title: Evolutionary conservation of biogenesis of beta-barrel membrane proteins.
abstract: The outer membranes of mitochondria and chloroplasts are distinguished by the presence of beta-barrel membrane proteins. The outer membrane of Gram-negative bacteria also harbours beta-barrel proteins. In mitochondria these proteins fulfil a variety of functions such as transport of small molecules (porin/VDAC), translocation of proteins (Tom40) and regulation of mitochondrial morphology (Mdm10). These proteins are encoded by the nucleus, synthesized in the cytosol, targeted to mitochondria as chaperone-bound species, recognized by the translocase of the outer membrane, and then inserted into the outer membrane where they assemble into functional oligomers. Whereas some knowledge has been accumulated on the pathways of insertion of proteins that span cellular membranes with alpha-helical segments, very little is known about how beta-barrel proteins are integrated into lipid bilayers and assembled into oligomeric structures. Here we describe a protein complex that is essential for the topogenesis of mitochondrial outer membrane beta-barrel proteins (TOB). We present evidence that important elements of the topogenesis of beta-barrel membrane proteins have been conserved during the evolution of mitochondria from endosymbiotic bacterial ancestors.
authors.affiliation: Adolf-Butenandt-Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, D-81377 München, Germany.
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Paschen
authors.forename: Thomas
authors.initials: T
authors.lastname: Waizenegger
authors.forename: Tincuta
authors.initials: T
authors.lastname: Stan
authors.forename: Marc
authors.initials: M
authors.lastname: Preuss
authors.forename: Marek
authors.initials: M
authors.lastname: Cyrklaff
authors.forename: Kai
authors.initials: K
authors.lastname: Hell
authors.forename: Doron
authors.initials: D
authors.lastname: Rapaport
authors.forename: Walter
authors.initials: W
authors.lastname: Neupert
mesh_terms: D002942:Circular Dichroism; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D024101:Mitochondrial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009492:Neurospora crassa / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011993:Recombinant Fusion Proteins