The RNA polymerase of Enterobacteria senses the physiological state of the cell by interaction with signal molecules such as ppGpp and responds by altering the rate of initiation of rRNA and t R N A species so as to limit or enhance the capacity for further growth.
Antigenic variability of bacterial RNA polymerases
โ Scribed by Nikiforov, V. G. ;Lebedev, A. N. ;Kalyaeva, E. S.
- Publisher
- Springer
- Year
- 1981
- Tongue
- English
- Weight
- 454 KB
- Volume
- 183
- Category
- Article
- ISSN
- 0026-8925
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โฆ Synopsis
Radioimmunoassay analysis of enteric and some other Gram-negative bacteria has shown that the antigenic structure of the RNA polymerase alpha subunit is more conserved than that of the beta and beta' subunits. Since anti-alpha antibodies do not affect RNA polymerase activity, the constraints which determine the low variability of the antigenic structure of the alpha subunit are not directly related to its functional role. The antigenic determinants of the alpha subunit located on the surface of the RNA polymerase molecule are more conserved than those involved in contacts with other subunits; an opposite tendency characterizes the beta subunit. The range of variability of the antigenic determinants buried inside the RNA polymerase molecule suggests that the subunits are attached to each other rather loosely. Immunological comparison of RNA polymerases provides a simple method for reconstructing bacterial genealogies. The genealogy of the bacteria examined is essentially in agreement with phylogenetic trees based on 16S and 5S rRNA sequence characterization. This argues against extensive interspecific transfer of genes coding for components of the transcription and translation apparatus.
๐ SIMILAR VOLUMES
The DNA-dependent RNA polymerases I, II, and IlI (ribonucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) from Achlya ambisexualis E87 (male), have been isolated. The highly purified RNA polymerase I was found to be composed of polypeptides with the following molecular weights (. 10-~):