F1 ATPase Research Articles

Introduction of a Sodium-Binding Motif into Subunits <i>a</i> and <i>c</i> of <i>Bacillus</i> sp. PS3 Proton F-ATPase Does Not Result in Sodium Specificity of the Enzyme

In bacteria F-type ATPase (F-ATPase) plays a key role in bioenergetics and couples ATP synthesis/hydrolysis with the transport of ions (H+ or Na+) across the membrane. The ion specificity of the enzyme is determined by the amino acid sequence of subunits c and а. Here, we introduced several mutations (7 in subunit c and 6 in subunit a) into F-ATPase of thermophilic bacterium Bacillus sp. PS3 in order to change the ion specificity of the enzyme from proton to sodium. The mutations did not affect the ATPase activity of the enzyme, but led to loss of proton conductivity and impaired the binding of subunit a to the c-subunit oligomer, rather than changed the ion specificity.

Effects of different trophic conditions on total fatty acids, amino acids, pigment and gene expression profiles in Euglena gracilis.

Euglena gracilis is a unique microalga that lacks a cell wall and is able to grow under different trophic culture conditions. In this study, cell growth, biomass production, and changes in the ultrastructure of E. gracilis cells cultivated photoautotrophically, mixotrophically, and under sequential-heterotrophy-photoinduction (SHP) were assessed. Mixotrophy induced the highest cell growth and biomass productivity (6.27 ± 0.59mg/L/d) in E. gracilis, while the highest content of fatty acids, 2.69 ± 0.04% of dry cell weight (DCW) and amino acids, 38.16 ± 0.08% of DCW was obtained under SHP condition. E. gracilis also accumulated significantly higher saturated fatty acids and lower unsaturated fatty acids when cultivated under SHP condition. Transcriptomic analysis showed that the expression of photosynthetic genes (PsbA, PsbC, F-type ATPase alpha and beta) was lower, carbohydrate and protein synthetic genes (glnA, alg14 and fba) were expressed higher in SHP-culture cells when compared to other groups. Different trophic conditions also induced changes in the cell ultrastructure, where paramylon and starch granules were more abundant in SHP-cultured cells. The findings generated in this study illustrated that aerobic SHP cultivation of E. gracilis possesses great potential in human and animal feed applications.

Mechanistic understanding of acclimation and energy metabolism of acetoclastic methanogens under different substrate to microorganism ratios

Mechanistic understanding of acetoclastic methanogenesis is pivotal for optimizing anaerobic digestion for efficient methane production. In this study, two different operational modes, continuous flow reactor (CFR) and sequencing batch reactor (SBR), accompanied with solids retention times (SRT) of 10 days (SBR10d and CFR10d) and 25 days (SBR25d and CFR25d) were implemented to elucidate their impacts on microbial communities and energy metabolism of methanogens in acetate-fed systems. Microbial community analysis revealed that the relative abundance of Methanosarcina (16.0%–46.0%) surpassed Methanothrix (3.7%–22.9%) in each reactor. SBRs had the potential to enrich both Methanothrix and Methanosarcina. Compared to SBRs, CFRs had lower total relative abundance of methanogens. Methanosarcina exhibited a superior enrichment in reactors with 10-day SRT, while Methanothrix preferred to be acclimated in reactors with 25-day SRT. The operational mode and SRT were also observed to affect the distribution of acetate-utilizing bacteria, including Pseudomonas, Desulfocurvus, Mesotoga, and Thauera. Regarding enzymes involved in energy metabolism, Ech and Vho/Vht demonstrated higher relative abundances at 10-day SRT compared to 25-day SRT, whereas Fpo and MtrA-H showed higher relative abundances in SBRs than those in CFRs. The relative abundance of genes encoding ATPase harbored by Methanothrix was higher than Methanosarcina at 25-day SRT. Additionally, the relative abundance of V/A-type ATPase (typically for methanogens) was observed higher in SBRs compared to CFRs, while the F-type ATPase (typically for bacteria) exhibited higher relative abundance in CFRs than that in SBRs.

