tonoplast Dotaz Zobrazit nápovědu
Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.
- MeSH
- Arabidopsis cytologie genetika metabolismus MeSH
- brassinosteroidy metabolismus MeSH
- mutace MeSH
- proteiny huseníčku genetika metabolismus MeSH
- proteiny regulující apoptózu genetika metabolismus MeSH
- signální transdukce * MeSH
- transport proteinů MeSH
- vakuoly metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
FM (Fei-Mao) styryl dyes are commonly used for the fluorescence imaging of plasma membrane (PM) and endocytosis in vivo. Thanks to their amphiphilic character, these dyes are incorporated in the outer leaflet of the PM lipid bilayer and emit fluorescence in its hydrophobic environment. The endocytic pathway of FM dye uptake starts with rapid PM staining and continues in PM invaginations and membrane vesicles during endocytosis, followed by staining of trans-Golgi network (TGN) and ending in tonoplast (vacuolar membrane). FM dyes do not stain endoplasmic reticulum and nuclear membrane. The time-lapse fluorescence microscopy could track endocytic vesicles and characterize the rate of endocytosis in vivo. On the other hand, fixable FM dyes (FX) can be used for the visualization of particular steps in the FM dye uptake in situ. Staining with FM dyes and subsequent microscopic observations could be performed on both tissue and cellular level. Here, we describe simple procedures for the effective FM dye staining and destaining in root tip of Arabidopsis thaliana seedlings and suspension-cultured tobacco cells.
- MeSH
- Arabidopsis cytologie ultrastruktura MeSH
- buněčná membrána ultrastruktura MeSH
- endocytóza * MeSH
- fluorescenční barviva analýza MeSH
- fluorescenční mikroskopie metody MeSH
- kořeny rostlin cytologie ultrastruktura MeSH
- optické zobrazování metody MeSH
- tabák cytologie ultrastruktura MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PbtA, a putative P(1B)-type ATPase from the Gram-negative soil bacterium Achromobacter xylosoxidans A8 responsible for Pb(2+)/Zn(2+)/Cd(2+)-resistance in Escherichia coli, was heterologously expressed in Saccharomyces cerevisiae. When present in Zn(2+)- and Pb(2+)/Cd(2+)-hypersensitive S. cerevisiae strains CM137 and DTY168, respectively, PbtA was able to restore Zn(2+)- and Pb(2+)-resistant phenotype. At the same time, the increase of Pb, Zn, and Cd accumulation in yeast was observed. However, Cd(2+)-tolerance of the pbtA-bearing yeasts dramatically decreased. The PbtA-eGFP fusion protein was localized primarily in the tonoplast and also in the plasma membrane and the perinuclear region corresponding to the endoplasmic reticulum at later growth stages. This indicates that PbtA protein is successfully incorporated into membranes in yeasts. Since PbtA caused a substantial increase of Pb(2+)/Zn(2+)-resistance and accumulation in baker's yeast, we propose its further use for the genetic modification of suitable plant species in order to obtain an effective tool for the phytoremediation of sites polluted by toxic transition metals.
- MeSH
- Achromobacter denitrificans enzymologie metabolismus MeSH
- adenosintrifosfatasy metabolismus MeSH
- bakteriální proteiny metabolismus MeSH
- buněčná membrána enzymologie metabolismus MeSH
- endoplazmatické retikulum enzymologie metabolismus MeSH
- kadmium metabolismus MeSH
- olovo metabolismus MeSH
- Saccharomyces cerevisiae enzymologie metabolismus MeSH
- zinek metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Transportation of low molecular weight cargoes into the plant vacuole represents an essential plant cell function. Several lines of evidence indicate that autophagy-related direct endoplasmic reticulum (ER) to vacuole (and also, apoplast) transport plays here a more general role than expected. This route is regulated by autophagy proteins, including recently discovered involvement of the exocyst subcomplex. Traffic from ER into the vacuole bypassing Golgi apparatus (GA) acts not only in stress-related cytoplasm recycling or detoxification, but also in developmentally-regulated biopolymer and secondary metabolite import into the vacuole (or apoplast), exemplified by storage proteins and anthocyanins. We propose that this pathway is relevant also for some phytohormones' (e.g., auxin, abscisic acid (ABA) and salicylic acid (SA)) degradation. We hypothesize that SA is not only an autophagy inducer, but also a cargo for autophagy-related ER to vacuole membrane container delivery and catabolism. ER membrane localized enzymes will potentially enhance the area of biosynthetic reactive surfaces, and also, abundant ER localized membrane importers (e.g., ABC transporters) will internalize specific molecular species into the autophagosome biogenesis domain of ER. Such active ER domains may create tubular invaginations of tonoplast into the vacuoles as import intermediates. Packaging of cargos into the ER-derived autophagosome-like containers might be an important mechanism of vacuole and exosome biogenesis and cytoplasm protection against toxic metabolites. A new perspective on metabolic transformations intimately linked to membrane trafficking in plants is emerging.
