Part:BBa_K4689069

Phosphoribulokinase (PRK)

Phosphoribulokinase (PRK) is a specialized enzyme found in the chloroplasts of photosynthetic organisms, including plants, algae, and cyanobacteria. It plays a crucial role in the CBB cycle, which is the primary process through which these organisms convert carbon dioxide (CO2) from the atmosphere into organic molecules.

Significance in the Calvin Cycle: PRK's significance in the Calvin cycle is paramount:

1. Regeneration of Ribulose-1,5-Bisphosphate (RuBP): In the CBB cycle, one of the key steps involves the carboxylation of RuBP by the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). This reaction incorporates CO2 into an organic molecule, creating a compound that is vital for carbon fixation. However, it also generates two molecules of 3-phosphoglycerate (3-PGA). To sustain the Calvin cycle, these 3-PGA molecules must be converted back into RuBP. PRK catalyzes the phosphorylation of ribulose-5-phosphate (Ru5P), using adenosine triphosphate (ATP), to regenerate RuBP.

2. Continuous Carbon Fixation: PRK's role in regenerating RuBP ensures the continuous operation of the Calvin cycle. Without this regeneration step, the cycle would stall, hampering the organism's ability to capture and assimilate atmospheric CO2 into organic compounds. This continuous carbon fixation is essential for the production of sugars and other organic molecules used for energy and growth.

3. Optimizing Photosynthesis: By facilitating the recycling of RuBP, PRK helps optimize photosynthesis. Efficient carbon fixation is essential for plant growth and the production of biomass, making PRK a critical enzyme for crop productivity and overall ecosystem health.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal AgeI site found at 74
  
• 1000
  COMPATIBLE WITH RFC[1000]

References:

1.Meloni, M., Gurrieri, L., Fermani, S., Velie, L., Sparla, F., Crozet, P., ... & Zaffagnini, M. (2023). Ribulose-1, 5-bisphosphate regeneration in the Calvin-Benson-Bassham cycle: Focus on the last three enzymatic steps that allow the formation of Rubisco substrate. Frontiers in Plant Science, 14, 1130430.

2.Yu, A., Xie, Y., Pan, X., Zhang, H., Cao, P., Su, X., & Li, M. (2020). Photosynthetic phosphoribulokinase structures: Enzymatic mechanisms and the redox regulation of the Calvin-Benson-Bassham cycle. The Plant Cell, 32(5), 1556-1573.