-
[show abstract]
[hide abstract]
ABSTRACT: An L-glucose-utilizing bacterium, Paracoccus sp. 43P, was isolated from soil by enrichment cultivation in a minimal medium containing L-glucose as the sole carbon source. In cell free extracts from this bacterium, NAD+-dependent L-glucose dehydrogenase was detected as having sole activity toward L-glucose. This enzyme, LgdA, was purified and the lgdA gene was found to be located in a cluster of putative inositol catabolic genes. LgdA showed similar dehydrogenase activity toward scyllo- and myo-inositols. L-gluconate dehydrogenase activity was also detected in cell free extracts, which represents the reaction product of LgdA activity toward L-glucose. Enzyme purification and gene cloning revealed that the corresponding gene resides in a nine gene cluster, the lgn cluster, which may participate in aldonate incorporation and assimilation. Kinetic and reaction product analysis of each gene product in the cluster indicated that they sequentially metabolize L-gluconate to glycolytic intermediates, D-glyceraldehyde-3-phosphate, and pyruvate through reactions of C-5 epimerization by dehydrogenase/reductase, dehydration, phosphorylation, and aldolase reaction, using a pathway similar to L-galactonate catabolism in Escherichia coli. Gene disruption studies indicated that the identified genes are responsible for L-glucose catabolism.
Journal of Biological Chemistry 10/2012; · 4.77 Impact Factor
-
Hideaki Takano,
Masato Kondo,
Noriyoshi Usui,
Toshimitsu Usui,
Hiromichi Ohzeki,
Ryuta Yamazaki,
Misato Washioka, Akira Nakamura,
Takayuki Hoshino,
Wataru Hakamata,
Teruhiko Beppu,
Kenji Ueda
[show abstract]
[hide abstract]
ABSTRACT: Members of the CarA/LitR family are MerR-type transcriptional regulators that contain a C-terminal cobalamin-binding domain. They are thought to be involved in light-induced transcriptional regulation in a wide variety of nonphototrophic bacteria. Based on the distribution of this kind of regulator, the current study examined carotenoid production in Thermus thermophilus, and it was found to occur in a light-induced manner. litR and carotenoid and cobalamin biosynthesis genes were all located on the large plasmid of this organism. litR or cobalamin biosynthesis gene knockout mutants were unable to switch off carotenoid production under dark conditions, while a mutant with a mutation in the downstream gene adjacent to litR (TT_P0055), which encodes a CRP/FNR family transcriptional regulator, was unable to produce carotenoids, irrespective of light conditions. Overall, genetic and biochemical evidence indicates that LitR is bound by cobalamin and associates with the intergenic promoter region between litR and crtB (phytoene synthase gene), repressing the bidirectional transcription of litR and crtB. It is probable that derepression of LitR caused by some photodependent mechanism induces the expression of TT_P0055 protein, which serves as a transcriptional activator for the crtB operon and hence causes the expression of carotenoid biosynthesis and the DNA repair system under light condition.
Journal of bacteriology 03/2011; 193(10):2451-9. · 3.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An Escherichia coli hygromycin B phosphotransferase (HPH) and its thermostabilized mutant protein, HPH5, containing five amino acid substitutions, D20G, A118V, S225P, Q226L, and T246A (Nakamura et al., J. Biosci. Bioeng., 100, 158-163 (2005)), obtained by an in vivo directed evolution procedure in Thermus thermophilus, were produced and purified from E. coli recombinants, and enzymatic comparisons were performed. The optimum temperatures for enzyme activity were 50 and 55 degrees C for HPH and HPH5 respectively, but the thermal stability of the enzyme activity and the temperature for protein denaturation of HPH5 increased, from 36 and 37.2 degrees C of HPH to 53 and 58.8 degrees C respectively. Specific activities and steady-state kinetics measured at 25 degrees C showed only slight differences between the two enzymes. From these results we concluded that HPH5 was thermostabilized at the protein level, and that the mutations introduced did not affect its enzyme activity, at least under the assay conditions.
