Biosynthesis of aromatic amino acids in Nocardia sp. 239: effects of amino acid analogues on growth and regulatory enzymes (original) (raw)
Related papers
1989
The regulation of aromatic amino acid biosynthesis in Nocardia sp. 239 was studied. In cell-free extracts 3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase activity was inhibited in a cumulative manner by tryptophan, phenylalanine and tyrosine. Chorismate mutase was inhibited by both phenylalanine and tyrosine, whereas prephenate dehydratase was very sensitive to inhibition by phenylalanine. Tyrosine was a strong activator of the latter enzyme, whereas anthranilate synthase was inhibited effectively by tryptophan.
Regulation of aromatic amino acid biosynthesis in higher plants
Archives of Biochemistry and Biophysics, 1974
The regulation of aromatic amino acid biosynthesis in Nocardia sp. 239 was studied. In cell-free extracts 3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase activity was inhibited in a cumulative manner by tryptophan, phenylalanine and tyrosine. Chorismate mutase was inhibited by both phenylalanine and tyrosine, whereas prephenate dehydratase was very sensitive to inhibition by phenylalanine. Tyrosine was a strong activator of the latter enzyme, whereas anthranilate synthase was inhibited effectively by tryptophan. No clear ...
Biochemical characterization of the Nocardia lactamdurans ACV synthetase
PLOS ONE, 2020
The L-δ-(α-aminoadipoyl)-L-cysteinyl-D-valine synthetase (ACVS) is a nonribosomal peptide synthetase (NRPS) that fulfills a crucial role in the synthesis of β-lactams. Although some of the enzymological aspects of this enzyme have been elucidated, its large size, at over 400 kDa, has hampered heterologous expression and stable purification attempts. Here we have successfully overexpressed the Nocardia lactamdurans ACVS in E. coli HM0079. The protein was purified to homogeneity and characterized for tripeptide formation with a focus on the substrate specificity of the three modules. The first L-α-aminoadipic acidactivating module is highly specific, whereas the modules for L-cysteine and L-valine are more promiscuous. Engineering of the first module of ACVS confirmed the strict specificity observed towards its substrate, which can be understood in terms of the non-canonical peptide bond position.
Underpinning the secondary metabolites from Nocardia spp
More than 70% of antibiotics, antibacterial agents and versatile bioactive micro-bial compounds have been produced by group of bacteria called actinomycetes, which is composed of the genus Streptomyces (68%) and the rare actinomycetes (32%). Among the rare actinomycetes with potential for production of bioactive compounds, the genus Nocardia is the most predominant one. As occasional pathogens, several of them are associated with infectious diseases called nocardiosis, but they are also producer of many secondary metabolites, exhibiting versatile therapeutic potential such as antimicrobial, antitumor, antioxidant and immunosuppressive activities. Due to these valuable properties and the application potential, Nocardia spp. has attracted much interest in academia and industry in recent years. Fundamentally, research concerned with secondary metabolites associated with Nocardia might have sublimed due to its pathogenic nature, however still rigorous genetic engineering and metabolic e...
Journal of bacteriology, 1991
A gene (lat) encoding lysine 6-aminotransferase was found upstream of the pcbAB (encoding alpha-aminoadipylcysteinyl-valine synthetase) and pcbC (encoding isopenicillin N synthase) genes in the cluster of early cephamycin biosynthetic genes in Nocardia lactamdurans. The lat gene was separated by a small intergenic region of 64 bp from the 5' end of the pcbAB gene. The lat gene contained an open reading frame of 1,353 nucleotides (71.4% G + C) encoding a protein of 450 amino acids with a deduced molecular mass of 48,811 Da. Expression of DNA fragments carrying the lat gene in Streptomyces lividans led to a high lysine 6-aminotransferase activity which was absent from untransformed S. lividans. The enzyme was partially purified from S. lividans(pULBS8) and showed a molecular mass of 52,800 Da as calculated by Sephadex gel filtration and polyacrylamide gel electrophoresis. DNA sequences which hybridized strongly with the lat gene of N. lactamdurans were found in four cephamycin-pro...
Microbiology, 1996
Addition of allophane, a phosphate-trapping agent, to two different strains of Nocardia lactamdurans exerted a large stimulatory effect on cephamycin biosynthesis. The biosynthesis of cephamycin is inhibited by inorganic phosphate at concentrations above 5 mM and allophane reversed this inhibitory effect. Allophane-supplemented cultures showed increased activities and/or an extended life in the cell of four cepharnycin biosynthetic enzymes : isopenicillin N synthase, the two-protein-component 7a-cephem methoxylase (7a-cephem hydroxylase and 7-hydroxycephem methyltransferase) and 3'-hydroxymethylcephem O-carbamoyltransferase. However, the first enzyme of the pathway, lysine 6-aminotransferase, was not stimulated by allophane. Allophane-supplemented cultures showed increased protein levels of (i) a-aminoadipyl-cysteinyl-valine synthetase (the condensing multienzyme that forms the tripeptide intermediate), and (ii) the two proteins involved in the 7a-cephem methoxylase, as shown by immunoblotting with antibodies against each of these proteins. Phosphate repressed the de novo synthesis of these proteins but did not increase their degradation. These results indicated that allophane stimulates expression of the cluster of genes extending from the pcbAB gene (encoding a-aminoadipyl-cysteinyl-valine synthetase) to cmcl-cmcl (encoding the two-protein methoxylase) and cmcH (encoding the 0-carbamoyltransferase). 0002-0952 0 1996 SGM