title: Cloning, sequencing and characterization of the biosynthetic gene cluster of sanglifehrin A, a potent cyclophilin inhibitor.
abstract: Sanglifehrin A (SFA), a potent cyclophilin inhibitor produced by Streptomyces flaveolus DSM 9954, bears a unique [5.5] spirolactam moiety conjugated with a 22-membered, highly functionalized macrolide through a linear carbon chain. SFA displays a diverse range of biological activities and offers significant therapeutic potential. However, the structural complexity of SFA poses a tremendous challenge for new analogue development via chemical synthesis. Based on a rational prediction of its biosynthetic origin, herein we report the cloning, sequencing and characterization of the gene cluster responsible for SFA biosynthesis. Analysis of the 92 776 bp contiguous DNA region reveals a mixed polyketide synthase (PKS)/non-ribosomal peptide synthetase (NRPS) pathway which includes a variety of unique features for unusual PKS and NRPS building block formation. Our findings suggest that SFA biosynthesis requires a crotonyl-CoA reductase/carboxylase (CCR) for generation of the putative unusual PKS starter unit (2R)-2-ethylmalonamyl-CoA, an iterative type I PKS for the putative atypical extender unit (2S)-2-(2-oxo-butyl)malonyl-CoA and a phenylalanine hydroxylase for the NRPS extender unit (2S)-m-tyrosine. A spontaneous ketalization of significant note, may trigger spirolactam formation in a stereo-selective manner. This study provides a framework for the application of combinatorial biosynthesis methods in order to expand the structural diversity of SFA.
authors.affiliation: State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Qu
authors.forename: Nan
authors.initials: N
authors.lastname: Jiang
authors.forename: Fei
authors.initials: F
authors.lastname: Xu
authors.forename: Lei
authors.initials: L
authors.lastname: Shao
authors.forename: Gongli
authors.initials: G
authors.lastname: Tang
authors.forename: Barrie
authors.initials: B
authors.lastname: Wilkinson
authors.forename: Wen
authors.initials: W
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D021983:Cyclophilins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D007783:Lactones / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D013141:Spiro Compounds / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013237:Stereoisomerism; D013302:Streptomyces / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D007783:Lactones; D013141:Spiro Compounds; C121329:sanglifehrin A; D021983:Cyclophilins