Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
A Trk/HKT-type K+ transporter from Trypanosoma brucei.
Mosimann M, Goshima S, Wenzler T, Lüscher A, Uozumi N, Mäser P.
???displayArticle.abstract???
The molecular mechanisms of K(+) homeostasis are only poorly understood for protozoan parasites. Trypanosoma brucei subsp. parasites, the causative agents of human sleeping sickness and nagana, are strictly extracellular and need to actively concentrate K(+) from their hosts' body fluids. The T. brucei genome contains two putative K(+) channel genes, yet the trypanosomes are insensitive to K(+) antagonists and K(+) channel-blocking agents, and they do not spontaneously depolarize in response to high extracellular K(+) concentrations. However, the trypanosomes are extremely sensitive to K(+) ionophores such as valinomycin. Surprisingly, T. brucei possesses a member of the Trk/HKT superfamily of monovalent cation permeases which so far had only been known from bacteria, archaea, fungi, and plants. The protein was named TbHKT1 and functions as a Na(+)-independent K(+) transporter when expressed in Escherichia coli, Saccharomyces cerevisiae, or Xenopus laevis oocytes. In trypanosomes, TbHKT1 is expressed in both the mammalian bloodstream stage and the Tsetse fly midgut stage; however, RNA interference (RNAi)-mediated silencing of TbHKT1 expression did not produce a growth phenotype in either stage. The presence of HKT genes in trypanosomatids adds a further piece to the enigmatic phylogeny of the Trk/HKT superfamily of K(+) transporters. Parsimonial analysis suggests that the transporters were present in the first eukaryotes but subsequently lost in several of the major eukaryotic lineages, in at least four independent events.
Allemann,
ATP production in isolated mitochondria of procyclic Trypanosoma brucei.
2000, Pubmed
Allemann,
ATP production in isolated mitochondria of procyclic Trypanosoma brucei.
2000,
Pubmed Altschul,
Basic local alignment search tool.
1990,
Pubmed Barrett,
Trypanosome glucose transporters.
1998,
Pubmed Barrett,
Human African trypanosomiasis: pharmacological re-engagement with a neglected disease.
2007,
Pubmed Benito,
Potassium- or sodium-efflux ATPase, a key enzyme in the evolution of fungi.
2002,
Pubmed Berriman,
The genome of the African trypanosome Trypanosoma brucei.
2005,
Pubmed Borst,
Surface receptors and transporters of Trypanosoma brucei.
1998,
Pubmed Brun,
Human African trypanosomiasis.
2010,
Pubmed Brun,
Cultivation and in vitro cloning or procyclic culture forms of Trypanosoma brucei in a semi-defined medium. Short communication.
1979,
Pubmed Davenport,
The Na+ transporter AtHKT1;1 controls retrieval of Na+ from the xylem in Arabidopsis.
2007,
Pubmed Defrise-Quertain,
Kinetic study of the plasma-membrane potential in procyclic and bloodstream forms of Trypanosoma brucei brucei using the fluorescent probe bisoxonol.
1996,
Pubmed de Koning,
Purine and pyrimidine transport in pathogenic protozoa: from biology to therapy.
2005,
Pubmed Doyle,
The structure of the potassium channel: molecular basis of K+ conduction and selectivity.
1998,
Pubmed Durell,
Evolutionary relationship between K(+) channels and symporters.
1999,
Pubmed Durell,
Structural models of the KtrB, TrkH, and Trk1,2 symporters based on the structure of the KcsA K(+) channel.
1999,
Pubmed Eddy,
Profile hidden Markov models.
1998,
Pubmed Eddy,
Multiple alignment using hidden Markov models.
1995,
Pubmed Ellekvist,
Molecular cloning of a K(+) channel from the malaria parasite Plasmodium falciparum.
2004,
Pubmed Ellekvist,
Critical role of a K+ channel in Plasmodium berghei transmission revealed by targeted gene disruption.
2008,
Pubmed Gaber,
TRK1 encodes a plasma membrane protein required for high-affinity potassium transport in Saccharomyces cerevisiae.
1988,
Pubmed Gierth,
Potassium transporters in plants--involvement in K+ acquisition, redistribution and homeostasis.
2007,
Pubmed Hannaert,
Plant-like traits associated with metabolism of Trypanosoma parasites.
2003,
Pubmed Harms,
Identification of the ABC protein SapD as the subunit that confers ATP dependence to the K+-uptake systems Trk(H) and Trk(G) from Escherichia coli K-12.