Bioscience Biotechnology and Biochemistry 10/2008; 72(9):2467-71. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In the genome of a thermophilic bacterium, Thermus thermophilus HB27, three genes, TTC0418, TTC0746 and TTC1975, were annotated as ATP-dependent protease La (Lon). Sequence comparisons indicated that TTC0418 and TTC0746 showed significant similarities to bacterial LonA-type proteases, such as Escherichia coli Lon protease, especially in regions corresponding to domains for ATP-binding and hydrolysis, and for proteolysis, but TTC1975 exhibited a similarity only at the C-terminal proteolytic domain. The enzymatic analyses, using purified recombinant proteins produced by E. coli, revealed that TTC0418 and TTC0746 exhibited peptidase and protease activities against two synthetic peptides and casein, respectively, in an ATP-dependent manner, and at the same time, both the enzymes had significant ATPase activities in the presence of substrates. On the other hand, TTC1975 possessed a protease activity against casein, but addition of ATP did not enhance this activity. Moreover, a T. thermophilus mutant deficient in both TTC0418 and TTC0746 showed a similar growth characteristic to an E. coli lon mutant, i.e., a growth defect lag after a nutritional downshift. These results indicate that TTC0418 and TTC0746 are actually members of bacterial LonA-type proteases with different substrate specificities, whereas TTC1975 should not be classified as a Lon protease. Finally, the effects of mutations deficient in these proteases were assessed on production of several heterologous gene products from Pyrococcus horikoshii and Geobacillus stearothermophilus. It was shown that TTC0746 mutation was more effective in improving production than the other two mutations, especially for production of P. horikoshii alpha-mannosidase and G. stearothermophilus alpha-amylase, indicating that the TTC0746 mutant of T. thermophilus HB27 may be useful for production of heterologous proteins from thermophiles and hyperthermophiles.
Extremophiles 04/2008; 12(2):285-96. · 2.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Reduction of inorganic sulfur compounds by the fungus Fusarium oxysporum was examined. When transferred from a normoxic to an anoxic environment, F. oxysporum reduced elemental sulfur to hydrogen sulfide (H2S). This reaction accompanied fungal growth and oxidation of the carbon source (ethanol) to acetate. Over 2-fold more of H2S than of acetate was produced, which is the theoretical correlation for the oxidation of ethanol to acetate. NADH-dependent sulfur reductase (SR) activity was detected in cell-free extracts of the H2S-producing fungus, and was found to be up-regulated under the anaerobic conditions. On the other hands both O2 consumption by the cells and cytochrome c oxidase activity by the crude mitochondrial fractions decreased. These results indicate that H2S production involving SR was due to a novel dissimilation mechanism of F. oxysporum, and that the fungus adapts to anaerobic conditions by replacing the energy-producing mechanism of O2 respiration with sulfur reduction.
Bioscience Biotechnology and Biochemistry 11/2007; 71(10):2402-7. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Aminoglycoside antibiotics, such as hygromycin, kanamycin, neomycin, spectinomycin and streptomycin, inhibit protein synthesis by acting on bacterial and eukaryotic ribosomes. Hygromycin B phosphotransferase (Hph; EC 2.7.1.119) converts hygromycin B to 7''-O-phosphohygromycin using a phosphate moiety from ATP, resulting in the loss of its cell-killing activity. The Hph protein has been crystallized for the first time using a thermostable mutant and the hanging-drop vapour-diffusion method. The crystal provided diffraction data to a resolution of 2.1 A and belongs to space group P3(2)21, with unit-cell parameters a = b = 71.0, c = 125.0 A. Crystals of complexes of Hph with hygromycin B and AMP-PNP or ADP have also been obtained in the same crystal form as that of the apoprotein.
Acta Crystallographica Section F Structural Biology and Crystallization Communications 09/2007; 63(Pt 8):685-8. · 0.51 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: YtvA of Bacillus subtilis consists of light, oxygen or voltage (LOV) domain and sulfate transporter and anti-sigma antagonist (STAS) domain, and was reported to act as a photoreceptor, sensing light signals through the LOV domain, like a plant blue light receptor, phototropin. At the same time, YtvA was reported to act as a positive regulator for stress responsive-gene expression regulated by sigma(B) factor. Here we indicate that, like phototropins, the conserved Cys residue among the LOV domains is required for light-sensing in YtvA in vitro, possibly by the photoadduct formation, and YtvA forms a homodimer via its LOV domain, independently to light signal. We also indicate that, when ytvA expression is in normal level, light itself does not trigger sigma(B) activation, but a photo-enhancement of sigma(B) activity, activated by salt stress, occurs only in the presence of ytvA. The conserved Cys residue in the LOV domain and the STAS domain seem to be responsible for light-sensing and signal-transmission to the sigma(B) regulatory network, respectively.