Eukaryotic yeast V1-ATPase rotary mechanism insights revealed by high-resolution single-molecule studies.

Vacuolar ATP-dependent proton pumps (V-ATPases) belong to a super-family of rotary ATPases and ATP synthases. The V1 complex consumes ATP to drive rotation of a central rotor that pumps protons across membranes via the Vo complex. Eukaryotic V-ATPases are regulated by reversible disassembly of subunit C, V1 without C, and VO. ATP hydrolysis is thought to generate an unknown rotary state that initiates regulated disassembly. Dissociated V1 is inhibited by subunit H that traps it in a specific rotational position. Here, we report the first single-molecule studies with high resolution of time and rotational position of Saccharomyces cerevisiae V1-ATPase lacking subunits H and C (V1ΔHC), which resolves previously elusive dwells and angular velocity changes. Rotation occurred in 120° power strokes separated by dwells comparable to catalytic dwells observed in other rotary ATPases. However, unique V1ΔHC rotational features included: 1) faltering power stroke rotation during the first 60°; 2) a dwell often occurring ∼45° after the catalytic dwell, which did not increase in duration at limiting MgATP; 3) a second dwell, ∼2-fold longer occurring 112° that increased in duration and occurrence at limiting MgATP; 4) limiting MgATP-dependent decreases in power stroke angular velocity where dwells were not observed. The results presented here are consistent with MgATP binding to the empty catalytic site at 112° and MgADP released at ∼45°, and provide important new insight concerning the molecular basis for the differences in rotary positions of substrate binding and product release between V-type and F-type ATPases.

Unraveling response mechanism of electron transport mechanism to uranium-exposure in Bacillus sp. X02

With the development of the uranium mining industry, the remediation of uranium pollution is an urgent environmental problem to be solved. Bioreduction is currently recognized as a U(VI) bioremediation method with good application prospects. However, inadequate reporting of uranium-reducing bacteria and low bioreduction efficiency are the main reasons limiting the application of the bioreduction method. In this paper, we isolated an efficient uranium-reducing bacterium, Bacillus sp. X02, explored the effect of U(VI) on bioreduction efficiency through electron transport mechanisms. The results showed that the maximum removal and reduction rate were 98.35 % and 62.43 %, respectively. Further studies revealed that the efficiency of extracellular electron transport of Bacillus sp. X02 was enhanced under U(VI) exposure. But uranium stress down-regulated the expression of F-type ATPase, Cytochrome c reductase ISP, Cytochrome c oxidase, and Cytochrome bd complex, inhibited the processes of complex III, complex IV, and ATP synthesis in the oxidative phosphorylation electron transport pathway, decreasing the electron transfer and U(VI) reduction capacity of Bacillus sp. X02 ultimately. This work proposed a new electron transfer pathway for U(VI) bioreduction and provided new insights into the effect of uranium on bioreduction efficiency.

Metabolic mechanism of thermal pretreatment combined with ethanol pre-fermentation to enhance anaerobic digestion of food waste: A comprehensive analysis of key enzyme-encoding genes

Ethanol pre-fermentation (EP) can enhance methanogenic efficiency and facilitate food waste (FW) hydrolysis, while ensuring anaerobic digestion (AD) system stability. FW contains high-water content, and thermal pretreatment (TP) can significantly enhance solids and soluble organic matter content. The study focused on investigating the mechanism of TP combined with EP (TP-EP) on the AD of FW. The results showed that TP-EP enriched hydrolyzing and acid-producing bacteria, as well as the methanogens Methanosarcina, and Methanothrix. Consequently, the degradation rates of soluble chemical oxygen demand, volatile fatty acids, and cumulative methane yield exhibited an increase of 9.54%, 5.94%, and 20.42%, respectively, in comparison to the control. EP promoted carbohydrate metabolism, while TP promoted amino acid metabolism and enhanced energy metabolism by enriching F-type ATPase and NADHase. When combined as TP-EP, the processes integrated the advantages and promoted substrate hydrolysis and energy metabolism while enhancing methanogenic metabolism.

