Periplasmic Carbonic Anhydrase Structural Gene (<i>Cah1</i>) Mutant in <i>Chlamydomonas reinhardtii</i>1

Van, Kyujung; Spalding, Martin H.

doi:10.1104/pp.120.3.757

Cited by 86 publications

(82 citation statements)

References 40 publications

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“…The current controversy about the physiological role of the periplasmic CA in C. reinhardtii underscores this problem. AZ clearly inhibits photosynthesis at high external pH and low inorganic carbon concentrations in C. reinhardtii (Moroney et al 1985), yet a C. reinhardtii mutant lacking the periplasmic CAH1 protein appears to grow normally (Van & Spalding 1999). This controversy will be discussed more in the next section.…”

Section: Unresolved Questionsmentioning

confidence: 99%

“…Van & Spalding (1999) reported that C. reinhardtii cells with a defective CAH1 gene grew as well as wild-type cells on low CO 2 concentrations. Their data would imply that the periplasmic CA is not required for optimal diffusion of CO 2 across the plasma membrane.…”

Section: Periplasmic Camentioning

confidence: 99%

“…There are a number of explanations for the different results obtained with inhibitors and mutants. The first is that most of Van and Spalding's growth and photosynthesis data were obtained at external pH close to neutral (Van & Spalding 1999). Perhaps the growth of the mutant would be impaired under more alkaline conditions.…”

Section: Periplasmic Camentioning

confidence: 99%

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Carbonic anhydrases in plants and algae

Moroney¹,

Bartlett²,

Samuelsson³

2001

Plant Cell Environ

108

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Carbonic anhydrases catalyse the reversible hydration of CO 2 , increasing the interconversion between CO 2 and HCO 3 -+ H + in living organisms. The three evolutionarily unrelated families of carbonic anhydrases are designated a-, b-and g-CA. Animals have only the a-carbonic anhydrase type of carbonic anhydrase, but they contain multiple isoforms of this carbonic anhydrase. In contrast, higher plants, algae and cyanobacteria may contain members of all three CA families. Analysis of the Arabidopsis database reveals at least 14 genes potentially encoding carbonic anhydrases. The database also contains expressed sequence tags (ESTs) with homology to most of these genes. Clearly the number of carbonic anhydrases in plants is much greater than previously thought. Chlamydomonas, a unicellular green alga, is not far behind with five carbonic anhydrases already identified and another in the EST database. In algae, carbonic anhydrases have been found in the mitochondria, the chloroplast thylakoid, the cytoplasm and the periplasmic space. In C 3 dicots, only two carbonic anhydrases have been localized, one to the chloroplast stroma and one to the cytoplasm. A challenge for plant scientists is to identify the number, location and physiological roles of the carbonic anhydrases.

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Section: Unresolved Questionsmentioning

confidence: 99%

Section: Periplasmic Camentioning

confidence: 99%

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Carbonic anhydrases in plants and algae

Moroney¹,

Bartlett²,

Samuelsson³

2001

Plant Cell Environ

108

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“…Glass bead transformations were performed as described previously (Van and Spalding, 1999). Air-dier mutant ad1 was transformed with linearized plasmid pSI103 (Sizova et al, 2001) and spread onto CO 2 -minimal plates containing 15 mg/mL paromomycin.…”

Section: Isolation Of Suppressors Growth Spot Tests and Genetic Anamentioning

confidence: 99%

Thylakoid Lumen Carbonic Anhydrase (CAH3) Mutation Suppresses Air-Dier Phenotype of LCIB Mutant in Chlamydomonas reinhardtii

2008

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An active CO 2 -concentrating mechanism is induced when Chlamydomonas reinhardtii acclimates to limiting inorganic carbon (Ci), either low-CO 2 (L-CO 2 ; air level; approximately 0.04% CO 2 ) or very low-CO 2 (VL-CO 2 ; approximately 0.01% CO 2 ) conditions. A mutant, ad1, which is defective in the limiting-CO 2 -inducible, plastid-localized LCIB, can grow in high-CO 2 or VL-CO 2 conditions but dies in L-CO 2 , indicating a deficiency in a L-CO 2 -specific Ci uptake and accumulation system. In this study, we identified two ad1 suppressors that can grow in L-CO 2 but die in VL-CO 2 . Molecular analyses revealed that both suppressors have mutations in the CAH3 gene, which encodes a thylakoid lumen localized carbonic anhydrase. Photosynthetic rates of L-CO 2 -acclimated suppressors under acclimation CO 2 concentrations were more than 2-fold higher than ad1, apparently resulting from a more than 20-fold increase in the intracellular concentration of Ci as measured by direct Ci uptake. However, photosynthetic rates of VL-CO 2 -acclimated cells under acclimation CO 2 concentrations were too low to support growth in spite of a significantly elevated intracellular Ci concentration. We conclude that LCIB functions downstream of CAH3 in the CO 2 -concentrating mechanism and probably plays a role in trapping CO 2 released by CAH3 dehydration of accumulated Ci. Apparently dehydration by the chloroplast stromal carbonic anhydrase CAH6 of the very high internal Ci caused by the defect in CAH3 provides Rubisco sufficient CO 2 to support growth in L-CO 2 -acclimated cells, but not in VL-CO 2 -acclimated cells, even in the absence of LCIB.CO 2 serves both as the substrate for photosynthesis and as an important signal to regulate plant growth and development, so variable CO 2 concentrations can impact photosynthesis, growth, and productivity of plants. Terrestrial C 4 plants have developed a CO 2 -concentrating mechanism (CCM) involving anatomical and biochemical adaptations to accumulate a higher concentration of CO 2 as substrate Rubisco and to suppress oxygenation of ribulose-1,5-bisP, a wasteful side reaction. In contrast, a different type of CCM is induced in the unicellular green microalga Chlamydomonas reinhardtii when the supply of dissolved inorganic carbon (Ci; CO 2 and HCO 3 2

