1
|
Douchi D, Liang F, Cano M, Xiong W, Wang B, Maness PC, Lindblad P, Yu J. Membrane-Inlet Mass Spectrometry Enables a Quantitative Understanding of Inorganic Carbon Uptake Flux and Carbon Concentrating Mechanisms in Metabolically Engineered Cyanobacteria. Front Microbiol 2019; 10:1356. [PMID: 31293533 PMCID: PMC6604854 DOI: 10.3389/fmicb.2019.01356] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 05/31/2019] [Indexed: 01/04/2023] Open
Abstract
Photosynthesis uses solar energy to drive inorganic carbon (Ci) uptake, fixation, and biomass formation. In cyanobacteria, Ci uptake is assisted by carbon concentrating mechanisms (CCM), and CO2 fixation is catalyzed by RubisCO in the Calvin-Benson-Bassham (CBB) cycle. Understanding the regulation that governs CCM and CBB cycle activities in natural and engineered strains requires methods and parameters that quantify these activities. Here, we used membrane-inlet mass spectrometry (MIMS) to simultaneously quantify Ci concentrating and fixation processes in the cyanobacterium Synechocystis 6803. By comparing cultures acclimated to ambient air conditions to cultures transitioning to high Ci conditions, we show that acclimation to high Ci involves a concurrent decline of Ci uptake and fixation parameters. By varying light input, we show that both CCM and CBB reactions become energy limited under low light conditions. A strain over-expressing the gene for the CBB cycle enzyme fructose-bisphosphate aldolase showed higher CCM and carbon fixation capabilities, suggesting a regulatory link between CBB metabolites and CCM capacity. While the engineering of an ethanol production pathway had no effect on CCM or carbon fixation parameters, additional fructose-bisphosphate aldolase gene over-expression enhanced both activities while simultaneously increasing ethanol productivity. These observations show that MIMS can be a useful tool to study the extracellular Ci flux and how CBB metabolites regulate Ci uptake and fixation.
Collapse
Affiliation(s)
- Damien Douchi
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Feiyan Liang
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Melissa Cano
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Wei Xiong
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Bo Wang
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Pin-Ching Maness
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Peter Lindblad
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Jianping Yu
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| |
Collapse
|
2
|
Zhao CS, Shao NF, Yang ST, Ren H, Ge YR, Feng P, Dong BE, Zhao Y. Predicting cyanobacteria bloom occurrence in lakes and reservoirs before blooms occur. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 670:837-848. [PMID: 30921717 DOI: 10.1016/j.scitotenv.2019.03.161] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/28/2019] [Accepted: 03/11/2019] [Indexed: 06/09/2023]
Abstract
With increased global warming, cyanobacteria are blooming more frequently in lakes and reservoirs, severely damaging the health and stability of aquatic ecosystems and threatening drinking water safety and human health. There is an urgent demand for the effective prediction and prevention of cyanobacterial blooms. However, it is difficult to effectively reduce the risks and loss caused by cyanobacterial blooms because most methods are unable to successfully predict cyanobacteria blooms. Therefore, in this study, we proposed a new cyanobacterial bloom occurrence prediction method to analyze the probability and driving factors of the blooms for effective prevention and control. Dominant cyanobacterial species with bloom capabilities were initially determined using a dominant species identification model, and the principal driving factors of the dominant species were then analyzed using canonical correspondence analysis (CCA). Cyanobacterial bloom probability was calculated using a newly-developed model, after which, the probable mutation points were identified and thresholds for the principal driving factors of cyanobacterial blooms were predicted. A total of 141 phytoplankton data sets from 90 stations were collected from six large-scale hydrology, water-quality ecology, integrated field surveys in Jinan City, China in 2014-2015 and used for model application and verification. The results showed that there were six dominant cyanobacterial species in the study area, and that the principal driving factors were water temperature, pH, total phosphorus, ammonia nitrogen, chemical oxygen demand, and dissolved oxygen. The cyanobacterial blooms corresponded to a threshold water temperature range, pH, total phosphorus (TP), ammonium nitrogen level, chemical oxygen demand, and dissolved oxygen levels of 19.5-32.5 °C, 7.0-9.38, 0.13-0.22 mg L-1, 0.38-0.63 mg L-1, 10.5-17.5 mg L-1, and 4.97-8.28 mg L-1, respectively. Comparison with research results from other global regions further supported the use of these thresholds, indicating that this method could be used in habitats beyond China. We found that the probability of cyanobacterial bloom was 0.75, a critical point for prevention and control. When this critical point was exceeded, cyanobacteria could proliferate rapidly, increasing the risk of cyanobacterial blooms. Changes in driving factors need to be rapidly controlled, based on these thresholds, to prevent cyanobacterial blooms. Temporal and spatial scales were critical factors potentially affecting the selection of driving factors. This method is versatile and can help determine the risk of cyanobacterial blooms and the thresholds of the principal driving factors. It can effectively predict and help prevent cyanobacterial blooms to reduce the global probability of occurrence, protect the health and stability of water ecosystems, ensure drinking water safety, and protect human health.