The exceptional form and function of the giant bacterium Ca. Epulopiscium viviparus revolves around its sodium motive force.

Epulopiscium spp. are the largest known heterotrophic bacteria; a large cigar-shaped individual is a million times the volume of Escherichia coli. To better understand the metabolic potential and relationship of Epulopiscium sp. type B with its host Naso tonganus, we generated a high-quality draft genome from a population of cells taken from a single fish. We propose the name Candidatus Epulopiscium viviparus to describe populations of this best-characterized Epulopiscium species. Metabolic reconstruction reveals more than 5% of the genome codes for carbohydrate active enzymes, which likely degrade recalcitrant host-diet algal polysaccharides into substrates that may be fermented to acetate, the most abundant short-chain fatty acid in the intestinal tract. Moreover, transcriptome analyses and the concentration of sodium ions in the host intestinal tract suggest that the use of a sodium motive force (SMF) to drive ATP synthesis and flagellar rotation is integral to symbiont metabolism and cellular biology. In natural populations, genes encoding both F-type and V-type ATPases and SMF generation via oxaloacetate decarboxylation are among the most highly expressed, suggesting that ATPases synthesize ATP and balance ion concentrations across the cell membrane. High expression of these and other integral membrane proteins may allow for the growth of its extensive intracellular membrane system. Further, complementary metabolism between microbe and host is implied with the potential provision of nitrogen and B vitamins to reinforce this nutritional symbiosis. The few features shared by all bacterial behemoths include extreme polyploidy, polyphosphate synthesis, and thus far, they have all resisted cultivation in the lab.

Resilience and Vulnerability to Stress-Induced Anhedonia: Unveiling Brain Gene Expression and Mitochondrial Dynamics in a Mouse Chronic Stress Depression Model.

The role of altered brain mitochondrial regulation in psychiatric pathologies, including Major Depressive Disorder (MDD), has attracted increasing attention. Aberrant mitochondrial functions were suggested to underlie distinct inter-individual vulnerability to stress-related MDD syndrome. In this context, insulin receptor sensitizers (IRSs) that regulate brain metabolism have become a focus of recent research, as their use in pre-clinical studies can help to elucidate the role of mitochondrial dynamics in this disorder and contribute to the development of new antidepressant treatment. Here, following 2-week chronic mild stress (CMS) using predation, social defeat, and restraint, MDD-related behaviour and brain molecular markers have been investigated along with the hippocampus-dependent performance and emotionality in mice that received the IRS dicholine succinate (DS). In a sucrose test, mice were studied for the key feature of MDD, a decreased sensitivity to reward, called anhedonia. Based on this test, animals were assigned to anhedonic and resilient-to-stress-induced-anhedonia groups, using a previously established criterion of a decrease in sucrose preference below 65%. Such assignment was based on the fact that none of control, non-stressed animals displayed sucrose preference that would be smaller than this value. DS-treated stressed mice displayed ameliorated behaviours in a battery of assays: sucrose preference, coat state, the Y-maze, the marble test, tail suspension, and nest building. CMS-vulnerable mice exhibited overexpression of the inflammatory markers Il-1β, tnf, and Cox-1, as well as 5-htt and 5-ht2a-R, in various brain regions. The alterations in hippocampal gene expression were the closest to clinical findings and were studied further. DS-treated, stressed mice showed normalised hippocampal expression of the plasticity markers Camk4, Camk2, Pka, Adcy1, Creb-ar, Nmda-2r-ar, and Nmda-2r-s. DS-treated and non-treated stressed mice who were resilient or vulnerable to anhedonia were compared for hippocampal mitochondrial pathway regulation using Illumina profiling. Resilient mice revealed overexpression of the mitochondrial complexes NADH dehydrogenase, succinate dehydrogenase, cytochrome bc1, cytochrome c oxidase, F-type and V-type ATPases, and inorganic pyrophosphatase, which were decreased in anhedonic mice. DS partially normalised the expression of both ATPases. We conclude that hippocampal reduction in ATP synthesis is associated with anhedonia and pro-inflammatory brain changes that are ameliorated by DS.

