This is a family of bacterial proteasome cofactors. The family member from Mycobacterium tuberculosis, protein Rv3780, was shown to form rings and cap proteasome core particles. It enhanced peptide and protein degradation by proteasomes in an adenosine triphosphate (ATP)-independent manner, promoting degradation of the heat shock protein repressor HspR [1,2].

1: An adenosine triphosphate-independent proteasome activator contributes to the virulence of Mycobacterium tuberculosis. Jastrab JB, Wang T, Murphy JP, Bai L, Hu K, Merkx R, Huang J, Chatterjee C, Ovaa H, Gygi SP, Li H, Darwin KH; Proc Natl Acad Sci U S A. 2015;112:E1763-E1772. PMID:25831519

2: Bacterial proteasome activator bpa (rv3780) is a novel ring-shaped interactor of the mycobacterial proteasome. Delley CL, Laederach J, Ziemski M, Bolten M, Boehringer D, Weber-Ban E; PLoS One. 2014;9:e114348. PMID:25469515