Collapse
Affiliation(s)
- C S Zhao
- College of Water Sciences, Beijing Normal University, Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, Beijing 100875, PR China; ICube, UdS, CNRS (UMR 7357), 300 Bld Sebastien Brant, CS 10413, 67412 Illkirch, France
| | - N F Shao
- School of Geography, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, PR China.
| | - S T Yang
- College of Water Sciences, Beijing Normal University, Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, Beijing 100875, PR China; Guizhou Normal University, Guiyang 550001, PR China.
| | - H Ren
- Administration of Yanma Reservoir, Zaozhuang 277200, PR China
| | - Y R Ge
- Jinan Survey Bureau of Hydrology and Water Resources, Jinan 250013, PR China
| | - P Feng
- Jinan Survey Bureau of Hydrology and Water Resources, Jinan 250013, PR China
| | - B E Dong
- Dongying Bureau of Hydrology and Water Resources, Dongying 257000, PR China
| | - Y Zhao
- Jinan Survey Bureau of Hydrology and Water Resources, Jinan 250013, PR China
| |
Collapse
|
3
|
Rosana ARR, Ventakesh M, Chamot D, Patterson-Fortin LM, Tarassova O, Espie GS, Owttrim GW. Inactivation of a low temperature-induced RNA helicase in Synechocystis sp. PCC 6803: physiological and morphological consequences. PLANT & CELL PHYSIOLOGY 2012; 53:646-658. [PMID: 22368073 DOI: 10.1093/pcp/pcs020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Inactivation of the DEAD box RNA helicase, crhR, has dramatic effects on the physiology and morphology of the photosynthetic cyanobacterium, Synechocystis sp. PCC 6803. These effects are observed at both normal growth temperature (30°C) and under cold stress (20°C), indicating that CrhR performs crucial function(s) at all temperatures. A major physiological effect is the rapid cessation of photosynthesis upon temperature downshift from 30 to 20°C. This defect does not originate from an inability to transport or accumulate inorganic carbon or a deficiency in photosynthetic capacity as the mutant has sufficient electron transport and enzymatic capacity to sustain photosynthesis at 30°C and inorganic carbon (Ci) accumulation at 20°C. Oxygen consumption in the presence of methyl viologen indicated that while electron transport capacity is sufficient to accumulate Ci, the mutant does not possess sufficient activity to sustain carbon fixation at maximal rates. These defects are correlated with severely impaired cell growth and decreased viability, cell size and DNA content at low temperature. The ΔcrhR mutant also progressively accumulates structural abnormalities at low temperature that cannot be attributed solely to reactive oxygen species (ROS)-induced photooxidative damage, suggesting that they are manifestations of pre-existing defects that are amplified over time. The data indicate that the observed physiological and morphological effects are intimately related to crhR mutation, implying that the lack of CrhR RNA unwinding/annealing activity results in the inability to execute one or more vital steps in photosynthesis that are required at all temperatures but are crucial at low temperature.
Collapse
|
4
|
Beckmann K, Messinger J, Badger MR, Wydrzynski T, Hillier W. On-line mass spectrometry: membrane inlet sampling. PHOTOSYNTHESIS RESEARCH 2009; 102:511-22. [PMID: 19653116 PMCID: PMC2847165 DOI: 10.1007/s11120-009-9474-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 07/09/2009] [Indexed: 05/18/2023]
Abstract
Significant insights into plant photosynthesis and respiration have been achieved using membrane inlet mass spectrometry (MIMS) for the analysis of stable isotope distribution of gases. The MIMS approach is based on using a gas permeable membrane to enable the entry of gas molecules into the mass spectrometer source. This is a simple yet durable approach for the analysis of volatile gases, particularly atmospheric gases. The MIMS technique strongly lends itself to the study of reaction flux where isotopic labeling is employed to differentiate two competing processes; i.e., O(2) evolution versus O(2) uptake reactions from PSII or terminal oxidase/rubisco reactions. Such investigations have been used for in vitro studies of whole leaves and isolated cells. The MIMS approach is also able to follow rates of isotopic exchange, which is useful for obtaining chemical exchange rates. These types of measurements have been employed for oxygen ligand exchange in PSII and to discern reaction rates of the carbonic anhydrase reactions. Recent developments have also engaged MIMS for online isotopic fractionation and for the study of reactions in inorganic systems that are capable of water splitting or H(2) generation. The simplicity of the sampling approach coupled to the high sensitivity of modern instrumentation is a reason for the growing applicability of this technique for a range of problems in plant photosynthesis and respiration. This review offers some insights into the sampling approaches and and the experiments that have been conducted with MIMS.
