Rubisco content and photosynthesis of leaves at different positions in transgenic rice with an overexpression of <i>RBCS</i>

Suzuki, Yuji; Miyamoto, Takeaki; Yoshizawa, Ryuichi; Mae, Tadahiko; Makino, Amane

doi:10.1111/j.1365-3040.2009.01937.x

Cited by 98 publications

(91 citation statements)

References 42 publications

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“…In this report, RNAi knockdown of RbcS did not influence the expression of RbcL. However, in rice, the expression levels of RbcS, RbcL, and Rubisco were apparently correlated with each other among nontransgenic, RbcS-antisense and RbcS-sense lines (Suzuki et al, 2009a). Consistent with this, the overexpression of sorghum RbcS led to increase in the expression of RbcL and the content of Rubisco in this study (Figs.…”

Section: Content and Activation Of Rubisco In Transgenic Ricesupporting

confidence: 77%

“…The DNA polymerase was first activated at 94°C for 2 min, and PCR was carried out for 25 cycles of 30 s at 94°C, 30 s at 58°C, and 30 s at 68°C, followed by a final extension step for 7 min at 68°C. Quantitative RT-PCR was performed essentially as described by Suzuki et al (2009a) using gene-specific primers listed in Supplemental Table S2. PCR was carried out using SYBR Premix Ex Taq GC (Takara) and Thermal Cycler Dice TP800 (Takara) according to the manufacturer's instruction.…”

Section: Rt-pcr Analysesmentioning

confidence: 99%

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Functional Incorporation of Sorghum Small Subunit Increases the Catalytic Turnover Rate of Rubisco in Transgenic Rice

et al. 2011

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Rubisco limits photosynthetic CO 2 fixation because of its low catalytic turnover rate (k cat ) and competing oxygenase reaction. Previous attempts to improve the catalytic efficiency of Rubisco by genetic engineering have gained little progress. Here we demonstrate that the introduction of the small subunit (RbcS) of high k cat Rubisco from the C 4 plant sorghum (Sorghum bicolor) significantly enhances k cat of Rubisco in transgenic rice (Oryza sativa). Three independent transgenic lines expressed sorghum RbcS at a high level, accounting for 30%, 44%, and 79% of the total RbcS. Rubisco was likely present as a chimera of sorghum and rice RbcS, and showed 1.32-to 1.50-fold higher k cat than in nontransgenic rice. Rubisco from transgenic lines showed a higher K m for CO 2 and slightly lower specificity for CO 2 than nontransgenic controls. These results suggest that Rubisco in rice transformed with sorghum RbcS partially acquires the catalytic properties of sorghum Rubisco. Rubisco content in transgenic lines was significantly increased over wild-type levels but Rubisco activation was slightly decreased. The expression of sorghum RbcS did not affect CO 2 assimilation rates under a range of CO 2 partial pressures. The J max /V cmax ratio was significantly lower in transgenic line compared to the nontransgenic plants. These observations suggest that the capacity of electron transport is not sufficient to support the increased Rubisco capacity in transgenic rice. Although the photosynthetic rate was not enhanced, the strategy presented here opens the way to engineering Rubisco for improvement of photosynthesis and productivity in the future.

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Section: Content and Activation Of Rubisco In Transgenic Ricesupporting

confidence: 77%

Section: Rt-pcr Analysesmentioning

confidence: 99%

Functional Incorporation of Sorghum Small Subunit Increases the Catalytic Turnover Rate of Rubisco in Transgenic Rice

et al. 2011

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“…Rubisco content increased to an extent similar to that of the rbcL mRNA level. In addition, the rbcL mRNA level declined to a level similar to that of total RBCS mRNA in RBCS-suppressed rice plants with the antisense technique or the RNA interference technique for individual RBCS genes (Suzuki et al, 2009a(Suzuki et al, , 2009bOgawa et al, 2012). These results imply that the coordinated expression of two genes is not fully explained by the translational modulation of the rbcL gene.…”

mentioning

confidence: 90%

“…On the other hand, when endogenous RBCS was overexpressed in rice, the rbcL mRNA level also increased concomitant with a drastic increase in the total RBCS mRNA level (Suzuki et al, 2007(Suzuki et al, , 2009a(Suzuki et al, , 2009b. Rubisco content increased to an extent similar to that of the rbcL mRNA level.…”

mentioning

confidence: 93%

Availability of Rubisco Small Subunit Up-Regulates the Transcript Levels of Large Subunit for Stoichiometric Assembly of Its Holoenzyme in Rice

