title: Acetolactate synthase from Bacillus subtilis serves as a 2-ketoisovalerate decarboxylase for isobutanol biosynthesis in Escherichia coli.
abstract: A pathway toward isobutanol production previously constructed in Escherichia coli involves 2-ketoacid decarboxylase (Kdc) from Lactococcus lactis that decarboxylates 2-ketoisovalerate (KIV) to isobutyraldehyde. Here, we showed that a strain lacking Kdc is still capable of producing isobutanol. We found that acetolactate synthase from Bacillus subtilis (AlsS), which originally catalyzes the condensation of two molecules of pyruvate to form 2-acetolactate, is able to catalyze the decarboxylation of KIV like Kdc both in vivo and in vitro. Mutational studies revealed that the replacement of Q487 with amino acids with small side chains (Ala, Ser, and Gly) diminished only the decarboxylase activity but maintained the synthase activity.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Shota
authors.initials: S
authors.lastname: Atsumi
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: James C
authors.initials: JC
authors.lastname: Liao
mesh_terms: D000095:Acetolactate Synthase / Q000378:metabolism*; D019943:Amino Acid Substitution; D001412:Bacillus subtilis / Q000201:enzymology* / Q000378:metabolism*; D000440:Butanols / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism*; D045782:Hemiterpenes; D007651:Keto Acids / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D019289:Pyruvic Acid / Q000378:metabolism
chemical_list: D000440:Butanols; D045782:Hemiterpenes; D007651:Keto Acids; D007773:Lactates; C006359:alpha-acetolactate; C040507:isobutyl alcohol; C001505:alpha-ketoisovalerate; D019289:Pyruvic Acid; D000095:Acetolactate Synthase; D002262:Carboxy-Lyases
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