A new pathway for polyketide synthesis in microorganisms

Chalcone synthases, which biosynthesize chalcones (the starting materials for many flavonoids,), have been believed to be specific to plants. However, the rppA gene from the Gram-positive, soil-living filamentous bacterium Streptomyces griseus encodes a 372-amino-acid protein that shows significant similarity to chalcone synthases. Several rppA-like genes are known, but their functions and catalytic properties have not been described. Here we show that a homodimer of RppA catalyses polyketide synthesis: it selects malonyl-coenzyme-A as the starter, carries out four successive extensions and releases the resulting pentaketide to cyclize to 1,3,6,8-tetrahydroxynaphthalene (THN). Site-directed mutagenesis revealed that, as in other chalcone synthases,, a cysteine residue is essential for enzyme activity. Disruption of the chromosomal rppA gene in S. griseus abolished melanin production in hyphae, resulting in ‘albino’ mycelium. THN was readily oxidized to form 2,5,7-trihydroxy-1,4-naphthoquinone (flaviolin), which then randomly polymerized to form various coloured compounds. THN formed by RppA appears to be an intermediate in the biosynthetic pathways for not only melanins but also various secondary metabolites containing a naphthoquinone ring. Therefore, RppA is a chalcone-synthase-related synthase that synthesizes polyketides and is found in the Streptomyces and other bacteria.

[1]  D. Hopwood.  Genetic Contributions to Understanding Polyketide Synthases , 1998 .

[2]  R. Boucher,et al.  Membrane-restricted regulation of Ca2+ release and influx in polarized epithelia , 1995, Nature.

[3]  M. Wheeler,et al.  Biosynthesis and Functions of Fungal Melanins , 1986 .

[4]  S. Randell,et al.  Coordinated clearance of periciliary liquid and mucus from airway surfaces. , 1998, The Journal of clinical investigation.

[5]  S. Anderson,et al.  Inhalation of hypertonic saline aerosol enhances mucociliary clearance in asthmatic and healthy subjects. , 1996, The European respiratory journal.

[6]  L. Thomashow,et al.  Characterization of a genomic locus required for synthesis of the antibiotic 2,4-diacetylphloroglucinol by the biological control agent Pseudomonas fluorescens Q2-87. , 1996, Molecular plant-microbe interactions : MPMI.

[7]  S. Ōmura,et al.  Biosynthesis of furaquinocins A and B , 1990 .

[8]  A. Silberberg.  On mucociliary transport. , 1990, Biorheology.

[9]  S. Anderson,et al.  Inhalation of dry-powder mannitol increases mucociliary clearance. , 1997, The European respiratory journal.

[10]  G. Schröder,et al.  Reaction mechanisms of homodimeric plant polyketide synthase (stilbenes and chalcone synthase). A single active site for the condensing reaction is sufficient for synthesis of stilbenes, chalcones, and 6'-deoxychalcones. , 1995, The Journal of biological chemistry.

[11]  M. King,et al.  Effect of increasing doses of hypertonic saline on mucociliary clearance in patients with cystic fibrosis. , 1997, Thorax.

[12]  G. Schröder,et al.  The role of cysteines in polyketide synthases. Site-directed mutagenesis of resveratrol and chalcone synthases, two key enzymes in different plant-specific pathways. , 1991, The Journal of biological chemistry.

[13]  M. Welsh,et al.  Loss of CFTR chloride channels alters salt absorption by cystic fibrosis airway epithelia in vitro. , 1998, Molecular cell.

[14]  G. Schröder,et al.  Reaction Mechanisms of Homodimeric Plant Polyketide Synthases (Stilbene and Chalcone Synthase) , 1995, The Journal of Biological Chemistry.

[15]  B. Reiss,et al.  Nucleotide sequence and exact localization of the neomycin phosphotransferase gene from transposon Tn5. , 1982, Gene.

[16]  E. Greenberg,et al.  Cystic Fibrosis Airway Epithelia Fail to Kill Bacteria Because of Abnormal Airway Surface Fluid , 1996, Cell.

[17]  P. Cole,et al.  Sodium chloride increases the ciliary transportability of cystic fibrosis and bronchiectasis sputum on the mucus-depleted bovine trachea. , 1997, The Journal of clinical investigation.

[18]  K. Chater,et al.  Denaturation of circular or linear DNA facilitates targeted integrative transformation of Streptomyces coelicolor A3(2): possible relevance to other organisms , 1997, Journal of bacteriology.

