In the model yeast Saccharomyces cerevisiae, Trk1 is the main K+ importer. It is involved in many important physiological processes, such as the maintenance of ion homeostasis, cell volume, intracellular pH, and plasma-membrane potential. The ScTrk1 protein can be of great interest to industry, as it was shown that changes in its activity influence ethanol production and tolerance in S. cerevisiae and also cell performance in the presence of organic acids or high ammonium under low K+ conditions. Nonconventional yeast species are attracting attention due to their unique properties and as a potential source of genes that encode proteins with unusual characteristics. In this work, we aimed to study and compare Trk proteins from Debaryomyces hansenii, Hortaea werneckii, Kluyveromyces marxianus, and Yarrowia lipolytica, four biotechnologically relevant yeasts that tolerate various extreme environments. Heterologous expression in S. cerevisiae cells lacking the endogenous Trk importers revealed differences in the studied Trk proteins' abilities to support the growth of cells under various cultivation conditions such as low K+ or the presence of toxic cations, to reduce plasma-membrane potential or to take up Rb+ . Examination of the potential of Trks to support the stress resistance of S. cerevisiae wild-type strains showed that Y. lipolytica Trk1 is a promising tool for improving cell tolerance to both low K+ and high salt and that the overproduction of S. cerevisiae's own Trk1 was the most efficient at improving the growth of cells in the presence of highly toxic Li+ ions.

• Klíčová slova
• Trk importers, heterologous expression, homeostasis, ion transporters, potassium, yeasts,
• MeSH
• biologický transport MeSH
• draslík metabolismus   MeSH
• fylogeneze MeSH
• proteiny přenášející kationty * genetika   MeSH
• Saccharomyces cerevisiae - proteiny * metabolismus   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• Yarrowia * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• draslík MeSH
• proteiny přenášející kationty * MeSH
• Saccharomyces cerevisiae - proteiny * MeSH
• TRK1 protein, S cerevisiae MeSH Prohlížeč

In baker's yeast (Saccharomyces cerevisiae), Trk1, a member of the superfamily of K-transporters (SKT), is the main K+ uptake system under conditions when its concentration in the environment is low. Structurally, Trk1 is made up of four domains, each similar and homologous to a K-channel α subunit. Because most K-channels are proteins containing four channel-building α subunits, Trk1 could be functional as a monomer. However, related SKT proteins TrkH and KtrB were crystallised as dimers, and for Trk1, a tetrameric arrangement has been proposed based on molecular modelling. Here, based on Bimolecular Fluorescence Complementation experiments and single-molecule fluorescence microscopy combined with molecular modelling; we provide evidence that Trk1 can exist in the yeast plasma membrane as a monomer as well as a dimer. The association of monomers to dimers is regulated by the K+ concentration.

• Klíčová slova
• K+ translocation, MD simulation, Saccharomyces cerevisiae, bimolecular fluorescence complementation, dimerisation, molecular modelling,
• MeSH
• biologický transport MeSH
• buněčná membrána metabolismus   MeSH
• draslík metabolismus   MeSH
• fungální proteiny metabolismus   MeSH
• proteiny přenášející kationty * genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny * genetika   metabolismus   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• translokace genetická MeSH
• transportní proteiny metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• draslík MeSH
• fungální proteiny MeSH
• proteiny přenášející kationty * MeSH
• Saccharomyces cerevisiae - proteiny * MeSH
• transportní proteiny MeSH
• TRK1 protein, S cerevisiae MeSH Prohlížeč

Several corresponding regions of human and mammalian genomes have been shown to affect sensitivity to the manifestation of metabolic syndrome via nutrigenetic interactions. In this study, we assessed the effect of sucrose administration in a newly established congenic strain BN.SHR20, in which a limited segment of rat chromosome 20 from a metabolic syndrome model, spontaneously hypertensive rat (SHR), was introgressed into Brown Norway (BN) genomic background. We mapped the extent of the differential segment and compared the genomic sequences of BN vs. SHR within the segment in silico. The differential segment of SHR origin in BN.SHR20 spans about 9 Mb of the telomeric portion of the short arm of chromosome 20. We identified non-synonymous mutations e.g., in ApoM, Notch4, Slc39a7, Smim29 genes and other variations in or near genes associated with metabolic syndrome in human genome-wide association studies. Male rats of BN and BN.SHR20 strains were fed a standard diet for 18 weeks (control groups) or 16 weeks of standard diet followed by 14 days of high-sucrose diet (HSD). We assessed the morphometric and metabolic profiles of all groups. Adiposity significantly increased only in BN.SHR20 after HSD. Fasting glycemia and the glucose levels during the oral glucose tolerance test were higher in BN.SHR20 than in BN groups, while insulin levels were comparable. The fasting levels of triacylglycerols were the highest in sucrose-fed BN.SHR20, both compared to the sucrose-fed BN and the control BN.SHR20. The non-esterified fatty acids and total cholesterol concentrations were higher in BN.SHR20 compared to their respective BN groups, and the HSD elicited an increase in non-esterified fatty acids only in BN.SHR20. In a new genetically defined model, we have isolated a limited genomic region involved in nutrigenetic sensitization to sucrose-induced metabolic disturbances.

