The N-terminal penultimate residue of 20S proteasome alpha1 influences its N(alpha) acetylation and protein levels as well as growth rate and stress responses of Haloferax volcanii.

ABSTRACT: Proteasomes are energy-dependent proteolytic machines. We elaborate here on the previously observed N(alpha) acetylation of the initiator methionine of the alpha1 protein of 20S core particles (CPs) of Haloferax volcanii proteasomes. Quantitative mass spectrometry revealed this was the dominant N-terminal form of alpha1 in H. volcanii cells. To further examine this, alpha1 proteins with substitutions in the N-terminal penultimate residue as well as deletion of the CP "gate" formed by the alpha1 N terminus were examined for their N(alpha) acetylation. Both the "gate" deletion and Q2A substitution completely altered the N(alpha)-acetylation pattern of alpha1, with the deletion rendering alpha1 unavailable for N(alpha) acetylation and the Q2A modification apparently enhancing cleavage of alph

SUBMITTER: Humbard MA 

PROVIDER: S-EPMC2698410 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature