title: Biosynthesis of 3-hydroxy-5-methyl-o-methyltyrosine in the saframycin/ safracin biosynthetic pathway.
abstract: The biosynthesis study of antibiotics saframycin (SFM) in Streptomyces lavendulae and safracin (SAC) in Pseudomonas fluorescens demonstrated that 3-hydroxy-5-methyl-Omethyltyrosine (3h5mOmTyr), a nonproteinogenic amino acid, is the precursor of the tetrahydroisoquinoline molecular core. In the biosynthetic gene cluster of SAC/SFM, sacD/ sfmD encodes a protein with high homology to each other but no sequence similarity to other known enzymes; sacF/ sfmM2 and sacG/sfmM3 encode methyltransferases for Cmethylation and O-methylation; and sacE/sfmF encodes a small protein with significant sequence similarity to the MbtH-like proteins, which are frequently found in the biosynthetic pathways of nonribosomal peptide antibiotics and siderophores. To address their function, the biosynthetic cassette of 3h5mOmTyr was heterologously expressed in S. coelicolor and P. putida, and an in-frame deletion and complementation in trans were carried out. The results revealed that (i) SfmD catalyzes the hydroxylation of aromatic rings;(ii) sacD/sacF/sacG in the SAC gene cluster and sfmD/sfmM2/sfmM3 in the SFM cluster are sufficient for the biosynthesis of 3h5mOmTyr; and (iii) the mbtH-like gene is not required for the biosynthesis of the 3h5mOmTyr precursor.
authors.affiliation: School of Life Science and Technology, Xi'an Jiaotong University, 28 Xianning West Road, Xi'an, Shaanxi 710049, China.
authors.forename: Cheng-Yu
authors.initials: CY
authors.lastname: Fu
authors.forename: Man-Cheng
authors.initials: MC
authors.lastname: Tang
authors.forename: Chao
authors.initials: C
authors.lastname: Peng
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: He
authors.forename: Wen
authors.initials: W
authors.lastname: Liu
authors.forename: Gong-Li
authors.initials: GL
authors.lastname: Tang
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D053898:Biosynthetic Pathways; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006900:Hydroxylation; D007546:Isoquinolines / Q000378:metabolism; D008781:Methyltyrosines / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D005810:Multigene Family; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism
chemical_list: C544271:3-hydroxy-5-methyl-O-methyltyrosine; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D007546:Isoquinolines; D008781:Methyltyrosines; C052748:saframycin D; C096067:saframycin E; C056792:saframycin G; C056794:saframycin F