Metabolic engineering of a genetic selection system with tunable stringency.
The biosynthesis of small molecules can be fine-tuned by (re)engineering metabolic flux within cells. We have adapted this approach to optimize an in vivo selection system for the conversion of prephenate to phenylpyruvate, a key step in the production of the essential aromatic amino acid phenylalanine. Careful control of prephenate concentration in a bacterial host lacking prephenate dehydratase, achieved through provision of a regulable enzyme that diverts it down a parallel biosynthetic pathway, provides the means to systematically increase selection pressure on replacements of the missing catalyst. Successful differentiation of dehydratases whose activities vary over a >50,000-fold range and the isolation of mechanistically informative prephenate dehydratase variants from large protein libraries illustrate the potential of the engineered selection strain for characterizing and evolving enzymes. Our approach complements other common methods for adjusting selection pressure and should be generally applicable to any selection system that is based on the conversion of an endogenous metabolite.
Kleeb
Andreas C
AC
Laboratory of Organic Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
Edalat
Maryam Hansson
MH
Gamper
Marianne
M
Haugstetter
Johannes
J
Giger
Lars
L
Neuenschwander
Martin
M
Kast
Peter
P
Hilvert
Donald
D
D000596:Amino Acids / Q000378:metabolism; D019020:Directed Molecular Evolution; D005818:Genetic Engineering / Q000379:methods; D014644:Genetic Variation; D007700:Kinetics; D008957:Models, Genetic; D008958:Models, Molecular; D010957:Plasmids; D011302:Prephenate Dehydratase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012641:Selection, Genetic; D012765:Shikimic Acid / Q000378:metabolism
D000596:Amino Acids; D011994:Recombinant Proteins; D012765:Shikimic Acid; D011302:Prephenate Dehydratase
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