The Journal of General and Applied Microbiology 05/2007; 53(2):81-8. · 0.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Two thermophilic strains, designated 607T and 606b, were isolated from a compost pile in Japan. The novel strains were Gram-positive, aerobic, spore-forming rods. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strains 607T and 606b were closely related to Bacillus naganoensis (94.0-94.1% similarity) and separated from clusters of the related genera Bacillus (<91.9%) and Sporolactobacillus (91.0-92.5%). In addition, some chemotaxonomic and physiological characteristics of strains 607T and 606b differed from those of B. naganoensis and the two related genera. Several differences in physiological characteristics and 16S-23S rRNA gene internal transcribed spacer region nucleotide sequences were observed between strains 607T and 606b; however, DNA-DNA hybridization indicated that these two strains belonged to the same species. From these results, it is proposed that strains 607T and 606b represent the type species of a new genus, Tuberibacillus calidus gen. nov., sp. nov., with strain 607T (=JCM 13397T=DSM 17572T) as the type strain. In addition, the results of phylogenetic analyses, as well as chemotaxonomic and physiological characterization, indicated that B. naganoensis and Bacillus laevolacticus did not belong to the genus Bacillus. Based on these results, it is proposed that B. naganoensis and B. laevolacticus should be transferred to Pullulanibacillus naganoensis gen. nov., comb. nov. and Sporolactobacillus laevolacticus comb. nov., respectively.
International journal of systematic and evolutionary microbiology 11/2006; 56(Pt 11):2545-51. · 2.27 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Four thermophilic, Gram-positive strains, designated H0165(T), 500275(T), C0170 and 700375, were isolated from a composting process in Japan. The isolates grew aerobically at about 65 degrees C on a solid medium with formation of substrate mycelia; spores were produced singly along the mycelia. These morphological characters resembled those of some type strains of species belonging to the family 'Thermoactinomycetaceae', except that aerial mycelia were not formed. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the closest related species to the isolates were members of the family 'Thermoactinomycetaceae', but that the isolates formed an independent phylogenetic lineage. Some chemotaxonomic characters of the isolates, such as DNA G+C contents of 58.7-60.3 mol%, MK-7 as the major menaquinone and cellular fatty acid profiles, differed from those of members of the family 'Thermoactinomycetaceae'. DNA-DNA hybridization showed that the isolates could be divided into two genomic groups, strain H0165(T) and the other three strains. These results indicated that the four isolates should be classified into two species of a novel genus in the family 'Thermoactinomycetaceae', for which the names Planifilum fimeticola gen. nov., sp. nov. (type strain H0165(T)=ATCC BAA-969(T)=JCM 12507(T)) and Planifilum fulgidum sp. nov. (type strain 500275(T)=ATCC BAA-970(T)=JCM 12508(T)) are proposed.
International journal of systematic and evolutionary microbiology 10/2005; 55(Pt 5):2101-4. · 2.27 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An in vivo-directed evolutionary strategy was used to obtain a thermostabilized Escherichia coli hygromycin B phosphotransferase, using a host-vector system of Thermus thermophilus. Introduction of the mutant gene containing two amino acid substitutions, S52T and W238C, which was previously reported by Cannio et al. [J. Bacteriol., 180, 3237-3240 (1998)], did not confer hygromycin resistance on T. thermophilus cells at 55 degrees C; however, five spontaneously-generated independent mutants were obtained by selection of the transformants at this temperature. Each mutant gene contained one amino acid substitution of either A118V or T246A. Further selection with increasing temperature, at 58 degrees C and then 61 degrees C, led to acquisition of three more substitutions: D20G, S225P and Q226L. These mutations cumulatively influenced the maximum growth temperature of the T. thermophilus transformants in the presence of hygromycin; T. thermophilus carrying a mutant gene containing all the five substitutions was able to grow at up to 67 degrees C. This mutant gene, hph5, proved useful as a selection marker in the T. thermophilus host-vector system, either on the plasmid or by genome integration, at temperatures up to 65 degrees C.
