Evidence for a specific phylogenetic relationship between the methanogens Methanococcus thermolithotrophicus and Methanothermus fervidus, and the sulfur respiring Thermoproteus tenax

Summary Using three dimensional ribosome structure as a probe of evolutionary relationships, we have investigated the relationship between the methanogens and the sulfur dependent archaebacteria or eocytes. Specifically, we show that the large ribosomal subunit structures of Thermoproteus tenax, Methanothermus fervidus and Methanococcus thermolithotrophicus are closely related. We interpret this (rotting the tree with the data of others) to suggest that the methanogens are derived from a sulfur dependent organism that had ribosomes of the Thermoproteus tenax type.