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Fig. 1 | AMB Express

Fig. 1

From: Exploring the oxygenase function of Form II Rubisco for production of glycolate from CO2

Fig. 1

Diagram of glycolate production via oxygenation function of Form II Rubisco in Synechocystis sp. PCC 6803. HCO3− is actively pumped (light blue) into the cytosol. While some of HCO3− spontaneously converts to CO2 in cytosol, most of HCO3− enters the carboxysome (blue hexagon) and is converted to CO2 by the sequestered carbonic anhydrase (CA). RuBP enters the carboxysome and the sequestered Rubisco of Synechocystis (6RBC Rubisco) combines RuBP with CO2 to generated two molecules of 3-phophoglycerate (3PGA). 3PGA escapes to the cytosol and RuBP is regenerated through the Calvin-Benson-Bassham (CBB) cycle. Photorespiration (gray dashed arrows) can be blocked by inactivating (red cross) two glycolate dehydrogenases (GlcDs) encoded by glcD1 and glcD2, respectively. The resulting strain WT-ΔglcD accumulates and excretes glycolate to the culture (yellow). Form II Rubisco from the endosymbiont of Riftia pachyptila (RPE Rubisco) was overexpressed in strain WT-ΔglcD and located in the cytosol. As cyanobacteria performs oxygenic photosynthesis, RPE Rubisco catalyzes the oxygenation of RuBP to 2-photoglycolate (2PG), facilitating glycolate production. As CO2 can freely diffuse to the cytosol (blue solid arrow), the elevated CO2 level inhibits the oxygenase function of RPE (purple solid line) and decreases glycolate production when the external inorganic carbon is supplied with CO2

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