Suzuki

Makino

2012

Plant Physiology

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Rubisco is composed of eight small subunits coded for by the nuclear RBCS multigene family and eight large subunits coded for by the rbcL gene in the plastome. For synthesis of the Rubisco holoenzyme, both genes need to be expressed coordinately. To investigate this molecular mechanism, the protein synthesis of two subunits of Rubisco was characterized in transgenic rice (Oryza sativa) plants with overexpression or antisense suppression of the RBCS gene. Total RBCS and rbcL messenger RNA (mRNA) levels and RBCS and RbcL synthesis simultaneously increased in RBCS-sense plants, although the increase in total RBCS mRNA level was greater. In RBCS-antisense plants, the levels of these mRNAs and the synthesis of the corresponding proteins declined to a similar extent. The amount of RBCS synthesized was tightly correlated with rbcL mRNA level among genotypes but not associated with changes in mRNA levels of other major chloroplast-encoded photosynthetic genes. The level of rbcL mRNA, in turn, was tightly correlated with the amount of RbcL synthesized, the molar ratio of RBCS synthesis to RbcL synthesis being identical irrespective of genotype. Polysome loading of rbcL mRNA was not changed. These results demonstrate that the availability of RBCS protein up-regulates the gene expression of rbcL primarily at the transcript level in a quantitative manner for stoichiometric assembly of Rubisco holoenzyme.

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“…For example, many plants increase the concentration of the relatively slow Rubsico to approximately one third of the soluble protein content in a leaf (23), making it a significant fraction of the cellular protein and nitrogen requirements. Faster pathway kinetics could facilitate a higher rate of carbon fixation given the same amount of resource allocation, or it could free some of the resources in favor of other processes.…”

mentioning

confidence: 99%

Design and analysis of synthetic carbon fixation pathways

Bar‐Even¹,

Noor²,

Lewis

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

438

394

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Carbon fixation is the process by which CO 2 is incorporated into organic compounds. In modern agriculture in which water, light, and nutrients can be abundant, carbon fixation could become a significant growth-limiting factor. Hence, increasing the fixation rate is of major importance in the road toward sustainability in food and energy production. There have been recent attempts to improve the rate and specificity of Rubisco, the carboxylating enzyme operating in the Calvin-Benson cycle; however, they have achieved only limited success. Nature employs several alternative carbon fixation pathways, which prompted us to ask whether more efficient novel synthetic cycles could be devised. Using the entire repertoire of approximately 5,000 metabolic enzymes known to occur in nature, we computationally identified alternative carbon fixation pathways that combine existing metabolic building blocks from various organisms. We compared the natural and synthetic pathways based on physicochemical criteria that include kinetics, energetics, and topology. Our study suggests that some of the proposed synthetic pathways could have significant quantitative advantages over their natural counterparts, such as the overall kinetic rate. One such cycle, which is predicted to be two to three times faster than the Calvin-Benson cycle, employs the most effective carboxylating enzyme, phosphoenolpyruvate carboxylase, using the core of the naturally evolved C4 cycle. Although implementing such alternative cycles presents daunting challenges related to expression levels, activity, stability, localization, and regulation, we believe our findings suggest exciting avenues of exploration in the grand challenge of enhancing food and renewable fuel production via metabolic engineering and synthetic biology. metabolic engineering | synthetic biology | photosynthesis | carboxylation | biological optimization I n the process of transforming sunlight into stored chemical energy, plants absorb approximately 10 times more CO 2 from the atmosphere than the total amount emitted by human activities globally (1). Moreover, agriculture, which is effectively a massive carbon fixation industry, makes use of the majority of cultivatable land on earth and accounts for most of the fresh water used by humanity (2). These figures point to the central role that carbon fixation by plants plays in our global ecological footprint. In nature, the factors limiting the growth of photosynthetic organisms vary among habitats and often include the availability of water, light, fixed nitrogen, iron, and phosphorus (e.g., ref.3). However, in agriculture today, the use of fertilizers and irrigation can make carbon fixation a rate-limiting factor. For example, many C3 plants have shown a significant increase in biomass when exposed to twice the atmospheric CO 2 concentration (4). Impressive growth enhancements have been demonstrated by addressing several biochemical limiting factors, related both to the light-dependent and light-independent reactions (5-9). For instance, tran...

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Rubisco content and photosynthesis of leaves at different positions in transgenic rice with an overexpression of RBCS

Cited by 98 publications

References 42 publications

Functional Incorporation of Sorghum Small Subunit Increases the Catalytic Turnover Rate of Rubisco in Transgenic Rice

Functional Incorporation of Sorghum Small Subunit Increases the Catalytic Turnover Rate of Rubisco in Transgenic Rice

Availability of Rubisco Small Subunit Up-Regulates the Transcript Levels of Large Subunit for Stoichiometric Assembly of Its Holoenzyme in Rice

Design and analysis of synthetic carbon fixation pathways

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