Engineering of Enhancing the Activity of Calvin-Benson Cycle Enzymes

Improving the photosynthetic efficiency of plants contributes to increased crop yields. Lifeasible has successfully developed a variety of reliable and economical solutions for engineering chloroplast photosynthesis. Here, our engineers focused on enhancing the activity of Calvin-Benson cycle enzymes by chloroplast genetic engineering to enhance photosynthesis.

Introduction

The Calvin-Benson cycle (CBC) is a key biological pathway that utilizes RuBisCO to convert atmospheric CO₂ to organic matter. In addition, CBC provides intermediates for many other pathways in the chloroplast, including the shikimate pathway for the biosynthesis of amino acids, lignin, isoprenoids, and precursors for nucleotide metabolism and cell wall synthesis. It has important implications for the global carbon cycle and crop production, and is widely distributed in most autotrophs, including plants, algae, cyanobacteria, etc. CBC consists of 11 different enzymes that catalyze 13 reactions and is initiated by Rubisco. Most research and engineering on the CBC cycle has focused on improving the efficiency of the carboxylation reaction by the enzyme RuBisCO. Moderate reductions in Calvin-Benson cycle enzymes such as sedoheptulose-1,7-bisphosphatase (SBPase) and fructose 1,6-bisphosphate aldolase (FBPA) lead to significant reductions in photosynthetic rate and plant growth. That is, these enzymes limit photosynthesis.

Fig. 1. Schematic representation of the Calvin-Benson cycle. (Simkin A J, et al., 2019)

Solutions

In recent years, tremendous efforts have been made to identify enzymes that can exert a high level of control over CBC flux, which may be used as engineering targets for enhanced photosynthesis. Based on the chloroplast transformation technology platform, Lifeasible can provide specialized solutions to enhance the activity of Calvin-Benson cycle enzymes. Our goal is to improve photosynthetic CO₂ fixation to increase photosynthetic rate and plant growth by increasing the activity of single or multiple Calvin-Benson cycle enzymes.

Enzymes with relatively large control coefficients are considered to be the main targets for photosynthesis improvement. Our engineers chose to overexpress sedoheptulose-1,7-bisphosphatase (SBPase) or fructose 1,6-bisphosphate aldolase (FBPA) in plants to enhance photosynthesis. In addition, we adopted the following strategy for multigene manipulation of specific targets in different crops to achieve co-expression of SBPase and FBPA in C₃ plants.

• Simultaneous Manipulation of the Calvin-Benson Cycle and Expression of ictB
  We co-expressed ictB with bifunctional cyFBP/SBPase in rice. Can result in cumulative increases in photosynthetic rate, tiller number, grain number or grain weight compared to plant expression.
• Simultaneous Manipulation of the Calvin-Benson Cycle and Photorespiration
  We increased the possibility of photorespiration and increased photosynthetic efficiency and yield in plants by overexpressing GCSh-protein simultaneously to increase photorespiration and enhance the activity of two enzymes (SBPase and FBPA) in the CB cycle.

Attractive Advantages of Our Solutions

• Yield enhancement through single- and polygenic regulation of different photosynthetic processes.
• Multigene manipulation of the C₃ pathway resulted in greater yield increases than single gene manipulation.
• Target specific operations for different species.
• Supported by a variety of advanced biological tools, such as genome editing methods, synthetic biology, etc.
• Allowing rapid, efficient and inexpensive insertion of multiple transgenes into plants.

Lifeasible's goal is to provide customers around the world with fully customized chloroplast engineered solutions for enhancing the activity of Calvin-Benson cycle enzymes. Our various strategies will fully meet your needs. Please contact us to discuss further details to ensure your next success.

References

1. Simkin A J, López-Calcagno P E, Raines C A. (2019) Feeding the world: improving photosynthetic efficiency for sustainable crop production[J]. Journal of Experimental Botany. 70(4): 1119-1140.
2. Michelet L, Zaffagnini M, Morisse S, et al. (2013) Redox regulation of the Calvin–Benson cycle: something old, something new[J]. Frontiers in plant science. 4: 470.