scholarly journals Erratum to: “Cloning of 9-cis-epoxycarotenoid dioxygenase (NCED) gene encoding a key enzyme during abscisic acid (ABA) biosynthesis and ABA-regulated ethylene production in detached young persimmon calyx”

2009 ◽  
Vol 54 (21) ◽  
pp. 3990-3990 ◽  
Author(s):  
Ping Leng ◽  
GuangLian Zhang ◽  
XiangXin Li ◽  
LiangHe Wang ◽  
ZhongMing Zheng
Keyword(s):  
Abscisic Acid ◽  
Ethylene Production ◽  
Gene Encoding ◽  
Key Enzyme ◽  
Nced Gene ◽  
Aba Biosynthesis

Sucrose and light regulation of a cold-inducible UDP-glucose pyrophosphorylase gene via a hexokinase-independent and abscisic acid-insensitive pathway in Arabidopsis

2001 ◽  
Vol 354 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Iwona CIERESZKO ◽  
Henrik JOHANSSON ◽  
Leszek A. KLECZKOWSKI
Keyword(s):  
Abscisic Acid ◽  
Okadaic Acid ◽  
Expression Profiles ◽  
Light Regulation ◽  
Plant Responses ◽  
Gene Encoding ◽  
Environmental Signals ◽  
Sugar Signalling ◽  
Key Enzyme ◽  
Aba Insensitive

UDP-glucose pyrophosphorylase (UGPase) is a key enzyme producing UDP-glucose, which is involved in an array of metabolic pathways concerned with, among other functions, the synthesis of sucrose and cellulose. An Arabidopsis thaliana UGPase-encoding gene, Ugp, was profoundly up-regulated by feeding sucrose to the excised leaves and by an exposure of plants to low temperature (5°C). The UGPase activity and its protein content also increased under conditions of sucrose feeding and exposure to cold. The sucrose effect on Ugp was apparently specific and was mimicked by exposure of dark-adapted leaves to light. Drought and O2 deficiency had some down-regulating effects on expression of Ugp. The sugar-signalling pathway for Ugp regulation was independent of hexokinase, as was found by using transgenic plants with increased and decreased expression of the corresponding gene. Subjecting mutants deficient in abscisic acid (ABA) to cold stress conditions had no effect on Ugp expression profiles. Okadaic acid was a powerful inhibitor of Ugp expression, whereas it up-regulated the gene encoding sucrose synthase (Sus1), indicating distinct transduction pathways in transmitting the sugar signal for the two genes in A. thaliana. We suggest that Ugp gene expression is mediated via a hexokinase-independent and ABA-insensitive pathway that involves an okadaic acid-responsive protein phosphatase. The data point towards Ugp as a possible regulatory entity that is closely involved in the homoeostatic readjustment of plant responses to environmental signals.

scholarly journals Transcriptome Reveals Roles of Lignin-Modifying Enzymes and Abscisic Acid in the Symbiosis of Mycena and Gastrodia elata

2021 ◽  
Vol 22 (12) ◽  
pp. 6557
Author(s):  
Li-Ying Ren ◽  
Heng Zhao ◽  
Xiao-Ling Liu ◽  
Tong-Kai Zong ◽  
Min Qiao ◽  
...  
Keyword(s):  
Biological Activity ◽  
Abscisic Acid ◽  
Lignin Degradation ◽  
Molecular Mechanisms ◽  
Receptor Protein ◽  
Gastrodia Elata ◽  
Upregulated Genes ◽  
Aba Biosynthesis ◽  
Seed Coats

