title: Functional cross-talk between fatty acid synthesis and nonribosomal peptide synthesis in quinoxaline antibiotic-producing streptomycetes.
abstract: Quinoxaline antibiotics are chromopeptide lactones embracing the two families of triostins and quinomycins, each having characteristic sulfur-containing cross-bridges. Interest in these compounds stems from their antineoplastic activities and their specific binding to DNA via bifunctional intercalation of the twin chromophores represented by quinoxaline-2-carboxylic acid (QA). Enzymatic analysis of triostin A-producing Streptomyces triostinicus and quinomycin A-producing Streptomyces echinatus revealed four nonribosomal peptide synthetase modules for the assembly of the quinoxalinoyl tetrapeptide backbone of the quinoxaline antibiotics. The modules were contained in three protein fractions, referred to as triostin synthetases (TrsII, III, and IV). TrsII is a 245-kDa bimodular nonribosomal peptide synthetase activating as thioesters for both serine and alanine, the first two amino acids of the quinoxalinoyl tetrapeptide chain. TrsIII, represented by a protein of 250 kDa, activates cysteine as a thioester. TrsIV, an unstable protein of apparent Mr about 280,000, was identified by its ability to activate and N-methylate valine, the last amino acid. QA, the chromophore, was shown to be recruited by a free-standing adenylation domain, TrsI, in conjunction with a QA-binding protein, AcpPSE. Cloning of the gene for the QA-binding protein revealed that it is the fatty acyl carrier protein, AcpPSE, of the fatty acid synthase of S. echinatus and S. triostinicus. Analysis of the acylation reaction of AcpPSE by TrsI along with other A-domains and the aroyl carrier protein AcmACP from actinomycin biosynthesis revealed a specific requirement for AcpPSE in the activation and also in the condensation of QA with serine in the initiation step of QA tetrapeptide assembly on TrsII. These data show for the first time a functional interaction between nonribosomal peptide synthesis and fatty acid synthesis.
authors.affiliation: Institut für Chemie, Arbeitsgruppe Biochemie und Molekularbiologie, Technische Universität Berlin, Franklinstrasse 29, D-10587 Berlin-Charlottenburg, Germany.
authors.forename: Gernot
authors.initials: G
authors.lastname: Schmoock
authors.forename: Frank
authors.initials: F
authors.lastname: Pfennig
authors.forename: Julien
authors.initials: J
authors.lastname: Jewiarz
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schlumbohm
authors.forename: Werner
authors.initials: W
authors.lastname: Laubinger
authors.forename: Florian
authors.initials: F
authors.lastname: Schauwecker
authors.forename: Ullrich
authors.initials: U
authors.lastname: Keller
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D001665:Binding Sites; D002264:Carboxylic Acids / Q000737:chemistry; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004448:Echinomycin / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000378:metabolism; D016678:Genome; D007700:Kinetics; D007783:Lactones / Q000737:chemistry; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010452:Peptide Biosynthesis; D046908:Peptide Biosynthesis, Nucleic Acid-Independent; D010455:Peptides / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011810:Quinoxalines / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013302:Streptomyces / Q000378:metabolism*; D048170:Streptomyces lividans / Q000378:metabolism; D013379:Substrate Specificity; D014633:Valine / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D002264:Carboxylic Acids; D007783:Lactones; D010455:Peptides; D011810:Quinoxalines; D011994:Recombinant Proteins; C031945:triostin A; D004448:Echinomycin; D004247:DNA; D064429:Fatty Acid Synthases; D014633:Valine