Flavodoxin from the nitrogen-fixing cyanobacterium Anabaena PCC 7119

Flavodoxin has been isolated and purified from cultures of the cyanobacterium Anabaena cultivated in a low-iron medium. This flavoprotein has a molecular weight of 20,000 and contains 1 molecule of flavin mononucleotide per mol of protein. Various biochemical characteristics are reported including amino-acid composition, isoelectric point and the fluorescence properties of the apoprotein. The extinction coefficients and isosbestic points were determined for the oxidized and semiquinone forms of flavodoxin. The electron paramagnetic resonance spectrum of the semiquinone exhibited a spectral linewidth of 23 G, which is typical for a neutral flavoprotein semiquinone. Kinetic measurements give a rate constant of 9.6×10⁷ (M^-1 min^-1) for the reduction of flavodoxin in the photosynthetic electron-transport chain by the photosystem I and 6.6×10⁶ for the reaction in which flavodoxin is reduced by ferredoxin-NADP⁺ oxidoreductase. The Michaelis constant for electron donation to nitrogenase by reduced flavodoxin is 8.5 M.Abbreviations FMN flavin mononucleotide - FNR ferredoxin-NADP⁺ oxidoreductase - PSI photosystem I     

Molecular evolution of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO)

Abstract The evolutionary relationship of the RuBisCO large subunit gene(s) ( rbcL ) of several prokaryotes was examined using the technique of heterologous DNA hybridization. Restriction fragments of cloned rbcL from Anacystis nidulans 6301, Chlamydomonas reinhardtii, Rhodospirillum rubrum , and maize were nick-translated and used as probes. The C. reinhardtii and maize probes hybridized with restriction fragment(s) only from cyanobacteria: Agmenellum quadruplicatum, Fremyella diplosiphon , and Mastigocladus laminosus . In addition, the A. nidulans probe hybridized with restriction fragment(s) from Alcaligenes eutrophus, Chromatium vinosum, Nitrobacter hamburgensis, Paracoccus denitrificans, Pseudomonas oxalaticus, Rhodomicrobium vannielii, Rhodopseudomonas capsulata, Rhodopseudomonas palustris, Rhodopseudomonas sphaeroides, Thiobacillus intermedius, Thiobacillus neapolitanus , and Thiothrix nivea . The elucidated fragment of Rhodopseudomonas species is presumably for the Form I RuBisCO LSU of these organisms. The R. rubrum probe hybridized only to a restriction fragment(s) from R. capsulata, R. palustris, R. sphaeroides, T. neapolitanus , and T. nivea . The fragment(s) of Rhodopseudomonas species is the Form II rbcL of these organisms. The restriction fragments of T. neapolitanus and T. nivea were also different from those elucidated by the A. nidulans probe, suggesting the presence of a second (different) rbcL in these organisms. Positive hybridization was not obtained using any of the probes with DNA from Beggiatoa alba, Chlorobium vibrioforme or Chloroflexus aurantiacus . It appears that all rbcL have evolved from a common ancestor. Our data are consistent with and supportive of the evolutionary scheme for RuBisCO proposed by Akazawa, Takabe, and Kobayashi [1].     

The effect of divalent metal ions on the activity of Mg++ depleted ribulose-1,5-bisphosphate oxygenase

Ribulose-1,5-bisphosphate carboxylase-oxygenase is deactivated by removal of Mg⁺⁺. The enzyme activities can be restored to a different extent by the addition of various divalent ions in the presence of CO₂. Incubation with Mg⁺⁺ and CO₂ restores both enzyme activities, whereas, the treatment of the enzyme with the transition metal ions (Mn⁺⁺, Co⁺⁺, and Ni⁺⁺) and CO₂ fully reactivates the oxygenase: however, the carboxylase activity remains low. In experiments where CO₂-free conditions were conscientiously maintained, no reactivation of RuBP oxygenase was observed, although Mn⁺⁺ ions were present. Other divalent cations such as Ca⁺⁺ and Zn⁺⁺, restore neither the carboxylase nor the oxygenase reaction. Furthermore, the addition of Mn⁺⁺ to the Mg⁺⁺ and CO₂ preactivated enzyme significantly inhibited carboxylase reactions, but increased the oxygenase reaction.Abbreviation RuBP ribulose-1,5-bisphosphate. The enyme unit for RuBP carboxylase is defined as mol CO₂ fixed·min^-1 and for the RuBP oxygenase as mol O₂ consumed · min^-1     

