Permanent loss of chromosome initiation in toluene-treated Bacillus subtilis cells

Novel tricyclics (e.g., GSK945237) as potent inhibitors of bacterial type IIA topoisomerases

During the course of our research on the lead optimisation of the NBTI (Novel Bacterial Type II Topoisomerase Inhibitors) class of antibacterials, we discovered a series of tricyclic compounds that showed good Gram-positive and Gram-negative potency. Herein we will discuss the various subunits that were investigated in this series and report advanced studies on compound 1 (GSK945237) which demonstrates good PK and in vivo efficacy properties.

Novel hydroxyl tricyclics (e.g., GSK966587) as potent inhibitors of bacterial type IIA topoisomerases

During the course of our research to find novel mode of action antibacterials, we discovered a series of hydroxyl tricyclic compounds that showed good potency against Gram-positive and Gram-negative pathogens. These compounds inhibit bacterial type IIA topoisomerases. Herein we will discuss structure-activity relationships in this series and report advanced studies on compound 1 (GSK966587) which demonstrates good PK and in vivo efficacy properties. X-ray crystallographic studies were used to provide insight into the structural basis for the difference in antibacterial potency between enantiomers.

Novel cyclohexyl-amides as potent antibacterials targeting bacterial type IIA topoisomerases

As part of our wider efforts to exploit novel mode of action antibacterials, we have discovered a series of cyclohexyl-amide compounds that has good Gram positive and Gram negative potency. The mechanism of action is via inhibition of bacterial topoisomerases II and IV. We have investigated various subunits in this series and report advanced studies on compound 7 which demonstrates good PK and in vivo efficacy properties.

Novel amino-piperidines as potent antibacterials targeting bacterial type IIA topoisomerases

We have identified a series of amino-piperidine antibacterials with a good broad spectrum potency. We report the investigation of various subunits in this series and advanced studies on compound 8. Compound 8 possesses good pharmacokinetics, broad spectrum antibacterial activity and demonstrates oral efficacy in a rat lung infection model.

Toluene embryopathy

Three children with microcephaly, central nervous system dysfunction, minor craniofacial and limb anomalies, and variable growth deficiency were born to women who inhaled large quantities of pure toluene throughout pregnancy. The features in our patients were reminiscent of the patterns of malformation previously described following in utero exposure to alcohol, certain anticonvulsants, and hyperphenylalaninemia. It is possible that there is a variable and nonspecific teratogenic phenotype characterized by alterations in growth, development, and morphogenesis. Careful evaluation and monitoring of infants exposed to toluene in utero are needed to determine the significance of our findings.

Neurological sequelae of toluene abuse

1 Twenty patients, aged eight to 14 years, were admitted to hospital over a six year period with an acute encephalopathy following toluene abuse. 2 In all cases toxicity was confined to the central nervous system. Electroencephalography performed in ten patients was abnormal in three. 3 Fourteen patients made a complete recovery, five had evidence of personality impairment but were lost to follow-up, one had a persistent cerebellar ataxia one year after admission, despite absence of exposure to toluene. 4 Solvent abuse may be impossible to establish on history, as in six of these patients. Blood assay of toluene is vital in such cases, as is an awareness that toluene abuse may lead to acute encephalopathy.

DNA-membrane association is necessary for initiation of chromosomal and plasmid replication in Bacillus subtilis

We examined the effect of the inhibition of initiation of DNA replication on the membrane association of the chromosomal origin of replication of Bacillus subtilis and the Staphylococcus aureus-Bacillus pumilus chimeric plasmid pSL103, using temperature-sensitive mutants of B. subtilis that have specifically affected initiation. Inhibition of initiation of the chromosome and pSL103 in the initiation mutant dna-1 results in a decrease in the membrane association of both a marker near the chromosomal origin, purA16, and the plasmid pSL103. The membrane association of both purA16 and pSL103 can be recovered by allowing initiation to resume at the permissive temperature. In another initiation mutant, dnaB19, only the initiation and membrane association of the host chromosome are affected at the nonpermissive temperature, whereas both initiation and membrane association are not affected in the plasmid pSL103. In experiments in vitro, DNA containing the purA16 marker and pSL103 DNA molecules are both selectively released during incubation of purified DNA-membrane complexes prepared from dna-1 cells at the nonpermissive temperature. On the other hand, only purA16 DNA is released in vitro from the DNA-membrane complex prepared from dnaB19 cells. This consistent coupling between initiation and membrane association indicates that DNA-membrane association is critical for the initiation of the B. subtilis chromosome and the plasmid pSL103.

Membrane association of a Staphylococcus aureus plasmid in Bacillus subtilis

The Staphylococcus aureus plasmid pUB110 was found to be enriched in deoxyribonucleic acid-membrane complexes isolated from Bacillus subtilis containing pUB110.

The synthesis of 3'-dATP and its use as an inhibitor of ATP-dependent DNA synthesis in toluene-treated Escherichia coli

A structural analogue of ATP, 3'-deoxyadenosine triphosphate (3'-dATP), has been synthesized from cordycepin (3'-deoxyadenosine), characterized, and determined to be an inhibitor of ATP-dependent DNA synthesis in Escherichia coli cells which have been reduced permeable to nucleoside triphosphates by treatment with toluene. The analogue is a competitive inhibitor of ATP and it inhibits replicative DNA synthesis 50% at concentrations of ca. 0.15 mM in the presence of 1.0 mM ATP and 4 x 10(8) cells/ml. The degree of inhibition of a given amount of 3'-dATP is inversely related to the cell concentration in the reaction mixture. The analogue interferes with some function of ATP which is continuously required during the course of the reaction and does not irreversibly inactivate the cells' DNA synthesis apparatus. 3'-Deoxyadenosine triphosphate may prove useful in elucidating the roles of ATP in DNA synthesis in more purified replicating systems.