title: Introduction of a synthetic CO₂-fixing photorespiratory bypass into a cyanobacterium.
abstract: Global photosynthetic productivity is limited by the enzymatic assimilation of CO2 into organic carbon compounds. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the carboxylating enzyme of the Calvin-Benson cycle, poorly discriminates between CO2 and O2, leading to photorespiration and the loss of fixed carbon and nitrogen. With the advent of synthetic biology, it is now feasible to design, synthesize, and introduce biochemical pathways in vivo. We engineered a synthetic photorespiratory bypass based on the 3-hydroxypropionate bi-cycle into the model cyanobacterium, Synechococcus elongatus sp. PCC 7942. The heterologously expressed cycle is designed to function as both a photorespiratory bypass and an additional CO2-fixing pathway, supplementing the Calvin-Benson cycle. We demonstrate the function of all six introduced enzymes and identify bottlenecks to be targeted in subsequent bioengineering. These results have implications for efforts to improve photosynthesis and for the "green" production of high value products of biotechnological interest.
authors.affiliation: From the Department of Plant and Microbial Biology.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Shih
authors.forename: Jan
authors.initials: J
authors.lastname: Zarzycki
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Kerfeld
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002248:Carbon Monoxide / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism*; D046940:Synechococcus / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D002248:Carbon Monoxide; D012273:Ribulose-Bisphosphate Carboxylase
keywords: 3-Hydroxypropionate Bi-cycle; Bioenergy; Chloroflexus; Cyanobacteria; Metabolic Engineering; Photosynthesis; Rubisco; Synechococcus; Synthetic Biology