共查询到20条相似文献,搜索用时 15 毫秒
1.
Imamura Machiko; Tsuzuki Mikio; Shiraiwa Yoshihiro; Miyachi Shigetoh 《Plant & cell physiology》1983,24(3):533-540
The effect of carbonic anhydrase (CA) on time courses of photosynthetic14C incorporation in the presence of 14CO2 or NaH14CO3 was studiedwith cells of Chlamydomonas reinhardtii which had been grownunder ordinary air (low-CO2 cells) or air enriched with 4% CO2(high-CO2 cells). Experimental data obtained at 20°C andpH 8.0 suggested that the major form of inorganic carbon utilizedby high-CO2 cells was CO2, while that utilized by low-CO2 cellswas HCO3. The cell suspension showed CA activity which was comparableto that observed in the sonicate of cells. Both activities werehigher in low-CO2 cells than in high-CO2 cells. The mechanism by which HCO3 is utilized by low-CO2 cellsof C. reinhardtii is discussed.
3Present address: Department of Biology, Faculty of Science,University of Niigata, Niigata 950-21, Japan. (Received August 4, 1982; Accepted January 19, 1983) 相似文献
2.
Role of Carbonic Anhydrase in Photosynthesis of Blue-Green Alga (Cyanobacterium) Anabaena variabilis ATCC 29413 总被引:2,自引:0,他引:2
The affinity for NaHCO3 (CO2) in photosynthesis of Anabaenavariabilis ATCC 29413 was much higher in the cells grown underordinary air (low-CO2 cells) than in those grown in air enrichedwith 24% CO2 (high-CO2 cells) (pH 8.0, 25?C). Ethoxyzolamide(50 µM) increased the Km(NaHCO3 in low-CO2 cells aboutnine times (from 14.3 to 125), while the maximum rate of photosynthesisdecreased about 20%. When high-CO2 cells were transferred tolow-CO2 conditions, carbonic anhydrase (CA) activity increased,while Km(NaHCO3) in photosynthesis decreased from 140 to 30µM within about 5 h. The addition of CA to the suspensionof both high- and low-CO2 cells enhanced the rates of photosyntheticO2 evolution under CO2-limiting conditions. The rate of 14CO2fixation was much faster than that of H14CO3 fixation.The former reaction was greatly suppressed, while the latterwas enhanced by the addition of CA. These results indicate thatthe active species of inorganic carbon utilized for photosynthesiswas free CO2 irrespective of the CO2 concentration given duringgrowth. It is suggested that CA plays an active role in increasingthe affinity for CO2 in photosynthesis of low-CO2 cells of thisblue-green alga. (Received January 24, 1984; Accepted October 22, 1984) 相似文献
3.
Chlorella vulgaris 11h cells grown in air enriched with 4% CO2(high-CO2 cells) had carbonic anhydrase (CA) activity whichwas 20 to 90 times lower than that of algal cells grown in ordinaryair (containing 0.04% CO2, low-CO2 cells). The CO2 concentrationduring growth did not affect either ribulose 1,5-bisphosphate(RuBP) carboxylase activity or its Km for CO2. When high-CO2 cells were transferred to low CO2 conditions,CA activity increased without a lag period, and this increasewas accompanied by an increase in the rate of photosynthetic14CO2 fixation under 14CO2-limiting conditions. On the otherhand, CA activity as well as the rate of photosynthetic 14CO2fixation at low 14CO2 concentrations decreased when low-CO2cells were transferred to high CO2 conditions. Diamox, an inhibitor of CA, at 0.1 mM did not affect photosynthesisof low-CO2 cells at high CO2 concentration (0.5%). Diamox inhibitedphotosynthesis only under low CO2 concentrations, and the lowerthe CO2 concentration, the greater was the inhibition. Consequently,the CO2 concentration at which the rate of photosynthesis attainedone-half its maximum rate (Km) greatly increased in the presenceof this inhibitor. When CO2 concentration was higher than 1%, the photosyntheticrate in low-CO2 cells decreased, while that in high-CO2 cellsincreased. Fractionation of the low-CO2 cells in non-aqueous medium bydensity showed that CA was fractionated in a manner similarto the distribution of chlorophyll and RuBP carboxylase. These observations indicate that CA enhances photosynthesisunder CO2-limiting conditions, but inhibits it at CO2 concentrationshigher than a certain level. The mechanism underlying the aboveregulatory functions of CA is discussed.
