Functional characterisation of Tim17 and Tim23 proteins in Arabidopsis thaliana

[Truncated abstract] Mitochondrial protein import is a multi-step process that requires the translocation of proteins across one or both mitochondrial membranes, that is achieved by multi-subunit proteins complexes called translocases. While the translocase of the outer membrane (TOM) has been extensively characterized in a variety of organisms, from Saccharomyces cerevisiae (single celled yeast) to plants and animals, the translocases of the inner membrane (TIM) have only been extensively characterized in yeast. The TIM17:23 complex is the main translocase in the inner membrane that mediates protein translocation through the inner membrane or lateral insertion into the inner membrane. The core components of this complex, Tim17 and Tim23, play an important role in the protein import pathway and are essential for cell viability in yeast. In Arabidopsis, three genes have been found to encode Tim17 and Tim23 proteins respectively, named as Tim17-1, Tim17-2, Tim17-3, Tim23-1, Tim23-2 and Tim23-3 (Murcha et al., 2007). It is unclear if the proteins encoded by these different genes have divergent functions. In this project, functional analysis of Tim17 and Tim23 was investigated using T-DNA insertion homozygote lines, obtained for each gene. Apart from Tim17-2, for which a homozygous T-DNA insertion was lethal, inactivation of any single gene of the Tim17 and Tim23 families did not result in a growth defective phenotype...