We have established Candida albicans, the most common human fungal pathogen, as a new model system to study mitochondrial protein import and biogenesis. We have used this system to investigate the contentious role of the connections between the ER and mitochondria and the interactions between the ER-mitochondrial encounter structure (ERMES) with the sorting and assembly machinery of the mitochondrial outer membrane (SAM complex). In C. albicans the majority of Sam50 and Mdm10, two key protein components of the SAM and ERMES complexes in Saccharomyces cerevisiae, are both found in ~400kDa complexes. We have discovered an additional Sam50 homologue in C. albicans which we named Sam51 (Hewitt, et al. 2012), that is found exclusively in a ~400kDa complex and not in smaller forms of the SAM complex. The lack of Sam51 in S. cerevisiae raises intriguing questions regarding the evolution of the roles of Sam50/51 in C. albicans in coordinating the mitochondrial-ER interactions via Mdm10. Studies of the dynamic interactions between mitochondria and the ER are revealing diverse and unexpected physiological functions of these protein-mediated connections. These findings make C. albicans an excellent system in which to explore the still unresolved questions of the roles of the SAM and ERMES complexes in protein and lipid transport and assembly.

Hewitt, V. L., E. Heinz, et al. (2012). "A model system for mitochondrial biogenesis reveals evolutionary rewiring of protein import and membrane assembly pathways." Proceedings of the National Academy of Sciences of the United States of America 109(49): E3358-3366.