title: The fused TrpEG from Streptomyces venezuelae is an anthranilate synthase, not a 2-amino-2-deoxyisochorismate [corrected] (ADIC) synthase.
abstract: The chloramphenicol producer Streptomyces venezuelae contains an enzyme, SvTrpEG, that has a high degree of amino acid sequence similarity to the phenazine biosynthetic enzyme PhzE of certain species of Pseudomonas. PhzE has the sequence signature of an anthranilate synthase, but recent evidence indicates that it catalyzes the production of 2-amino-2-deoxyisochorismate [corrected] (ADIC), an intermediate in the two-step anthranilate synthase reaction, not anthranilate. In order to determine if SvTrpEG is likewise an ADIC synthase, we have cloned the gene for SvTrpEG, expressed the recombinant enzyme in Escherichia coli, and purified the enzyme. Analysis of the SvTrpEG-catalyzed reaction mixture using UV-visible spectrophotometry, fluorescence spectrometry, and high-performance liquid chromatography shows that the product of the reaction is anthranilate, not ADIC. Our results therefore reveal that, despite its sequence similarity to PhzE, SvTrpEG is an anthranilate synthase, not an ADIC synthase.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, Washington, DC 20059, USA.
authors.forename: Meseret
authors.initials: M
authors.lastname: Ashenafi
authors.forename: Renee
authors.initials: R
authors.lastname: Carrington
authors.forename: Alvin C
authors.initials: AC
authors.lastname: Collins
authors.forename: W Malcolm
authors.initials: WM
authors.lastname: Byrnes
mesh_terms: D000878:Anthranilate Synthase / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002384:Catalysis; D002827:Chorismic Acid / Q000378:metabolism; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics*; D007700:Kinetics; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics; D012475:Salmonella / Q000201:enzymology / Q000235:genetics; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics*; D013816:Thermodynamics; D014170:Transformation, Genetic
chemical_list: D000878:Anthranilate Synthase; D002827:Chorismic Acid