Gastrodia elata is a well-known medicinal and heterotrophic orchid. Its germination, limited by the impermeability of seed coat lignin and inhibition by abscisic acid (ABA), is triggered by symbiosis with fungi such as Mycena spp. However, the molecular mechanisms of lignin degradation by Mycena and ABA biosynthesis and signaling in G. elata remain unclear. In order to gain insights into these two processes, this study analyzed the transcriptomes of these organisms during their dynamic symbiosis. Among the 25 lignin-modifying enzyme genes in Mycena, two ligninolytic class II peroxidases and two laccases were significantly upregulated, most likely enabling Mycena hyphae to break through the lignin seed coats of G. elata. Genes related to reduced virulence and loss of pathogenicity in Mycena accounted for more than half of annotated genes, presumably contributing to symbiosis. After coculture, upregulated genes outnumbered downregulated genes in G. elata seeds, suggesting slightly increased biological activity, while Mycena hyphae had fewer upregulated than downregulated genes, indicating decreased biological activity. ABA biosynthesis in G. elata was reduced by the downregulated expression of 9-cis-epoxycarotenoid dioxygenase (NCED-2), and ABA signaling was blocked by the downregulated expression of a receptor protein (PYL12-like). This is the first report to describe the role of NCED-2 and PYL12-like in breaking G. elata seed dormancy by reducing the synthesis and blocking the signaling of the germination inhibitor ABA. This study provides a theoretical basis for screening germination fungi to identify effective symbionts and for reducing ABA inhibition of G. elata seed germination.

scholarly journals Isolation and Characterization of a Mutant of the Marine Bacterium Alcanivorax borkumensis SK2 Defective in Lipid Biosynthesis

2010 ◽  
Vol 76 (9) ◽  
pp. 2884-2894 ◽  
Author(s):  
Efraín Manilla-Pérez ◽  
Alvin Brian Lange ◽  
Stephan Hetzler ◽  
Marc Wältermann ◽  
Rainer Kalscheuer ◽  
...  
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
Marine Bacterium ◽  
Neutral Lipids ◽  
Nile Red ◽  
Dry Weight ◽  
Wax Ester ◽  
Gene Encoding ◽  
Isolation And Characterization ◽  
Key Enzyme

ABSTRACT In many microorganisms, the key enzyme responsible for catalyzing the last step in triacylglycerol (TAG) and wax ester (WE) biosynthesis is an unspecific acyltransferase which is also referred to as wax ester synthase/acyl coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT; AtfA). The importance and function of two AtfA homologues (AtfA1 and AtfA2) in the biosynthesis of TAGs and WEs in the hydrocarbon-degrading marine bacterium Alcanivorax borkumensis SK2 have been described recently. However, after the disruption of both the AtfA1 and AtfA2 genes, reduced but substantial accumulation of TAGs was still observed, indicating the existence of an alternative TAG biosynthesis pathway. In this study, transposon-induced mutagenesis was applied to an atfA1 atfA2 double mutant to screen for A. borkumensis mutants totally defective in biosynthesis of neutral lipids in order to identify additional enzymes involved in the biosynthesis of these lipids. At the same time, we have searched for a totally TAG-negative mutant in order to study the function of TAGs in A. borkumensis. Thirteen fluorescence-negative mutants were identified on Nile red ONR7a agar plates and analyzed for their abilities to synthesize lipids. Among these, mutant 2 M131 was no longer able to synthesize and accumulate TAGs if pyruvate was used as the sole carbon source. The transposon insertion was localized in a gene encoding a putative cytochrome c family protein (ABO_1185). Growth and TAG accumulation experiments showed that the disruption of this gene resulted in the absence of TAGs in 2 M131 but that growth was not affected. In cells of A. borkumensis SK2 grown on pyruvate as the sole carbon source, TAGs represented about 11% of the dry weight of the cells, while in the mutant 2 M131, TAGs were not detected by thin-layer and gas chromatography analyses. Starvation and lipid mobilization experiments revealed that the lipids play an important role in the survival of the cells. The function of neutral lipids in A. borkumensis SK2 is discussed.

scholarly journals The Bacillus subtilis yqjI Gene Encodes the NADP+-Dependent 6-P-Gluconate Dehydrogenase in the Pentose Phosphate Pathway

2004 ◽  
Vol 186 (14) ◽  
pp. 4528-4534 ◽  
Author(s):  
Nicola Zamboni ◽  
Eliane Fischer ◽  
Dietmar Laudert ◽  
Stéphane Aymerich ◽  
Hans-Peter Hohmann ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Glucose Dehydrogenase ◽  
Reducing Power ◽  
Pentose Phosphate ◽  
Gene Encoding ◽  
Metabolic Intermediates ◽  
The Third ◽  
Key Enzyme ◽  
Sequence Similarities

