Updated project metadata. Bacillus subtilis YjoB has been an uncharacterized AAA+ ATPase which consists of a single ATPase domain and a unique N-terminal domain. To understand the molecular function of YjoB, we identified YjoB-binding proteins through proteomics approaches, and analyzed the relationship between YjoB and its binding proteins. YjoB was coeluted with catalase and iron-sulfur cluster proteins in affinity purification and enhanced the activity of a catalase by specifically preventing heat-induced aggregation of catalase.