5Y7L

Solution structure of Hbeta4 extracellular loop of BK potassium channel

Summary for 5Y7L

• Entry DOI: 10.2210/pdb5y7l/pdb
• Descriptor: Calcium-activated potassium channel subunit beta-4 (1 entity in total)
• Functional Keywords: beta4, bk, metal binding protein
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 1
• Total formula weight: 14114.56

Authors

Wang, Y.,Lan, W.,Ding, J.,Cao, C. (deposition date: 2017-08-17, release date: 2018-08-01, Last modification date: 2024-11-13)

Primary citation

Wang, Y.,Lan, W.,Yan, Z.,Gao, J.,Liu, X.,Wang, S.,Guo, X.,Wang, C.,Zhou, H.,Ding, J.,Cao, C.
Solution structure of extracellular loop of human beta 4 subunit of BK channel and its biological implication on ChTX sensitivity.
Sci Rep, 8:4571-4571, 2018

PubMed Abstract: Large-conductance Ca- and voltage-dependent K (BK) channels display diverse biological functions while their pore-forming α subunit is coded by a single Slo1 gene. The variety of BK channels is correlated with the effects of BKα coexpression with auxiliary β (β1-β4) subunits, as well as newly defined γ subunits. Charybdotoxin (ChTX) blocks BK channel through physically occluding the K-conduction pore. Human brain enriched β4 subunit (hβ4) alters the conductance-voltage curve, slows activation and deactivation time courses of BK channels. Its extracellular loop (hβ4-loop) specifically impedes ChTX to bind BK channel pore. However, the structure of β4 subunit's extracellular loop and the molecular mechanism for gating kinetics, toxin sensitivity of BK channels regulated by β4 are still unclear. To address them, here, we first identified four disulfide bonds in hβ4-loop by mass spectroscopy and NMR techniques. Then we determined its three-dimensional solution structure, performed NMR titration and electrophysiological analysis, and found that residue Asn123 of β4 subunit regulated the gating and pharmacological characteristics of BK channel. Finally, by constructing structure models of BKα/β4 and thermodynamic double-mutant cycle analysis, we proposed that BKα subunit might interact with β4 subunit through the conserved residue Glu264(BKα) coupling with residue Asn123(β4).

PubMed: 29545539
DOI: 10.1038/s41598-018-23016-y

Experimental method

SOLUTION NMR