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Identifier

000369297

Title

Μοριακοί μηχανισμοί στόχευσης πρωτεϊνών στην εσωτερική μεμβράνη και στο διαμεμβρανικό χώρο των μιτοχονδρίων

Alternative Title

Molecular mechanisms of protein targeting to the inner membrane and to the intermembrane space of mitochondria

Author

Πετράκης, Νικόλαος Λεωνίδας

Thesis advisor

Κουτσολέλος, Αθανάσιος
Τοκατλίδης, Κωνσταντίνος

Abstract

Mitochondria from the yeast Saccharomyces cerevisiae contain more than 900 different proteins. Most of those are synthesized to the cytosol and they have to be targeted to the right submitochondrial compartment via a very complex mechanism which is consisted of many different protein complexes. Different types of protein are targeted to the mitochondrion via different import pathways. Many different import pathways are well-studied, but very little is known about the insertion pathway to the inner membrane of proteins with one transmembrane domain and without a typical presequence. In the current work, we studied the import and the insertion to the membrane of Subunit e of the F₀/F₁ ATP synthase (Su e) as an example of inner membrane protein with one transmembrane domain without a typical presequence. We found that its import pathway includes small Tim chaperones of the intermembrane space and that its insertion to the membrane can be performed without the presence of any of the known complexes that insert proteins to the inner membrane. Also, we found that the targeting signal is at the N-terminal part of the protein and that the positive charge at position 8 is very important for its import. Furthermore, we studied the targeting signal Mia40 substrates to Mia40, the oxidase which folds the proteins to the intermembrane space. The targeting signal to the intermembrane space of Tim10 is at aminoacids 30 to 39 to its sequence and that sequence binds the proteins to Mia40 via hydrophobic interactions. This sequence can target non physiological substrates to Mia40. Also, the prerequisites of a sequence to be a targeting signal for Mia40 were found, giving us the ability to predict the targeting to Mia40.

Language

Greek

Subject

Membrane insertion

Mia40

Mitochondrial ATP synthase

Protein targeting

Small Tims

Targeting Sequence

Αλληλουχία στόχευσης

Διαμεμβανικός χώρος

Ενσωμάτωση στη μεμβράνη