Journal of Bioscience and Bioengineering 09/2005; 100(2):158-63. · 1.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A nitrogen-fixing bacterium, designated strain 6H33b(T), was isolated from a compost pile in Japan. The nitrogenase activity of this strain was detected based on its acetylene-reducing activity under low oxygen concentrations (2-4%). An analysis of the genes responsible for nitrogen fixation in this strain, nifH and nifD, indicated a close relationship to those of Pseudomonas stutzeri A15 (A1501). Sequence similarity searches based on the 16S rRNA gene sequences showed that strain 6H33b(T) belongs within the genus Pseudomonas sensu stricto; closest similarity was with Pseudomonas indica (97.3%). A comparison of several taxonomic characteristics of 6H33b(T) with those of P. indica and some type strains of the genus Pseudomonas sensu stricto indicated that 6H33b(T) could be distinguished from P. indica based on the presence of nitrogen fixation ability, the absence of nitrate reduction and denitrification abilities and the utilization of some sugars and organic acids. Phylogenetic analyses and the results of DNA-DNA hybridization experiments also indicated that strain 6H33b(T) represents a species distinct from P. indica. From these results, it is proposed that strain 6H33b(T) (=ATCC BAA-1049(T)=JCM 12708(T)) is classified as the type strain of a novel species of the genus Pseudomonas sensu stricto under the name Pseudomonas azotifigens sp. nov.
International journal of systematic and evolutionary microbiology 08/2005; 55(Pt 4):1539-44. · 2.27 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We isolated a small multicopy cryptic plasmid, pNHK101, from Thermus sp. TK10 for use as a replicon of a Thermus expression vector. The nucleotide sequence of pNHK101 revealed that this plasmid was 1564bp long, with a total G+C content of 66.8%, which was in agreement with that of Thermus genomic DNA. The sequence did not show any significant similarities to any other plasmids; also, the amino acid sequences of four putative open reading frames, found in the plasmid, did not show strong similarities to those in the databases, except the ORF1, which had very slight similarities to several replication proteins of plasmids from other bacteria. pNHK101 was able to replicate in Thermus thermophilus HB27 with copy number about 80, and was stably maintained at 60 degrees C, but became unstable at 70 degrees C. Based on pNHK101, we constructed a plasmid vector, pKMH052, containing the highly thermostable kanamycin resistance gene as a selective marker. The copy number of pKMH052 decreased to about one-fourth of that of pNHK101, but stability at 60 degrees C did not alter under non-selective conditions. pKMH052 was compatible with pTT8, and interestingly, the presence of pTT8 in the same cells improved the stability of pKMH052 at 70 degrees C. Cloning of the crtB gene of T. thermophilus HB27 encoding phytoene synthase into pKMH052, and introduction into T. thermophilus cells resulted in a 2.8-fold production of carotenoids, indicating the potential use of this plasmid for overexpression of genes from thermophiles and hyperthermophiles.
Plasmid 08/2005; 54(1):70-9. · 1.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A flavocytochrome protein was isolated from the actinomycete Streptomyces antibioticus. The purified protein contained protoheme and FAD, and its M(r) was estimated to be 52000. The absorption spectra in its resting oxidized, dithionite-reduced, carbon monoxide-bound, and oxygenated (O(2)-bound) forms were characteristic of those of flavohemoglobin (Fhb). The N-terminal amino acid sequence showed high identities to those of other Fhb's. Furthermore, the actinomycete flavocytochrome scavenged nitric oxide in the presence of NADH. These results demonstrated that the flavocytochrome is the first Fhb purified from actinomycetes. The actinomycete Fhb was produced in S. antibioticus cells in large amounts without any external nitric oxide (NO) stress, which is indicative of a physiological function of Fhb other than detoxification of NO.