Mechanistic insights into synergistic facilitation of copper/zinc ions and dewatered swine manure-derived biochar on anaerobic digestion of swine wastewater

Biochar-assisted anaerobic digestion (AD) has been proposed an advanced system for swine wastewater (SW) management. However, the effects of metallic nutrients in SW, such as copper/zinc ions (Cu2+/Zn2+), on the biochar-assisted AD of SW are not well understood. This study investigated the influences of individual Cu2+/Zn2+ or dewatered swine manure-derived biochar, as well as their combined additions, on the AD of SW. The results showed that exposure to 50 mg/L Cu2+/Zn2+ temporary inhibited methane production, but the addition of 20 g/L biochar alleviated this inhibition by shortening the methanogenic lag time and increasing methane yield. Following a period of acclimation, both Cu2+/Zn2+ and biochar promoted methane production, although metagenomic analysis revealed distinct mechanisms underlying their promotion. Cu2+/Zn2+ enhanced ATP processing, including electron exchange between NADH/NAD+ and succinate/fumarate transformation, by 26.0–35.8%. Additionally, the gene encoding Coenzyme M methylation was upregulated by 36.2% along with enrichments of Methanocullus and Methanosarcina, contributing to accelerated hydrolysis and methanogenesis rates by 54.7% and 44.8%, respectively. On the other hand, biochar mainly stimulated bacterial F-type ATPase activities by 28.4%, likely facilitating direct interspecies electron transfer between Geobacter and Methanosarcina for syntrophic methanogenesis. The combined addition of Cu2+/Zn2+ and biochar resulted in “win-win” benefits, significantly increasing the maximum methane production rate from 40.3 mL CH4/d to 53.7 mL CH4/d. Moreover, the introduction of biochar into AD of SW facilitated the transformation of more Cu2+/Zn2+ from a reducible Fe–Mn oxides form to a residual form, which potentially reduced the metallic toxicity of the digestate for soil amendment. The findings of this study provide novel insights into understanding the synergistic impacts of heavy metals and biochar in regulating SW during AD, as well as the management of associated digestate.

Phytotoxic effects of polyethylene microplastics combined with cadmium on the photosynthetic performance of maize (Zea mays L.)

Microplastics (MPs) and cadmium (Cd) has attracted increasing attention due to their combined toxicity to terrestrial vegetation. Photosynthesis which utilizes light energy to synthesize organic substances is crucial for crop production. However, the plant photosynthetic response to the joint toxicity of MPs and Cd is still unknown. Here, we studied the effects of polyethylene (PE) MPs on the photosynthetic performance of two maize cultivars Xianyu 335 (XY) and Zhengdan 958 (ZD) grown in a Cd contaminated soil. Results showed that the leaf Cd concentration in XY and ZD reached 26.1 and 31.9 μg g−1, respectively. PE-MPs did not influence the leaf Cd content, but posed direct and negative effects on photosynthesis by increasing the malondialdehyde content, reducing the chlorophyll content, inhibiting photosynthetic capacity, disrupting the PSII donor side, blocking electron transfer in different photosystems, and suppressing the oxidation and reduction states of PSI. Transcriptomic analysis revealed that the inhibitory effect of combined PE-MPs and Cd on maize photosynthesis was attributed to suppressed expression of the genes encoding PSII, PSI, F-type ATPase, cytochrome b6/f complex, and electron transport between PSII and PSI. Using WGCNA, we identified a MEturquoise module highly correlated with photosynthetic traits. Hub genes bridging carbohydrate metabolism, amino acid metabolism, lipid metabolism, and translation provided the molecular mechanisms of PE-MPs and Cd tolerance in maize plants. The comprehensive information on the phytotoxicity mechanisms of Cd stress in the presence or absence of PE-MPs on the photosynthesis of maize is helpful for cloning Cd and PE-MP resistance genes in the future.

