Synthesis of substituted 6-anilinouracils and their inhibition of DNA polymerase IIIC and Gram-positive bacterial growth.
ABSTRACT Certain substituted 6-anilinouracils are potent and selective inhibitors of Gram+ bacterial DNA polymerase IIIC (pol IIIC). In addition, analogues with 3-substituents in the uracil ring have potent antibacterial activity against Gram+ organisms in culture. In an attempt to find optimal anilino substituents for pol IIIC binding and optimal 3-substituents for antibacterial activity, we have prepared several series of 3-substituted-6-aminouracils and assayed their activity against pol IIIC from Bacillus subtilis and a panel of Gram+ and Gram- bacteria in culture. The 6-(3-ethyl-4-methylanilino) group and closely related substituent patterns maximized pol IIIC inhibition potency. Among a series of 3-(substituted-butyl)-6-(3-ethyl-4-methylanilino)uracils, basic amino substituents increased pol IIIC inhibition, but decreased antibacterial activity. The most potent antibacterials were simple hydroxybutyl and methoxybutyl derivatives, and hydrophobically substituted piperidinylbutyl derivatives.
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ABSTRACT: New antibiotics with novel modes of action are required to combat the growing threat posed by multi-drug resistant bacteria. Over the last decade, genome sequencing and other high-throughput techniques have provided tremendous insight into the molecular processes underlying cellular functions in a wide range of bacterial species. We can now use these data to assess the degree of conservation of certain aspects of bacterial physiology, to help choose the best cellular targets for development of new broad-spectrum antibacterials. DNA replication is a conserved and essential process, and the large number of proteins that interact to replicate DNA in bacteria are distinct from those in eukaryotes and archaea; yet none of the antibiotics in current clinical use acts directly on the replication machinery. Bacterial DNA synthesis thus appears to be an underexploited drug target. However, before this system can be targeted for drug design, it is important to understand which parts are conserved and which are not, as this will have implications for the spectrum of activity of any new inhibitors against bacterial species, as well as the potential for development of drug resistance. In this review we assess similarities and differences in replication components and mechanisms across the bacteria, highlight current progress towards the discovery of novel replication inhibitors, and suggest those aspects of the replication machinery that have the greatest potential as drug targets.Current drug targets 12/2011; 13(3):352-72. · 3.93 Impact Factor
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ABSTRACT: Based on the finding that aerobic Gram-positive antibacterials that inhibit DNA polymerase IIIC (pol IIIC) were potent inhibitors of the growth of anaerobic Clostridium difficile (CD) strains, we chose to clone and express the gene for pol IIIC from this organism. The properties of the recombinant enzyme are similar to those of related pol IIICs from Gram-positive aerobes, e.g. B. subtilis. Inhibitors of the CD enzyme also inhibited B. subtilis pol IIIC, and were competitive with respect to the cognate substrate 2'-deoxyguanosine 5'-triphosphate (dGTP). Significantly, several of these inhibitors of the CD pol IIIC had potent activity against the growth of CD clinical isolates in culture.Current Enzyme Inhibition 10/2011; 7(3):147-153.
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ABSTRACT: Condensin—an SMC-kleisin complex—is essential for efficient segregation of sister chromatids in eukaryotes [1, 2, 3 and 4]. In Escherichia coli and Bacillus subtilis, deletion of condensin subunits results in severe growth phenotypes and the accumulation of cells lacking nucleoids [ 5 and 6]. In many other bacteria and under slow growth conditions, however, the reported phenotypes are much milder or virtually absent [ 7, 8, 9 and 10]. This raises the question of what role prokaryotic condensin might play during chromosome segregation under various growth conditions. In B. subtilis and Streptococcus pneumoniae, condensin complexes are enriched on the circular chromosome near the single origin of replication by ParB proteins bound to parS sequences [ 11 and 12]. Using conditional alleles of condensin in B. subtilis, we demonstrate that depletion of its activity results in an immediate and severe defect in the partitioning of replication origins. Multiple copies of the chromosome remain unsegregated at or near the origin of replication. Surprisingly, the growth and chromosome segregation defects in rich medium are suppressed by a reduction of replication fork velocity but not by partial inhibition of translation or transcription. Prokaryotic condensin likely prevents the formation of sister DNA interconnections at the replication fork or promotes their resolution behind the fork.Current Biology 01/2014; 24. · 9.49 Impact Factor