title: Characterization of the amicetin biosynthesis gene cluster from Streptomyces vinaceusdrappus NRRL 2363 implicates two alternative strategies for amide bond formation.
abstract: Amicetin, an antibacterial and antiviral agent, belongs to a group of disaccharide nucleoside antibiotics featuring an α-(1→4)-glycoside bond in the disaccharide moiety. In this study, the amicetin biosynthesis gene cluster was cloned from Streptomyces vinaceusdrappus NRRL 2363 and localized on a 37-kb contiguous DNA region. Heterologous expression of the amicetin biosynthesis gene cluster in Streptomyces lividans TK64 resulted in the production of amicetin and its analogues, thereby confirming the identity of the ami gene cluster. In silico sequence analysis revealed that 21 genes were putatively involved in amicetin biosynthesis, including 3 for regulation and transportation, 10 for disaccharide biosynthesis, and 8 for the formation of the amicetin skeleton by the linkage of cytosine, p-aminobenzoic acid (PABA), and the terminal (+)-α-methylserine moieties. The inactivation of the benzoate coenzyme A (benzoate-CoA) ligase gene amiL and the N-acetyltransferase gene amiF led to two mutants that accumulated the same two compounds, cytosamine and 4-acetamido-3-hydroxybenzoic acid. These data indicated that AmiF functioned as an amide synthethase to link cytosine and PABA. The inactivation of amiR, encoding an acyl-CoA-acyl carrier protein transacylase, resulted in the production of plicacetin and norplicacetin, indicating AmiR to be responsible for attachment of the terminal methylserine moiety to form another amide bond. These findings implicated two alternative strategies for amide bond formation in amicetin biosynthesis.
authors.affiliation: CAS Key Laboratory of Marine Bio-resources Sustainable Utilization, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People’s Republic of China.
authors.forename: Gaiyun
authors.initials: G
authors.lastname: Zhang
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhang
authors.forename: Sumei
authors.initials: S
authors.lastname: Li
authors.forename: Ji
authors.initials: J
authors.lastname: Xiao
authors.forename: Guangtao
authors.initials: G
authors.lastname: Zhang
authors.forename: Yiguang
authors.initials: Y
authors.lastname: Zhu
authors.forename: Siwen
authors.initials: S
authors.lastname: Niu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Ju
authors.forename: Changsheng
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000577:Amides / Q000737:chemistry* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000096:biosynthesis; D000998:Antiviral Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D006031:Glycosylation; D008969:Molecular Sequence Data; D005810:Multigene Family; D011741:Pyrimidine Nucleosides / Q000096:biosynthesis / Q000737:chemistry; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D048170:Streptomyces lividans / Q000201:enzymology / Q000235:genetics
chemical_list: D000577:Amides; D000900:Anti-Bacterial Agents; D000998:Antiviral Agents; D001426:Bacterial Proteins; D011741:Pyrimidine Nucleosides; C004413:amicetin; C015399:norplicacetin