Exp Neurobiol.  2022 Oct;31(5):277-288. 10.5607/en22038.

Glutamate Permeability of Chicken Best1

• Lee JM
• Gadhe CG
• Kang H
• Pae AN
• Leec CJ

• KMID: 2535059
• DOI: http://doi.org/10.5607/en22038

Abstract

Bestrophin-1 (Best1) is a calcium (Ca ²⁺ )-activated chloride (Cl ^- ) channel which has a phylogenetically conserved channel structure with an aperture and neck in the ion-conducting pathway. Mammalian mouse Best1 (mBest1) has been known to have a permeability for large organic anions including gluconate, glutamate, and D-serine, in addition to several small monovalent anions, such as Cl ^- , bromine (Br ^- ), iodine (I ^- ), and thiocyanate (SCN ^- ). However, it is still unclear whether non-mammalian Best1 has a glutamate permeability through the ion-conducting pathway. Here, we report that chicken Best1 (cBest1) is permeable to glutamate in a Ca ²⁺ -dependent manner. The molecular docking and molecular dynamics simulation showed a glutamate binding at the aperture and neck of cBest1 and a glutamate permeation through the ion-conducting pore, respectively. Moreover, through electrophysiological recordings, we calculated the permeability ratio of glutamate to Cl ^- (P _Glutamate /P _Cl ) as 0.28 based on the reversal potential shift by ion substitution from Cl ^- to glutamate in the internal solution. Finally, we directly detected the Ca ²⁺ -dependent glutamate release through cBest1 using the ultrasensitive two-cell sniffer patch technique. Our results propose that Best1 homologs from non-mammalian (cBest1) to mammalian (mBest1) have a conserved permeability for glutamate.

Keyword

Chicken Best1; Glutamate permeability; Molecular docking simulation; Molecular dynamics simulation; Whole-cell patch-clamp recording; Two-cell sniffer patch