title: ATP drives direct photosynthetic production of 1-butanol in cyanobacteria.
abstract: While conservation of ATP is often a desirable trait for microbial production of chemicals, we demonstrate that additional consumption of ATP may be beneficial to drive product formation in a nonnatural pathway. Although production of 1-butanol by the fermentative coenzyme A (CoA)-dependent pathway using the reversal of β-oxidation exists in nature and has been demonstrated in various organisms, the first step of the pathway, condensation of two molecules of acetyl-CoA to acetoacetyl-CoA, is thermodynamically unfavorable. Here, we show that artificially engineered ATP consumption through a pathway modification can drive this reaction forward and enables for the first time the direct photosynthetic production of 1-butanol from cyanobacteria Synechococcus elongatus PCC 7942. We further demonstrated that substitution of bifunctional aldehyde/alcohol dehydrogenase (AdhE2) with separate butyraldehyde dehydrogenase (Bldh) and NADPH-dependent alcohol dehydrogenase (YqhD) increased 1-butanol production by 4-fold. These results demonstrated the importance of ATP and cofactor driving forces as a design principle to alter metabolic flux.
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*; D000105:Acetyl Coenzyme A / Q000378:metabolism; D000214:Acyl Coenzyme A / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D053858:Metabolic Networks and Pathways; D009243:NAD / Q000378:metabolism; D010788:Photosynthesis; D046940:Synechococcus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*
chemical_list: D000214:Acyl Coenzyme A; D001426:Bacterial Proteins; D009243:NAD; C010667:acetoacetyl CoA; D000105:Acetyl Coenzyme A; D000255:Adenosine Triphosphate; D020001:1-Butanol; D000426:Alcohol Dehydrogenase; D000445:Aldehyde Oxidoreductases; C056375:butyraldehyde dehydrogenase (Coenzyme A-linked); D000444:Aldehyde Dehydrogenase; D003066:Coenzyme A Ligases; C023747:acetoacetyl-CoA synthetase