• Klíčová slova
• animal model, congenic rat, metabolic syndrome, nutrigenetics,
• MeSH
• apolipoproteiny M genetika   MeSH
• celogenomová asociační studie MeSH
• hypertenze * metabolismus   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• lidské chromozomy, pár 20 metabolismus   MeSH
• mastné kyseliny MeSH
• metabolický syndrom * genetika   metabolismus   MeSH
• nutrigenomika MeSH
• omezení příjmu potravy MeSH
• potkani inbrední BN MeSH
• potkani inbrední SHR MeSH
• proteiny přenášející kationty * genetika   MeSH
• sacharosa škodlivé účinky   MeSH
• savci genetika   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• apolipoproteiny M MeSH
• Apom protein, rat MeSH Prohlížeč
• mastné kyseliny MeSH
• proteiny přenášející kationty * MeSH
• sacharosa MeSH
• SLC39A7 protein, human MeSH Prohlížeč

Iron-induced oxidative stress can cause or exacerbate retinal degenerative diseases. Retinal iron overload has been reported in several mouse disease models with systemic or neural retina-specific knockout (KO) of homologous ferroxidases ceruloplasmin (Cp) and hephaestin (Heph). Cp and Heph can potentiate ferroportin (Fpn) mediated cellular iron export. Here, we used retina-specific Fpn KO mice to test the hypothesis that retinal iron overload in Cp/Heph DKO mice is caused by impaired iron export from neurons and glia. Surprisingly, there was no indication of retinal iron overload in retina-specific Fpn KO mice: the mRNA levels of transferrin receptor in the retina were not altered at 7-10-months age. Consistent with this, levels and localization of ferritin light chain were unchanged. To "stress the system", we injected iron intraperitoneally into Fpn KO mice with or without Cp KO. Only mice with both retina-specific Fpn KO and Cp KO had modestly elevated retinal iron levels. These results suggest that impaired iron export through Fpn is not sufficient to explain the retinal iron overload in Cp/Heph DKO mice. An increase in the levels of retinal ferrous iron caused by the absence of these ferroxidases, followed by uptake into cells by ferrous iron importers, is most likely necessary.

• Klíčová slova
• Age-related macular degeneration, Ceruloplasmin, Ferroportin, Ferrous, Iron, Retina,
• MeSH
• ceruloplasmin genetika   metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• přetížení železem * MeSH
• proteiny přenášející kationty * genetika   MeSH
• retina metabolismus   MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• ceruloplasmin MeSH
• metal transporting protein 1 MeSH Prohlížeč
• proteiny přenášející kationty * MeSH
• železo MeSH

METAL TOLERANCE PROTEIN8 (MTP8) of Arabidopsis thaliana is a member of the CATION DIFFUSION FACILITATOR (CDF) family of proteins that transports primarily manganese (Mn), but also iron (Fe). MTP8 mediates Mn allocation to specific cell types in the developing embryo, and Fe re-allocation as well as Mn tolerance during imbibition. We analysed if an overexpression of MTP8 driven by the CaMV 35S promoter has an effect on Mn tolerance during imbibition and on Mn and Fe storage in seeds, which would render it a biofortification target. Fe, Mn and Zn concentrations in MTP8-overexpressing lines in wild type and vit1-1 backgrounds were analysed by ICP-MS. Distribution of metals in intact seeds was determined by synchrotron µXRF tomography. MTP8 overexpression led to a strongly increased Mn tolerance of seeds during imbibition, supporting its effectiveness in loading excess Mn into the vacuole. In mature seeds, MTP8 overexpression did not cause a consistent increase in Mn and Fe accumulation, and it did not change the allocation pattern of these metals. Zn concentrations were consistently increased in bulk samples. The results demonstrate that Mn and Fe allocation is not determined primarily by the MTP8 expression pattern, suggesting either a cell type-specific provision of metals for vacuolar sequestration by upstream transport processes, or the determination of MTP8 activity by post-translational regulation.

