Summary

The super-selective affinity labelling procedure for the active center of RNA Polymerase from Escherichia coli (Grachev et al., 1987a) was successfully applied to the enzyme from archaebacteria. Using adenosine-5'-trimetaphosphate or the p-hydroxybenzaldehyde ester of ATP, the second largest subunit B ' of the RNA polymerase from methanogenic/halophilic and sulphate reducing archaebacteria, and the largest subunit B of the non-methanogenic thermophilic archaebacterium Sulfolohus sp. strain B 12 are labelled specifically. The labelling reaction is strictly template-dependent and blocked by the transcription in-hibitor heparin. We present evidence that adenosine-5'-trimetaphosphate is attached close to the catalytic center of the RNA polymerase via a phosphoamide bond to lys or his residues. The specific affinity labelling of subunit B ' from methanogens/halophiles together with the earlier observed immunological cross-reactivity (Gropp et al., 1986) indicates that this subunit as well as subunit B " contains amino acid sequences which are homologous to sequences in subunit B of the enzyme from non-methanogenic thermophilic archaebacteria and in subunit ß from E. coli RNA polymerase