title: A glutamic acid 3-methyltransferase encoded by an accessory gene locus important for daptomycin biosynthesis in Streptomyces roseosporus.
abstract: In many peptide antibiotics, modified amino acids are important for biological activity. The amino acid 3-methyl-glutamic acid (3mGlu) has been found only in three cyclic lipopeptide antibiotics: daptomycin and the A21978C family produced by Streptomyces roseosporus, calcium-dependent antibiotic produced by Streptomyces coelicolor and A54145 produced by Streptomyces fradiae. We studied the non-ribosomal peptide synthetase genes involved in A21978C biosynthesis and the downstream genes, dptG, dptH, dptI and dptJ predicted to encode a conserved protein of unknown function, a thioesterase, a methyltransferase (MTase) and a tryptophan 2,3-dioxygenase respectively. Deletion of dptGHIJ reduced overall lipopeptide yield and led to production of a series of novel A21978C analogues containing Glu12 instead of 3mGlu12. Complementation by only dptI, or its S. coelicolor homologue, glmT, restored the biosynthesis of the 3mGlu-containing compounds in the mutant. Compared with A21978C, the Glu12-containing derivatives were less active against Staphylococcus aureus. Further genetic analyses showed that members of the dptGHIJ locus cooperatively contributed to optimal A21978C production; deletion of dptH, dptI or dptJ genes reduced the yield significantly, while expression of dptIJ or dptGHIJ from the strong ermEp* promoter substantially increased lipopeptide production. The results indicate that these genes play important roles in the biosynthesis of daptomycin, and that dptI encodes a Glu MTase.
authors.affiliation: Cubist Pharmaceuticals, Inc., 65 Hayden Avenue, Lexington, MA 02421, USA. kien.nguyen@cubist.com
authors.forename: Kien T
authors.initials: KT
authors.lastname: Nguyen
authors.forename: David
authors.initials: D
authors.lastname: Kau
authors.forename: Jian-Qiao
authors.initials: JQ
authors.lastname: Gu
authors.forename: Paul
authors.initials: P
authors.lastname: Brian
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Wrigley
authors.forename: Richard H
authors.initials: RH
authors.lastname: Baltz
authors.forename: Vivian
authors.initials: V
authors.lastname: Miao
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D017576:Daptomycin / Q000096:biosynthesis*; D018698:Glutamic Acid / Q000031:analogs & derivatives / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013302:Streptomyces / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: C425779:3-methylglutamic acid; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018698:Glutamic Acid; D008780:Methyltransferases; D017576:Daptomycin