Immuno-gold localization of glutamine synthetase in a nitrogen-fixing cyanobacterium (Anabaena cylindrica)

Localization of glutamine synthetase in thin sections of nitrogen-fixing Anabaena cylindrica was performed using immuno-gold/transmission electronmicroscopy. The enzyme was present in all of the three cell types possible; vegetative cells, heterocysts and akinetes. The specific gold label was always more pronounced in heterocysts compared with vegetative cells, and showed a uniform distribution in all three types. No specific label was associated with subcellular inclusions such as carboxysomes, cyanophycin granules and polyphosphate granules. When anti-glutamine synthetase antiserum was omitted, no label was observed.Abbreviation GS glutamine synthetase     

Hydrogen metabolism in isolated heterocysts of Anabaena 7120

Isolated heterocysts of Anabaena 7120 evolve H₂ in an ATP-dependent nitrogenase-catalyzed process that is inhibited by N₂ and C₂H₂. Heterocysts have an active uptake hydrogenase that only requires an electron acceptor of positive redox potential, e.g., methylene blue, dichlorophenolindophenol or potassium ferricyanide. O₂ supplied at low partial pressures is a very effective physiological oxidant for H₂ uptake. High concentrations of O₂ are inhibitory to H₂ uptake. The oxyhydrogen reaction in heterocysts appears to be mediated by a cytochrome-cytochrome oxidase system, and it supports ATP synthesis via oxidative phosphorylation. Attempts to demonstrate acetylene reduction in isolated heterocysts employing H₂ as an electron donor were unsuccessful. It is suggested that the uptake hydrogenase functions to conserve reductant that otherwise would be dissipated via nitrogenase-catalyzed H₂ evolution.     

Characterization of the pyrenoid isolated from unicellular green algaChlamydomonas reinhardtii: Particulate form of RuBisCO protein

Summary The pyrenoid is a protein complex in the chloroplast stroma of eukaryotic algae. After the treatment with mercury chloride, pyrenoids were isolated by sucrose density gradient centrifugation from cell-wall less mutant cells, CW-15, as well as wild type cells, C-9, of unicellular green algaChlamydomonas reinhardtii. Pyrenoids were characterized as a fraction whose protein/chlorophyll ratio was very high, and also examined by Nomarski differential interference microscopy. Most of the components consisted of 55 kDa and 16 kDa polypeptides (11) which were immunologically identified as the large and small subunit of RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) protein, respectively. Some minor polypeptides were also detected. Substantial amount of RuBisCO protein is present as a particulate form in the pyrenoid in addition to the soluble form in algal chloroplast stroma.Abbreviations BPB bromophenol blue - DAB 3,3-diaminobenzidine - DTT dithiothreitol - ELISA enzyme-linked immunosorbent assay - High-CO₂ cells cells grown under air enriched with 4% CO₂ - Low-CO₂ cells cells grown under ordinary air (containing 0.04% CO₂) - NP-40 nonionic detergent (Nonidet) P-40 - PAGE polyacrylamide gel electrophoresis - PAP peroxidase-antiperoxidase conjugate - RuBisCO ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP ribulose-1,5-bisphosphate - SDS sodium dodecylsulfate     

Light and metabolite regulation of the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase and the corresponding mRNAs in the unicellular alga Chlorogonium

In the unicellular green alga Chlorogonium elongatum, the synthesis of the plastid enzyme ribulose bisphosphate carboxylase/oxygenase (RuBPCase) and its mRNAs is under the control of light and acetate. Acetate is the sole metabolizable organic carbon source for this organism. Light greatly promotes the synthesis of RuBPCase and the increase in the concentration of the mRNAs of both subunits of the enzyme while acetate has a strong inhibitory effect on this process. There is a good agreement between RuBPCase synthesis and the amount of translateable RuBPCase mRNA present in cells which are cultured under different conditions (autotrophic, heterotrophic, mixotrophic). During the transition period after transfer of the cells from heterotrophic to autotrophic growth conditions the amounts of the large and small subunits of the enzyme increase well coordinated. In contrast to the protein subunits the two subunit-mRNAs accumulate with different kinetics.Abbreviations LSU large subunit of RuBPCase - poly(A)^- RNA - poly(A)⁺RNA non-, poly-adenylated RNA - RuBPCase ribulose-1,5-bisphosphate carboxylase/oxygenase EC 4.1.1.39 - SSU small subunit of RuBPCase     

