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About the Authors:
Khatira Anwari
Affiliation: Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
Sebastian Poggio
Affiliation: Department of Molecular, Cellular and Developmental Biology and Microbial Pathogenesis Section, Yale University, New Haven, Connecticut, United States of America
Andrew Perry
Affiliation: Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
Xenia Gatsos
Affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
Sri Harsha Ramarathinam
Affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
Nicholas A. Williamson
Affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
Nicholas Noinaj
Affiliation: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
Susan Buchanan
Affiliation: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
Kipros Gabriel
Affiliation: Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
Anthony W. Purcell
Affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
Christine Jacobs-Wagner
Affiliations Department of Molecular, Cellular and Developmental Biology and Microbial Pathogenesis Section, Yale University, New Haven, Connecticut, United States of America, Howard Hughes Medical Institute, Yale University, New Haven, Connecticut, United States of America
Trevor Lithgow
* E-mail: [email protected]
Affiliation: Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
Introduction
Mitochondria are essential organelles, derived in the first eukaryotes from intracellular bacterial symbionts. Phylogenetic reconstructions show that these endosymbionts were of α-proteobacterial descent, and key aspects of mitochondrial biology evolved from the bacterial ancestor [1]–[4]. The outer membranes of mitochondria have β-barrel proteins and these are assembled by the SAM complex. An essential feature of the SAM complex is its modular nature. Protein subunits that are important, but not essential, for the core function of β-barrel assembly can be titrated from the complex by increasing the concentration of detergent used in purification. In this way the essential protein “modules” such as Mdm10 and Mim1, can be selectively removed from the holo-SAM complex [5]–[10]. This modular machine in the outer membrane receives its substrates via small TIM chaperones that link the protein translocation device (the TOM complex) with the SAM complex [11], [12].
A central and essential component of the mitochondrial SAM complex, Sam50, is...