1This work was reported at the International Symposium on PhotosyntheticCO2-Assimilation and Photorespiration, Sofia, August, 1977 (18).Requests for reprints should be addressed to S. Miyachi, RadioisotopeCentre, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan. (Received December 11, 1978; ) 相似文献
4.
In Dunaliella tertiolecta, D. bioculata and D. viridis the activitiesof phosphoenolpyruvate carboxylase and carbonic anhydrase werehigher in the cells grown in ordinary air (low-CO2 cells) thanin those grown in air enriched with 15% CO2 (high-CO2cells), whereas in Porphyridium cruentum R-1 there was no differencein phosphoenolpyruvate carboxylase activity between these twotypes of cells. Apparent Km(NaHCO3) values for photosynthesisin low-CO2 cells of all species tested were smaller than thosein high-CO2 cells. Most of the 14C was incorporated into 3-phosphoglycerate,sugar mono- and di-phosphates during the initial periods ofphotosynthetic NaH14CO3 indicating that both types of cellsin D. tertiolecta are C3 plants. (Received May 27, 1985; Accepted June 25, 1985) 相似文献
5.
Form of inorganic carbon utilized for photosynthesis in Chlorella vulgaris 11 h cells 总被引:2,自引:0,他引:2
The rate of photosynthetic 14CO2 fixation in Chlorella vulgaris11h cells in the presence of 0.55 mM NaH14CO3 at pH 8.0 (20?C)was greatly enhanced by the addition of carbonic anhydrase (CA).However, when air containing 400 ppm 14CO2 was bubbled throughthe algal suspension, the rate of 14CO2 fixation immediatelyafter the start of the bubbling was suppressed by CA. Theseeffects of CA were observed in cells which had been grown inair containing 2% CO2 (high-CO2 cells) as well as those grownin ordinary air (containing 0.04% CO2, low-CO2 cells). We thereforeconcluded that, irrespective of the CO2 concentration givento the algal cells during growth, the active species of inorganiccarbon absorbed by Chlorella cells is free CO2 and they cannotutilize bicarbonate. The effects observed in the high-CO2 cellswere much more pronounced than those in the high-CO2 cells.This difference was accounted for by the difference in the affinityfor CO2 in photosynthesis between the high- and low-CO2 cells. (Received May 19, 1978; ) 相似文献
6.
In cells of cyanobacterium Anabaena variabilis grown under ordinaryair (low-CO2 cells), the transport of both CO2 and HCO3was significantly enhanced by Na+. This effect was pronouncedas the external pH increased. When low-CO2 cells were treatedwith an inhibitor of carbonic anhydrase (CA), only CO2 transportbut not HCO3 transport, was inhibited. The initial rateof photosynthetic carbon fixation as a function of the concentrationof internal inorganic carbon (IC) was practically the same irrespectiveof whether CO2 or HCO3 was externally supplied. Theseresults suggest that IC is actively transported through theplasma membrane in a form of HCO3 probably by some transporterand that the transmembrane Na+ gradient is involved in thisIC transport system. Free CO2 may be hydrated by CA to HCO3and then transported to the cells by this transporter. On the other hand, CO2 is actively taken up by cells grown withair containing 5% CO2 (high-CO2 cells) though the enhancingeffect of Na+ was much smaller in high- CO2 cells than in low-CO2cells. The initial rate of fixation as a function of internal IC concentrationindicated that the rate of the carboxylation reaction of accumulatedIC is higher in I0W-CO2 cells than in high-CO2 cells. The studieswith ethoxyzolamide indicated that even in low-CO2 cells, CAdoes not function inside Anabaena cells. These results suggestthat inside the low-CO2 cells of Anabaena, some mediator(s)facilitates the transport of IC to RuBPCase. (Received January 23, 1987; Accepted April 24, 1987) 相似文献
7.
