| dc.contributor.advisor | Rehling, Peter Prof. Dr. | |
| dc.contributor.author | Schulz, Christian | |
| dc.date.accessioned | 2014-05-09T09:19:56Z | |
| dc.date.available | 2014-05-09T09:19:56Z | |
| dc.date.issued | 2014-05-09 | |
| dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-0022-5EAD-B | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-4496 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-4496 | |
| dc.language.iso | eng | de |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | |
| dc.subject.ddc | 570 | de |
| dc.title | Protein interactions along the presequence import pathway | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Rehling, Peter Prof. Dr. | |
| dc.date.examination | 2013-11-11 | |
| dc.description.abstracteng | In this thesis the mechanisms of protein transport by the translocase of the inner mitochondrial membrane (TIM23) was investigated. Purified presequence peptides containing a p-benzophenyalalanine were established as a tool to identify and proximate presequence binding sites. Receptors could be identified, revealing Tim50 as a so far unknown presequence receptor of TIM23. It contains two separate binding sites in its intermembrane space (IMS) domain. One is formed by the C-terminal presequence binding domain (PBD) and the second by a negatively charged groove located in the core domain.
The PBD is needed for efficient transport across the inner mitochondrial membrane, rendering it essential for cell viability in yeast. It is not involved in the establishment of transport intermediates at the level of the outer membrane translocase (TOM), recruitment of Tim50 to TIM23 and the regulation of Tim50s interaction with Tim21. The presequence hand-over in the IMS occurs from Tim50IMS to Tim23IMS. In this process a trimeric complex is formed, with Tim50 binding the presequence as well as Tim23. Subsequently, Tim23 receives the presequence and dissociates from Tim50 due to overlapping binding sites.
Additionally, an assay to test integration of subunits into the active TIM23 complex was established. It made use of the two membrane spanning translocation intermediate generated by arresting b2(167)∆-DHFR. The formed supercomplex required the ATPase activity of Hsp70 in the import motor (PAM). Using this assay it was shown that the PAM subunits Tim44 and Pam18 as well as the TIM23 subunit Tim21 integrated into the active TIM23 complex.
The oscillation between free and translocase-bound Pam18 depends on Mgr2, but not Tim21. In contrast Tim44 oscillated Mgr2 independent. Hence, the regulatory subunits of the import motor seem to follow the cyclic recruitment of Hsp70 which is recruited to the translocase exit site by Tim44 in the ATP state in order to engage the precursor and diffuses into the matrix upon Pam18 stimulated ATP hydrolysis. Conformational changes within Tim44 and Pam18 during this activation process might lead to their loss from the translocase and therefore requires continuous recruitment to the active TIM23 complex. | de |
| dc.contributor.coReferee | Tittmann, Kai Prof. Dr. | |
| dc.subject.eng | mitochondria | de |
| dc.subject.eng | protein translocation | de |
| dc.subject.eng | presequence | de |
| dc.subject.eng | Tim50 | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-11858/00-1735-0000-0022-5EAD-B-6 | |
| dc.affiliation.institute | Biologische Fakultät für Biologie und Psychologie | de |
| dc.subject.gokfull | Biologie (PPN619462639) | de |
| dc.identifier.ppn | 785291881 | |