• Klíčová slova
• Arabidopsis thaliana, biofortification, iron, manganese, seed development, synchrotron µXRF, zinc,
• MeSH
• Arabidopsis * genetika   metabolismus   MeSH
• mangan metabolismus   MeSH
• proteiny přenášející kationty * genetika   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• semena rostlinná metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• mangan MeSH
• proteiny přenášející kationty * MeSH

Salt stress disturbs the cellular osmotic and ionic balance, which then creates a negative impact on plant growth and development. The Na+ and Cl- ions can enter into plant cells through various membrane transporters, including specific and non-specific Na+ , K+ , and Ca2+ transporters. Therefore, it is important to understand Na+ and K+ transport mechanisms in plants along with the isolation of genes, their characterization, the structural features, and their post-translation regulation under salt stress. This review summarizes the molecular insights of plant ion transporters, including non-selective cation transporters, cyclic nucleotide-gated cation transporters, glutamate-like receptors, membrane intrinsic proteins, cation proton antiporters, and sodium proton antiporter families. Further, we discussed the K+ transporter families such as high-affinity K+ transporters, HAK/KUP/KT transporters, shaker type K+ transporters, and K+ efflux antiporters. Besides the ion transport process, we have shed light on available literature on epigenetic regulation of transport processes under salt stress. Recent advancements of salt stress sensing mechanisms and various salt sensors within signaling transduction pathways are discussed. Further, we have compiled salt-stress signaling pathways, and their crosstalk with phytohormones.

• MeSH
• draslík metabolismus   MeSH
• epigeneze genetická MeSH
• proteiny přenášející kationty * genetika   MeSH
• regulace genové exprese u rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• rostliny * MeSH
• solný stres * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• draslík MeSH
• proteiny přenášející kationty * MeSH
• rostlinné proteiny MeSH

Arid/semi-arid and coastal agricultural areas of the world are especially vulnerable to climate change-driven soil salinity. Salinity tolerance in plants is a complex trait, with salinity negatively affecting crop yield. Plants adopt a range of mechanisms to combat salinity, with many transporter genes being implicated in Na+-partitioning processes. Within these, the high-affinity K+ (HKT) family of transporters play a critical role in K+ and Na+ homeostasis in plants. Among HKT transporters, Type I transporters are Na+-specific. While Arabidopsis has only one Na + -specific HKT (AtHKT1;1), cereal crops have a multiplicity of Type I and II HKT transporters. AtHKT1; 1 (Arabidopsis thaliana) and HKT1; 5 (cereal crops) 'exclude' Na+ from the xylem into xylem parenchyma in the root, reducing shoot Na+ and hence, confer sodium tolerance. However, more recent data from Arabidopsis and crop species show that AtHKT1;1/HKT1;5 alleles have a strong genetic association with 'shoot sodium accumulation' and concomitant salt tolerance. The review tries to resolve these two seemingly contradictory effects of AtHKT1;1/HKT1;5 operation (shoot exclusion vs shoot accumulation), both conferring salinity tolerance and suggests that contrasting phenotypes are attributable to either hyper-functional or weak AtHKT1;1/HKT1;5 alleles/haplotypes and are under strong selection by soil salinity levels. It also suggests that opposite balancing mechanisms involving xylem ion loading in these contrasting phenotypes exist that require transporters such as SOS1 and CCC. While HKT1; 5 is a crucial but not sole determinant of salinity tolerance, investigation of the adaptive benefit(s) conferred by naturally occurring intermediate HKT1;5 alleles will be important under a climate change scenario.

• Klíčová slova
• Allele, Exclusion, Haplotype, Potassium, Salinity, Sodium, Xylem loading,
• MeSH
• draslík metabolismus   MeSH
• kořeny rostlin genetika   metabolismus   MeSH
• proteiny přenášející kationty * genetika   MeSH
• půda MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• salinita MeSH
• sodík metabolismus   MeSH
• symportéry * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• draslík MeSH
• proteiny přenášející kationty * MeSH
• půda MeSH
• rostlinné proteiny MeSH
• sodík MeSH
• symportéry * MeSH

The existence of programmed cell death in Saccharomyces cerevisiae has been reported for many years. Glucose induces the death of S. cerevisiae in the absence of additional nutrients within a few hours, and the absence of active potassium uptake makes cells highly sensitive to this process. S. cerevisiae cells possess two transporters, Trk1 and Trk2, which ensure a high intracellular concentration of potassium, necessary for many physiological processes. Trk1 is the major system responsible for potassium acquisition in growing and dividing cells. The contribution of Trk2 to potassium uptake in growing cells is almost negligible, but Trk2 becomes crucial for stationary cells for their survival of some stresses, e.g. anhydrobiosis. As a new finding, we show that both Trk systems contribute to the relative thermotolerance of S. cerevisiae BY4741. Our results also demonstrate that Trk2 is much more important for the cell survival of glucose-induced cell death than Trk1, and that stationary cells deficient in active potassium uptake lose their ATP stocks more rapidly than cells with functional Trk systems. This is probably due to the upregulated activity of plasma-membrane Pma1 H+-ATPase, and consequently, it is the reason why these cells die earlier than cells with functional active potassium uptake.