Antibody was raised against Porphyridium carbonic anhydrase(CA) which was electrophoretically recovered from the gel afterSDS-polyacrylamide slab gel electrophoresis (SDS-PAGE) of thepartially purified enzyme. The antiserum reacted with CA ofPorphyridium, but not with that of Chlamydomonas reinhardtii.Even though the antiserum did not react with CA from P. cruentumR-l in Ouchterlony's double immunodiffusion, it blocked theenzyme activity in the presence of 1% Nonidet P-40 and 1% TritonX-100. After Western blotting and enzyme-linked immunostaining(ELIS), only one band which reacted with the antiserum was detectedin the extract of low-CO2 cells (grown under ordinary air) ofP cruentum, while no significant band was detected in that ofhigh-CO2 cells (grown under air enriched with 15% CO2).Immunogold electron microscopy of low-CO2 cells of P. cruentumR-l using this antibody revealed that most of the CA was localizedin the chloroplast, with some in the cytoplasm. No specificbinding of gold particles was observed in the high-CO2 cells.
1Present address: National Institute for Basic Biology, Myodaiji,Okazaki 444, Japan (Received May 18, 1987; Accepted September 7, 1987) 相似文献
8.
Cells of Dunaliella tertiolecta which had been grown in ordinaryair (low-CO2 cells) had high carbonic anhydrase (CA) activityon the cell surface and mainly utilized HCO3 for photosynthesis.When CA activity on the cell surface was inhibited by Diamoxor subtilisin, the cells utilized CO2. When bovine CA was added,the subtilisin-treated low-CO2 cells utilized mainly HCO3.When grown in air containing 2% CO2, the cells had low CA activityon the cell surface, and preferred CO2 to HCO3. Kineticanalysis of these results indicated that low-CO2 cells of D.tertiolecta absorb CO2 which was converted from HCO3via the CA located on the cell surface. (Received June 29, 1985; Accepted October 9, 1985) 相似文献
9.
Utilization Modes of Inorganic Carbon for Photosynthesis in Various Species of Chlorella 总被引:5,自引:0,他引:5
Rates of CO2 and HCC3 fixation in cells of various Chlorellaspecies in suspension were compared from the amounts of 14Cfixed during the 5 s after the injection of a solution containingonly 14CO2 or H14CO3. Results indicated that irrespectiveof the CO2 concentration during growth, Chlorella vulgaris 11h and C. miniata mainly utilized CO2, whereas C. vulgaris C-3,C. sp. K. and C. ellipsoidea took up HCO3 in additionto CO2. Cells of C. pyrenoidosa that had been grown with 1.5%CO2 (high-CO2 cells) mainly utilized CO2, whereas those grownwith air (low-CO2 cells) utilized HCO3 in addition toCO2. Cells that utilized HCO3 had carbonic anhydrase(CA) on their surfaces. The effects of Diamox and CA on the rates of CO2 and HCO3fixation are in accord with the inference that HCO3 wasutilized after conversion to CO2 via the CA located on the cellsurface. CA was found in both the soluble and insoluble fractions;the CA on the cell surface was insoluble. Independent of the modes of utilization, the apparent Km (NaHCO3)for photosynthesis was much lower in low-CO2 cells than in high-CO2ones. The fact that the CA in the soluble fraction in C. vulgarisC-3 was closely correlated with the Km(NaHCO3) indicates thatsoluble CA lowers the Km.
1 Dedicated to the late Professor Joji Ashida, one of the foundersand first president of the Japanese Society of Plant Physiologists.
4 On leave from Research and Production Laboratory of Algology,Bulgarian Academy of Sciences, Sofia. (Received September 14, 1982; Accepted March 1, 1983) 相似文献
10.
Time courses of photosynthetic 14CO2 fixation and its simulationare presented for Chlorella cells grown under low CO2 concentration(low-CO2 cells) and subsequently exposed to 0.2 mM NaH14CO3or 130 ppm 14CO2 in the presence or absence of carbonic anhydrase(CA) in the suspending medium. It was shown that Chlorella cells utilized only free CO2 whenNaHCO3 was given in the presence or absence of CA, or when CO2was bubbled in the absence of CA. However, the present simulationindicated that both CO3 and HCO3 were utilized when CO2was given in the presence of CA. Based on these results, weconcluded that 1) Chlorella cells absorb only free CO2 and 2)this gas is provided to algal cells in two ways, i.e., by directand indirect CO2 supply. Usually, the dissolved CO2 is directlyutilized by the algal cells (direct supply of CO2). However,when the concentration of dissolved CO2 is extremely low andwhen there is CA, CO2 reconverted from HCO3 is also utilizedby Chlorella cells (indirect supply of CO2). The utilizationof HCO3 indicated by the above simulation was explainedby the indirect supply of CO2. We further assumed that the indirectsupply of CO2 to ribulose 1,5-bisphosphate carboxylase occursmainly in the chloroplasts of low-CO2 cells containing highCA. Thus, under low CO2 concentrations, low-CO2 cells can carryout more efficient CO2 fixation than high-CO2 cells, resultingin the lower apparent Km(CO2).
