title: Characterization of the sugar-O-methyltransferase LobS1 in lobophorin biosynthesis.
abstract: Lobophorins A (1) and B (2) belong to a large group of spirotetronate natural products with potent antibacterial and antitumor activities. The cloning of the lobophorin biosynthesis gene cluster from the deep-sea-derived Streptomyces sp. SCSIO 01127 identified a sugar-O-methyltransferase-encoding gene lobS1. The lobS1 inactivation mutant accumulated two new lobophorin analogs 3 and 4, different from 1 and 2 by lacking the 4-methyl group at the terminal L-digitoxose, respectively. Biochemical experiments verified that LobS1 was a SAM-dependent sugar-O-methyltransferase that required divalent metal ions for better activity. Antibacterial assays revealed compounds 3 and 4 were generally less potent than compounds 1 and 2. These findings suggest that the methylation on the terminal digitoxose by LobS1 tailors lobophorin biosynthesis and highlights the importance of this methylation for antibacterial potence.
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, RNAM Center for Marine Microbiology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou, 510301, China.
authors.forename: Ji
authors.initials: J
authors.lastname: Xiao
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yiguang
authors.initials: Y
authors.lastname: Zhu
authors.forename: Sumei
authors.initials: S
authors.lastname: Li
authors.forename: Guangtao
authors.initials: G
authors.lastname: Zhang
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhang
authors.forename: Kumar
authors.initials: K
authors.lastname: Saurav
authors.forename: Changsheng
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D018942:Macrolides / Q000737:chemistry / Q000378:metabolism*; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D012623:Seawater / Q000382:microbiology; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018942:Macrolides; C121297:lobophorin A; C121298:lobophorin B; D008780:Methyltransferases