title: The reducible complexity of a mitochondrial molecular machine.
abstract: Molecular machines drive essential biological processes, with the component parts of these machines each contributing a partial function or structural element. Mitochondria are organelles of eukaryotic cells, and depend for their biogenesis on a set of molecular machines for protein transport. How these molecular machines evolved is a fundamental question. Mitochondria were derived from an alpha-proteobacterial endosymbiont, and we identified in alpha-proteobacteria the component parts of a mitochondrial protein transport machine. In bacteria, the components are found in the inner membrane, topologically equivalent to the mitochondrial proteins. Although the bacterial proteins function in simple assemblies, relatively little mutation would be required to convert them to function as a protein transport machine. This analysis of protein transport provides a blueprint for the evolution of cellular machinery in general.
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia.
authors.forename: Abigail
authors.initials: A
authors.lastname: Clements
authors.forename: Dejan
authors.initials: D
authors.lastname: Bursac
authors.forename: Xenia
authors.initials: X
authors.lastname: Gatsos
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Perry
authors.forename: Srgjan
authors.initials: S
authors.lastname: Civciristov
authors.forename: Nermin
authors.initials: N
authors.lastname: Celik
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Likic
authors.forename: Sebastian
authors.initials: S
authors.lastname: Poggio
authors.forename: Christine
authors.initials: C
authors.lastname: Jacobs-Wagner
authors.forename: Richard A
authors.initials: RA
authors.lastname: Strugnell
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; C077016:TIM44 protein, S cerevisiae; C489671:TIMM44 protein, human