Photosynthesis and photorespiration in a mutant of the cyanobacterium Synechocystis PCC 6803 lacking carboxysomes

A mutant of the cyanobacterium Synechocystis PCC 6803 was obtained by replacing the gene of the carboxylation enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) with that of the photosynthetic bacterium Rhodospirillum rubrum. This mutant consequently lacks carboxysomes — the protein complexes in which the original enzyme is packed. It is incapable of growing at atmospheric CO₂ levels and has an apparent photosynthetic affinity for inorganic carbon (C_i) which is 1000 times lower than that of the wild type, yet it accumulates more C_i than the wild type. The mutant appears to be defective in its ability to utilize the intracellular C_i pool for photosynthesis. Unlike the carboxysomal carboxylase activity of Rubisco, which is almost insensitive to inhibition by O₂ in vitro, the soluble enzyme is competitively inhibited by O₂. The photosynthetic rate and C_i compensation point of the wild type were hardly affected by low O₂ levels. Above 100 μM O₂, however, both parameters became inhibited. The CO₂ compensation point of the mutant was linearly dependent on O₂ concentration. The higher sensitivity of the mutant to O₂ inhibition than that expected from in-vitro kinetics parameters of Rubisco, indicates a low capacity to recycle photorespiratory metabolites to Calvin-cycle intermediates.     

Long-term chilling of young tomato plants under low light

The properties of two Calvin-cycle key enzymes, i.e. stromal fructose-1,6-bisphosphatase (sFBPase) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were studied in the cultivated tomato (Lycopersicon esculentum Mill.) and in four lines of a wild tomato (L. peruvianum Mill.) from different altitudes. During chilling for 14 d at 10°C and low light, the activation energy (E_A) of the reaction catalyzed by sFBPase decreased by 5–10 kJ·mol^–1 inL. esculentum and the threeL. peruvianum lines from high altitudes. InL. peruvianum, no loss or only small losses of enzyme activity were observed during the chilling. Together with the change in E_A, this indicates that the latter species is able to acclimate its Calvin-cycle enzymes to low temperatures. InL. esculentum, the chilling stress resulted in the irreversible loss of 57% of the initial sFBPase activity. Under moderately photoinhibiting chilling conditions for 3 d, theL. peruvianum line from an intermediate altitude showed the largest decreases in both the ratio of variable to maximum chlorophyll fluorescence (F_v/F_m) and the in-vivo activation state of sFBPase, while the otherL. peruvianum lines showed no inhibition of sFBPase activation. Ribulose-1,5-bisphosphate carboxylase/oxygenase was isolated by differential ammonium-sulfate precipitation and gel filtration and characterized by two-dimensional electrophoresis. The enzyme fromL. esculentum had three isoforms of the small subunit of Rubisco, each with different isoelectric points. Of these, theL. peruvianum enzyme contained only the two more-acidic isoforms. Arrhenius plots of the specific activity of purified Rubisco showed breakpoints at approx. 17°C. Upon chilling, the specific activity of the enzyme fromL. esculentum decreased by 51%, while E_A below the breakpoint temperature increased from 129 to 189 kJ·mol^–1. In contrast, Rubisco from theL. peruvianum lines from high altitudes was unaffected by chilling. We tested several possibile explanations for Rubisco inactivation, using two-dimensional electrophoresis, analytical ultracentrifugation, gel filtration and inhibitor tests. No indications were found for differential expression of the subunit isoforms, proteolysis, aggregation, subunit disassembly, or inhibitor accumulation in the enzyme from chilledL. esculentum. We suggest that the activity loss in theL. esculentum enzyme upon chilling is the result of a modification of sulfhydryl groups or other sidechains of the protein.Abbreviations a.s.l. above sea level - Chl chlorophyll - DTT dithiothreitol - E_A activation energy - FBP fructose-1,6-bisphosphate - F_v/F_m ratio of variable to maximum chlorophyll fluorescence - HL high light (500 mol photons·m^–2·s^–1) - LSU large subunit of Rubisco - ME 2-mercaptoethanol - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP ribulose-1,5-bisphosphate - sFBPase stromal fructose-1,6-bisphosphatase - SSU small subunit of Rubisco     

Isolation and partial characterization of pyrenoids from the brown alga Pilayella littoralis (L.) Kjellm.