3Department of Biology, Faculty of Science, Niigata University,Niigata, Japan. (Received April 2, 1980; ) 相似文献
11.
The ratio of the extracellular to the intracellular activityof carbonic anhydrase (CA) in cells of Chlorella ellipsoideaC-27, adapted to low levels of CO2 for 24 h (low-CO2 cells),was about one to one. Treatment of intact cells with PronaseP inactivated about one-half of the extracellular CA activitywithout affecting photosynthetic activity. The CA activity incell homogenates and in cell-wall ghosts liberated during celldivision was completely inactivated by the same treatment. Pretreatmentwith Glycosidase mix, Chitosanase and Macerozyme enhanced theinactivation of the CA activity in intact cells. These resultssuggest that extracellular CA is evenly distributed throughoutthe whole cell-wall region. The apparent K1/2 for dissolved inorganic carbon (DIC) in low-CO2cells doubled when extracellular CA was inactivated by treatmentwith Pronase P, but the K1/2 obtained was still one-half ofthat in high-CO2 cells. Photosynthetic 14CO2-fixation in low-CO2cells was enhanced by acetazolamide, whereas H14CO3-fixationwas suppressed. The results suggest that CO2 is a dominant substrateutilized by cells and that HCO3 is utilized after conversionto CO2. The present results show that both intracellular andextracellular CA contribute to the increase in affinity forDIC during photosynthesis in low-CO2 cells of Chlorella ellipsoideaC-27. (Received May 7, 1990; Accepted July 18, 1990) 相似文献
12.
13.
Carbonic anhydrase (CA) activity was detected in homogenatesfrom Anabaena variabilis ATCC 29413, M-2 and M-3, but not inthe suspension of the intact cells. Activity was higher in cellsgrown in ordinary air (low-CO2 cells) than in those grown inair enriched with 24% CO2 (high-CO2 cells). Fractionationby centrifugation indicated that the CA from A. variabilis ATCC29413 is soluble, whereas both soluble and insoluble forms existin A. variabilis M-2 and M-3. The addition of dithiothreitoland Mg2 $ greatly decreased the CA activity of A. variabilisATCC 29413. The specific activity of the CA from A. variabilis ATCC 29413was increased ca. 200 times by purification with ammonium sulfate,DEAE-Sephadex A-50 and Sephadex G-100. Major and minor CA peaksin Sephadex G-100 chromatography showed respective molecularweights of 48,000 and 25,000. The molecular weight of the CAdetermined by polyacrylamide disc gel electrophoresis was 42,000?5,000.The activity of CA was inhibited by ethoxyzolamide (I50=2.8?10-9M), acetazolamide (I50=2.5?10-7 M) and sulfanilamide (I50=2.9?10-6M). (Received January 5, 1984; Accepted April 26, 1984) 相似文献
14.
Two cDNA clones exclusively induced under an extremely high-CO2concentration (20%) were isolated from Chlorococcum littoraleby differential screening and named HCR (high-CO2 response)1 and 2, respectively. The amino acid sequence of the proteinencoded by HCR2 exhibited homology to the gp91-phox protein,a critical component of a human phagocyte oxidoreductase, andto the yeast ferric reductases, Saccharomyces cerevisiae FRE1and FRE2 and Schizosaccharomyces pombe Frpl. The induction ofboth HCR mRNAs required extremely high-CO2 conditions and irondeficiency, being suppressed under air conditions and by ironsufficiency, suggesting that the expression of these two HCRgenes required extremely high-CO2 conditions and iron deficiencyin combination. The HCR2 protein was detected in the membranefractions of cells grown under conditions which would favorthe induction of HCR2-mRNA and the protein level was loweredwhen the cells were transferred from iron deficient to 10 µMFeSO4 conditions (with 20% CO2). (Received September 10, 1997; Accepted November 14, 1997) 相似文献
15.