Collapse
Affiliation(s)
- Katrin Beckmann
- School of Biology, Australian National University, Canberra, ACT 0200 Australia
- Max Planck Institut für Bioanorganische Chemie, 45470 Mülheim an der Ruhr, Germany
| | - Johannes Messinger
- School of Biology, Australian National University, Canberra, ACT 0200 Australia
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | | | - Tom Wydrzynski
- School of Biology, Australian National University, Canberra, ACT 0200 Australia
| | - Warwick Hillier
- School of Biology, Australian National University, Canberra, ACT 0200 Australia
| |
Collapse
|
5
|
|
6
|
Li Q, Canvin DT. Energy sources for HCO3- and CO2 transport in air-grown cells of synechococcus UTEX 625. PLANT PHYSIOLOGY 1998; 116:1125-32. [PMID: 9501145 PMCID: PMC35082 DOI: 10.1104/pp.116.3.1125] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/1997] [Accepted: 11/17/1997] [Indexed: 05/21/2023]
Abstract
Light-dependent inorganic C (Ci) transport and accumulation in air-grown cells of Synechococcus UTEX 625 were examined with a mass spectrometer in the presence of inhibitors or artificial electron acceptors of photosynthesis in an attempt to drive CO2 or HCO3- uptake separately by the cyclic or linear electron transport chains. In the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, the cells were able to accumulate an intracellular Ci pool of 20 mm, even though CO2 fixation was completely inhibited, indicating that cyclic electron flow was involved in the Ci-concentrating mechanism. When 200 m N,N-dimethyl-p-nitrosoaniline was used to drain electrons from ferredoxin, a similar Ci accumulation was observed, suggesting that linear electron flow could support the transport of Ci. When carbonic anhydrase was not present, initial CO2 uptake was greatly reduced and the extracellular [CO2] eventually increased to a level higher than equilibrium, strongly suggesting that CO2 transport was inhibited and that Ci accumulation was the result of active HCO3- transport. With 3-(3,4-dichlorophenyl)-1, 1-dimethylurea-treated cells, Ci transport and accumulation were inhibited by inhibitors of CO2 transport, such as COS and Na2S, whereas Li+, an HCO3--transport inhibitor, had little effect. In the presence of N,N-dimethyl-p-nitrosoaniline, Ci transport and accumulation were not inhibited by COS and Na2S but were inhibited by Li+. These results suggest that CO2 transport is supported by cyclic electron transport and that HCO3- transport is supported by linear electron transport.
Collapse
Affiliation(s)
- Q Li
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | | |
Collapse
|
7
|
McGinn PJ, Canvin DT, Coleman JR. Influx and efflux of inorganic carbon during steady-state photosynthesis of air-grown Anabaena variabilis. ACTA ACUST UNITED AC 1997. [DOI: 10.1139/b97-903] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The inward and outward fluxes of inorganic carbon in illuminated cell suspensions of air-grown Anabaena variabilis were measured by mass spectrometry under conditions of inorganic carbon disequilibrium. The inclusion of 25 mM NaCl significantly enhanced both inward inorganic carbon influx during CO2 fixation and outward CO2 efflux when CO2 fixation was blocked by the Calvin cycle inhibitor, iodoacetamide. At low, steady-state concentrations of inorganic carbon (< 100μM), CO2 fixation was nearly entirely supported by HCO3− transport in the presence of 25 mM NaCl. At approximately 150 μM inorganic carbon, the contributions of CO2 and HCO3− transport to CO2 fixation were about equal. Above this, CO2 transport provided most of the substrate for CO2 fixation. The affinity (K0.5) of photosynthesizing cells for CO2, HCO3− and total inorganic carbon was determined and mean values of 1.7, 9.5, and 8.2 μM, respectively, were determined. Maximum rates of inward CO2 and HCO3− transport and CO2 fixation during steady state were 255.7, 307.3, and 329.1 μmol∙mg−1 Chl∙h−1, respectively. Permeability coefficients for CO2 of 9.8 × 10−8 m∙s−1 and 2.8 × 10−7 m∙s−1 were calculated for the plasma membrane and carboxysomal surface areas, respectively, from the dark efflux rates assuming an internal pH of 7.2. A permeability coefficient for HCO3− across the plasma membrane of 7.6 × 10−9 m∙s−1 was calculated from the dark inorganic carbon efflux corrected for the corresponding dark CO2 efflux. Sodium sulphide (Na2S, 200 μM) blocked CO2 transport. In the presence of 25 mM NaCl, net CO2 efflux was approximately seven times greater than in its absence, when CO2 transport and fixation were both blocked, indicating greater CO2 leakage as a result of larger internal inorganic carbon pools in the presence of NaCl. The rapidity and amount of C16O2 generated from the exchange of 18O from 18O-enriched HCO3− with water in cell suspensions suggested that the internal inorganic carbon pool may be rapidly equilibrated. Key words: Anabaena variabilis, CO2-concentrating mechanism, CO2 transport, HCO3− transport, CO2 efflux, permeability coefficient.
