Protein composition of Methanococcus thermolithotrophicus flagella

Sodium dodecyl sulfate – polyacrylamide gel electrophoresis of flagella from the thermophilic methanogen Methanococcus thermolithotrophicus indicated that they were composed of three major proteins, with molecular weights of 62 000,44 000, and 26 000, whereas all previously studied flagella of mesophilic methanogens consisted of two subunits. Proteins were isolated by preparative electrophoresis followed by complete removal of sodium dodecyl sulfate and their renaturation. It was shown that at least two of the proteins contain a thermostable domain whose complete denaturation proceeds only upon prolonged boiling in the presence of sodium dodecyl sulfate. Key words: flagellin, thermostability, archaebacteria, Methanococcus thermolithotrophicus.