- MeSH
- anthokyaniny metabolismus MeSH
- autofagie MeSH
- biologický transport MeSH
- cytoplazma metabolismus MeSH
- endoplazmatické retikulum metabolismus MeSH
- Golgiho aparát metabolismus MeSH
- regulátory růstu rostlin metabolismus MeSH
- rostlinné buňky metabolismus MeSH
- vakuoly metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Metal accumulation in seeds is a prerequisite for germination and establishment of plants but also for micronutrient delivery to humans. To investigate metal transport processes and their interactions in seeds, we focused on METAL TOLERANCE PROTEIN8 (MTP8), a tonoplast transporter of the manganese (Mn) subclade of cation diffusion facilitators, which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds. The x-ray fluorescence imaging showed that expression of MTP8 was responsible for Mn localization in subepidermal cells on the abaxial side of the cotyledons and in cortical cells of the hypocotyl. Accordingly, under low Mn availability, MTP8 increased seed stores of Mn, required for efficient seed germination. In mutant embryos lacking expression ofVACUOLAR IRON TRANSPORTER1(VIT1), MTP8 built up iron (Fe) hotspots inMTP8-expressing cells types, suggesting that MTP8 transports Fe in addition to Mn. Inmtp8 vit1double mutant seeds, Mn and Fe were distributed in all cell types of the embryo. An Fe transport function of MTP8 was confirmed by its ability to complement Fe hypersensitivity of a yeast mutant defective in vacuolar Fe transport. Imbibingmtp8-1mutant seeds in the presence of Mn or subjecting seeds to wet-dry cycles showed that MTP8 conferred Mn tolerance. During germination, MTP8 promoted reallocation of Fe from the vasculature. These results indicate that cell type-specific accumulation of Mn and Fe in seeds depends on MTP8 and that this transporter plays an important role in the generation of seed metal stores as well as for metal homeostasis and germination efficiency under challenging environmental conditions.
- MeSH
- Arabidopsis embryologie genetika metabolismus MeSH
- biologické modely MeSH
- genový knockout MeSH
- homeostáza * MeSH
- klíčení * genetika MeSH
- mangan metabolismus MeSH
- mutace genetika MeSH
- promotorové oblasti (genetika) genetika MeSH
- proteiny huseníčku metabolismus MeSH
- proteiny přenášející kationty metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- Saccharomyces cerevisiae metabolismus MeSH
- semena rostlinná embryologie genetika MeSH
- spektrometrie rentgenová emisní MeSH
- testy genetické komplementace MeSH
- vývojová regulace genové exprese MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
Formins are evolutionarily conserved eukaryotic proteins engaged in actin nucleation and other aspects of cytoskeletal organization. Angiosperms have two formin clades with multiple paralogs; typical plant Class I formins are integral membrane proteins that can anchor cytoskeletal structures to membranes. For the main Arabidopsis housekeeping Class I formin, FH1 (At3g25500), plasmalemma localization was documented in heterologous expression and overexpression studies. We previously showed that loss of FH1 function increases cotyledon epidermal pavement cell shape complexity via modification of actin and microtubule organization and dynamics. Here, we employ transgenic Arabidopsis expressing green fluorescent protein-tagged FH1 (FH1-GFP) from its native promoter to investigate in vivo behavior of this formin using advanced microscopy techniques. The fusion protein is functional, since its expression complements the fh1 loss-of-function mutant phenotype. Accidental overexpression of FH1-GFP results in a decrease in trichome branch number, while fh1 mutation has the opposite effect, indicating a general role of this formin in controlling cell shape complexity. Consistent with previous reports, FH1-GFP associates with membranes. However, the protein exhibits surprising actin- and secretory pathway-dependent dynamic localization and relocates between cellular endomembranes and the plasmalemma during cell division and differentiation in root tissues, with transient tonoplast localization at the transition/elongation zones border. FH1-GFP also accumulates in actin-rich regions of cortical cytoplasm and associates with plasmodesmata in both the cotyledon epidermis and root tissues. Together with previous reports from metazoan systems, this suggests that formins might have a shared (ancestral or convergent) role at cell-cell junctions.
Russula atropurpurea can accumulate remarkably high concentrations of Zn in its sporocarps. We have previously demonstrated that 40 % of the intracellular Zn in this species is sequestered by MT-like RaZBP peptides. To see what other mechanisms for the handling of the accumulated Zn are available to R. atropurpurea, we searched its transcriptome for cDNAs coding for transporters of the cation diffusion facilitator (CDF) family. The transcriptome search enabled us to identify RaCDF1 and RaCDF2, which were further subjected to functional studies in metal sensitive Saccharomyces cerevisiae. The expression of RaCDF1 and its translational fusion with green fluorescent protein (GFP) protected the yeasts against Zn and Co, but not Cd or Mn, toxicity and led to increased Zn accumulation in the cells. The GFP fluorescence, observed in the RaCDF1::GFP-expressing yeasts on tonoplasts, indicated that the RaCDF1-mediated Zn and Co tolerance was a result of vacuolar sequestration of the metals. The expression of RaCDF2 supported Zn, but not Mn, tolerance in the yeasts and reduced the cellular uptake of Zn, which is congruent with the proposed idea of the Zn-efflux function of RaCDF2, supported by the localization of GFP-derived fluorescence on the plasma membrane of the yeasts expressing functional RaCDF2::GFP. Contrarily, RaCDF2 increased the sensitivity to Co and Cd in the yeasts and significantly promoted Cd uptake, which suggested that it can act as a bidirectional metal transporter. The notion that RaCDF1 and RaCDF2 are genuine CDF transporters in R. atropurputrea was further reinforced by the fact that the RaCDF-associated metal tolerance and uptake phenotypes were lost upon the replacement of histidyl (in RaCDF1) and aspartyl (in RaCDF2), which are highly conserved in the second transmembrane domain and known to be essential for the function of CDF proteins.
- MeSH
- aktivace transkripce MeSH
- antifungální látky farmakologie MeSH
- fungální proteiny chemie genetika metabolismus MeSH
- fyziologická adaptace MeSH
- geny hub MeSH
- kobalt farmakologie MeSH
- membránové transportní proteiny chemie genetika metabolismus MeSH
- mikrobiální testy citlivosti MeSH
- mikrobiální viabilita MeSH
- mykorhiza genetika metabolismus MeSH
- regulace genové exprese u hub MeSH
- Saccharomyces cerevisiae účinky léků růst a vývoj MeSH
- sekvence aminokyselin MeSH
- zinek metabolismus farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
