title: Inducible overproduction of the Aspergillus nidulans pentafunctional AROM protein and the type-I and -II 3-dehydroquinases from Salmonella typhi and Mycobacterium tuberculosis.
abstract: The aroQ gene of Mycobacterium tuberculosis, encoding a type-II 3-dehydroquinase, and the aroD gene of Salmonella typhi, encoding a type-I 3-dehydroquinase, have been highly overexpressed in Escherichia coli using the powerful trc promoter contained within the expression vector pKK233-2. The M. tuberculosis type-II 3-dehydroquinase has been purified in bulk from overproducing strains of E. coli to greater than 95% homogeneity. The protein is extremely heat-stable, is active as a homododecamer and has the lowest reported Km value of any type-II 3-dehydroquinase. The pentafunctional aromA gene of Aspergillus nidulans has been overexpressed more than 120-fold in an A. nidulans aromA- qutB- double mutant from a truncated quinate-inducible qutE promoter, such that the AROM protein is visible as a significant fraction (approx. 6%) in cell-free crude extracts. The M. tuberculosis aroQ gene has been fused to the same truncated qutE promoter and shown to encode quinate-inducible 3-dehydroquinase activity that allows a qutE- mutant strain of A. nidulans to utilize quinate as sole carbon source.
authors.affiliation: Department of Biochemistry and Genetics, University of Newcastle upon Tyne, U.K.
authors.forename: J D
authors.initials: JD
authors.lastname: Moore
authors.forename: H K
authors.initials: HK
authors.lastname: Lamb
authors.forename: T
authors.initials: T
authors.lastname: Garbe
authors.forename: S
authors.initials: S
authors.lastname: Servos
authors.forename: G
authors.initials: G
authors.lastname: Dougan
authors.forename: I G
authors.initials: IG
authors.lastname: Charles
authors.forename: A R
authors.initials: AR
authors.lastname: Hawkins
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics*; D001233:Aspergillus nidulans / Q000201:enzymology*; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005800:Genes, Fungal; D006836:Hydro-Lyases / Q000235:genetics* / Q000302:isolation & purification; D008190:Lyases / Q000235:genetics*; D009097:Multienzyme Complexes / Q000235:genetics*; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D010770:Phosphotransferases / Q000235:genetics*; D017853:Phosphotransferases (Alcohol Group Acceptor); D011401:Promoter Regions, Genetic; D011801:Quinic Acid / Q000494:pharmacology; D011994:Recombinant Proteins / Q000096:biosynthesis; D012485:Salmonella typhi / Q000201:enzymology*; D014166:Transferases
chemical_list: D009097:Multienzyme Complexes; D011994:Recombinant Proteins; C019728:arom enzyme; D011801:Quinic Acid; D000429:Alcohol Oxidoreductases; D014166:Transferases; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); D008190:Lyases; D006836:Hydro-Lyases; C020000:3-dehydroquinate dehydratase