Interaction between Bacillus subtilis YsxC and ribosomes (or rRNAs)

• 50S ribosome-YsxC binding occurs independently on the nucleotide-bound state of YsxC.
• The stoichiometry of YsxC-ribosome depends on the binding buffer.
• Binding of YsxC to ribosomal 50S results in the stimulation of YsxC GTPase activity.
• YsxC binds 16S and 23S ribosomal RNAs, but not 5S ribosomal RNAs.

YsxC is an essential P-loop GTPase, that binds to the 50S ribosomal subunit, and is required for the proper assembly of the ribosome. The aim of this study was to characterize YsxC ribosome interactions.The stoichiometry of YsxC ribosome subunit complex was evaluated. We showed that YsxC binding to the 50S ribosomal subunit is not affected by GTP, but in the presence of GDP the stoichiometry of YsxC-ribosome is decreased. YsxC GTPase activity was stimulated upon 50S ribosomal subunit binding. In addition, it is shown for the first time that YsxC binds both 16S and 23S ribosomal RNAs.