Specific inhibition of outgrowth of Bacillus subtilis spores by novobiocin

The preferential inhibition of Bacillus subtilis spore outgrowth by chloroquine

Chloroquine inhibited the outgrowth of Bacillus subtilis spores at a 10-fold lower concentration than that required to prevent vegetative growth. Analysis of macromolecular synthesis in outgrowing spores and vegetative cells in the presence of chloroquine indicated that it acted preferentially on transcription. Differential sensitivity of outgrowing spores and vegetative cells to chloroquine was not due to changes in the specificity of the RNA-polymerase, since RNA-polymerase activity measured in permeabilized cells was not affected differently by the drug. The preferential inhibition of spore outgrowth was not evident at pH 8.0, at which the majority of chloroquine is in a monovalent, more lipophilic, form. In the presence of inhibitors affecting membrane potential, vegetative cells were as sensitive to chloroquine as outgrowing spores. Measurement of [14C]-chloroquine uptake showed that early outgrowing spores accumulated twice as much drug as resistant late outgrowing spores and seven times more than vegetative cells. Treatment of vegetative cells with metabolic inhibitors led them to accumulate chloroquine to the levels found in outgrowing spores. Therefore, the preferential inhibition of outgrowing spores by chloroquine is the result of increased uptake of the drug, reflecting differences in energy metabolism from vegetative cells.

Heat-induced temperature sensitivity of outgrowing Bacillus cereus spores

Inactivation of Bacillus cereus spores during cooling (10 degrees C/h) from 90 degrees C occurred in two phases. One phase occurred during cooling from 90 to 80 degrees C; the second occurred during cooling from 46 to 38 degrees C. In contrast, no inactivation occurred when spores were cooled from a maximum temperature of 80 degrees C. Inactivation of spores at a constant temperature of 45 degrees C was induced by initial heat treatments from 80 to 90 degrees C. The higher temperatures accelerated the rate of inactivation. Germination of spores was required for 45 degrees C inactivation to occur; however, faster germination was not the cause of accelerated inactivation of spores receiving higher initial heat treatments. Repair of possible injury was not observed in Trypticase soy broth (BBL Microbiology Systems), peptone, beef extract, starch, or L-alanine at 30 or 35 degrees C. Microscopic evaluation of spores outgrowing at 45 degrees C revealed that when inactivation occurred, outgrowth halted at the swelling stage. Inhibition of protein synthesis by chloramphenicol at the optimum temperature also stopped outgrowth at swelling; thus protein synthesis may play a role in the 45 degree C inactivation mechanism.

[Molecular biology of the germination of Bacillus spores]

The review deals with recent results and problems of gene expression during germination of Bacillus spores. Three problems were selected: 1. The activation of metabolism as a prerequisite for the synthesis of nucleic acids and proteins. 2. The activation of nucleic acid and protein synthesis during germination. 3. The gene expression programme of germinating spores. Using the highly sensitive two-dimensional polyacrylamide gel analysis three major classes of proteins were distinguished, depending on the time of onset and duration of their syntheses: a) proteins made throughout germination (main class), b) proteins whose synthesis started only after a lag phase and then continued throughout germination, and c) proteins which are synthesized only during the early phases of germination. The programme of protein synthesis is an indicator for the control of gene expression during germination. The regulation of expression of these major gene groups during spore outgrowth is discussed.

Inhibition of DNA synthesis accompanied by stimulation of protein synthesis in novobiocin-treated developing sea urchins

Novobiocin, an inhibitor of bacterial DNA gyrase, induces abnormalities in developing embryo of the American sea urchin Arbacia punctulata. In addition this drug is also a specific inhibitor of DNA synthesis. This block in DNA synthesis is accompanied by a stimulation in protein synthesis. This effect appears to be characteristic of novobiocin, as hydroxyurea another inhibitor of DNA synthesis in the developing sea urchin, does not stimulate protein production. The present findings constitute the first report of a novobiocin-induced specific inhibition of DNA synthesis in a higher eukaryote.

[Effect of nalidixic acid on the activation of RNA synthesis in outgrowing spores of Bacillus subtilis]

Outgrowth of B. subtilis spores depends on the action of DNA gyrase (comp. Matsuda and Kameyama 1980). Application of nalidixic acid (100 micrograms/ml) to dormant spores of Bacillus subtilis prevents the outgrowth. Application of nalidixic acid (100 micrograms/ml) during the early outgrowth phase (after a 20 min germination period) does not prevent, but only delay spore outgrowth. Germination of spores is not influenced. Nalidixic acid is an effective inhibitor of RNA synthesis in outgrowing spores, whereas vegetative cells are more resistant. Spores can grow out inspite of a remarkably reduced intensity of RNA synthesis. Nalidixic acid particularly inhibits the synthesis of stable RNA, probably that of ribosomal RNA. We suggest that DNA gyrase-catalyzed alterations in DNA structure are involved in the regulation of the gene expressional program of outgrowing B. subtilis spores.

Bacillus subtilis deoxyribonucleic acid gyrase

Bacillus subtilis 168 was shown to contain a deoxyribonucleic acid (DNA) gyrase activity which closely resembled those of the enzymes isolated from Escherichia coli and Micrococcus luteus in its enzymatic requirements, substrate specificity, and sensitivity to several antibiotics. The enzyme was purified from the wild type and nalidixic acid-resistant and novobiocin-resistant mutants of B. subtilis and was functionally characterized in vitro. The genetic loci nalA and novA but not novB were shown to code for portions of the functional gyrase. Enzyme from the antibiotic-resistant mutants was resistant to the drug in vitro. The most striking observation was the remarkable similarity between the B. subtilis enzyme and other DNA gyrases, especially with respect to the oxolinic acid-induced DNA cleavage in the presence of sodium dodecyl sulfate. All of the enzymes appeared to possess the same specificity of cutting sites regardless of the source or type of DNA used. This result implies that gyrase binding to DNA is highly specific.