Distinct Forms of Mitochondrial TOM-TIM Supercomplexes Define Signal-Dependent States of Preprotein Sorting

• DOI: 10.1128/mcb.00749-09
• Publication Date: 2009-11-03T03:04:36Z
• Authors: Agnieszka Chacinska; Martin van der Laan; Carola S. Mehnert; Bernard Guiard; David U. Mick; Dana P. Hutu; Kaye N. Truscott; Nils Wiedemann; Chris Meisinger; Nikolaus Pfanner; Peter Rehling
• Keywords: 0301 basic medicine; 0303 health sciences; Saccharomyces cerevisiae Proteins; Membrane Transport Proteins; Saccharomyces cerevisiae; Protein Sorting Signals; Mitochondrial Membrane Transport Proteins; Mitochondria; Mitochondrial Proteins; Protein Transport; Tetrahydrofolate Dehydrogenase; 03 medical and health sciences; 0601 (four-digit-FOR); Multiprotein Complexes; Mitochondrial Precursor Protein Import Complex Proteins; Carrier Proteins

Mitochondrial import of cleavable preproteins occurs at translocation contact sites, where the translocase outer membrane (TOM) associates with presequence inner (TIM23) in a supercomplex. Different views exist on mechanism how TIM23 mediates preprotein sorting to either matrix or membrane. On one hand, two forms were proposed, transport form containing translocase-associated motor (PAM; TIM23-PAM) and Tim21 (TIM23(SORT)). other it was reported that PAM are permanently associated single-entity translocase. We have accumulated distinct intermediates analyze translocases their active, preprotein-carrying state. identified different active TOM-TIM23 supercomplexes, TOM-TIM23(SORT) TOM-TIM23-PAM. These supercomplexes do not represent separate pathways but dynamic exchange during sorting. Depending signals preproteins, switches between supercomplex required for completion import.