Collapse
|
8
|
Miller AG, Salon C, Canvin DT, Espie GS. Measurement of the amount and isotopic composition of the CO2 released from the cyanobacterium Synechococcus UTEX 625 after rapid quenching of the active CO2 transport system. ACTA ACUST UNITED AC 1997. [DOI: 10.1139/b97-109] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Air-grown cells of the cyanobacterium Synechococcus UTEX 625 were suspended in a cuvette connected to a mass spectrometer and supplied with H13C18O3− to investigate the intracellular interconversion between CO2 and HCO3− as determined from the isotopic composition of CO2 appearing in the extracellular medium under a wide variety of experimental conditions. Upon injection of H13C18O3− to the cell suspension in the light, the extracellular [13C16O2] increased. As the CO2 species were 13C labelled, this demonstrated that the 18O-depleted CO2 was originating from the added H13C18O3−. A comparison of the rates of 13C16O16O appearance in the medium with the formation of 13C16O16O from spontaneous dehydration–hydration in the extracellular medium in the presence of cells demonstrated that most of it had to originate from a series of intracellular dehydration–hydration cycles of H13C18O3− that had been recently transported into the cells. During the time course of the experiments both the m/z (mass to charge) = 49 (i.e., 13C18O18O) and 47 (i.e., 13C18O16O) signals decreased constantly, whereas the m/z = 45 signal (i.e.,13C16O2) always increased. Inhibiting CO2 fixation enhanced the amount of CO2 arising in the medium but did not change its isotopic composition, and the CO2 was always fully depleted of 18O. When the CO2 transport system was inhibited by darkening the cells, adding inhibitors such as Na2S or COS, or quenching the uptake of inorganic 13C with an excess of inorganic 12C, the magnitude of the extracellular [13C16O2] was increased but the CO2 species were still always depleted of 18O. Various incubation times of the illuminated cells in the presence of H13C18O3− were used to obtain a variety of internal Ci pool sizes. When the inhibitor (COS) was added, the amount of 13C16O2 arising during the response time of the mass spectrometer was equivalent to the amount of CO2 that would have been present in the whole cell if CO2 and HCO3− were in equilibrium throughout the entire cell volume, but it was at least 40 times higher than the amount of CO2 that would have been present in the cell if the CO2 was confined to the carboxysomes. Experiments were also conducted at pH 9.0 where the spontaneous rate of 13C16O2 production from H13C1803− dehydration–hydration would be negligible, and again the same features were observed. Results show that intracellular HCO3− and CO2 are in rapid equilibrium throughout the entire cell volume. Key words: Synechococcus UTEX 625, cyanobacteria, CO2 leakage, 18O exchange, active CO2 transport, carboxysomes, inorganic C concentrating mechanism.
Collapse
|
9
|
Ritchie RJ, Nadolny C, Larkum AWD. Driving Forces for Bicarbonate Transport in the Cyanobacterium Synechococcus R-2 (PCC 7942). PLANT PHYSIOLOGY 1996; 112:1573-1584. [PMID: 12226464 PMCID: PMC158090 DOI: 10.1104/pp.112.4.1573] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Air-grown Synechococcus R-2 (PCC 7942) cultures grown in BG-11 medium are very alkaline (outside pH is 10.0) and use HCO3- as their inorganic carbon source. The cells showed a dependence on Na+ for photosynthesis, but low Na+ conditions (1 mol m-3) were sufficient to support saturating photosynthesis. The intracellular dissolved inorganic carbon in the light was greater than 20 mol m-3 in both low-Na+ conditions and in BG-11 medium containing the usual [Na+] (24 mol m-3, designated high-Na+ conditions). The electrochemical potential for HCO3- in the light was in excess of 25 kJ mol-1, even in high-Na+ conditions. The Na+-motive force was greater than -12 kJ mol-1 under both Na+ conditions. On thermodynamic grounds, an Na+-driven co-port process would need to have a stoichiometry of 2 or greater ([greater than or equal to]2Na+ in/HCO3-1 in), but we show that Na+ or K+ fluxes cannot be linked to HCO3- transport. Na+ and K+ fluxes were unaffected by the presence or absence of dissolved inorganic carbon. In low-Na+ conditions, Na+ fluxes are too low to support the observed net 14C-carbon fixation rate. Active transport of HCO3- hyperpolarizes (not depolarizes) the membrane potential.
Collapse
Affiliation(s)
- R. J. Ritchie
- Biology A-12, School of Biological Sciences, The University of Sydney, New South Wales 2006, Australia
| | | | | |
Collapse
|
10
|
Singh S, Negi S, Bharati N, Singh H. Common nitrogen control of caesium uptake, caesium toxicity and ammonium (methylammonium) uptake in the cyanobacterium Nostoc muscorum. FEMS Microbiol Lett 1994. [DOI: 10.1111/j.1574-6968.1994.tb06774.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
|
11
|
Espie GS, Kandasamy RA. Na-Independent HCO(3) Transport and Accumulation in the Cyanobacterium Synechococcus UTEX 625. PLANT PHYSIOLOGY 1992; 98:560-8. [PMID: 16668677 PMCID: PMC1080226 DOI: 10.1104/pp.98.2.560] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The active transport and intracellular accumulation of HCO(3) (-) by air-grown cells of the cyanobacterium Synechococcus UTEX 625 (PCC 6301) was strongly promoted by 25 millimolar Na(+).Na(+)-dependent HCO(3) (-) accumulation also resulted in a characteristic enhancement in the rate of photosynthetic O(2) evolution and CO(2) fixation. However, when Synechococcus was grown in standing culture, high rates of HCO(3) (-) transport and photosynthesis were observed in the absence of added Na(+). The internal HCO(3) (-) pool reached levels up to 50 millimolar, and an accumulation ratio as high as 970 was observed. Sodium enhanced HCO(3) (-) transport and accumulation in standing culture cells by about 25 to 30% compared with the five- to eightfold enhancement observed with air-grown cells. The ability of standing culture cells to utilize HCO(3) (-) from the medium in the absence of Na(+) was lost within 16 hours after transfer to air-grown culture and was reacquired during subsequent growth in standing culture. Studies using a mass spectrometer indicated that standing culture cells were also capable of active CO(2) transport involving a high-affinity transport system which was reversibly inhibited by H(2)S, as in the case for air-grown cells. The data are interpreted to indicate that Synechococcus possesses a constitutive CO(2) transport system, whereas Na(+)-dependent and Na(+)-independent HCO(3) (-) transport are inducible, depending upon the conditions of growth. Intracellular accumulation of HCO(3) (-) was always accompanied by a quenching of chlorophyll a fluorescence which was independent of CO(2) fixation. The extent of fluorescence quenching was highly dependent upon the size of the internal pool of HCO(3) (-) + CO(2). The pattern of fluorescence quenching observed in response to added HCO(3) (-) and Na(+) in air-grown and standing culture cells was highly characteristic for Na(+)-dependent and Na(+)-independent HCO(3) (-) accumulation. It was concluded that measurements of fluorescence quenching provide an indirect means for following HCO(3) (-) transport and the dynamics of intracellular HCO(3) (-) accumulation and dissipation.
