scholarly journals Red/far-red light signals regulate the activity of the carbon-concentrating mechanism in cyanobacteria

2021 ◽  
Vol 7 (34) ◽  
pp. eabg0435
Author(s):  
Nadav Oren ◽  
Stefan Timm ◽  
Marcus Frank ◽  
Oliver Mantovani ◽  
Omer Murik ◽  
...  
Keyword(s):  
Desiccation Tolerance ◽  
Inorganic Carbon ◽  
Red Light ◽  
Negev Desert ◽  
Light Perception ◽  
Inhibitory Protein ◽  
Bisphosphate Carboxylase ◽  
Liquid Cultures ◽  
Light Inhibition ◽  
Light Signals

Desiccation-tolerant cyanobacteria can survive frequent hydration/dehydration cycles likely affecting inorganic carbon (Ci) levels. It was recently shown that red/far-red light serves as signal-preparing cells toward dehydration. Here, the effects of desiccation on Ci assimilation by Leptolyngbya ohadii isolated from Israel’s Negev desert were investigated. Metabolomic investigations indicated a decline in ribulose-1,5-bisphosphate carboxylase/oxygenase carboxylation activity, and this was accelerated by far-red light. Far-red light negatively affected the Ci affinity of L. ohadii during desiccation and in liquid cultures. Similar effects were evident in the non–desiccation-tolerant cyanobacterium Synechocystis. The Synechocystis Δcph1 mutant lacking the major phytochrome exhibited reduced photosynthetic Ci affinity when exposed to far-red light, whereas the mutant ΔsbtB lacking a Ci uptake inhibitory protein lost the far-red light inhibition. Collectively, these results suggest that red/far-red light perception likely via phytochromes regulates Ci uptake by cyanobacteria and that this mechanism contributes to desiccation tolerance in strains such as L. ohadii.

The influence of red and blue light on the rate of photosynthesis and the CO2 compensation point at various oxygen concentrations

1970 ◽  
Vol 48 (6) ◽  
pp. 1251-1257 ◽  
Author(s):  
N. P. Voskresenskaya ◽  
G. S. Grishina ◽  
S. N. Chmora ◽  
N. M. Poyarkova
Keyword(s):  
Nicotiana Tabacum ◽  
Blue Light ◽  
Photosynthetic Rate ◽  
Prolonged Exposure ◽  
Red Light ◽  
Compensation Point ◽  
Gas Analyzer ◽  
Co2 Compensation Point ◽  
Rate Of Photosynthesis ◽  
Light Inhibition

Apparent photosynthesis of attached leaves of Phaseolus vulgaris, Vicia faba, Pisum sativum, and Nicotiana tabacum at various intensities of blue and red light was measured by infrared CO2 gas analyzer in a closed system. Simultaneously the CO2 compensation point was measured.It was found that light-limited photosynthetic rate in blue light was equal to or more than that in red light. Inhibition of photosynthesis, which sometimes occurred at light-saturated intensities of blue light, could be avoided by addition of red light, prolonged exposure of the plants to blue light, or by lowering the O2 concentration. Accordingly, the increase of photosynthetic rate due to change of O2 concentration from 21 to 3% O2 is higher in blue light only when photosynthesis is inhibited by blue light at 21% O2. The data on the action of blue and red light on the CO2 compensation point seems to exclude the activation of photorespiration by blue light.The possible effects of blue light on apparent photosynthesis are discussed on the basis of the results presented.

scholarly journals pH determines the energetic efficiency of the cyanobacterial CO2 concentrating mechanism

2016 ◽  
Vol 113 (36) ◽  
pp. E5354-E5362 ◽  
Author(s):  
Niall M. Mangan ◽  
Avi Flamholz ◽  
Rachel D. Hood ◽  
Ron Milo ◽  
David F. Savage
Keyword(s):  
Intracellular Ph ◽  
Inorganic Carbon ◽  
Quantitative Description ◽  
Carbon Accumulation ◽  
Energetic Efficiency ◽  
Ribulose Bisphosphate Carboxylase ◽  
Competitive Reaction ◽  
Bisphosphate Carboxylase ◽  
Concentrating Mechanism ◽  
Ribulose Bisphosphate Carboxylase Oxygenase

