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SUMMARY: Polyribosomes and ribosomes were isolated from vegetative Myxococcus xanthus FB and myxospores. The sedimentation coefficients of monoribosomes and ribosomal subunits were the same as those for equivalent particles from Escherichia coli. Conditions for the dissociation of the ribosomes and the unfolding of the subunits (in strong salt or very low concentrations of magnesium salts) differed from those required for analogous processes in E. coli. The stability of the 30 S subunits differed in preparations from vegetative M. xanthus and myxospores. Spermidine promoted the unfolding of the larger (50 S) subunit in low-magnesium buffer.
Proteins were isolated from ribosomal subunits of Myxococcus xanthus, fractionated by polyacrylamide-gel electrophoresis and a catalogue was compiled. The proteins derived from ‘native’ subunits and from subunits partly unfolded in strong salt and from ribosomal subunits derived from vegetative cells and myxospores were compared. A difference in the profile of proteins from the 30 S subunits of myxospores and vegetative cells was found. The significance of these results is discussed in the light of the dissociation properties of the ribosomes and also the morphogenetic cycle of M. xanthus.