Collapse
Affiliation(s)
- G S Espie
- Department of Botany, Erindale College, University of Toronto, Mississauga, Ontario, Canada L5L 1C6
| | | |
Collapse
|
12
|
Espie GS, Miller AG, Canvin DT. High Affinity Transport of CO(2) in the Cyanobacterium Synechococcus UTEX 625. PLANT PHYSIOLOGY 1991; 97:943-53. [PMID: 16668535 PMCID: PMC1081108 DOI: 10.1104/pp.97.3.943] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The active transport of CO(2) in Synechococcus UTEX 625 was measured by mass spectrometry under conditions that preclude HCO(3) (-) transport. The substrate concentration required to give one half the maximum rate for whole cell CO(2) transport was determined to be 0.4 +/- 0.2 micromolar (mean +/- standard deviation; n = 7) with a range between 0.2 and 0.66 micromolar. The maximum rates of CO(2) transport ranged between 400 and 735 micromoles per milligram of chlorophyll per hour with an average rate of 522 for seven experiments. This rate of transport was about three times greater than the dissolved inorganic carbon saturated rate of photosynthetic O(2) evolution observed under these conditions. The initial rate of chlorophyll a fluorescence quenching was highly correlated with the initial rate of CO(2) transport (correlation coefficient = 0.98) and could be used as an indirect method to detect CO(2) transport and calculate the substrate concentration required to give one half the maximum rate of transport. Little, if any, inhibition of CO(2) transport was caused by HCO(3) (-) or by Na(+)-dependent HCO(3) (-) transport. However, (12)CO(2) readily interfered with (13)CO(2) transport. CO(2) transport and Na(+)-dependent HCO(3) (-) transport are separate, independent processes and the high affinity CO(2) transporter is not only responsible for the initial transport of CO(2) into the cell but also for scavenging any CO(2) that may leak from the cell during ongoing photosynthesis.
Collapse
Affiliation(s)
- G S Espie
- Department of Biology, Concordia University, Montreal, Quebec, Canada H3G 1M8
| | | | | |
Collapse
|
13
|
Ogawa T. Cloning and Inactivation of a Gene Essential to Inorganic Carbon Transport of Synechocystis PCC6803. PLANT PHYSIOLOGY 1991; 96:280-4. [PMID: 16668165 PMCID: PMC1080746 DOI: 10.1104/pp.96.1.280] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A clone (HP-1) which transforms the high CO(2)-requiring mutant (RKb) of Synechocystis PCC6803 defective in inorganic carbon transport to the wild-type (WT) phenotype was isolated from a WT genomic library. The clone contained a 5.4 kilobase-pair DNA insert. Complementation tests with subclones derived from HP-1 allowed the mutation in RKb to be located within 141 base-pair nucleotides. Sequencing of nucleotides in this region revealed an open reading frame encoding a hydrophobic protein consists of 80 amino acids. A defined mutant (M9) constructed by inactivating this putative inorganic carbon transport gene, designated ictA, was unable to transport CO(2) and HCO(3) (-) into the intracellular inorganic carbon pool. Cloning and sequence analysis of the respective RKb gene revealed a base substitution which generates a stop codon in the middle of ictA.