Many carbon-fixing bacteria rely on a CO2 concentrating mechanism (CCM) to elevate the CO2 concentration around the carboxylating enzyme ribulose bisphosphate carboxylase/oxygenase (RuBisCO). The CCM is postulated to simultaneously enhance the rate of carboxylation and minimize oxygenation, a competitive reaction with O2 also catalyzed by RuBisCO. To achieve this effect, the CCM combines two features: active transport of inorganic carbon into the cell and colocalization of carbonic anhydrase and RuBisCO inside proteinaceous microcompartments called carboxysomes. Understanding the significance of the various CCM components requires reconciling biochemical intuition with a quantitative description of the system. To this end, we have developed a mathematical model of the CCM to analyze its energetic costs and the inherent intertwining of physiology and pH. We find that intracellular pH greatly affects the cost of inorganic carbon accumulation. At low pH the inorganic carbon pool contains more of the highly cell-permeable H2CO3, necessitating a substantial expenditure of energy on transport to maintain internal inorganic carbon levels. An intracellular pH ≈8 reduces leakage, making the CCM significantly more energetically efficient. This pH prediction coincides well with our measurement of intracellular pH in a model cyanobacterium. We also demonstrate that CO2 retention in the carboxysome is necessary, whereas selective uptake of HCO3− into the carboxysome would not appreciably enhance energetic efficiency. Altogether, integration of pH produces a model that is quantitatively consistent with cyanobacterial physiology, emphasizing that pH cannot be neglected when describing biological systems interacting with inorganic carbon pools.

The inorganic carbon requirements for nitrogen assimilation

1991 ◽  
Vol 69 (5) ◽  
pp. 1139-1145 ◽  
Author(s):  
David H. Turpin ◽  
Greg C. Vanlerberghe ◽  
Alan M. Amory ◽  
Robert D. Guy
Keyword(s):  
Amino Acid ◽  
Phosphoenolpyruvate Carboxylase ◽  
Nitrogen Assimilation ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Sufficient Conditions ◽  
Acid Synthesis ◽  
Amino Acid Synthesis ◽  
Bisphosphate Carboxylase ◽  
N Assimilation

In the green alga Selenastrum minutum (Naeg.) Collins the assimilation of NH4+ into the full suite of protein amino acids requires at least three separate and distinct inorganic carbon fixing reactions, catalyzed by the enzymes ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC), and carbamoyl phosphate synthetase. In this paper we examine the requirements for CO2 fixation of NH4+ assimilation in this organism. When grown under N-sufficient conditions, NH4+ assimilation is directly dependent upon photosynthetic CO2 fixation to provide carbon skeletons for amino acid synthesis. When cultured under N-limited conditions, the cells accumulate starch, which is then available for amino acid synthesis. This alleviates the requirement of photosynthetic CO2 fixation for NH4+ assimilation. N-limited cells, however, still exhibit a nonphotosynthetic CO2 requirement for N assimilation that is mediated through PEPC. This activity of PEPC increases during N assimilation to replenish TCA cycle intermediates consumed during amino acid synthesis. The in vivo activity of this enzyme is tightly regulated so that there are ~0.3 moles C fixed per mole N assimilated. In S. minutum PEPC is regulated primarily by the ratio of glutamine/glutamate, thus providing a mechanism by which primary NH4+ assimilation modulates the supply of carbon for amino acid biosynthesis. Activation of PEPC during NH4+ assimilation occurs in both the light and the dark. Key words: dissolved inorganic carbon, nitrogen assimilation, phosphoenolpyruvate carboxylase, photosynthesis, amino acid synthesis, respiration.

Red light inhibition of spore germination in Ophioglossum crotalophoroides

2006 ◽  
Vol 84 (7) ◽  
pp. 1156-1158 ◽  
Author(s):  
Dean P. Whittier
Keyword(s):  
Soil Moisture ◽  
White Light ◽  
Spore Germination ◽  
Mycorrhizal Fungi ◽  
Red Light ◽  
Active Form ◽  
Light Inhibition

Spores of Ophioglossum crotalophoroides Walt., which give rise to subterranean, nonphotosynthetic, mycorrhizal gametophytes, germinate in the dark and not in the light. Red light, like white light, prevents the germination of these spores. Germination occurs after exposure to far-red. The effects of far-red light can be reversed by red light and those of red light can be partly reversed by far-red light, confirming the involvement of phytochrome. With the spores of O. crotalophoroides, the active form of phytochrome, Pfr, prohibits germination. The photoinhibition of germination by white or red light insures that these spores germinate underground in nature. Hypogean germination improves the chances for adequate soil moisture and for the young gametophytes to be colonized by mycorrhizal fungi.

