus values ranged from -1.8 to -2.5 um. The dataset of hASIC1a included 3,235 micrographs.

The eluted protein in Ni-NTA affinity chromatography was further purified by size-exclusion chromatography in 20 mM Tris (pH 8.0), 200 mM NaCl, 0.05% DDM, 0.01% CHS using a Superdex200 10/300GL column (GE HealthCare).The protein was concentrated to about 5 mg/ml based on A280 measurement, using a 100-kDa cutoff Centricon (Millipore).

Purified hASIC1a-DeltaC (3 ul) at a concentration of 2.7 mg/ml was added to the freshly plasma-cleaned holey carbon grid (Quantifol, R1.2/1.3, 300 mesh, Cu), blotted for 5 s at 100% humidity with a Vitrobot Mark IV (ThermoFisher Scientific) and plunge frozen into liquid ethane cooled by liquid nitrogen.

ASIC1,Amiloride-sensitive cation channel 2,neuronal,Brain sodium channel 2,BNaC2

MHHHHHHHHMELKAEEEEVGGVQPVSIQAFASSSTLHGLAHIFSYERLSLKRALWALCFLGSLAVLLCVCTERVQYYFHY
HHVTKLDEVAASQLTFPAVTLCNLNEFRFSQVSKNDLYHAGELLALLNNRYEIPDTQMADEKQLEILQDKANFRSFKPKP
FNMREFYDRAGHDIRDMLLSCHFRGEVCSAEDFKVVFTRYGKCYTFNSGRDGRPRLKTMKGGTGNGLEIMLDIQQDEYLP
VWGETDETSFEAGIKVQIHSQDEPPFIDQLGFGVAPGFQTFVACQEQRLIYLPPPWGTCKAVTMDSDLDFFDSYSITACR
IDCETRYLVENCNCRMVHMPGDAPYCTPEQYKECADPALDFLVEKDQEYCVCEMPCNLTRYGKELSMVKIPSKASAKYLA
KKFNKSEQYIGENILVLDIFFEVLNYETIEQKKAYEIAGLLGDIGGQMGLFIGASILTVLELFDYAYEVIKHKLCRR

National Natural Science Foundation of China (NSFC)

Ministry of Science and Technology (MoST, China)

ASIC, human, resting state, cryo-EM structure, MEMBRANE PROTEIN

MELKAEEEEVGGVQPVSIQAFASSSTLHGLAHIFSYERLSLKRALWALCFLGSLAVLLCVCTERVQYYFHYHHVTKLDEV
AASQLTFPAVTLCNLNEFRFSQVSKNDLYHAGELLALLNNRYEIPDTQMADEKQLEILQDKANFRSFKPKPFNMREFYDR
AGHDIRDMLLSCHFRGEVCSAEDFKVVFTRYGKCYTFNSGRDGRPRLKTMKGGTGNGLEIMLDIQQDEYLPVWGETDETS
FEAGIKVQIHSQDEPPFIDQLGFGVAPGFQTFVACQEQRLIYLPPPWGTCKAVTMDSDLDFFDSYSITACRIDCETRYLV
ENCNCRMVHMPGDAPYCTPEQYKECADPALDFLVEKDQEYCVCEMPCNLTRYGKELSMVKIPSKASAKYLAKKFNKSEQY
IGENILVLDIFFEVLNYETIEQKKAYEIAGLLGDIGGQMGLFIGASILTVLELFDYAYEVIKHKLCRR