Collapse
Affiliation(s)
- T Ogawa
- Solar Energy Research Group, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan
| |
Collapse
|
14
|
Ogawa T. Mutants of Synechocystis PCC6803 Defective in Inorganic Carbon Transport. PLANT PHYSIOLOGY 1990; 94:760-5. [PMID: 16667776 PMCID: PMC1077296 DOI: 10.1104/pp.94.2.760] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Eighty mutants of Synechocystis PCC6803 that require high CO(2) for growth were examined with a mass spectrometer for their ability to take up CO(2) in the light. Two of these mutants (type A) did not show any CO(2) uptake while the rest of the mutants (type B) took up CO(2) actively. Type A mutants (RKa and RKb) and one type B mutant (RK11) were partially characterized. At 3% CO(2), growth rates of the mutants and the wild type (WT) were similar. Under air levels of CO(2), growth of RKa and RKb was very slow, and RK11 did not grow at all. The photosynthetic affinities for inorganic carbon (C(i)) in these three mutants were about 100 times lower than the affinity in WT. The following characteristics of type A mutants indicated that the mutants have a defect in their CO(2)-transport system: (a) the activity of (13)C(18)O(2) uptake in RKa and RKb in the light was less than 5% the activity in WT, and (b) each mutant had only a low level of activity of (14)CO(2) uptake as measured by the method of silicone oil-filtering centrifugation. The HCO(3) (-)-transport system was also impaired in these mutants. The activity of H(14)CO(3) (-) uptake was negligibly low in RKb and was one-third the activity of WT in RKa. On the other hand, the type B mutant, RK11, transported CO(2) and HCO(3) (-) into the intracellular C(i) pool as actively as WT but was unable to utilize it for photosynthesis. Complementation analysis of type A mutants indicated that RKa and RKb have mutations in different regions of the genome. These results suggested that at least two kinds of proteins are involved in the C(i)-transport system.
Collapse
Affiliation(s)
- T Ogawa
- Solar Energy Research Group, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan
| |
Collapse
|
15
|
Ogawa T. Mutants of Synechocystis PCC6803 Defective in Inorganic Carbon Transport. PLANT PHYSIOLOGY 1990; 94:760-765. [PMID: 16667776 DOI: 10.2307/4273156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Eighty mutants of Synechocystis PCC6803 that require high CO(2) for growth were examined with a mass spectrometer for their ability to take up CO(2) in the light. Two of these mutants (type A) did not show any CO(2) uptake while the rest of the mutants (type B) took up CO(2) actively. Type A mutants (RKa and RKb) and one type B mutant (RK11) were partially characterized. At 3% CO(2), growth rates of the mutants and the wild type (WT) were similar. Under air levels of CO(2), growth of RKa and RKb was very slow, and RK11 did not grow at all. The photosynthetic affinities for inorganic carbon (C(i)) in these three mutants were about 100 times lower than the affinity in WT. The following characteristics of type A mutants indicated that the mutants have a defect in their CO(2)-transport system: (a) the activity of (13)C(18)O(2) uptake in RKa and RKb in the light was less than 5% the activity in WT, and (b) each mutant had only a low level of activity of (14)CO(2) uptake as measured by the method of silicone oil-filtering centrifugation. The HCO(3) (-)-transport system was also impaired in these mutants. The activity of H(14)CO(3) (-) uptake was negligibly low in RKb and was one-third the activity of WT in RKa. On the other hand, the type B mutant, RK11, transported CO(2) and HCO(3) (-) into the intracellular C(i) pool as actively as WT but was unable to utilize it for photosynthesis. Complementation analysis of type A mutants indicated that RKa and RKb have mutations in different regions of the genome. These results suggested that at least two kinds of proteins are involved in the C(i)-transport system.
Collapse
Affiliation(s)
- T Ogawa
- Solar Energy Research Group, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan
| |
Collapse
|
16
|
Badger MR, Price GD. Carbon Oxysulfide Is an Inhibitor of Both CO(2) and HCO(3) Uptake in the Cyanobacterium Synechococcus PCC7942. PLANT PHYSIOLOGY 1990; 94:35-9. [PMID: 16667708 PMCID: PMC1077185 DOI: 10.1104/pp.94.1.35] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Carbon oxysulfide (COS) was reinvestigated as an inhibitor of active inorganic carbon transport in cells of Synechococcus PCC7942 adapted to growth at low inorganic carbon. COS inhibited both CO(2) and HCO(3) (-) transport processes in a reversible (in the short term) and mixed competitive manner. The inhibition of COS was established using both silicone oil centrifugation experiments and O(2)-evolution studies. The K(i) for COS inhibition was 29 micromolar for CO(2) transport and 110 micromolar for HCO(3) (-) transport. These results support a model of inorganic carbon transport with a central CO(2) pump and an inducible HCO(3) (-) utilizing accessory protein which supplies CO(2) to the primary pump.
Collapse
Affiliation(s)
- M R Badger
- Research School of Biological Sciences, Australian National University, P. O. Box 475, Canberra ACT 2601, Australia
| | | |
Collapse
|
17
|
Bédu S, Peltier G, Sarrey F, Joset F. Properties of a Mutant from Synechocystis PCC6803 Resistant to Acetazolamide, an Inhibitor of Carbonic Anhydrase. PLANT PHYSIOLOGY 1990; 93:1312-5. [PMID: 16667618 PMCID: PMC1062673 DOI: 10.1104/pp.93.4.1312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A spontaneous mutant of the cyanobacterium Synechocystis PCC6803 was isolated for its resistance to acetazolamide, an inhibitor of carbonic anhydrase. The mutant showed a deficiency in oxygen exchange between CO(2) and H(2)O, a lower level of stable internal CO(2) pool and a decreased capacity to adapt its photosynthetic affinity under limited inorganic carbon regime. The initial rate of uptake of inorganic carbon was identical to that of wild-type cells. It is demonstrated that the mutation affects the carbonic anhydrase activity. This could result from either of two impairments: a deficiency in the enzyme activity detectable by mass spectrometric determinations, or a modification of the cellular compartment in which the enzyme is located, preventing its activity.
