title: Synthetic metabolic engineering-a novel, simple technology for designing a chimeric metabolic pathway.
abstract: BACKGROUND
  The integration of biotechnology into chemical manufacturing has been recognized as a key technology to build a sustainable society. However, the practical applications of biocatalytic chemical conversions are often restricted due to their complexities involving the unpredictability of product yield and the troublesome controls in fermentation processes. One of the possible strategies to overcome these limitations is to eliminate the use of living microorganisms and to use only enzymes involved in the metabolic pathway. Use of recombinant mesophiles producing thermophilic enzymes at high temperature results in denaturation of indigenous proteins and elimination of undesired side reactions; consequently, highly selective and stable biocatalytic modules can be readily prepared. By rationally combining those modules together, artificial synthetic pathways specialized for chemical manufacturing could be designed and constructed.
  
  
  RESULTS
  A chimeric Embden-Meyerhof (EM) pathway with balanced consumption and regeneration of ATP and ADP was constructed by using nine recombinant E. coli strains overproducing either one of the seven glycolytic enzymes of Thermus thermophilus, the cofactor-independent phosphoglycerate mutase of Pyrococcus horikoshii, or the non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase of Thermococcus kodakarensis. By coupling this pathway with the Thermus malate/lactate dehydrogenase, a stoichiometric amount of lactate was produced from glucose with an overall ATP turnover number of 31.
  
  
  CONCLUSIONS
  In this study, a novel and simple technology for flexible design of a bespoke metabolic pathway was developed. The concept has been testified via a non-ATP-forming chimeric EM pathway. We designated this technology as "synthetic metabolic engineering". Our technology is, in principle, applicable to all thermophilic enzymes as long as they can be functionally expressed in the host, and thus would be potentially applicable to the biocatalytic manufacture of any chemicals or materials on demand.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Ye
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Honda
authors.forename: Takaaki
authors.initials: T
authors.lastname: Sakai
authors.forename: Kenji
authors.initials: K
authors.lastname: Okano
authors.forename: Takeshi
authors.initials: T
authors.lastname: Omasa
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Hirota
authors.forename: Akio
authors.initials: A
authors.lastname: Kuroda
authors.forename: Hisao
authors.initials: H
authors.lastname: Ohtake
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering; D010736:Phosphoglycerate Mutase / Q000235:genetics / Q000378:metabolism; D019711:Pyrococcus / Q000201:enzymology; D013696:Temperature; D019712:Thermococcus / Q000201:enzymology; D016963:Thermus thermophilus / Q000201:enzymology
chemical_list: D019344:Lactic Acid; D000255:Adenosine Triphosphate; D008291:Malate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D010736:Phosphoglycerate Mutase; D005947:Glucose