ABSTRACT Despite the importance of the oxidative pentose phosphate (PP) pathway as a major source of reducing power and metabolic intermediates for biosynthetic processes, almost no direct genetic or biochemical evidence is available for Bacillus subtilis. Using a combination of knockout mutations in known and putative genes of the oxidative PP pathway and 13C-labeling experiments, we demonstrated that yqjI encodes the NADP+-dependent 6-P-gluconate dehydrogenase, as was hypothesized previously from sequence similarities. Moreover, YqjI was the predominant isoenzyme during glucose and gluconate catabolism, and its role in the oxidative PP pathway could not be played by either of two homologues, GntZ and YqeC. This conclusion is in contrast to the generally held view that GntZ is the relevant isoform; hence, we propose a new designation for yqjI, gndA, the monocistronic gene encoding the principal 6-P-gluconate dehydrogenase. Although we demonstrated the NAD+-dependent 6-P-gluconate dehydrogenase activity of GntZ, gntZ mutants exhibited no detectable phenotype on glucose, and GntZ did not contribute to PP pathway fluxes during growth on glucose. Since gntZ mutants grew normally on gluconate, the functional role of GntZ remains obscure, as does the role of the third homologue, YqeC. Knockout of the glucose-6-P dehydrogenase-encoding zwf gene was primarily compensated for by increased glycolytic fluxes, but about 5% of the catabolic flux was rerouted through the gluconate bypass with glucose dehydrogenase as the key enzyme.

Investigation of the diversity of homoacetogenic bacteria in mesophilic and thermophilic anaerobic sludges using the formyltetrahydrofolate synthetase gene

2008 ◽  
Vol 57 (5) ◽  
pp. 675-680 ◽  
Author(s):  
P. Ryan ◽  
C. Forbes ◽  
E. Colleran
Keyword(s):  
Granular Sludge ◽  
Anaerobic Sludge ◽  
Heterotrophic Growth ◽  
Autotrophic Growth ◽  
Gene Encoding ◽  
Formyltetrahydrofolate Synthetase ◽  
Homoacetogenic Bacteria ◽  
Wide Range ◽  
Key Enzyme ◽  
Acetyl Coa Pathway

Homoacetogenic bacteria are strict anaerobes capable of autotrophic growth on H2/CO2 or CO, and of heterotrophic growth on a wide range of sugars, alcohols, methoxylated aromatic compounds and one carbon compounds, yielding acetate as their sole metabolic end-product. Batch activity tests on anaerobic granular sludge, using H2/CO2 as a substrate and 2-bromoethanesulfonate (BES) as a specific methanogenic inhibitor revealed that H2/CO2 conversion and concomitant acetate production commenced only after a lag period of 60–100 h. This finding suggests that the homoacetogenic population of digester sludge could be maintained by heterotrophic growth on sugars or other organic compounds, rather than by autotrophic growth on H2/CO2. In the present study, two upflow anaerobic sludge bed (UASB) reactors were operated at 37°C and 55°C for two distinct trial periods, each characterised by the application of influents designed to enrich for homoacetogenic bacteria. Specific primers designed for the amplification of the functional gene encoding formyltetrahydrofolate synthetase (FTHFS), a key enzyme in the acetyl-CoA pathway of acetogenesis, were used as a specific probe for acetogenic bacteria. The diversity of acetogens in the granular sludge cultivated in each reactor was revealed by application of FTHFS targeted PCR. Results show that biomass acetogenic composition was dependent upon the operational temperature of the reactor and the substrate supplied as influent.

Abstract 5455: A Novel Haplotype on GCH1 Gene, Encoding GTP Cyclohydrolase 1, Regulates Vascular Biopterin Synthesis, eNOS Coupling and Vascular Redox in Human Vessels

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Charalambos Antoniades ◽  
Cheerag Shirodaria ◽  
Thomasz Guzik ◽  
Tim Van-Assche ◽  
Ravi Pillai ◽  
...  
Keyword(s):  
Vascular Endothelium ◽  
Inflammatory Cells ◽  
Gtp Cyclohydrolase ◽  
Gene Encoding ◽  
Enos Uncoupling ◽  
Key Enzyme ◽  
Biopterin Synthesis ◽  
No Bioavailability ◽  
Gch1 Gene ◽  
O2 Production