• Klíčová slova
• ATP content, GICD, Saccharomyces cerevisiae, potassium uptake, stationary cells, thermotolerance,
• MeSH
• buněčná smrt MeSH
• draslík metabolismus   MeSH
• glukosa metabolismus   MeSH
• mikrobiální viabilita MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae cytologie   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• draslík MeSH
• glukosa MeSH
• proteiny přenášející kationty MeSH
• Saccharomyces cerevisiae - proteiny MeSH
• TRK1 protein, S cerevisiae MeSH Prohlížeč
• TRK2 protein, S cerevisiae MeSH Prohlížeč

The maintenance of K+ and Ca2+ homeostasis is crucial for many cellular functions. Potassium is accumulated in cells at high concentrations, while the cytosolic level of calcium, to ensure its signalling function, is kept at low levels and transiently increases in response to stresses. We examined Ca2+ homeostasis and Ca2+ signalling in Saccharomyces cerevisiae strains lacking plasma-membrane K+ influx (Trk1 and Trk2) or efflux (Tok1, Nha1 and Ena1-5) systems. The lack of K+ exporters slightly increased the cytosolic Ca2+, but did not alter the Ca2+ tolerance or Ca2+-stress response. In contrast, the K+-importers Trk1 and Trk2 play important and distinct roles in the maintenance of Ca2+ homeostasis. The presence of Trk1 was vital mainly for the growth of cells in the presence of high extracellular Ca2+, whilst the lack of Trk2 doubled steady-state intracellular Ca2+ levels. The absence of both K+ importers highly increased the Ca2+ response to osmotic or CaCl2 stresses and altered the balance between Ca2+ flux from external media and intracellular compartments. In addition, we found Trk2 to be important for the tolerance to high KCl and hygromycin B in cells growing on minimal media. All the data describe new interconnections between potassium and calcium homeostasis in S. cerevisiae.

• Klíčová slova
• K+-transporter, Trk1, Trk2, calcium, osmotic shock, potassium, yeast,
• MeSH
• chlorid draselný farmakologie   MeSH
• cinnamáty farmakologie   MeSH
• draslík metabolismus   MeSH
• homeostáza * MeSH
• hygromycin B analogy a deriváty   farmakologie   MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae účinky léků   genetika   metabolismus   MeSH
• signální transdukce * MeSH
• vápník metabolismus   farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorid draselný MeSH
• cinnamáty MeSH
• draslík MeSH
• hygromycin A MeSH Prohlížeč
• hygromycin B MeSH
• proteiny přenášející kationty MeSH
• Saccharomyces cerevisiae - proteiny MeSH
• TRK1 protein, S cerevisiae MeSH Prohlížeč
• TRK2 protein, S cerevisiae MeSH Prohlížeč
• vápník MeSH

The yeast Trk1 polypeptide, like other members of the Superfamily of K Transporters (SKT proteins) consists of four Membrane-Pore-Membrane motifs (MPMs A-D) each of which is homologous to a single K-channel subunit. SKT proteins are thought to have evolved from ancestral K-channels via two gene duplications and thus single MPMs might be able to assemble when located on different polypeptides. To test this hypothesis experimentally we generated a set of partial gene deletions to create alleles encoding one, two, or three MPMs, and analysed the cellular localisation and interactions of these Trk1 fragments using GFP tags and Bimolecular Fluorescence Complementation (BiFC). The function of these partial Trk1 proteins either alone or in combinations was assessed by expressing the encoding genes in a K+-uptake deficient strain lacking also the K-channel Tok1 (trk1,trk2,tok1Δ) and (i) analysing their ability to promote growth in low [K+] media and (ii) by ion flux measurements using "microelectrode based ion flux estimation" (MIFE). We found that proteins containing only one or two MPM motifs can interact with each other and assemble with a polypeptide consisting of the rest of the Trk system to form a functional K+-translocation system.

• Klíčová slova
• Bimolecular Fluorescence Complementation – BiFC, K(+)-transport, MPM motif, Microelectrode based Ion Flux Estimation - MIFE, Saccharomyces cerevisiae, Trk1 – potassium translocation system,
• MeSH
• aminokyselinové motivy MeSH
• draslík metabolismus   MeSH
• draslíkové kanály genetika   metabolismus   MeSH
• iontový transport fyziologie   MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• draslík MeSH
• draslíkové kanály MeSH
• proteiny přenášející kationty MeSH
• Saccharomyces cerevisiae - proteiny MeSH
• TRK1 protein, S cerevisiae MeSH Prohlížeč