When Chlorella oulgaris ll h cells grown in air containing 4%CO2 (high-CO2 cells) were given low concentrations of14CO2 (<150ppm), the initial rate of photosynthetic 14CO2 fixation wasvery low and linear 14CO2 fixation was observed after an inductionperiod which lasted for ca. 45 min. No such induction period was observed when high-CO2 cells weregiven high concentrations of 14CO2 (10,000 ppm) or when IOW-CO2cells were given either low or high concentrations of 14CO2,supporting the observations by Briggs and Whittingham (l). However,irrespective of CO2 concentrations during growth and of 14CO2concentrations during the experiments, most of the 14C was incorporatedinto phosphate esters during the initial periods of photosynthetic14CO2 fixation. These results are in sharp contrast to the reportby Graham and Whittingham (4).
1 Requests for reprints should be addressed to S. Miyachi, RadioisotopeCentre, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan. (Received June 30, 1979; ) 相似文献
16.
Intracellular accumulation of inorganic carbon (Ci) and itsfixation in photosynthesis were investigated using siliconeoil layer filtering centrifugation technique with the cellsof Chlorella vulgaris 11h grown under ordinary air. Both CO2and HCO3 were transported into the cells from the reactionmedium and accumulated in the cells, but the rate of transportwas much faster for the former than the latter. 14C-fixationfrom the total transported Ci was much more efficient when CO2was added in the external medium than when HCO3 was added.This indicates that CO2 and HCO3 were not converted tothe common compound in the cells during the initial period ofphotosynthesis. Accumulation of Ci into the cells was much lesssusceptible to low temperature than its fixation. Accumulationof Ci was also observed in the dark. Ethoxyzolamide, an inhibitorof carbonic anhydrase (CA), inhibited the fixation of accumulatedCO2 in the cells, suggesting that CA enhanced the supply ofCO2 to the reaction site of ribulose bisphosphate carboxylasein the stroma. Mechanism for transport and fixation of Ci duringphotosynthesis in low-CO2 cells of C. vulgaris 1lh was proposedfrom these results. (Received March 19, 1986; Accepted June 26, 1986) 相似文献
17.
Two Polypeptides Inducible by Low Levels of CO2 in Soluble Protein Fractions from Chlorella regularis Grown at Low or High pH 总被引:1,自引:0,他引:1
Previous studies suggested that certain protein(s) other thancarbonic anhydrase might play an important role in the facilitatedtransport of dissolved inorganic carbon (DIC) from the mediumto the site of CO2 fixation by ribulose-1,5-bisphosphate carboxylase/oxygenasein the unicellular green alga Chlorella regularis adapted tolow-CO2 (ordinary air) conditions [Shiraiwa et al. (1991) Jpn.J. Phycol. 39: 355; Satoh and Shiraiwa (1992) Research in Photosynthesis,Vol. III, p. 779]. The proteins that might be involved in thisfacilitated transport of DIC were investigated by pulse-labelingof induced proteins with 35S-sulfate during adaptation of cellsgrown under high-CO2 conditions to low CO2. Analysis by SDS-PAGErevealed that synthesis of two polypeptides, with molecularmasses of 98 and 24 kDa, respectively, was induced under low-CO2conditions. The 24-kDa polypeptide was induced at pH 5.5 butnot at pH 8.0, whereas the 98-kDa polypeptide was induced atboth pH 5.5 and pH 8.0. The possible role of these polypeptidesin the facilitated transport of DIC in Chlorella regularis isdiscussed. (Received October 30, 1995; Accepted February 26, 1996) 相似文献
18.