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“…Southern-and northern-blot analyses were performed as described by Van and Spalding (1999). Total RNA was purified with TRIzol reagent (Life Technologies, Gaithersburg, MD) from air-induced cells exposed to limiting CO 2 (aeration with normal air) and Hybond N ϩ nylon transfer membrane (Amersham Pharmacia Biotech Inc., Piscat-…”

Section: Dna-and Rna-blot Analysismentioning

confidence: 99%

Insertional Mutants of Chlamydomonas reinhardtii That Require Elevated CO2 for Survival

et al. 2001

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Aquatic photosynthetic organisms live in quite variable conditions of CO 2 availability. To survive in limiting CO 2 conditions, Chlamydomonas reinhardtii and other microalgae show adaptive changes, such as induction of a CO 2 -concentrating mechanism, changes in cell organization, increased photorespiratory enzyme activity, induction of periplasmic carbonic anhydrase and specific polypeptides (mitochondrial carbonic anhydrases and putative chloroplast carrier proteins), and transient down-regulation in the synthesis of Rubisco. The signal for acclimation to limiting CO 2 in C. reinhardtii is unidentified, and it is not known how they sense a change of CO 2 level. The limiting CO 2 signals must be transduced into the changes in gene expression observed during acclimation, so mutational analyses should be helpful for investigating the signal transduction pathway for low CO 2 acclimation. Eight independently isolated mutants of C. reinhardtii that require high CO 2 for photoautotrophic growth were tested by complementation group analysis. These mutants are likely to be defective in some aspects of the acclimation to low CO 2 because they differ from wild type in their growth and in the expression patterns of five low CO 2 -inducible genes (Cah1, Mca1, Mca2, Ccp1, and Ccp2). Two of the new mutants formed a single complementation group along with the previously described mutant cia-5, which appears to be defective in the signal transduction pathway for low CO 2 acclimation. The other mutations represent six additional, independent complementation groups.Acclimation to changed environmental conditions is a key to survival for all organisms. In response to perceived environmental signals, organisms may exhibit specific adaptive changes, such as changes in the expression of key genes to survive specific environmental changes. Because CO 2 can vary substantially in aquatic habitats and represents the major substrate for photosynthetic CO 2 fixation via the enzyme Rubisco, CO 2 concentration is an important environmental signal in aquatic photosynthetic organisms including cyanobacteria and Chlamydomonas reinhardtii.Unlike terrestrial higher plants, aquatic photosynthetic organisms can face difficulties in acquiring CO 2 . Because the CO 2 diffusion rate in water is much slower than that in air (Badger and Spalding, 2000), the CO 2 supply to Rubisco in these aquatic photosynthetic organisms can become limited. C. reinhardtii and other aquatic photosynthetic organisms have a genetic program to allow them to acclimate to low CO 2 . This acclimation includes induction of a CO 2 -concentrating mechanism (CCM) that allows the cells to acquire CO 2 efficiently by increasing the CO 2 concentration around Rubisco under limiting CO 2 conditions (Badger et al., 1980; for review, see Spalding, 1998; Kaplan and Reinhold, 1999).Along with the induction of the CCM, C. reinhardtii shows adaptive changes to limiting CO 2 conditions, such as changes in cell organization (Geraghty and Spalding, 1996), increased photorespiratory enzyme ac...

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Periplasmic Carbonic Anhydrase Structural Gene (Cah1) Mutant in Chlamydomonas reinhardtii1

Cited by 86 publications

References 40 publications

Carbonic anhydrases in plants and algae

Carbonic anhydrases in plants and algae

Thylakoid Lumen Carbonic Anhydrase (CAH3) Mutation Suppresses Air-Dier Phenotype of LCIB Mutant in Chlamydomonas reinhardtii

Insertional Mutants of Chlamydomonas reinhardtii That Require Elevated CO2 for Survival

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