Bioscience Biotechnology and Biochemistry 06/2004; 68(5):1106-12. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The complete nucleotide sequence of pTT8, a cryptic plasmid from Thermus thermophilus HB8, was determined. pTT8 was 9328bp long and its G+C content was 69%. pTT8 contained eight putative open reading frames, three of which showed extensive similarities to the plasmid addiction proteins PasA and PasB of pTC-F14 and pAM10.6, and the RepA protein of the ColE2-related plasmids, respectively. During the analysis of pTT8-based plasmid pPP442, which had been obtained during a promoter-screening experiment, we occasionally isolated a plasmid with a relatively high-copy-number. This plasmid, pPP442m, contained a 1025 bp fragment derived from the genome of the HB27 host strain immediately upstream of the putative repA gene. Using the ori region of pPP442m, we constructed an expression vector, pTEV131m, with an estimated high-copy-number of 30-40. This plasmid was stably maintained in T. thermophilus HB27 under nonselective conditions for at least 100 generations. Cloning of the alpha-amylase gene of Bacillus stearothermophilus DY-5 into pTEV131m gave more than twofold production of the enzyme compared with pTEV131, the parental plasmid.
Plasmid 06/2004; 51(3):227-37. · 1.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The niaD gene of the fungus Aspergillus nidulans encodes an assimilatory nitrate reductase and exogenous ammonium represses its expression. Under anoxic conditions, however, A. nidulans expressed niaD even in the presence of ammonium and used the gene product for dissimilatory nitrate reduction (ammonia fermentation). This transcription regulation mechanism under anaerobiosis is critical for the fungus to ferment ammonium.
Bioscience Biotechnology and Biochemistry 05/2004; 68(4):978-80. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An in vivo disruption-integration vector system for Thermus thermophilus was developed and used for the functional analysis of an evolutionary-related archaeal protein for lysine biosynthesis. In contrast to fungal one, the putative homoaconitase of T. thermophilus consists of two subunits and catalyzes the second and third steps of lysine biosynthesis. ORFs from hyperthermophilic archaeon Pyrococcus horikoshii, PH1726 and PH1724, share a high degree of amino acid identity with the T. thermophilus subunits LysT and LysU, respectively. In the present report, gene encoding the putative small subunit of archaeal homoaconitase, PH1724, was integrated into the lysU locus of T. thermophilus. The archaeal gene was expressed under the control of PslpA promoter and functional analyses were performed. Transformants were able to grow on minimal medium without lysine when PH1724 ORF was integrated, whereas the lysU disruption led to lysine auxotrophy. Chromosomal integration was verified by PCR analysis, and homoaconitase assay showed that the archaeal gene product functions as a small subunit of homoaconitase, possibly by forming a heterodimer with the LysT subunit of T. thermophilus. These results strongly suggest the functional relation of P. horikoshii PH1724 with LysU in the Thermus lysine biosynthetic pathway, together with functional assignment of LysU as small subunit of homoaconitase. In addition, the provided results indicate that archaeal genes products from hyperthermophiles can be studied in a thermophilic eubacterium such as T. thermophilus.
FEMS Microbiology Letters 05/2004; 233(2):315-24. · 2.04 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fungal ammonia fermentation is a novel dissimilatory metabolic mechanism that supplies energy under anoxic conditions. The fungus Fusarium oxysporum reduces nitrate to ammonium and simultaneously oxidizes ethanol to acetate to generate ATP (Zhou, Z., Takaya, N., Nakamura, A., Yamaguchi, M., Takeo, K., and Shoun, H. (2002) J. Biol. Chem. 277, 1892-1896). We identified the Aspergillus nidulans genes involved in ammonia fermentation by analyzing fungal mutants. The results showed that assimilatory nitrate and nitrite reductases (the gene products of niaD and niiA) were essential for reducing nitrate and for anaerobic cell growth during ammonia fermentation. We also found that ethanol oxidation is coupled with nitrate reduction and catalyzed by alcohol dehydrogenase, coenzyme A (CoA)-acylating aldehyde dehydrogenase, and acetyl-CoA synthetase (Acs). This is similar to the mechanism suggested in F. oxysporum except A. nidulans uses Acs to produce ATP instead of the ADP-dependent acetate kinase of F. oxysporum. The production of Acs requires a functional facA gene that encodes Acs and that is involved in ethanol assimilation and other metabolic processes. We purified the gene product of facA (FacA) from the fungus to show that the fungus acetylates FacA on its lysine residue(s) specifically under conditions of ammonia fermentation to regulate its substrate affinity. Acetylated FacA had higher affinity for acetyl-CoA than for acetate, whereas non-acetylated FacA had more affinity for acetate. Thus, the acetylated variant of the FacA protein is responsible for ATP synthesis during fungal ammonia fermentation. These results showed that the fungus ferments ammonium via coupled dissimilatory and assimilatory mechanisms.
