[Immunoelectron-microscopic determination of the localization of tryptophanyl-tRNA synthetase in eubacterial cells of Escherichia coli and Methanococcus halophilus archaebacteria].

Localization of tryptophanyl-tRNA-synthetase (TRS) was studied in halophilic archaebacterium Methanococcus halophilus and eubacterium E. coli. Ultrathin sections of the cells, fixed with glutaraldehyde and embedded in "Lowicryl K4M" at -35 degrees C, were treated with colloidal gold complexes containing monoclonal antibodies Aml against TRS. The latter bind specifically to TRS isolated both from eucaryotes, archae- and eubacteria. According to the label distribution three zones in M. halophilus and E. coli can be distinguished: (i) about 75% of the whole amount of gold particles are localized in the cytoplasm, the distribution of label being more or less homogeneous; (ii) cytoplasmic regions, adjacent to nucleoid, are intensively labelled (about 20% of the whole amount of label); (iii) very few gold particles (not more than 10% of the whole amount) are present in the nucleoid. The data obtained show, that the distribution of TRS in the nucleoid and cytoplasm of archaebacterium M. halophilus is close to the distribution of TRS, found in E. coli. It supports our previous conclusion that the structural organization of transcription-translation apparatus in methanogen and halophilic archaebacteria is similar to that in eubacteria.