2001,
Pubmed Hirumi,
Continuous cultivation of Trypanosoma brucei blood stream forms in a medium containing a low concentration of serum protein without feeder cell layers.
1989,
Pubmed Huson,
Dendroscope: An interactive viewer for large phylogenetic trees.
2007,
Pubmed Jackson,
Origins of amino acid transporter loci in trypanosomatid parasites.
2007,
Pubmed Kesteloot,
Relationship of serum sodium, potassium, calcium, and phosphorus with blood pressure. Belgian Interuniversity Research on Nutrition and Health.
1988,
Pubmed Krogh,
Predicting transmembrane protein topology with a hidden Markov model: application to complete genomes.
2001,
Pubmed Landfear,
Drugs and transporters in kinetoplastid protozoa.
2008,
Pubmed Legros,
Treatment of human African trypanosomiasis--present situation and needs for research and development.
2002,
Pubmed Mäser,
Glycine residues in potassium channel-like selectivity filters determine potassium selectivity in four-loop-per-subunit HKT transporters from plants.
2002,
Pubmed
,
Xenbase Mäser,
Altered shoot/root Na+ distribution and bifurcating salt sensitivity in Arabidopsis by genetic disruption of the Na+ transporter AtHKT1.
2002,
Pubmed Mäser,
Drug transport and drug resistance in African trypanosomes.
2003,
Pubmed Nakamura,
Cloning of the trkAH gene cluster and characterization of the Trk K(+)-uptake system of Vibrio alginolyticus.
1998,
Pubmed Nolan,
Factors that determine the plasma-membrane potential in bloodstream forms of Trypanosoma brucei.
2000,
Pubmed Oberholzer,
A vector series for rapid PCR-mediated C-terminal in situ tagging of Trypanosoma brucei genes.
2006,
Pubmed Platten,
Nomenclature for HKT transporters, key determinants of plant salinity tolerance.
2006,
Pubmed Räz,
The Alamar Blue assay to determine drug sensitivity of African trypanosomes (T.b. rhodesiense and T.b. gambiense) in vitro.
1997,
Pubmed Rodríguez-Navarro,
Dual system for potassium transport in Saccharomyces cerevisiae.
1984,
Pubmed Rubio,
Sodium-driven potassium uptake by the plant potassium transporter HKT1 and mutations conferring salt tolerance.
1995,
Pubmed
,
Xenbase Saier,
TCDB: the Transporter Classification Database for membrane transport protein analyses and information.
2006,
Pubmed Schachtman,
Structure and transport mechanism of a high-affinity potassium uptake transporter from higher plants.
1994,
Pubmed
,
Xenbase Stiles,
Identification of surface-membrane P-type ATPases resembling fungal K(+)- and Na(+)-ATPases, in Trypanosoma brucei, Trypanosoma cruzi and Leishmania donovani.
2003,
Pubmed Stumpe,
Requirement of a large K+-uptake capacity and of extracytoplasmic protease activity for protamine resistance of Escherichia coli.
1997,
Pubmed Stumpe,
Requirement of a large K+-uptake capacity and of extracytoplasmic protease activity for protamine resistance of Escherichia coli
1997,
Pubmed Sunarpi,
Enhanced salt tolerance mediated by AtHKT1 transporter-induced Na unloading from xylem vessels to xylem parenchyma cells.
2005,
Pubmed Tholema,
Change to alanine of one out of four selectivity filter glycines in KtrB causes a two orders of magnitude decrease in the affinities for both K+ and Na+ of the Na+ dependent K+ uptake system KtrAB from Vibrio alginolyticus.
1999,
Pubmed Tholema,
All four putative selectivity filter glycine residues in KtrB are essential for high affinity and selective K+ uptake by the KtrAB system from Vibrio alginolyticus.
2005,
Pubmed Thompson,
CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice.
1994,
Pubmed Waller,
Characterization of two putative potassium channels in Plasmodium falciparum.
2008,
Pubmed Ward,
Plant ion channels: gene families, physiology, and functional genomics analyses.
2009,
Pubmed Wirtz,
A tightly regulated inducible expression system for conditional gene knock-outs and dominant-negative genetics in Trypanosoma brucei.
1999,
Pubmed Zeng,
Epitope tagging of the yeast K(+) carrier Trk2p demonstrates folding that is consistent with a channel-like structure.
2004,
Pubmed Zilberstein,
Transport of nutrients and ions across membranes of trypanosomatid parasites.
1993,
Pubmed
