Intralineage diversity of archaebacterial ribosomes: a dichotomy of ribosome features separates sulfur-dependent archaebacteria and methanococcaceae from other archaebacterial taxa

• Published in: Journal of molecular evolution 1986-12, Vol.23 (4), p.343-353
• Main Authors: TEICHNER, A, LONDEI, P, CAMMARANO, P
• Format: Article
• Language: English
• Subjects: Bacteriology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Microbiology; Systematics
• ISSN: 0022-2844; 1432-1432
• DOI: 10.1007/BF02100644

The aggregate masses and relative protein contents of eubacterial and archaebacterial ribosomes have been estimated from the buoyant densities of the ribosomal subunits and the anhydrous weights of the rRNA species. In contrast to the situation in eubacteria, archaebacterial ribosomes fall into two size classes that differ only in the relative abundances of their protein moieties. Eubacterial-sized ribosomes are harbored by extreme halophiles and all methanogens but the Methanococcaceae. Ribosomes heavier than those of eubacteria are found in the Methanococcaceae and all sulfur-dependent thermophiles. The data indicate that a change in ribosome structure occurred within the "methanogen" branch; therefore, although ribosome composition is distributed in archaebacteria, its distribution does not break them into two separate kingdoms: The Methanococcaceae and Methanobacteriaceae are related to each other far more closely than either is to the sulfur-dependent thermophiles, and the root of the archaebacterial tree definitely does not lie between Methanobacterium and Methanococcus .