Template Specificity Of RNA Polymerase Research Articles

For Want of a Template

For Want of a Template

Bacteriophages: How Bacterial Spores Capture and Protect Phage DNA

A recent study explains how bacterial spores capture and protect phage DNA, which remains free in the host cytoplasm but is unable to initiate the virulence pathway that leads to lysis of actively growing bacterial cells.

Template specificity and subunits of RNA polymerase from asporogenous mutants of Bacillus subtilis.

In order to investigate relations between template specificity of RNA polymerase and sporulation, RNA polymerase activities in partially purified preparations from various asporogenous mutants were measured with poly[d(A-T)] or DNA from phage PBS 15 as template. Results obtained suggest that morphological changes occurring during sporulation may not be tightly linked temporally to transcriptional events.Subunits of RNA polymerase from these mutants were analyzed by sodium dodecyl sulfate – polyacrylamide gel electrophoresis after purification by (NH4)2SO4 precipitation, DEAE-cellulose chromatography, phosphocellulose chromatography, and glycerol gradient centrifugation. Phenylmethylsulfonyl fluoride was present throughout the purification procedure to prevent proteolytic degradation. It was found that β and β′ subunits were present in 1:1 ratio in all preparations. In addition to β, β′, and α subunits, a protein having a molecular weight of 95 000 was found in enzyme preparations from a wild-type strain and stage II mutants harvested at t5–t9. This protein was absent in stage 0 mutants and in all strains harvested in log phase. The enzyme containing this protein was eluted from phosphocellulose column with 0.6 M KCl rather than 0.35 M KCl, which eluted the enzyme without the 95 000 dalton protein. Furthermore the enzyme with this protein showed a sedimentation coefficient higher than that of the enzyme without the 95 000 dalton protein.

Direct assay for sigma factor activity and demonstration of the loss of this activity during sporulation in Bacillus subtilis.

Summary. The change in template specificity of RNA polymerase, which in Bacillus subtilis takes place during the two hours following cessation of exponential growth (to--t2), has been confirmed with enzyme extracted in the presence of several protease inhibitors. With these enzyme preparations no alteration of the fl subunits could be detected. It is concluded that such an alteration cannot account for the loss by the enzyme of the ability to transcribe phage ~e DNA. An assay specific for vegetative sigma factor activity is described. When applied to crude extracts prepared in the presence of protease inhibitors, it was possible to demonstrate directly a loss in this activity, occurring between t o and t 2. This loss seems to account for the change in RNA polymerase template specificity which takes place during the same time period.

Change in the Template Specificity of RNA Polymerase during Sporulation of Bacillus subtilis

RNA polymerase from sporulating cells of Bacillus subtilis fails to transcribe phage ϕe DNA in vitro while RNA polymerase from vegetative cells is active with the same template.

Modification of transcription following interaction of template specific monomers of Bacillus subtilis RNA polymerase.

The template specificity of RNA polymerase from B. subtilis may be altered by factors reminiscent of the sigma factor in E. coli.