Search Results (8)

Plant plasma membrane (PM) H⁺-ATPase functions as a proton-motive force by exporting cellular protons to establish a transmembrane chemical gradient of H⁺ ions and an accompanying electrical gradient. These gradients are crucial for plant growth and development and for plant responses to abiotic and biotic stresses. In this study, a comprehensive identification of the PM H⁺-ATPase gene family was conducted across four cotton species. Specifically, 14 genes were identified in the diploid species Gossypium arboreum and Gossypium raimondii, whereas 39 and 43 genes were identified in the tetraploid species Gossypium hirsutum and Gossypium barbadense, respectively. The characteristics of this gene family were subsequently compared and analyzed using bioinformatics. Chromosomal localization and collinearity analyses elucidated the distribution characteristics of this gene family within the cotton genomes. Gene structure and phylogenetic analyses demonstrated the conservation of this family across cotton species, whereas the examination of cis-acting elements in gene promoters highlighted their involvement in environmental stress and hormone response categories. An expression profile analysis revealed eight genes whose expression was upregulated under salt stress conditions, and quantitative real-time PCR results suggested that the cotton PM H⁺-ATPase genes may play crucial roles in conferring resistance to salt stress. These findings establish a robust foundation for subsequent investigations into the functions of cotton PM H⁺-ATPase genes and may offer valuable insights for selecting genes for resistance breeding programs. Full article

Two metagenome-assembled genomes (MAGs), GKL-01 and GKL-02, related to the family Thiotrichaceae have been assembled from the metagenome of bacterial mat obtained from a sulfide-rich thermal spring in the North Caucasus. Based on average amino acid identity (AAI) values and genome-based phylogeny, MAG GKL-01 represented a new genus within the Thiotrichaceae family. The GC content of the GKL-01 DNA (44%) differed significantly from that of other known members of the genus Thiothrix (50.1–55.6%). We proposed to assign GKL-01 to a new species and genus ‘Candidatus Thiocaldithrix dubininis’ gen. nov., sp. nov. GKL-01. The phylogenetic analysis and estimated distances between MAG GKL-02 and the genomes of the previously described species of the genus Thiothrix allowed assigning GKL-02 to a new species with the proposed name ‘Candidatus Thiothrix putei’ sp. nov. GKL-02 within the genus Thiothrix. Genome data first revealed the presence of both Na⁺-ATPases and H⁺-ATPases in several Thiothrix species. According to genomic analysis, bacteria GKL-01 and GKL-02 are metabolically versatile facultative aerobes capable of growing either chemolithoautotrophically or chemolithoheterotrophically in the presence of hydrogen sulfide and/or thiosulfate or chemoorganoheterotrophically. Full article

Plasma membrane (PM) H⁺-ATPase is a master enzyme involved in various plant physiological processes, such as stomatal movements in leaves and nutrient uptake and transport in roots. Overexpression of Oryza sativa PM H⁺-ATPase 1 (OSA1) has been known to increase NH₄⁺ uptake in rice roots. Although electrophysiological and pharmacological experiments have shown that the transport of many substances is dependent on the proton motive force provided by PM H⁺-ATPase, the exact role of PM H⁺-ATPase on the uptake of nutrients in plant roots, especially for the primary macronutrients N, P, and K, is still largely unknown. Here, we used OSA1 overexpression lines (OSA1-oxs) and gene-knockout osa1 mutants to investigate the effect of modulation of PM H⁺-ATPase on the absorption of N, P, and K nutrients through the use of a nutrient-exhaustive method and noninvasive microtest technology (NMT) in rice roots. Our results showed that under different concentrations of P and K, the uptake rates of P and K were enhanced in OSA1-oxs; by contrast, the uptake rates of P and K were significantly reduced in roots of osa1 mutants when compared with wild-type. In addition, the net influx rates of NH₄⁺ and K⁺, as well as the efflux rate of H⁺, were enhanced in OSA1-oxs and suppressed in osa1 mutants under low concentration conditions. In summary, this study indicated that overexpression of OSA1 stimulated the uptake rate of N, P, and K and promoted flux rates of cations (i.e., H⁺, NH₄⁺, and K⁺) in rice roots. These results may provide a novel insight into improving the coordinated utilization of macronutrients in crop plants. Full article

Plasma membrane H⁺-ATPases of fungi, yeasts, and plants act as proton pumps to generate an electrochemical gradient, which is essential for secondary transport and intracellular pH maintenance. Saccharomyces cerevisiae has two genes (PMA1 and PMA2) encoding H⁺-ATPases. In contrast, plants have a larger number of genes for H⁺-ATPases. In Ustilago maydis, a biotrophic basidiomycete that infects corn and teosinte, the presence of two H⁺-ATPase-encoding genes has been described, one with high identity to the fungal enzymes (pma1, UMAG_02851), and the other similar to the plant H⁺-ATPases (pma2, UMAG_01205). Unlike S. cerevisiae, these two genes are expressed jointly in U. maydis sporidia. In the present work, mutants lacking one of these genes (Δpma1 and Δpma2) were used to characterize the role of each one of these enzymes in U. maydis physiology and to obtain some of their kinetic parameters. To approach this goal, classical biochemical assays were performed. The absence of any of these H⁺-ATPases did not affect the growth or fungal basal metabolism. Membrane potential tests showed that the activity of a single H⁺-ATPase was enough to maintain the proton-motive force. Our results indicated that in U. maydis, both H⁺-ATPases work jointly in the generation of the electrochemical proton gradient, which is important for secondary transport of metabolites and regulation of intracellular pH. Full article