Collapse
Affiliation(s)
- S Bédu
- Unité de Métabolisme Energétique, B.P. 3, 13275 Marseille Cedex 9, France
| | | | | | | |
Collapse
|
18
|
Espie GS, Miller AG, Canvin DT. Selective and Reversible Inhibition of Active CO(2) Transport by Hydrogen Sulfide in a Cyanobacterium. PLANT PHYSIOLOGY 1989; 91:387-94. [PMID: 16667030 PMCID: PMC1062004 DOI: 10.1104/pp.91.1.387] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The active transport of CO(2) in the cyanobacterium Synechococcus UTEX 625 was inhibited by H(2)S. Treatment of the cells with up to 150 micromolar H(2)S + HS(-) at pH 8.0 had little effect on Na(+)-dependent HCO(3) (-) transport or photosynthetic O(2) evolution, but CO(2) transport was inhibited by more than 90%. CO(2) transport was restored when H(2)S was removed by flushing with N(2). At constant total H(2)S + HS(-) concentrations, inhibition of CO(2) transport increased as the ratio of H(2)S to HS(-) increased, suggesting a direct role for H(2)S in the inhibitory process. Hydrogen sulfide does not appear to serve as a substrate for transport. In the presence of H(2)S and Na(+) -dependent HCO(3) (-) transport, the extracellular CO(2) concentration rose considerably above its equilibrium level, but was maintained far below its equilibrium level in the absence of H(2)S. The inhibition of CO(2) transport, therefore, revealed an ongoing leakage from the cells of CO(2) which was derived from the intracellular dehydration of HCO(3) (-) which itself had been recently transported into the cells. Normally, leaked CO(2) is efficiently transported back into the cell by the CO(2) transport system, thus maintaining the extracellular CO(2) concentration near zero. It is suggested that CO(2) transport not only serves as a primary means of inorganic carbon acquisition for photosynthesis but also serves as a means of recovering CO(2) lost from the cell. A schematic model describing the relationship between the CO(2) and HCO(3) (-) transport systems is presented.
Collapse
Affiliation(s)
- G S Espie
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | | | | |
Collapse
|
19
|
Miller AG, Espie GS, Canvin DT. Use of Carbon Oxysulfide, a Structural Analog of CO(2), to Study Active CO(2) Transport in the Cyanobacterium Synechococcus UTEX 625. PLANT PHYSIOLOGY 1989; 90:1221-31. [PMID: 16666875 PMCID: PMC1061868 DOI: 10.1104/pp.90.3.1221] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Carbon oxysulfide (carbonyl sulfide, COS) is a close structural analog of CO(2). Although hydrolysis of COS (to CO(2) and H(2)S) does occur at alkaline pH (>9), at pH 8.0 the rate of hydrolysis is slow enough to allow investigation of COS as a possible substrate and inhibitor of the active CO(2) transport system of Synechococcus UTEX 625. A light-dependent uptake of COS was observed that was inhibited by CO(2) and the ATPase inhibitor diethylstilbestrol. The COS taken up by the cells could not be recovered when the lights were turned off or when acid was added. It was concluded that most of the COS taken up was hydrolyzed by intracellular carbonic anhydrase. The production of H(2)S was observed and COS removal from the medium was inhibited by ethoxyzolamide. Bovine erythrocyte carbonic anhydrase catalysed the stoichiometric hydrolysis of COS to H(2)S. The active transport of CO(2) was inhibited by COS in an apparently competitive manner. When Na(+)-dependent HCO(3) (-) transport was allowed in the presence of COS, the extracellular [CO(2)] rose considerably above the equilibrium level. This CO(2) appearing in the medium was derived from the dehydration of transported HCO(3) (-) and was leaked from the cells. In the presence of COS the return to the cells of this leaked CO(2) was inhibited. These results showed that the Na(+)-dependent HCO(3) (-) transport was not inhibited by COS, whereas active CO(2) transport was inhibited. When COS was removed by gassing with N(2), a normal pattern of CO(2) uptake was observed. The silicone fluid centrifugation method showed that COS (100 micromolar) had little effect upon the initial rate of HCO(3) (-) transport or CO(2) fixation. The steady state rate of CO(2) fixation was, however, inhibited about 50% in the presence of COS. This inhibition can be at least partially explained by the significant leakage of CO(2) from the cells that occurred when CO(2) uptake was inhibited by COS. Neither CS(2) nor N(2)O acted like COS. It is concluded that COS is an effective and selective inhibitor of active CO(2) transport.
