The 2 PAN ATPases from Halobacterium display N-ter heterogeneity and form labile complexes with the 20S proteasome.

Hala Chamieh , Dorian Guetta , Bruno Franzetti (1)

1 IBS - UMR 5075 - Institut de biologie structurale

The PAN proteins from Archaea represent homologs of the eukaryotic 26S proteasome regulatory ATPases. In vitro, the PAN complex has been previously shown to have a stimulatory effect on the peptidase activities of the 20S core. By using gradient ultracentrifugation experiments we found that, in cellular extracts, the 2 PAN proteins from Halobacterium do not form stable high molecular weight complexes. Only PAN B was found to associate transiently with the 20S proteasome, thus suggesting that the 2 PAN proteins are not functionally redundant. The PAN B-20S proteasome complexes associate in an ATP-dependent manner and are stabilized upon nucleotide binding. The 2 PAN were immunodetected in cellular extracts as N-ter truncated polypeptides. RNA mapping experiments and sequence analysis indicated that this process involved transcript heterogeneities and dual translational initiation mechanisms. Taken together, our results suggest that PAN N-ter modifications and their intra cellular dynamics of assembly/association may constitute important determinants of proteolysis regulation.

Mots clés: Life Sciences

Hala Chamieh, Dorian Guetta, Bruno Franzetti. The 2 PAN ATPases from Halobacterium display N-ter heterogeneity and form labile complexes with the 20S proteasome.. Biochemical Journal, 2008, 411 (2), pp.387-397. ⟨10.1042/BJ20071502⟩. ⟨hal-00478911⟩