In order to isolate high yields of pyrenoids from the brown alga Pilayella littoralis it is necessary to pretreat them with 0.1% HgCl₂ in sea water for 3 h. Without this pretreatment there is a substantial loss of pyrenoid ground substance and yields are low. Pyrenoid fractions of high purity have been obtained using silica sol gradients. A partial characterization has shown the pyrenoid to be proteinaceous and lacking chlorophyll. SDS polyacrylamide gel electrophoresis has shown that the majority of protein present is accounted for by two polypeptides which resemble the large and small subunits of ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39).Abbreviations DTT dithiothreitol - HEPES N-2-hydroxyethylniperazine N¹-2-ethanesulfonic acid - PEG polyethylene glycol - PVPP polyvinylpolypyrrolidone - RuBP ribulose-1,5-bisphosphate - RuBPCase ribulose-1,5-bisphosphate carboxylase - SDS sodium dodecyl sulphate     

Proteolysis and transition-state-analogue binding of mutant forms of ribulose-1,5-bisphosphate carboxylase/oxygenase from Chlamydomonas reinhardtii

Trypsin digestion reduces the sizes of both the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) from the green alga Chlamydomonas reinhardtii. Incubation of either CO₂/Mg²⁺ -activated or nonactivated enzyme with the transition-state analogue carboxyarabinitol bisphosphate protects a trypsin-sensitive site of the large subunit, but not of the small subunit. Incubation of the nonactivated enzyme with ribulosebisphosphate (RuBP) provided the same degree of protection. Thus, the very tight binding that is a characteristic of the transitionstate analogue is apparently not required for the protection of the trypsin-sensitive site of the large subunit. Mutant enzymes that have reduced CO₂/O₂ specificities failed to bind carboxyarabinitol bisphosphate tightly. However, their large-subunit trypsin-sensitive sites could still be protected. The K _m values for RuBP were not significantly changed for the mutant enzymes, but the V _max values for carboxylation were reduced substantially. These results indicate that the failure of the mutant enzymes to bind the transition-state analogue tightly is primarily the consequence of an impairment in the second irreversible binding step. Thus, in all of the mutant enzymes, defects appear to exist in stabilizing the transition state of the carboxylation step, which is precisely the step proposed to influence the CO₂/O₂ specificity of Rubisco.Abbreviations and Symbols CABP 2-carboxyarabinitol 1,5-bisphosphate - enol-RuBP 2,3-enediolate of ribulose 1,5-bisphosphate - K _c K _m for CO₂ - K _o K _m for O₂ - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP ribulose 1,5-bisphosphate - V _c V _max for carboxylation - V _o V _max for oxygenation Paper No. 9313, Journal Series, Nebraska Agricultural Research DivisionThis work was supported by National Science Foundation grant DMB-8703820. We thank Drs. Archie Portis and Raymond Chollet for their helpful comments, and also thank Dr. Chollet for graciously providing CABP and [¹⁴C]CABP.     

Cold-hardening results in increased activity of enzymes involved in carbon metabolism in leaves of winter rye (Secale cereale L.)

