TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes

Abstract Potassium channels from prokaryotes and eukaryotes are usually recognized by a typical amino acid sequence TXTGY(F)G representing the ionic selectivity filter. Using a screening approach with ion channel family profiles but without the above motif, we identified a gene in Trypanosoma brucei...

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Autores principales:	Michael E. Steinmann, Remo S. Schmidt, Peter Bütikofer, Pascal Mäser, Erwin Sigel
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/1b1429f81af046fc82b5172f1e3cea90
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spelling	oai:doaj.org-article:1b1429f81af046fc82b5172f1e3cea902021-12-02T16:06:04ZTbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes10.1038/s41598-017-00752-12045-2322https://doaj.org/article/1b1429f81af046fc82b5172f1e3cea902017-04-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-00752-1https://doaj.org/toc/2045-2322Abstract Potassium channels from prokaryotes and eukaryotes are usually recognized by a typical amino acid sequence TXTGY(F)G representing the ionic selectivity filter. Using a screening approach with ion channel family profiles but without the above motif, we identified a gene in Trypanosoma brucei that exhibits homology to inward rectifying potassium channels. We report here cloning of this ion channel named TbIRK. The protein is localized to acidocalcisomes in procyclic and in bloodstream form parasites. Functional properties of this channel were established after expression in Xenopus oocytes. Currents recorded in potassium medium show inward rectification and little time dependence. Surprisingly, this channel retains selectivity for potassium ions over sodium ions >7, in spite of the lack of the classical selectivity filter. The sequence GGYVG was predicted in silico to replace this filter motif. Point mutations of the corresponding glycine residues confirmed this at the functional level. The channel is inhibited by caesium ions but remains unaffected by barium ions up to 10 mM. TbIRK is to our knowledge the first potassium channel in T. brucei that localizes to the acidocalcisomes, organelles involved in the storage of phosphates and the response to osmotic stress that occurs during the life cycle of trypanosomes.Michael E. SteinmannRemo S. SchmidtPeter BütikoferPascal MäserErwin SigelNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-10 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Michael E. Steinmann Remo S. Schmidt Peter Bütikofer Pascal Mäser Erwin Sigel TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes
description	Abstract Potassium channels from prokaryotes and eukaryotes are usually recognized by a typical amino acid sequence TXTGY(F)G representing the ionic selectivity filter. Using a screening approach with ion channel family profiles but without the above motif, we identified a gene in Trypanosoma brucei that exhibits homology to inward rectifying potassium channels. We report here cloning of this ion channel named TbIRK. The protein is localized to acidocalcisomes in procyclic and in bloodstream form parasites. Functional properties of this channel were established after expression in Xenopus oocytes. Currents recorded in potassium medium show inward rectification and little time dependence. Surprisingly, this channel retains selectivity for potassium ions over sodium ions >7, in spite of the lack of the classical selectivity filter. The sequence GGYVG was predicted in silico to replace this filter motif. Point mutations of the corresponding glycine residues confirmed this at the functional level. The channel is inhibited by caesium ions but remains unaffected by barium ions up to 10 mM. TbIRK is to our knowledge the first potassium channel in T. brucei that localizes to the acidocalcisomes, organelles involved in the storage of phosphates and the response to osmotic stress that occurs during the life cycle of trypanosomes.
format	article
author	Michael E. Steinmann Remo S. Schmidt Peter Bütikofer Pascal Mäser Erwin Sigel
author_facet	Michael E. Steinmann Remo S. Schmidt Peter Bütikofer Pascal Mäser Erwin Sigel
author_sort	Michael E. Steinmann
title	TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes
title_short	TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes
title_full	TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes
title_fullStr	TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes
title_full_unstemmed	TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes
title_sort	tbirk is a signature sequence free potassium channel from trypanosoma brucei locating to acidocalcisomes
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/1b1429f81af046fc82b5172f1e3cea90
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TbIRK is a signature sequence free potassium channel from Trypanosoma brucei locating to acidocalcisomes

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