Physiological aspects of CO2 and HCO3− transport by cyanobacteria: a review

1990 ◽  
Vol 68 (6) ◽  
pp. 1291-1302 ◽  
Author(s):  
Anthony G. Miller ◽  
George S. Espie ◽  
David T. Canvin
Keyword(s):  
Active Transport ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Structural Analog ◽  
Transport Systems ◽  
Ribulose Bisphosphate Carboxylase ◽  
High Concentration ◽  
Bisphosphate Carboxylase ◽  
Ribulose Bisphosphate Carboxylase Oxygenase ◽  
Inorganic Carbon Transport

Cyanobacteria grown at air levels of CO2, or lower, have a very high photosynthetic affinity for CO2. For ceils grown in carbon-limited chemostats at pH 9.6, the K0.5 (CO2) for whole cell CO2 fixation is about 3 nM. This is in spite of a K0.5 (CO2) for cyanobacterial ribulose bisphosphate carboxylase/oxygenase of about 200 μM. It is now clear that cyanobacteria can photosynthesize at very low CO2 concentrations because they raise the CO2 concentration dramatically around the carboxylase. This rise in the intracellular CO2 concentration involves the active transport of HCO3− and CO2, perhaps by separate transport systems. The transport of HCO3− often requires millimolar levels of Na+, and this provides a ready means of initiating HCO3− transport. The active transport of CO2 requires only micromolar levels of Na+. In the rather dense cell suspensions used in transport studies the extent of CO2 uptake is often limited by the rate at which CO2 can be formed from the HCO3− in the medium. The addition of carbonic anhydrase relieves this kinetic limitation on CO2 transport. The active transport of CO2 can be selectively inhibited by the structural analog carbon oxysulfide (COS). When HCO3− transport is allowed in the presence of COS there is a substantial net leakage of CO2 from the cells. This leaked CO2 results from the intracellular dehydration of the accumulated HCO3−. This CO2 is normally scavenged by the active CO2 pump. If cells are allowed to transport H13C18O18O18O− for 5 s and if CO2 transport is suddenly quenched by the addition of COS, then a rapid leakage of 13C16O16O occurs. If the rapidly released CO2 was actually present in the cells before the addition of the COS, then the intracellular CO2 concentration would have been about 0.6 mM. Not only is this a high concentration, but since the leaked CO2 was completely depleted of the initial 18O, it must have been in rapid equilibrium with the total dissolved inorganic carbon within the cells. Cells grown on high levels of inorganic carbon, either as CO2 or HCO3−, lack the active HCO3− system but still retain a capacity, albeit reduced, for CO2 transport. Cyanobacteria seem to adjust their complement of inorganic carbon transport systems so that the K0.5 for transport is close to the inorganic carbon concentration of the growth medium.

Analysis of high CO2 requiring mutants indicates a central role for the 5′ flanking region of rbc and for the carboxysomes in cyanobacterial photosynthesis

1990 ◽  
Vol 68 (6) ◽  
pp. 1303-1310 ◽  
Author(s):  
Aaron Kaplan
Keyword(s):  
Inorganic Carbon ◽  
Quantitative Model ◽  
Photosynthetic Performance ◽  
Kanamycin Resistance ◽  
Open Reading Frames ◽  
Bisphosphate Carboxylase ◽  
Insertional Inactivation ◽  
Flanking Region ◽  
Inorganic Carbon Transport ◽  
Reading Frames

The mutants E1 and O221, isolated from Synechococcus sp. PCC7942, exhibit a very low apparent photosynthetic affinity for both extracellular and intracellular inorganic carbon and hence require high CO2 concentrations for growth. These mutants possess defective carboxysomes, but the activity of ribulose 1,5-bisphosphate carboxylase is normal. The mutations in these mutants have been mapped to the 5′-flanking region of rbc, and two open reading frames, the functions of which are not yet known, have been identified in this region. Insertional inactivation (by inserting a kanamycin-resistance cartridge) of one of these open reading frames, where the mutation in O221 is located, resulted in a new high CO2 requiring phenotype. This mutant contains defective carboxysomes similar to those of O221. The role of the rbc and its 5′-flanking region in the photosynthetic performance of cyanobacteria and the structural organization of the carboxysomes are discussed in view of our recently proposed quantitative model for inorganic carbon transport and photosynthesis in cyanobacteria.

