The yjoB gene of Bacillus subtilis encodes a protein that is a novel member of the AAA family.

The yjoB gene of Bacillus subtilis encodes a 48.8-kDa protein belonging to the AAA family. Members of this family contain a 200-250-amino acid residues AAA domain carrying a Walker A and B ATP-binding site assumed to be part of a molecular chaperone. The yjoB gene belongs to the sigmaW regulon, and members of this regulon have been reported to be transiently induced when cells enter the stationary growth phase. This assumption was confirmed here for yjoB by Western blot experiments and by analysis of a transcriptional fusion. Purified YjoB protein exhibited ATPase activity but was unable to prevent aggregation of denatured citrate synthase. An alignment of YjoB with a subgroup of AAA proteins present in Archaea suggests that YjoB might be involved in the modulation of the activity of one or more proteases.