Light- and CO₂-saturated photosynthesis of nonhardened rye (Secale cereale L. cv. Musketeer) was reduced from 18.10 to 7.17 mol O₂·m^–2·s^–1 when leaves were transferred from 20 to 5°C for 30 min. Following cold-hardening at 5°C for ten weeks, photosynthesis recovered to 15.05 mol O₂·m^–2·s^–1,comparable to the nonhardened rate at 20°C. Recovery of photosynthesis was associated with increases in the total activity and activation of enzymes of the photosynthetic carbon-reduction cycle and of sucrose synthesis. The total hexose-phosphate pool increase by 30% and 120% for nonhardened and cold-hardened leaves respectively when measured at 5°C. The large increase in esterified phosphate in coldhardened leaves occurred without a limitation in inorganic phosphate supply. In contrast, the much smaller increase in esterified phosphate in nonhardened leaves was associated with an inhibition of ribulose-1,5-bisphosphate carboxylase/oxygenase and sucrose-phosphate synthase activation. It is suggested that the large increases in hexose phosphates in cold-hardened leaves compensates for the higher substrate threshold concentrations needed for enzyme activation at low temperatures. High substrate concentrations could also compensate for the kinetic limitations imposed by product inhibition from the accumulation of sucrose at 5°C. Nonhardened leaves appear to be unable to compensate in this fashion due to an inadequate supply of inorganic phosphate.Abbreviations DHAP dihydroxyacetone phosphate - Fru6P fructose-6-phosphate - Fru 1,6BP fructose-1,6-bisphosphate - Fru1,6BPase fructose-1,6-bisphosphatase - Glc6P glucose-6-phosphate - PGA 3-phosphoglycerate - PPFD photosynthetic photon flux density - CH cold-hardened rye grown at 5°C - NH nonhardened rye grown at 24°C - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP ribulose-1,5-bisphosphate - SPS sucrose-phosphate synthase - UDPGlc uridine 5-diphosphoglucose This work was supported by operating grants from the Swedish Natural Sciences Research Council to G.Ö. and P.G.     

Evolution of the tetraploidCapsella bursa-pastoris (Brassicaceae): Isoelectric focusing analysis of Rubisco

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) and its subunits (large subunits = LSU, small subunits = SSU) were isolated from threeCapsella spp. by gel electrophoresis and polypeptide composition was analyzed by isoelectric focusing (IEF) in the presence of 8M urea. The described techniques are recommended for large scale systematic studies. Multiple IEF banding patterns of the SSU are probably the outcome of a heterogenous multigene family. The two diploid speciesC. rubella andC. grandiflora show an identical IEF pattern and could be differentiated from the putative allotetraploidC. bursa-pastoris only by the SSU banding pattern. Uniqueness of some SSU bands in the tetraploid and in the two diploid species, respectively, may indicate an ancient alloploid origin of tetraploidC. bursa-pastoris followed by events leading to divergences in the genomes of the allotetraploid and its presumed diploid progenitors after the hybridization event (SSU gene elimination, acquisition of new SSU genes).     

Sucrose synthase and RuBisCo expression is similarly regulated by the nitrogen source in the nitrogen-fixing cyanobacterium Anabaena sp.

In higher plants and cyanobacteria, sucrose (Suc) metabolism is carried out by a similar set of enzymes. The function and regulation of Suc metabolism in cyanobacteria has begun to be elucidated. In strains of Anabaena sp., filamentous nitrogen-fixing cyanobacteria, Suc synthase (SuS, EC 2.4.1.13) controls Suc cell level through the cleavage of the disaccharide. The present work shows that there are two sus genes in Anabaena (Nostoc) sp. that are co-regulated regarding the nitrogen source; however, only susA accounts for the extractable SuS activity and for the control of the Suc level. Primer extension analysis has uncovered the sequence of the Anabaena susA and susB ammonium-activated putative promoters, which share a high sequence similarity with that of rbcLS encoding ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39) and other ammonium up-regulated genes. Moreover, susA and rbcLS expression is developmentally co-localized to the vegetative cells of the nitrogen-fixing cyanobacterial filaments. Our results strongly suggest the existence of a regulatory network that would coordinate the expression of key genes for Suc and nitrogen metabolism, carbon fixation, and development in Anabaena sp.     

