Template specificity of transcription during sporulation of Bacillus subtilis

Minichromosome from BK virus as a template for transcription in vitro

BK virus DNA can be extracted from virions as a nucleoprotein complex containing about 20 nucleosomes. Transcription of this "minichromosome" with Escherichia coli RNA polymerase indicates that both initiation and elongation of RNA chains are reduced by the presence of nucleosomes. Hybridization analysis of RNA made on the complex shows preferential transcription of one region of BK virus genome. No increase in strand selection is observed with respect to transcription of purified superhelical BK virus DNA.

Bacillus subtilis mutant temperature sensitive in the synthesis of ribonucleic acid

A Bacillus subtilis temperature-sensitive mutant (PB1653) has been isolated in which the rate of ribonucleic acid (RNA) synthesis sharply decreases after shift to 45 degrees C. Both stable and unstable RNAs are affected by the mutation. The possibility that the block of transcription at high temperature could be due to a "stringent" effect, mediated by an increase in the concentration of "magic spot" nucleotides, has been ruled out. Treatment with chloramphenicol (or streptomycin) rapidly restores the rate of RNA synthesis at 45 degrees C. The synthesis of RNA in the mutant during the early phases of spore germination is not temperature sensitive. The phage-specific transcription during infection with SPP1 phage, at high temperature, is less affected than that of the bacterial chromosome. In vitro experiments indicate that, in the mutant at high temperature, RNA polymerase undergoes a change in template specificity. The rna-53 mutation has been located on the B. subtilis genetic map near the hisA locus.

Evolution of the transcription complex during sporulation of Bacillus subtilis

Ribonucleic acid polymerase activity in partially purified extract of cells of Bacillus subtilis harvested at different times (t-1, to, t1, and t2) was studied by zone centrifugation. During the course of sporulation, vegetative sigma-factor activity decreased and the transcription complex lost some of its affinity for active sigma factor. The complex underwent a two-stage change in sedimentation value, from 14.5S in vegetative growth phase to a 13S species very early in sporulation to a 16S species at later times. Two SpoO mutants have been studied by zone centrifugation. One strain, a rifampin-resistant (RfmR) mutant, failed to show any modification of the transcription complex, whereas the other, a Rfms strain, underwent a partial evolution of the transcription complex after to.

In vivo and in vitro transcription of SPP1 DNA by host RNA polymerase

Most (if not all) SPP1 RNA can be synthesized in infected cells in the presence of chloramphenicol, or in vitro by Bacillus subtilis RNA polymerase.