title: Metabolic engineering of cyanobacteria for 1-butanol production from carbon dioxide.
abstract: Production of chemicals and fuels directly from CO(2) is an attractive approach to solving the energy and environmental problems. 1-Butanol, a chemical feedstock and potential fuel, has been produced by fermentation of carbohydrates, both in native Clostridium species and various engineered hosts. To produce 1-butanol from CO(2), we transferred a modified CoA-dependent 1-butanol production pathway into a cyanobacterium, Synechococcus elongatus PCC 7942. We demonstrated the activity of each enzyme in the pathway by chromosomal integration and expression of the genes. In particular, Treponema denticola trans-enoyl-CoA reductase (Ter), which utilizes NADH as the reducing power, was used for the reduction of crotonyl-CoA to butyryl-CoA instead of Clostridium acetobutylicum butyryl-CoA dehydrogenase to by-pass the need of Clostridial ferredoxins. Addition of polyhistidine-tag increased the overall activity of Ter and resulted in higher 1-butanol production. Removal of oxygen is an important factor in the synthesis of 1-butanol in this organism. This result represents the first autotrophic 1-butanol production.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
authors.forename: Ethan I
authors.initials: EI
authors.lastname: Lan
authors.forename: James C
authors.initials: JC
authors.lastname: Liao
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D044926:Butyryl-CoA Dehydrogenase / Q000096:biosynthesis / Q000235:genetics; D002245:Carbon Dioxide / Q000378:metabolism*; D046969:Clostridium acetobutylicum / Q000201:enzymology / Q000235:genetics; D044943:Fatty Acid Desaturases / Q000096:biosynthesis / Q000235:genetics; D005818:Genetic Engineering; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000378:metabolism; D046940:Synechococcus / Q000235:genetics / Q000378:metabolism; D048373:Treponema denticola / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D002245:Carbon Dioxide; D020001:1-Butanol; D044943:Fatty Acid Desaturases; D044926:Butyryl-CoA Dehydrogenase