Biophysical characterization of cytosolic domains of three import receptors from Arabidopsis thaliana

[Truncated abstract] Eukaryotic cells are characterized by the presence of several organelles that are surrounded by membranes. The majority of proteins destined to these organelles are nuclear encoded, synthesized in the cytosol and translocated across the membrane aided by specific receptors, into destined locations in the organelles. The receptors involved in protein translocation can be classified into two categories: 1) those that recognize precursor proteins through interaction with their specific presequences and 2) those that recognize cytosolic transporters (chaperones) which are involved in the delivery of precursor proteins to the import machinery for the specific organelle to which they are targeted.

The projects aim to biophysically characterize the cytosolic domains of three import receptors from Arabidopsis thaliana and identifying their interactions with their binding partners. The first part of the study focuses on the cytosolic domain of Metaxin, an outer mitochondrial membrane protein. To date literature is not available delineating the exact domain boundaries of the cytosolic region of the protein. Mutational studies aid in identifying the region that can be expressed as a soluble dimer however time and concentration dependent aggregation prohibits further characterization.