Localization of GroEL determined by in vivo incorporation of a fluorescent amino acid

The molecular chaperone GroEL is required for bacterial growth under all conditions, mediating folding assistance, via its central cavity, to a diverse set of cytosolic proteins; yet the subcellular localization of GroEL remains unresolved. An earlier study, using antibody probing of fixed Escherichia coli cells, indicated colocalization with the cell division protein FtsZ at the cleavage furrow, while a second E. coli study of fixed cells indicated more even distribution throughout the cytoplasm. Here, for the first time, we have examined the spatial distribution of GroEL in living cells using incorporation of a fluorescent unnatural amino acid into the chaperone. Fluorescence microscopy indicated that GroEL is diffusely distributed, both under normal and stress conditions. Importantly, the present procedure uses a small, fluorescent unnatural amino acid to visualize GroEL in vivo, avoiding the steric demands of a fluorescent protein fusion, which compromises proper GroEL assembly. Further, this unnatural amino acid incorporation avoids artifacts that can occur with fixation and antibody staining.     

Purification and properties of ribulose 1,5-bisphosphate carboxylase from sunflower leaves

Extracts from sunflower leaves possess a high ribulose-1,5-bisphosphate (RuBP) carboxylase capacity but this enzyme activity is not stable. A purification procedure, developed with preservation of carboxylase activity by MgSO₄, yielded purified RuBP carboxylase with high specific activity (40 nkat mg^-1 protein). Measurement of kinetic parameters showed high Km values (RuBP, HCO ₃ ^- ) and high Vmax of the reaction catalyzed by this sunflower enzyme; the results are compared with those obtained for soybean carboxylase. Enzyme characteristics are discussed in relation to stabilization and activation procedures and to the high photosynthesis rates of this C₃ species.     

Differential expression of the genes for ribulose-1,5-bisphosphate carboxylase and light-harvesting chlorophyll a/b protein in the developing barley leaf

The expression of genes in particular for light-harvesting chlorophyll a/b protein (LHCP) and ribulose-1,5-bisphosphate carboxylase (RuBPCase) has been studied in the developing barley leaf. This has been done by analysis of the occurrence of both proteins within the different regions (1 to 6, beginning from the base) of the primary 7-day-old leaf. It has been found that LHCP already appears in the base of the leaf, whereas RuBPCase is primarily expressed in the apical expanding part of the leaf. The distribution of the mRNAs for both proteins within this gradient is in accordance with that of the proteins themselves, indicating that gene expression is not regulated at the level of translation in both cases. The poly(A) mRNA for LHCP occurs mainly in the basic sections 2 and 3, whereas that for RuBPCase is found throughout the leaf but primarily in the apical sections of the leaf.Abbreviations LHCP light-harvesting chlorophyll a/b protein - RuBPCase ribulose-1,5-bisphosphate carboxylase - TCA trichloroacetic acid     

Regulatory factors involved in gene expression (subunits of ribulose-1,5-bisphosphate carboxylase) in mustard (Sinapis alba L.) cotyledons

Phytochrome-controlled appearance of ribulose-1,5-bisphosphate carboxylase (RuBP-Case) and its subunits (large subunit LSU, small subunit SSU) was studied in the cotyledons of the mustard (Sinapis alba L.) seedling. The main results were as follows: (i) Control of RuBPCase appearance by phytochrome is a modulation of a process which is turned on by an endogenous factor between 30 and 33 h after sowing (25° C). Only 12 h later the process begins to respond to phytochrome. (ii) The rise in the level of RuBP-Case is the consequence of a strictly coordinated synthesis de novo of the subunits. (iii) While the levels of translatable mRNA for SSU are compatible with the rate of SSU synthesis the relatively high LSU mRNA levels are not reflected in the rates of in-vivo LSU or RuBPCase syntheses. (iv) Gene expression is also abolished in the case of nuclear-encoded SSU if intraplastidic translation and concomitant plastidogenesis is inhibited by chloramphenicol, pointing to a plastidic factor as an indispensable prerequisite for expression of the SSU gene(s). (v) Regarding the control mechanism for SSU gene expression, three factors seem to be involved: an endogenous factor which turns on gene expression, phytochrome which modulates gene expression, and the plastidic factor which is an indispensable prerequisite for the appearance of translatable SSU mRNA.Abbreviations CAP chloramphenicol - cFR continuous farred light - LSU large subunit of RuBPCase - NADP-GPD NADPH-dependent glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13) - Pfr far-red-absorbing form of phytochrome - pSSU precursor of SSU - RuBPCase ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) - SSU small subunit of RuBPCase