title: [Overproduction of noncanonical amino acids by Escherichia coli cells].
abstract: Overproduction of noncanonical amino acids norvaline and norleucine by Escherichia coli with inactivated acetohydroxy acid synthases was demonstrated. The cultivation conditions for the overproduction of noncanonical amino acids were studied. The effect of the restoration of acetohydroxy acid synthase activity, increased expression of the leuABCD operon, and inactivation of the biosynthetic threonine deaminase on norvaline and norleucine synthesis was studied. When grown under valine limitation, E. coli cells with inactivated acetohydroxy acid synthases and an elevated level of expression of the valine operon were shown to accumulate norvaline and norleucine (up to 0.8 and 4 g/l, respectively). These results confirm the existing hypothesis of norvaline and norleucine formation from 2-ketobutyrate by leucine biosynthesis enzymes.
authors.forename: E V
authors.initials: EV
authors.lastname: Sycheva
authors.forename: T A
authors.initials: TA
authors.lastname: Iampol'skaia
authors.forename: E S
authors.initials: ES
authors.lastname: Preobrazhenskaia
authors.forename: A E
authors.initials: AE
authors.lastname: Novikova
authors.forename: N G
authors.initials: NG
authors.lastname: Matrosov
authors.forename: N V
authors.initials: NV
authors.lastname: Stoĭnova
mesh_terms: D000095:Acetolactate Synthase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D002087:Butyrates / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D020868:Gene Silencing; D007535:Isomerases / Q000235:genetics / Q000378:metabolism; D007930:Leucine / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009646:Norleucine / Q000096:biosynthesis*; D009876:Operon; D016415:Sequence Alignment; D013913:Threonine Dehydratase / Q000096:biosynthesis; D014633:Valine / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D002087:Butyrates; C005087:alpha-ketobutyric acid; D009646:Norleucine; C005313:norvaline; D000095:Acetolactate Synthase; C032241:isopropylmalate isomerase; D013913:Threonine Dehydratase; D007535:Isomerases; D007930:Leucine; D014633:Valine