Environmental regulation of CO2-concentrating mechanisms in microalgae

1998 ◽  
Vol 76 (6) ◽  
pp. 1010-1017 ◽  
Author(s):  
John Beardall ◽  
Andrew Johnston ◽  
John Raven
Keyword(s):  
Inorganic Carbon ◽  
Light Availability ◽  
Phosphorus Limitation ◽  
Aeration Rate ◽  
Carbon Accumulation ◽  
Ribulose Bisphosphate Carboxylase ◽  
Carbon Utilization ◽  
Bisphosphate Carboxylase ◽  
Inorganic Carbon Transport ◽  
Carbon Transport

Most microalgae possess a mechanism for actively transporting inorganic carbon that concentrates CO2 at the active site of the carbon fixing enzyme ribulose bisphosphate carboxylase-oxygenase (Rubisco). This review considers the effects of environmental factors on the capacity and activity of microalgal CO2-concentrating mechanisms. Limitation of energy supply by light availability decreases the rate of inorganic carbon transport and cells grown under light-limited conditions have a reduced capacity for CO2 accumulation. Phosphorus limitation also reduces the capacity of algal cells to accumulate CO2, whereas both the rate of supply of nitrogen and the form in which it is made available interact in various complex ways with carbon utilization. The potential role of other nutrients in modulating inorganic carbon transport is also discussed. The capacity of algae for carbon accumulation is also affected by CO2 supply, which, in turn, is a function of the interactions between ionic strength of the growth medium, pH, cell density in culture, aeration rate, and inorganic carbon concentration in the medium. The effects of these interacting parameters are discussed, together with an assessment of the possible roles and significance of CO2-concentrating mechanisms to microalgae in marine and freshwater ecosystems.Key words: carbon acquisition, microalgae, CO2-concentrating mechanism, light, nutrient limitation, CO2 supply.

scholarly journals The role of the seed coat in the light sensivity in Raphanus sativus L. cv. redondo gigante seeds

1997 ◽  
Vol 11 (1) ◽  
pp. 55-60
Author(s):  
Maura Lúcia Costa Gonçalves ◽  
Massanori Takaki
Keyword(s):  
Seed Coat ◽  
Raphanus Sativus ◽  
Red Light ◽  
Light Sensitivity ◽  
Percentage Germination ◽  
Raphanus Sativus L ◽  
Light Inhibition ◽  
Glycol Solution ◽  
High Inhibition

The role of the seed coat in the light sensitivity of seeds of Raphanus sativus L. cv. redondo gigante was analysed by germination tests of intact and naked seeds. Far-red light caused high inhibition of seed germination, while under white and red lights low inhibition was found. Naked seeds presented no light sensitivity with high percentage germination under light and darkness. However, incubation of naked seeds in -0.6MPa polyethylene glycol solution resulted in light inhibition as observed in intact seeds. The analysis of the seed coat transmitted light indicated that the filtered light presented the same photoequilibrium of phytochrome when compared to the white light, with a decrease of only 33% in the light irradiance which reaches the embryo.

Red Light Signals Repair

2006 ◽  
Vol 2006 (322) ◽  
pp. tw57-tw57
Keyword(s):  
Red Light ◽  
Light Signals

Effects of nitrogen limitation on uptake of inorganic carbon and specific activity of ribulose-1,5-bisphosphate carboxylase/oxygenase in green microalgae

1991 ◽  
Vol 69 (5) ◽  
pp. 1146-1150 ◽  
Author(s):  
John Beardall ◽  
Simon Roberts ◽  
Jenny Millhouse
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Growth Rates ◽  
Nitrogen Limitation ◽  
Inorganic Carbon ◽  
Marked Decrease ◽  
Specific Activity ◽  
Green Microalgae ◽  
Bisphosphate Carboxylase ◽  
Cell Basis

The effects of nitrogen limitation on the characteristics of inorganic carbon-dependent O2 evolution have been examined in the green microalgae Chlorella emersonii and Gloeomonas sp. When cells were grown under 5% CO2 or air, decreasing the growth rate (increasing nitrogen limitation) caused a decrease in maximum rates of photosynthetic O2 evolution, although when expressed on a per cell basis such changes were only evident at growth rates below 0.16 day−1. Severe nitrogen limitation also caused a marked decrease in k1/2 (CO2) in light- and CO2-dependent O2 evolution. Although values for this parameter were not as low as for low CO2 grown cells with a fully induced CO2-concentrating mechanism, they were less than one-half the corresponding values from cells with the mechanism fully repressed. Nitrogen-limitation also resulted in decreases in the activity and cellular content of ribulose-1,5-bisphosphate carboxylase/oxygenase. The changes to activity and levels of this enzyme were not equivalent so the specific activity decreased dramatically between growth rates of 0.57 and 0.25 day−1. Similar effects were noted in Gloeomonas and in air-grown Chlorella. The results are discussed in relation to regulation of CO2 uptake and assimilation in microalgae. Key words: microalgae, CO2 assimilation, nitrogen limitation, Rubisco, Chlorella.

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