Shigetoh Miyachi Mikio Tsuzuki Isao Maruyama Miroslav Gantar Shizuko Miyachi Hisashi Matsushima 《Journal of phycology》1986,22(3):313-319
Effects of CO2 concentration during growth on intracellular structure were studied with ftve species of Chlorella and Scenedesmus obliquus. Cells grown under ordinary air conditions (low-CO2 cells) had a well developed pyrenoid surrounded by starch, while those grown under high CO2 conditions (high-CO2 cells) had a less developed pyrenoid or no detectable pyrenoid. Two mitochondria, one at each side of the neck of the projection of the chloroplast close to the pyrenoid, were found in low CO2 cells of C. vulgaris 11h. Usually, lamellar stacks extended in parallel in the chloroplast of low-CO2 cells of C. vulgaris 11h, while a grana-like structure was found in high-CO2 cells. However, in C. pyrenoidosa, grana like structures were found more commonly in low-CO2 cells than in high-CO2 cells. These results suggest that development of pyrenoid starch is generally correlated with growth under low CO2 conditions, whereas CO2-effects on lamellar stacking are species dependent. 相似文献
19.
Yokota Akiho; Iwaki Toshio; Miura Kazuo; Wadano Akira; Kitaoka Shozaburo 《Plant & cell physiology》1987,28(8):1363-1376
We constructed a mathematical model for simulating the relationshipsof extracellular concentration of dissolved inorganic carbon(DIC), the rates of photosynthetic CO2 fixation and glycolatesynthesis, and the concentrations of intrachloroplast CO2 andO2 in Chlamydomonas reinhardtii. When we compared the photosyntheticrates of I0W-CO2 (air)-grown C. reinhardtii measured experimentallyand the rates simulated with the incubation conditions in themodel, the model was found to function well. The calculatedrates for glycolate synthesis also matched the measured ratesbetween 80 to 200 µM extracellular DIC, found in the presenceof 1 mM aminooxyacetate. The conformity of the calculated ratesto the measured ones of the glycolate synthesis encouraged usto estimate the O2 concentration at the active site of ribulosebisphosphate carboxylase/oxygenase; the results were 0.36 and0.40 mM at 80 and 200 µM extracellular DIC, respectively.These high concentrations of O2 were due to stimulation of photosyntheticCO2 fixation and further O2 evolution by a CO2- concentratingmechanism in the low-CO2-grown cells. These cells were calculatedto consume 43% of ATP formed photosynthetically for CO2 concentrationat 200 µM extracellular DIC. The model modified to simulatethese relationships in high-CO2 (3 to 5% CO2)-grown C. reinhardtiipredicted O2 concentration in chloroplasts to be 0.36 mM ina 1% CO2 atmosphere. This high concentration of O2 caused activeglycolate synthesis at the measured rate in the high-CO2-growncells even in the presence of 1% CO2. The comparisons of themeasured and simulated rates of photosynthesis in low- and high-CO2-grownC. reinhardtii indicated that no matter how the CO2 accumulatedin the chloroplasts, it increased the O2 concentration in theorganelles, and consequently enhanced glycolate synthesis.
1This paper is the twenty-first in a series on glycolate metabolismin Euglena gracilis. (Received March 11, 1987; Accepted August 17, 1987) 相似文献
20.
Changes of some photosynthetic properties of high-CO2 grown cells of Chlorella pyrenoidosa during adaptation to low-CO2 conditions have been investigated. The Km value of photosynthesis of the high-CO2 grown cells for dissolved inorganic carbon was 3.3 millimolar and decreased to 25 to 30 micromolar within 4 hours after transferring to air. In the presence of saturating CO2 concentrations the photosynthetic activity of the high-CO2 grown cells was 1.5 times as high as that of the low-CO2 grown cells. There was a significant rise of the photosynthetic activity during adaptation of the high-CO2 grown cells to air, followed by a steady decrease. The activity of ribulose 1,5-bisphosphate carboxylase/oxygenase in both the high- and low-CO2 grown cells was close to the photosynthetic activity of the cells. The concentration of ribulose 1,5-bisphosphate (RuBP) was higher in the low-CO2 adapting and low-CO2 grown cells than in the high-CO2 grown cells regardless of the photosynthetic rate. This seems to be due to an increased RuBP regeneration activity during adaptation followed by maintenance of the new higher concentration. The RuBP level always exceeded the concentration of ribulose 1,5-bisphosphate carboxylase/oxygenase RuBP binding sites in both the high- and low-CO2 grown cells at any dissolved inorganic carbon concentration. 相似文献