title: Enhancement and selective production of phoslactomycin B, a protein phosphatase IIa inhibitor, through identification and engineering of the corresponding biosynthetic gene cluster.
abstract: Phoslactomycins (PLMs), potent and selective inhibitors of serine threonine phosphatases, are of interest for their antitumor and antiviral activity. Multiple analogs and low titers in the fermentation process have hampered the development of this class of natural products. The entire 75-kb PLM biosynthetic gene cluster of Streptomyces sp. HK-803 was cloned, sequenced, and analyzed. The loading domain and seven extension modules of the PLM polyketide synthase generate an unusual linear unsaturated polyketide chain containing both E- and Z-double bonds from a cyclohexanecarboxylic acid (CHC) primer. Hydroxylation of the CHC-derived side chain of the resulting PLM-B by PlmS2, and a subsequent esterification, produces the remaining PLM analogs. A new PCR targeting technology allowed rapid and facile allelic replacement of plmS2. The resulting mutant selectively produced the PLM-B, at 6-fold higher titers than the wild type strain. This mutant and the biosynthetic gene cluster will facilitate engineered microbial production of hybrid PLMs with improved properties.
authors.affiliation: Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia 23219, USA.
authors.forename: Nadaraj
authors.initials: N
authors.lastname: Palaniappan
authors.forename: Beom Seok
authors.initials: BS
authors.lastname: Kim
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Sekiyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Osada
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Reynolds
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis; D004926:Escherichia coli / Q000378:metabolism; D005813:Genes, Synthetic; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D005810:Multigene Family; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D013302:Streptomyces / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D007783:Lactones; D009943:Organophosphorus Compounds; C060449:phoslactomycin B; D010749:Phosphoprotein Phosphatases