Your browser does not support JavaScript!

Home    Λειτουργική ανάλυση της μετατοπασης tim12 του μιτοχονδριακού συμπλόκου μετατόπισης πρωτεϊνών tim22  

Results - Details

Add to Basket
[Add to Basket]
Identifier uch.biology.msc//2005lionaki
Title Λειτουργική ανάλυση της μετατοπασης tim12 του μιτοχονδριακού συμπλόκου μετατόπισης πρωτεϊνών tim22
Author Λιονάκη, Ειρήνη
Abstract Tim12 is a mitochondrial intermembrane space (IMS) protein of Saccharomyces cerevisiae. It belongs to the family of the small Tims (Translocases of the Inner Membrane). The small Tims assemble into soluble complexes that chaperone the hydrophobic polytopic inner membrane proteins through the aqueous IMS. Tim12 is the only small Tim that is exclusively associated to the IMS side of the inner membrane (IM). It is part of the TIM22 complex that inserts the polytopic preproteins into the inner membrane. Its precise function in the import pathway of the pre-proteins is not known, although it’s known that Tim12 functions after the recognition of the substrate by the TIM10 complex. In this study, we analyzed proline to alanine mutants in each of the three proline residues (P46, P53 and P88) of Tim12. We found that P88A mutant is lethal, in contrast to P46A mutant. However, the P88A mutation does not affect the import of Tim12 in mitochondria, or targeting to the IM surface. Recombinant wild type and mutant Tim12 display the same oligomerization behaviour in vitro, whilst, for both of them the dimer is the most stable form. With peptide spot analysis, using a membrane with immobilized peptides of the substrate AAC, we found that both the wild type and the P88A mutant dimers interact with the transmembrane domains of AAC. Migration on sucrose gradients revealed that the proline mutants maintain the capacity to interact with the Tim9 monomer as does the wild type Tim12. However, as shown by limited proteolysis the tryptic profile of TimP88A upon interaction with Tim9 is slightly different from that of Tim12wt upon interaction with T9. We propose that proline 88 is crucial for structural changes of the Tim12 molecule during its interaction with Tim9, which are necessary for the downstream translocation of the substrate onto the TIM22 complex and its final insertion into the inner membrane.
Language Greek
Issue date 2005-11-28
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Views 226

Digital Documents
No preview available

Download document
View document
Views : 1