Collapse
Affiliation(s)
- A G Miller
- Department of Biology, Queen's University, Kingston, Ontario, Canada, K7L 3N6
| | | | | |
Collapse
|
20
|
Sültemeyer DF, Miller AG, Espie GS, Fock HP, Canvin DT. Active CO(2) Transport by the Green Alga Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 1989; 89:1213-9. [PMID: 16666686 PMCID: PMC1055998 DOI: 10.1104/pp.89.4.1213] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Mass spectrometric measurements of dissolved free (13)CO(2) were used to monitor CO(2) uptake by air grown (low CO(2)) cells and protoplasts from the green alga Chlamydomonas reinhardtii. In the presence of 50 micromolar dissolved inorganic carbon and light, protoplasts which had been washed free of external carbonic anhydrase reduced the (13)CO(2) concentration in the medium to close to zero. Similar results were obtained with low CO(2) cells treated with 50 micromolar acetazolamide. Addition of carbonic anhydrase to protoplasts after the period of rapid CO(2) uptake revealed that the removal of CO(2) from the medium in the light was due to selective and active CO(2) transport rather than uptake of total dissolved inorganic carbon. In the light, low CO(2) cells and protoplasts incubated with carbonic anhydrase took up CO(2) at an apparently low rate which reflected the uptake of total dissolved inorganic carbon. No net CO(2) uptake occurred in the dark. Measurement of chlorophyll a fluorescence yield with low CO(2) cells and washed protoplasts showed that variable fluorescence was mainly influenced by energy quenching which was reciprocally related to photosynthetic activity with its highest value at the CO(2) compensation point. During the linear uptake of CO(2), low CO(2) cells and protoplasts incubated with carbonic anhydrase showed similar rates of net O(2) evolution (102 and 108 micromoles per milligram of chlorophyll per hour, respectively). The rate of net O(2) evolution (83 micromoles per milligram of chlorophyll per hour) with washed protoplasts was 20 to 30% lower during the period of rapid CO(2) uptake and decreased to a still lower value of 46 micromoles per milligram of chlorophyll per hour when most of the free CO(2) had been removed from the medium. The addition of carbonic anhydrase at this point resulted in more than a doubling of the rate of O(2) evolution. These results show low CO(2) cells of Chlamydomonas are able to transport both CO(2) and HCO(3) (-) but CO(2) is preferentially removed from the medium. The external carbonic anhydrase is important in the supply to the cells of free CO(2) from the dehydration of HCO(3) (-).
Collapse
Affiliation(s)
- D F Sültemeyer
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | | | | | | | | |
Collapse
|
21
|
Espie GS, Miller AG, Canvin DT. Characterization of the na-requirement in cyanobacterial photosynthesis. PLANT PHYSIOLOGY 1988; 88:757-63. [PMID: 16666379 PMCID: PMC1055656 DOI: 10.1104/pp.88.3.757] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The Na(+) requirement for photosynthesis and its relationship to dissolved inorganic carbon (DIC) concentration and Li(+) concentration was examined in air-grown cells of the cyanobacterium Synechococcus leopoliensis UTEX 625 at pH 8. Analysis of the rate of photosynthesis (O(2) evolution) as a function of Na(+) concentration, at fixed DIC concentration, revealed two distinct regions to the response curve, for which half-saturation values for Na(+) (K((1/2))[Na(+)]) were calculated. The value of both the low and the high K((1/2))(Na(+)) was dependent upon extracellular DIC concentration. The low K((1/2))(Na(+)) decreased from 1000 micromolar at 5 micromolar DIC to 200 micromolar at 140 micromolar DIC whereas over the same DIC concentration range the high K((1/2))(Na(+)) decreased from 10 millimolar to 1 millimolar. The most significant increases in photosynthesis occurred in the 1 to 20 millimolar range. A fraction of total photosynthesis, however, was independent of added Na(+) and this fraction increased with increased DIC concentration. A number of factors were identified as contributing to the complexity of interaction between Na(+) and DIC concentration in the photosynthesis of Synechococcus. First, as revealed by transport studies and mass spectrometry, both CO(2) and HCO(3) (-) transport contributed to the intracellular supply of DIC and hence to photosynthesis. Second, both the CO(2) and HCO(3) (-) transport systems required Na(+), directly or indirectly, for full activity. However, micromolar levels of Na(+) were required for CO(2) transport while millimolar levels were required for HCO(3) (-) transport. These levels corresponded to those found for the low and high K((1/2))(Na(+)) for photosynthesis. Third, the contribution of each transport system to intracellular DIC was dependent on extracellular DIC concentration, where the contribution from CO(2) transport increased with increased DIC concentration relative to HCO(3) (-) transport. This change was reflected in a decrease in the Na(+) concentration required for maximum photosynthesis, in accord with the lower Na(+)-requirement for CO(2) transport. Lithium competitively inhibited Na(+)-stimulated photosynthesis by blocking the cells' ability to form an intracellular DIC pool through Na(+)-dependent HCO(3) (-) transport. Lithium had little effect on CO(2) transport and only a small effect on the size of the pool it generated. Thus, CO(2) transport did not require a functional HCO(3) (-) transport system for full activity. Based on these observations and the differential requirement for Na(+) in the CO(2) and HCO(3) (-) transport system, it was proposed that CO(2) and HCO(3) (-) were transported across the membrane by different transport systems.
Collapse
Affiliation(s)
- G S Espie
- Department of Biology, Queen's University, Kingston, Ontario, Canada, K7L 3N6
| | | | | |
Collapse
|