title: Role of mitochondrial processing peptidase and AAA proteases in processing of the yeast acetohydroxyacid synthase precursor.
abstract: We studied presequence processing of the mitochondrial-matrix targeted acetohydroxyacid synthase (Ilv2). C-terminal 3HA-tagging altered the cleavage pattern from a single step to sequential two-step cleavage, giving rise to two Ilv2-3HA forms (A and B). Both cleavage events were dependent on the mitochondrial processing peptidase (MPP). We present evidence for the involvement of three AAA ATPases, m- and i-AAA proteases, and Mcx1, in Ilv2-3HA processing. Both, precursor to A-form and A-form to B-form cleavage were strongly affected in a ∆yme1 mutant. These defects could be suppressed by overexpression of MPP, suggesting that MPP activity is limiting in the ∆yme1 mutant. Our data suggest that for some substrates AAA ATPases could play an active role in the translocation of matrix-targeted proteins.
authors.affiliation: Institut für Lebensmittelwissenschaft und Biotechnologie Fg. Hefegenetik und Gärungstechnologie (150f) Universität Hohenheim Stuttgart Germany.
authors.forename: Suvarna
authors.initials: S
authors.lastname: Dasari
authors.affiliation: Institut für Lebensmittelwissenschaft und Biotechnologie Fg. Hefegenetik und Gärungstechnologie (150f) Universität Hohenheim Stuttgart Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Kölling
keywords: acetohydroxyacid synthase; i‐AAA; mitochondrial import; mitochondrial processing peptidase; m‐AAA; presequence processing