Geraniol ameliorates testicular damage in diabetic rats via inhibition of redox parameters and mitochondrial-mediated apoptosis

BackgroundDiabetes is a disease characterized by high levels of reactive oxygen species that trigger a series of events that culminate in programmed cell death. Terpenoids from plants used in traditional Chinese medicine have preventive and therapeutic potential. However, it is not known if geraniol, a monoterpene will prevent testicular damage in diabetic rats. Thus, this study investigated the antioxidant, and antiapoptotic effects of geraniol on testicular damage in diabetic male Wistar rats. Also, the interactions between geraniol with rat liver F1 ATPase and oxidized rat cytochrome c were investigated. MethodsA single intraperitoneal dose of streptozotocin (60 mg/kg) was used to induce diabetes in rats. Male Wistar rats were divided into 4 groups - CT (control), DA (Diabetic, 60 mg/kg streptozotocin), GE (Geraniol-treated, 60 mg/kg streptozotocin + 200 mg/kg geraniol), and GL (Glibenclamide-treated, 60 mg/kg streptozotocin + 5 mg/kg Glibenclamide). Rats were sacrificed by cervical dislocation under anesthesia after 21 days of treatment. Testicular superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), cytochrome c, caspase 9 and caspase 3, and testosterone (testes and plasma) were determined spectrophotometrically. The interactions between geraniol, and glibenclamide, with rat liver F1-ATPase (1MAB) and oxidized rat cytochrome c (5FD4) were assessed by molecular docking. ResultsThe results showed that SOD, and CAT levels were significantly (p<0.05) lowered in the DA group. Significant increases in SOD, CAT, and GSH levels were observed in the testes of rats in the GE and GL groups. Also, cytochrome c, caspase 9, and caspase 3 levels in rat testes were significantly lowered in the GE and GL groups when compared to the DA group. Furthermore, testosterone levels in the plasma and testes of rats in the GE and GL groups were significantly (p<0.05) increased in the treated groups when compared to the DA group. The binding affinities of geraniol for 1MAB (-5.4 Kcal/mol) and 5DF4 (-6.1 Kcal/mol) were comparable to that of glibenclamide (-5.5 Kcal/mol; -7.5 Kcal/mol, respectively). ConclusionThis study shows that geraniol has the potential to ebb testicular damage in diabetic rats through the inhibition of oxidative stress, caspase activation, rat liver F1-ATPase, and oxidized rat cytochrome c. This study suggests the use of geraniol-rich diet in traditional Chinese medicine.

Rotary properties of hybrid F1-ATPases consisting of subunits from different species

F1-ATPase (F1) is an ATP-driven rotary motor protein ubiquitously found in many species as the catalytic portion of FoF1-ATP synthase. Despite the highly conserved amino acid sequence of the catalytic core subunits: α and β, F1 shows diversity in the maximum catalytic turnover rate Vmax and the number of rotary steps per turn. To study the design principle of F1, we prepared eight hybrid F1s composed of subunits from two of three genuine F1s: thermophilic Bacillus PS3 (TF1), bovine mitochondria (bMF1), and Paracoccus denitrificans (PdF1), differing in the Vmax and the number of rotary steps. The Vmax of the hybrids can be well fitted by a quadratic model highlighting the dominant roles of β and the couplings between α-β. Although there exist no simple rules on which subunit dominantly determines the number of steps, our findings show that the stepping behavior is characterized by the combination of all subunits.

F-type proton-pumping ATPase mediates acid tolerance in Streptococcus mutans.

