ABSTRACT
Cells containing reporters which are specifically induced via selected promoters are used in pharmaceutical drug discovery and in environmental biology. They are used in screening for novel drug candidates and in the detection of bioactive compounds in environmental samples. In this study, we generated and validated a set of five Bacillus subtilis promoters fused to the firefly luciferase reporter gene suitable for cell-based screening, enabling the as yet most-comprehensive high-throughput diagnosis of antibiotic interference in the major biosynthetic pathways of bacteria: the biosynthesis of DNA by the yorB promoter, of RNA by the yvgS promoter, of proteins by the yheI promoter, of the cell wall by the ypuA promoter, and of fatty acids by the fabHB promoter. The reporter cells mainly represent novel antibiotic biosensors compatible with high-throughput screening. We validated the strains by developing screens with a set of 14,000 pure natural products, representing a source of highly diverse chemical entities, many of them with antibiotic activity (6% with anti-Bacillus subtilis activity of
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacillus subtilis/cytology , Bacillus subtilis/drug effects , Biosensing Techniques/methods , Bacillus subtilis/metabolism , Bacterial Proteins/antagonists & inhibitors , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cell Membrane/drug effects , Cell Membrane/metabolism , DNA, Bacterial/antagonists & inhibitors , DNA, Bacterial/metabolism , Fatty Acids/antagonists & inhibitors , Fatty Acids/metabolism , Microbial Sensitivity Tests/methods , Promoter Regions, Genetic , RNA, Bacterial/antagonists & inhibitors , RNA, Bacterial/metabolismSubject(s)
4-Butyrolactone/analogs & derivatives , 4-Butyrolactone/chemical synthesis , Biological Products , Enzyme Inhibitors/chemical synthesis , cdc25 Phosphatases/antagonists & inhibitors , 4-Butyrolactone/chemistry , 4-Butyrolactone/pharmacology , Cell Survival/drug effects , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Oxidation-Reduction , Stereoisomerism , Structure-Activity Relationship , Tumor Cells, Cultured/enzymologyABSTRACT
Biologically active natural products can be regarded as evolutionary selected and biologically validated starting points in structural space for the development of compound libraries. For libraries designed and synthesized around a given natural product, a higher hit rate and the identification of biologically relevant hits can be expected, justifying a probably higher investment in the development of the corresponding syntheses. This approach requires the development of complex multistep reaction sequences on the solid phase. Employing the protein phosphatase Cdc25 inhibitor dysidiolide as an example, we demonstrate that this goal can be achieved successfully. The reaction sequences developed led to dysidiolide analogues in overall 8-12 linear steps with the longest sequence on the solid support amounting to up to 11 sequential transformations. The desired products were obtained in overall yields ranging from 6% to 27% and in multimilligram amounts starting from 100 mg of resin. The transformations applied include a variety of very different reaction types widely used in organic synthesis (i.e., an asymmetric cycloaddition employing a removable chiral auxiliary, different organometallic transformations, olefination reactions, different oxidation reactions, acidic hydrolyses, and a nucleophilic substitution). Biological investigation of the eight dysidiolide analogues synthesized showed that they inhibit Cdc25C in the low micromolar range with the IC(50) value varying by a factor of 20 and that they display considerable and differing biological activities in cytotoxicity assays employing different cancer cell lines.
