title: Semisynthetic production of unnatural L-alpha-amino acids by metabolic engineering of the cysteine-biosynthetic pathway.
abstract: There is an increasing demand for peptide-mimicking molecules to modulate the interactions between proteins of pharmaceutical and agrochemical interest and their target polypeptides. Unnatural L-alpha-amino acids differing from the 20 naturally proteinogenic amino acids only in their side chain are ideal for this purpose, but their chemical synthesis is complex. Here we describe a fermentation-based approach for biosynthesis of unnatural amino acids after re-engineering the cysteine-biosynthetic pathway in Escherichia coli. O-acetylation of serine, the committed step of the pathway, was released from feedback inhibition by mutating the serine acetyltransferase gene. Next, the naturally broad substrate specificity of O-acetylserine sulfhydrylase was exploited for the direct in vivo incorporation of an unnatural side chain in a semisynthetic fermentation process comparable to the production of beta-lactams. O-acetyl-L-serine extruded from the cells by way of the O-acetylserine efflux protein was amenable to further biotransformations.
authors.affiliation: Wacker Chemie GmbH Consortium für elektrochemische Industrie GmbH, Zielstattstr. 20, 81379 Munich, Germany. thomas.maier@wacker.com
authors.forename: Thomas H P
authors.initials: TH
authors.lastname: Maier
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis* / Q000138:chemical synthesis / Q000145:classification / Q000302:isolation & purification*; D001711:Biotransformation; D003001:Cloning, Molecular; D003541:Cystathionine beta-Synthase / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005818:Genetic Engineering / Q000379:methods; D018716:Molecular Mimicry; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000138:chemical synthesis / Q000145:classification / Q000302:isolation & purification; D013045:Species Specificity; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D000596:Amino Acids; D011994:Recombinant Proteins; D003541:Cystathionine beta-Synthase; D003545:Cysteine