More than 95,000 protein–protein interactions of Arabidopsis thaliana have been published and deposited in databases. This dataset was supplemented by approximately 900 additional interactions, which were identified in the literature from the years 2002–2021. These protein–protein interactions were used as the basis for a Cytoscape network and were supplemented with data on subcellular localization, gene ontologies, biochemical properties and co-expression. The resulting network has been exemplarily applied in unraveling the PPI-network of the plant vacuolar proton-translocating ATPase (V-ATPase), which was selected due to its central importance for the plant cell. In particular, it is involved in cellular pH homeostasis, providing proton motive force necessary for transport processes, trafficking of proteins and, thereby, cell wall synthesis. The data points to regulation taking place on multiple levels: (a) a phosphorylation-dependent regulation by 14-3-3 proteins and by kinases such as WNK8 and NDPK1a, (b) an energy-dependent regulation via HXK1 and the glucose receptor RGS1 and (c) a Ca²⁺-dependent regulation by SOS2 and IDQ6. The known importance of V-ATPase for cell wall synthesis is supported by its interactions with several proteins involved in cell wall synthesis. The resulting network was further analyzed for (experimental) biases and was found to be enriched in nuclear, cytosolic and plasma membrane proteins but depleted in extracellular and mitochondrial proteins, in comparison to the entity of protein-coding genes. Among the processes and functions, proteins involved in transcription were highly abundant in the network. Subnetworks were extracted for organelles, processes and protein families. The degree of representation of organelles and processes reveals limitations and advantages in the current knowledge of protein–protein interactions, which have been mainly caused by a high number of database entries being contributed by only a few publications with highly specific motivations and methodologies that favor, for instance, interactions in the cytosol and the nucleus. Full article

Although Carnobacterium maltaromaticum derived from dairy products has been used as a lactic acid bacterium industrially, several studies have reported potential pathogenicity and disease outbreaks. Because strains derived from diseased fish and dairy products are considered potentially virulent and beneficial, respectively, their genotypic and phenotypic characteristics have attracted considerable attention. A genome-wide comparison of 30 genome sequences (13, 3, and 14 strains from diseased aquatic animals, dairy products, and processed food, respectively) was carried out. Additionally, one dairy and two nondairy strains were incubated in nutrient-rich (diluted liquid media) and nutrient-deficient environments (PBS) at pH 10 to compare their alkaline resistance in accordance with different nutritional environments by measuring their optical density and viable bacterial cell counts. Interestingly, only dairy strains carried 11 shared accessory genes, and 8 genes were strongly involved in the V-type ATPase gene cluster. Given that V-type ATPase contributes to resistance to alkaline pH and salts using proton motive force generated via sodium translocation across the membrane, C. maltaromaticum with a V-type ATPase might use nutrients in food under high pH. Indeed, the dairy strain carrying the V-type ATPase exhibited the highest alkaline resistance only in the nutrient-rich environment with significant upregulation of V-type ATPase expression. These results suggest that the gene cluster of V-type ATPase and increased alkaline resistance of dairy strains facilitate adaptation in the long-term ripening of alkaline dairy products. Full article

Plant vacuoles are unique compartments that play a critical role in plant growth and development. The vacuolar H⁺-ATPase (V-ATPase), together with the vacuolar H⁺-pyrophosphatase (V-PPase), generates the proton motive force that regulates multiple cell functions and impacts all aspects of plant life. We investigated the effect of V-ATPase activity in the vacuole on plant growth and development. We used an Arabidopsisthaliana (L.) Heynh. double mutant, vha-a2 vha-a3, which lacks two tonoplast-localized isoforms of the membrane-integral V-ATPase subunit VHA-a. The mutant is viable but exhibits impaired growth and leaf chlorosis. Nitrate assimilation led to excessive ammonium accumulation in the shoot and lower nitrogen uptake, which exacerbated growth retardation of vha-a2 vha-a3. Ion homeostasis was disturbed in plants with missing VHA-a2 and VHA-a3 genes, which might be related to limited growth. The reduced growth and excessive ammonium accumulation of the double mutant was alleviated by potassium supplementation. Our results demonstrate that plants lacking the two tonoplast-localized subunits of V-ATPase can be viable, although with defective growth caused by multiple factors, which can be alleviated by adding potassium. This study provided a new insight into the relationship between V-ATPase, growth, and ammonium accumulation, and revealed the role of potassium in mitigating ammonium toxicity. Full article

In mesophyll cells of the aquatic monocot Vallisneria, red light induces rotational cytoplasmic streaming, which is regulated by the cytoplasmic concentration of Ca²⁺. Our previous investigations revealed that red light induces Ca²⁺ efflux across the plasma membrane (PM), and that both the red light-induced cytoplasmic streaming and the Ca²⁺ efflux are sensitive to vanadate, an inhibitor of P-type ATPases. In this study, pharmacological experiments suggested the involvement of PM H⁺-ATPase, one of the P-type ATPases, in the photoinduction of cytoplasmic streaming. We hypothesized that red light would activate PM H⁺-ATPase to generate a large H⁺ motive force (PMF) in a photosynthesis-dependent manner. We demonstrated that indeed, photosynthesis increased the PMF and induced phosphorylation of the penultimate residue, threonine, of PM H⁺-ATPase, which is a major activation mechanism of H⁺-ATPase. The results suggested that a large PMF generated by PM H⁺-ATPase energizes the Ca²⁺ efflux across the PM. As expected, we detected a putative Ca²⁺/H⁺ exchange activity in PM vesicles isolated from Vallisneria leaves. Full article