[19]  S. Donadio,et al.  Polyketide synthesis: prospects for hybrid antibiotics. , 1993, Annual review of microbiology.

[20]  K. Shin‐ya,et al.  Biosynthetic studies of naphterpin, a terpenoid metabolite of streptomyces , 1990 .

[21]  M. King,et al.  Effect of hypertonic saline, amiloride, and cough on mucociliary clearance in patients with cystic fibrosis. , 1996, American journal of respiratory and critical care medicine.

[22]  中西 香爾,et al.  Comprehensive natural products chemistry , 1999 .

[23]  Bangera Mg,et al.  Characterization of a genomic locus required for synthesis of the antibiotic 2,4-diacetylphloroglucinol by the biological control agent Pseudomonas fluorescens Q2-87. , 1996 .

[24]  J. Hull,et al.  Elemental content of airway surface liquid from infants with cystic fibrosis. , 1998, American journal of respiratory and critical care medicine.

[25]  James M. Wilson,et al.  Human β-Defensin-1 Is a Salt-Sensitive Antibiotic in Lung That Is Inactivated in Cystic Fibrosis , 1997, Cell.

[26]  J. Wine.  The genesis of cystic fibrosis lung disease. , 1999, The Journal of clinical investigation.

[27]  Y. Kubo,et al.  Heterologous expression and product identification of Colletotrichum lagenarium polyketide synthase encoded by the PKS1 gene involved in melanin biosynthesis. , 1999, Bioscience, biotechnology, and biochemistry.

[28]  P. Jensen,et al.  Marinone and debromomarinone: Antibiotic sesquiterpenoid naphthoquinones of a new structure class from a marine bacterium , 1992 .

[29]  Dudley H. Williams,et al.  On the biosynthesis of the antibiotic vancomycin , 1982 .

[30]  D. Pavia,et al.  Enhanced clearance of secretions from the human lung after the administration of hypertonic saline aerosol. , 2015, The American review of respiratory disease.

[31]  J. Sambrook,et al.  Molecular Cloning: A Laboratory Manual , 2001 .

[32]  K. Chater,et al.  Hybridization and DNA sequence analyses suggest an early evolutionary divergence of related biosynthetic gene sets encoding polyketide antibiotics and spore pigments in Streptomyces spp. , 1993, Gene.

[33]  Y. Helariutta,et al.  New pathway to polyketides in plants , 1998, Nature.

[34]  H. Naganawa,et al.  Structures of new antibiotics napyradiomycins. , 1986, The Journal of antibiotics.

[35]  Yuemao Shen,et al.  Engineered biosynthesis of novel polyketides from Streptomyces spore pigment polyketide synthases , 1998 .

[36]  P. Dimroth,et al.  6-Methylsalicylic acid synthetase from Penicillium patulum. Some catalytic properties of the enzyme and its relation to fatty acid synthetase. , 1976, European journal of biochemistry.

[37]  J. Morton,et al.  Short‐term efficacy of ultrasonically nebulized hypertonic saline in cystic fibrosis , 1996, Pediatric pulmonology.

[38]  J. Schröder.  A family of plant-specific polyketide synthases: facts and predictions , 1997 .

[39]  C. Hutchinson,et al.  Polyketide synthase gene manipulation: a structure-function approach in engineering novel antibiotics. , 1995, Annual review of microbiology.

[40]  Steven J. M. Jones,et al.  Sequencing and analysis of genes involved in the biosynthesis of a vancomycin group antibiotic. , 1998, Chemistry & biology.

[41]  J. Schröder.  1.27 – The Chalcone/Stilbene Synthase-type Family of Condensing Enzymes , 1999 .

[42]  S. Horinouchi,et al.  A Streptomyces griseus gene (sgaA) suppresses the growth disturbance caused by high osmolality and a high concentration of A-factor during early growth. , 1997, Microbiology.

[43]  S. Horinouchi,et al.  Overexpression of a gene cluster encoding a chalcone synthase-like protein confers redbrown pigment production in Streptomyces griseus. , 1995, The Journal of antibiotics.

[44]  P. Quinton,et al.  Elemental composition of human airway surface fluid in healthy and diseased airways. , 1993, The American review of respiratory disease.

[45]  S. Randell,et al.  Evidence for Periciliary Liquid Layer Depletion, Not Abnormal Ion Composition, in the Pathogenesis of Cystic Fibrosis Airways Disease , 1998, Cell.