Journal of Biological Chemistry 04/2004; 279(13):12414-20. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fungal ammonia fermentation is a novel dissimilatory metabolic mechanism that supplies energy under anoxic conditions. The
fungus Fusarium oxysporum reduces nitrate to ammonium and simultaneously oxidizes ethanol to acetate to generate ATP (Zhou, Z., Takaya, N., Nakamura,
A., Yamaguchi, M., Takeo, K., and Shoun, H. (2002) J. Biol. Chem. 277, 1892–1896). We identified the Aspergillus nidulans genes involved in ammonia fermentation by analyzing fungal mutants. The results showed that assimilatory nitrate and nitrite
reductases (the gene products of niaD and niiA) were essential for reducing nitrate and for anaerobic cell growth during ammonia fermentation. We also found that ethanol
oxidation is coupled with nitrate reduction and catalyzed by alcohol dehydrogenase, coenzyme A (CoA)-acylating aldehyde dehydrogenase,
and acetyl-CoA synthetase (Acs). This is similar to the mechanism suggested in F. oxysporum except A. nidulans uses Acs to produce ATP instead of the ADP-dependent acetate kinase of F. oxysporum. The production of Acs requires a functional facA gene that encodes Acs and that is involved in ethanol assimilation and other metabolic processes. We purified the gene product
of facA (FacA) from the fungus to show that the fungus acetylates FacA on its lysine residue(s) specifically under conditions of
ammonia fermentation to regulate its substrate affinity. Acetylated FacA had higher affinity for acetyl-CoA than for acetate,
whereas non-acetylated FacA had more affinity for acetate. Thus, the acetylated variant of the FacA protein is responsible
for ATP synthesis during fungal ammonia fermentation. These results showed that the fungus ferments ammonium via coupled dissimilatory
and assimilatory mechanisms.
Journal of Biological Chemistry 03/2004; 279(13):12414-12420. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The denitrifying fungus Cylindrocarpon tonkinense contains two isozymes of cytochrome P450nor. One isozyme, P450nor1, uses NADH specifically as its electron donor whereas the other isozyme P450nor2 prefers NADPH to NADH. Here we show that P450nor1 is localized in both cytosol and mitochondria, like P450nor of Fusarium oxysporum, while P450nor2 is exclusively in cytosol. We also found that the addition of glucose as a carbon source to the culture media leads to the production of much more P450nor2 in the fungal cells than a non-fermentable substrate (glycerol or acetate) does. These results suggest that the NADP-dependent pentose phosphate cycle acts predominantly in C. tonkinense as the glycolysis pathway under the denitrifying conditions, which was confirmed by the observation that glucose induced enzyme activities involved in the cycle. These results showed that P450nor2 should act as the electron sink under anaerobic, denitrifying conditions to regenerate NADP+ for the pentose phosphate cycle.
Bioscience Biotechnology and Biochemistry 06/2003; 67(5):1109-14. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The denitrifying fungus Cylindrocarpon tonkinense was thought to be able to denitrify only nitrite (NO2-) but not nitrate (NO3-) to form nitrous oxide (N2O). Here we found, however, that C. tonkinense can denitrify NO3- under certain conditions. Presence of ammonium (NH3+) in addition to NO3- and the use of a fermentable sugar as an electron donor were key conditions for inducing the denitrifying activity. Such induction accompanied a remarkable increase in the intracellular level of the enzyme activities related to NO3- metabolism. These activities contained assimilatory type NADPH (or NADH)-dependent NO3- reductase (aNar), dissimilatory nitrite reductase (dNir), and nitric oxide reductase (P450nor), but did not contain ubiquinol-dependent, dissimilatory NO3- reductase (dNar). The denitrification was inhibited by tungstate, an inhibitor of Nar. These results demonstrated occurrence of a novel type of denitrification in C. tonkinense, in which assimilatory type Nar is possibly involved.
Bioscience Biotechnology and Biochemistry 06/2003; 67(5):1115-20. · 1.28 Impact Factor