Background: GTP cyclohydrolase (GTPCH) is a key enzyme in biopterins synthesis, while tetrahydrobiopterin (BH4) is a regulator of eNOS coupling in vascular endothelium. A novel haplotype in GCH1 gene, combining dbSNPs: rs8007267G/A, rs3783641A/T and rs10483639C/G, affects GTPCH activity and biopterins levels in inflammatory cells. We examined the effect of this haplotype on vascular biopterins, eNOS coupling and redox state in human vessels from patients with coronary atherosclerosis. Methods: Samples of saphenous veins (SV) were obtained from 347 patients undergoing CABG. Vasorelaxations of SV to acetylcholine (ACh) and vascular O2- (± eNOS inhibitor LNAME) were determined. Biopterins were measured by HPLC. The haplotypes were defined as X (rs8007267A+ rs3783641T+ rs10483639G) or O (all other haplotypes). Results: The haplotype distribution was OO:245(71%), OX:95(27%) and XX:7(2%). Carriers of the X haplotype had lower plasma (Fig. a ) and vascular (Fig. b ) BH4. The X haplotype was associated with higher vascular O2- (XX+XO: 2.97±0.44 vs OO:1.90±0.10 RLU/Sec/mg, p<0.01), greater LNAME-inhibitable O2- (Fig. c ) suggesting eNOS uncoupling) and lower NO bioavailability (Fig. d ) in human vessels. The X haplotype was also associated with higher plasma ox-LDL (51.0±2.2 in XX+XO vs 44.2±1.4 U/L in OO p<0.05) and lower BH4:total biopterins ratio (43.1±3.2 in XX+XO vs 51.7±2.1% in OO, p<0.05). Conclusions: This novel haplotype on GCH1 gene regulates biopterins biosynthesis in both plasma and vascular endothelium. This haplotype also regulates eNOS coupling, O2- production and NO bioavailability in human vessels, and may play a role in atherogenesis.

scholarly journals Formate-Dependent H2 Production by the Mesophilic Methanogen Methanococcus maripaludis

2008 ◽  
Vol 74 (21) ◽  
pp. 6584-6590 ◽  
Author(s):  
Boguslaw Lupa ◽  
Erik L. Hendrickson ◽  
John A. Leigh ◽  
William B. Whitman
Keyword(s):  
Dry Weight ◽  
Maximal Activity ◽  
Growth Conditions ◽  
H2 Production ◽  
Resting Cells ◽  
Wild Type ◽  
Methanococcus Maripaludis ◽  
Gene Encoding ◽  
Major Pathway ◽  
Key Enzyme

ABSTRACT Methanococcus maripaludis, an H2- and formate-utilizing methanogen, produced H2 at high rates from formate. The rates and kinetics of H2 production depended upon the growth conditions, and H2 availability during growth was a major factor. Specific activities of resting cells grown with formate or H2 were 0.4 to 1.4 U�mg−1 (dry weight). H2 production in formate-grown cells followed Michaelis-Menten kinetics, and the concentration of formate required for half-maximal activity (Kf ) was 3.6 mM. In contrast, in H2-grown cells this process followed sigmoidal kinetics, and the Kf was 9 mM. A key enzyme for formate-dependent H2 production was formate dehydrogenase, Fdh. H2 production and growth were severely reduced in a mutant containing a deletion of the gene encoding the Fdh1 isozyme, indicating that it was the primary Fdh. In contrast, a mutant containing a deletion of the gene encoding the Fdh2 isozyme possessed near-wild-type activities, indicating that this isozyme did not play a major role. H2 production by a mutant containing a deletion of the coenzyme F420-reducing hydrogenase Fru was also severely reduced, suggesting that the major pathway of H2 production comprised Fdh1 and Fru. Because a Δfru-Δfrc mutant retained 10% of the wild-type activity, an additional pathway is present. Mutants possessing deletions of the gene encoding the F420-dependent methylene-H4MTP dehydrogenase (Mtd) or the H2-forming methylene-H4MTP dehydrogenase (Hmd) also possessed reduced activity, which suggested that this second pathway was comprised of Fdh1-Mtd-Hmd. In contrast to H2 production, the cellular rates of methanogenesis were unaffected in these mutants, which suggested that the observed H2 production was not a direct intermediate of methanogenesis. In conclusion, high rates of formate-dependent H2 production demonstrated the potential of M. maripaludis for the microbial production of H2 from formate.

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