Streptococcus mutans is highly sensitive to inhibitors of proton-pumping F-type ATPase (F-ATPase) under acidic conditions. Herein, we investigated the role of S. mutans F-ATPase in acid tolerance using a bacterium expressing the F-ATPase β subunit at lower levels than the wild-type strain. We generated a mutant S. mutans expressing the catalytic β subunit of F-ATPase at lower levels than the wild-type bacterium. The mutant cells exhibited a significantly slower growth rate at pH 5.30, whereas the rate was essentially the same as that of wild-type cells at pH 7.40. In addition, the colony-forming ability of the mutant was decreased at pH<4.30 but not at pH 7.40. Thus, the growth rate and survival of S. mutans expressing low levels of the β subunit were reduced under acidic conditions. Together with our previous observations, this study indicates that F-ATPase is involved in the acid tolerance mechanism of S. mutans by secreting protons from the cytoplasm.

Comammox Nitrospira and Ammonia-Oxidizing Archaea Are Dominant Ammonia Oxidizers in Sediments of an Acid Mine Lake Containing High Ammonium Concentrations.

Exploring nitrifiers in extreme environments is vital to expanding our understanding of nitrogen cycle and microbial diversity. This study presents that complete ammonia oxidation (comammox) Nitrospira, together with acidophilic ammonia-oxidizing archaea (AOA), dominate in the nitrifying guild in sediments of an acid mine lake (AML). The lake water was characterized by acidic pH below 5 with a high ammonium concentration of 175 mg-N/liter, which is rare on the earth. Nitrification was active in sediments with a maximum nitrate production potential of 70.5 μg-N/(g-dry weight [dw] day) for mixed sediments. Quantitative PCR assays determined that in AML sediments, comammox Nitrospira and AOA amoA genes had relative abundances of 52% and 41%, respectively, among the total amoA genes. Further assays with 16S rRNA and amoA gene amplicon sequencing and metagenomics confirmed their dominance and revealed that the comammox Nitrospira found in sediments belonged to comammox Nitrospira clade A.2. Metagenomic binning retrieved a metagenome-assembled genome (MAG) of the comammox Nitrospira from sediments (completeness = 96.76%), and phylogenomic analysis suggested that it was a novel comammox Nitrospira. Comparative genomic investigation revealed that this comammox Nitrospira contained diverse metal resistance genes and an acidophile-affiliated F-type ATPase. Moreover, it had a more diverse genomic characteristic on nitrogen metabolism than the AOA in sediments and canonical AOB did. The results suggest that comammox Nitrospira is a versatile nitrifier that can adapt to acidic environments even with high ammonium concentrations. IMPORTANCE Ammonia-oxidizing archaea (AOA) was previously considered the sole dominant ammonia oxidizer in acidic environments. This study, however, found that complete ammonia oxidation (comammox) Nitrospira was also a dominant ammonia oxidizer in the sediments of an acidic mine lake, which had an acidic pH < 5 and a high ammonium concentration of 175 mg-N/liter. In combination with average nucleotide identity analysis, phylogenomic analysis suggested it is a novel strain of comammox Nitrospira. Moreover, the adaption of comammox Nitrospira to the acidic lake had been comprehensively investigated based on genome-centric metagenomic approaches. The outcomes of this study significantly expand our understanding of the diversity and adaptability of ammonia oxidizers in the acidic environments.

The curious case of the disassembling ATP synthase studied using molecular dynamics simulations.

