Mitochondrial large-conductance potassium channel from Dictyostelium discoideum. (March 2015)

• Record Type: Journal Article
• Authors: Laskowski, Michal; Kicinska, Anna; Szewczyk, Adam; Jarmuszkiewicz, Wieslawa
• Is Part Of: International journal of biochemistry & cell biology. Volume 60(2015:Mar.)
• Page Start: 167
• Page End: 175
• Publication Date: 2015-03
• Subjects: Dictyostelium discoideum -- Mitochondria -- Potassium channel -- Electrophysiology -- Bioenergetics; BKCa channel plasma membrane large-conductance Ca2+-activated potassium channel -- NS11021 1-(3, 5-bis-trifluoromethyl-phenyl)-3-[4-bromo-2-(1H-tetrazol-5-yl)-phenyl]-thiourea -- NS1619 1, 3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazole-2-one -- mitoBKCa channel mitochondrial large-conductance Ca2+-activated potassium channel -- PLB planar lipid bilayer -- ROS reactive oxygen species -- ΔΨ mitochondrial membrane electrical potential; Biochemistry -- Periodicals; Cytology -- Periodicals; Biochemistry -- Periodicals; Cell Biology -- Periodicals; Biochimie -- Périodiques; Cytologie -- Périodiques; Biochimie; Cytologie; Biochemistry; Cytology; Ressource Internet (Descripteur de forme); Périodique électronique (Descripteur de forme); Periodicals; 572.05
• DOI: 10.1016/j.biocel.2015.01.006
• Languages: English
• ISSNs: 1357-2725

Abstract

Abstract: In the present study, we describe the existence of a large-conductance calcium-activated potassium (BKCa ) channel in the mitochondria of Dictyostelium discoideum . A single-channel current was recorded in a reconstituted system, using planar lipid bilayers. The large-conductance potassium channel activity of 258 ± 12 pS was recorded in a 50/150 mM KCl gradient solution. The probability of channel opening (the channel activity) was increased by calcium ions and NS1619 (potassium channel opener) and reduced by iberiotoxin (BKCa channel inhibitor). The substances known to modulate BKCa channel activity influenced the bioenergetics of D. discoideum mitochondria. In isolated mitochondria, NS1619 and NS11021 stimulated non-phosphorylating respiration and depolarized membrane potential, indicating the channel activation. These effects were blocked by iberiotoxin and paxilline. Moreover, the activation of the channel resulted in attenuation of superoxide formation, but its inhibition had the opposite effect. Immunological analysis with antibodies raised against mammalian BKCa channel subunits detected a pore-forming α subunit and auxiliary β subunits of the channel in D. discoideum mitochondria. In conclusion, we show for the first time that mitochondria of D. discoideum, a unicellular ameboid protozoon that facultatively forms multicellular structures, contain a large-conductance calcium-activated potassium channel with electrophysiological, biochemical and molecular properties similar to those of the channels previously described in mammalian and plant mitochondria.