Transcription in Archaebacteria

DNA dependent RNA polymerases from archaebacteria are complex molecules made up of 9 to 11 components yielding characteristic patterns in SDS Polyacrylamid gel electrophoresis. All components except one, in few cases two, of the smallest, are present but once per enzyme monomer.

DNA dependent RNA polymerases of archaebacteria differ from those of eubacteria in their complexity, their composition and thus their subunit patterns. They resemble each other and those of eukaryotes, especially yeast RNA polymerase A (I) in these respects.

All archaebacterial RNA polymerases are completely insensitive to rifampicin, streptolydigin and α amanitin.

They are stimulated by the alkaloid silybin which selectively enhances transcription by eukaryotic RNA polymerase A (I).

First results concerning the function of their components and some aspects of the transcription by these enzymes are discussed. Implications of the comparative analysis of RNA polymerase structure for taxonomic purposes are described.