Cellular bioenergetic processes responsible for providing energy to most lifeforms, photosynthesis and respiration, involve cooperative networks of proteins integrated into membrane domains. Exascale computational approaches, hand-in-hand with experiments, are necessary to learn how these processes are achieved. In particular, computations will reveal key organizational principles that underlie the efficient energy harvesting of protein networks. Application of these principles will aid the design of better man-made biohybrid devices in order to harness renewable energy for the world's future energy needs. The universal process of ATP synthesis, a component of the photosynthetic energy harvesting and respiration can now be investigated at atomic detail through the molecular dynamics of a complex biological motor, ATP synthase, that transforms an ion gradient existing across the cell membrane into the synthesis of ATP from ADP. The reversibility of this biomotor is essential for energy-transcending processes in all living systems, yet, the mechanism of its action remains fragmentary. To investigate this mechanism, we performed simulations on full bacterial and bovine F-type ATPase models utilizing Nanoscale Molecular Dynamics software. First, we monitored a water channel located near key acidic residues in the bacterial ATPase c-ring to observe its behavior both before and after proton transfer occurred in this region, and we discovered what we hypothesize to be a mechanism that prevents the back-transport of protons. Second, we designed models for the bovine ATPase to examine its overall stability, degree of water leakage in the membrane-inserted region, and “hook” (subunit e) behavior in the presence of varying voltages. We have preliminarily highlighted the instability of the catalytic stock and significant unfolding of the hook in all models, as well as increased water leakage in models that did not contain a lipid plug inserted into the c-ring.

Direct identification of the rotary angle of ATP cleavage in F1-ATPase from Bacillus PS3

F1-ATPase is the world’s smallest biological rotary motor driven by ATP hydrolysis at three catalytic β subunits. The 120° rotational step of the central shaft γ consists of 80° substep driven by ATP binding and a subsequent 40° substep. In order to correlate timing of ATP cleavage at a specific catalytic site with a rotary angle, we designed a new F1-ATPase (F1) from thermophilic Bacillus PS3 carrying β(E190D/F414E/F420E) mutations, which cause extremely slow rates of both ATP cleavage and ATP binding. We produced an F1 molecule that consists of one mutant β and two wild-type βs (hybrid F1). As a result, the new hybrid F1 showed two pausing angles that are separated by 200°. They are attributable to two slowed reaction steps in the mutated β, thus providing the direct evidence that ATP cleavage occurs at 200° rather than 80° subsequent to ATP binding at 0°. This scenario resolves the long-standing unclarified issue in the chemomechanical coupling scheme and gives insights into the mechanism of driving unidirectional rotation.

V-ATPase a3 Subunit in Secretory Lysosome Trafficking in Osteoclasts.

Vacuolar-type ATPase (V-ATPase) shares its structure and rotational catalysis with F-type ATPase (F-ATPase, ATP synthase). However, unlike subunits of F-ATPase, those of V-ATPase have tissue- and/or organelle-specific isoforms. Structural diversity of V-ATPase generated by different combinations of subunit isoforms enables it to play diverse physiological roles in mammalian cells. Among these various roles, this review focuses on the functions of lysosome-specific V-ATPase in bone resorption by osteoclasts. Lysosomes remain in the cytoplasm in most cell types, but in osteoclasts, secretory lysosomes move toward and fuse with the plasma membrane to secrete lysosomal enzymes, which is essential for bone resorption. Through this process, lysosomal V-ATPase harboring the a3 isoform of the a subunit is relocated to the plasma membrane, where it transports protons from the cytosol to the cell exterior to generate the acidic extracellular conditions required for secreted lysosomal enzymes. In addition to this role as a proton pump, we recently found that the lysosomal a3 subunit of V-ATPase is essential for anterograde trafficking of secretory lysosomes. Specifically, a3 interacts with Rab7, a member of the Rab guanosine 5'-triphosphatase (GTPase) family that regulates organelle trafficking, and recruits it to the lysosomal membrane. These findings revealed the multifunctionality of lysosomal V-ATPase in osteoclasts; V-ATPase is responsible not only for the formation of the acidic environment by transporting protons, but also for intracellular trafficking of secretory lysosomes by recruiting organelle trafficking factors. Herein, we summarize the molecular mechanism underlying secretory lysosome trafficking in osteoclasts, and discuss the possible regulatory role of V-ATPase in organelle trafficking.

