Processing and topology of the yeast mitochondrial phosphatidylserine decarboxylase 1
13.09.2012
Horvath SE, Böttinger L, Vöegtle FN, Wiedemann N, Meisinger C, Becker T, Daum G.
J Biol Chem. 2012; 287(44):36744-55
The phosphatidylserine decarboxylase 1 (Psd1) of the mitochondrial inner membrane synthesizes the majority of the cellular phosphatidylethanolamine (PE) of the yeast cell. The biogenesis and topology of this enzyme is so far poorly understood. We show that the precursor of Psd1 is recognized by Tom22 and Tom70 of the TOM complex on the mitochondrial surface. After transport across the mitochondrial membranes the precursor is processed by the mitochondrial processing peptidase and by Oct1. Finally, autoprocessing by Psd1 at a conserved LGST-motif leads the separation of a intermembrane space localized Psd1 alpha-subunit from the inner membrane-anchored Psd1 beta-subunit. Both subunits remain in close contact to allow optimal Psd1 activity. Strikingly, self-processing of Psd1 does not depend on proper localization to the mitochondrial inner membrane, but targeting of Psd1 to the inner mitochondrial membrane is crucial to obtain full enzymatic activity.
