z-logo
Premium
GxxxG motifs hold the TIM23 complex together
Author(s) -
DemishteinZohary Keren,
Marom Milit,
Neupert Walter,
Mokranjac Dejana,
Azem Abdussalam
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13266
Subject(s) - transmembrane protein , biology , translocase of the inner membrane , microbiology and biotechnology , transmembrane domain , translocase , inner mitochondrial membrane , membrane protein , mitochondrion , mitochondrial membrane transport protein , genetics , membrane , gene , chromosomal translocation , receptor
Approximately 99% of the mitochondrial proteome is nucleus‐encoded, synthesized in the cytosol, and subsequently imported into and sorted to the correct compartment in the organelle. The translocase of the inner mitochondrial membrane 23 ( TIM 23) complex is the major protein translocase of the inner membrane, and is responsible for translocation of proteins across the inner membrane and their insertion into the inner membrane. Tim23 is the central component of the complex that forms the import channel. A high‐resolution structure of the import channel is still missing, and structural elements important for its function are unknown. In the present study, we analyzed the importance of the highly abundant GxxxG motifs in the transmembrane segments of Tim23 for the structural integrity of the TIM 23 complex. Of 10 glycines present in the GxxxG motifs in the first, second and third transmembrane segments of Tim23, mutations of three of them in transmembrane segments 1 and 2 resulted in a lethal phenotype, and mutations of three others in a temperature‐sensitive phenotype. The remaining four caused no obvious growth phenotype. Importantly, none of the mutations impaired the import and membrane integration of Tim23 precursor into mitochondria. However, the severity of growth impairment correlated with the destabilization of the TIM 23 complex. We conclude that the GxxxG motifs found in the first and second transmembrane segments of Tim23 are necessary for the structural integrity of the TIM 23 complex.

This content is not available in your region!

Continue researching here.

Having issues? You can contact us here