Transcriptomic insights into the molecular mechanism of wheat response to stripe rust fungus

The wheat crop (Triticum aestivum L.) is the widely cultivated and most important staple foods of worlds. Stripe (yellow) rust is prompted by Puccinia striiformis f. sp. tritici (Pst) to reduces the yield and grain quality of the wheat significantly. Although many resistant cultivars have been successfully used in wheat breeding, the size of the regulating network and the underlying molecular mechanisms of wheat to response Pst still unknown. Therefore, in order to identify differentially expression genes (DEGs) and the regulate network related to Pst resistance, 15 cDNA libraries were constructed from wheat with CYR34 infection. In this study, a highly susceptible cv. Chuanyu12 (CY12) was used to study the transcriptome profiles after being inoculated with Pst physiological race CYR34. The DEGs were investigated at 24h, 48h, 72h, and 7 days post-inoculation. Certain key genes and pathways of response for Pst-CYR34 in CY12 were identified. The results revealed that Pst-CYR34 inhibited the DEGs related to energy metabolism, biosynthesis, carbon fixation, phenylalanine metabolism, and plant hormone signaling pathways after post-inoculation at 24h, 48h, 72h, and 7d. Light-harvesting chlorophyll protein complex in photosystem I and photosystem II; F-type ATPase, cytochrome b6/f/complex, and photosynthetic electron transport; ethylene, salicylic acid (SA), and jasmonic acid (JA); and lignin and flavonoids biosynthesis in CY12 are among the down-regulated DEGs. The expression patterns of these DEGs were verified via Quantitative Real-time PCR analysis. Our results give insights into the foundation for further exploring the molecular mechanisms regulating networks of Pst response and opens the door for bread wheat Pst resistance breeding.

Regulatory Mechanisms and Environmental Adaptation of the F-ATPase Family.

The F-type ATPase family of enzymes, including ATP synthases, are found ubiquitously in biological membranes. ATP synthesis from ADP and inorganic phosphate is driven by an electrochemical H+ gradient or H+ motive force, in which intramolecular rotation of F-type ATPase is generated with H+ transport across the membranes. Because this rotation is essential for energy coupling between catalysis and H+-transport, regulation of the rotation is important to adapt to environmental changes and maintain ATP concentration. Recently, a series of cryo-electron microscopy images provided detailed insights into the structure of the H+ pathway and the multiple subunit arrangement. However, the regulatory mechanism of the rotation has not been clarified. This review describes the inhibition mechanism of ATP hydrolysis in bacterial enzymes. In addition, properties of the F-type ATPase of Streptococcus mutans, which acts as a H+-pump in an acidic environment, are described. These findings may help in the development of novel antimicrobial agents.

GhHSP24.7 mediates mitochondrial protein acetylation to regulate stomatal conductance in response to abiotic stress in cotton

During seed germination, the cotton chaperone protein HSP24.7 regulates the release, from the mitochondrial electron transport chain, of reactive oxygen species (ROS), a stimulative signal regulating germination. The function of HSP24.7 during vegetative stages remains largely unknown. Here we propose that suppression of GhHSP24.7 in cotton seedlings increases tolerance to heat and drought stress. Elevation of GhHSP24.7 was found to be positively associated with endogenous levels of ROS. We identified a new client protein of GhHSP24.7, cotton lysine deacetylase (GhHDA14), which is involved in mitochondrial protein modification. Elevated levels of GhHSP24.7 suppressed deacetylase activity in mitochondria, leading to increased acetylation of mitochondrial proteins enriched in the subunit of F-type ATPase, V-type ATPase, and cytochrome C reductase, ultimately reducing leaf ATP content. Consequently, in combination with altered ROS content, GhHSP24.7 transgenic lines were unable to coordinate stomatal closure under stress. The regulation circuit composed of GhHSP24.7 and GhHDA14 represents a post-translation level mechanism in plant abiotic stress responses that integrates the regulation of ROS and ATP.