title: Biogenesis of beta-barrel proteins in evolutionary context.
abstract: The vast majority of outer membrane (OM) proteins in Gram-negative bacteria belongs to the class of membrane-embedded β-barrel proteins. Besides Gram-negative bacteria, the presence of β-barrel proteins is restricted to the OM of the eukaryotic organelles mitochondria and chloroplasts that were derived from prokaryotic ancestors. The assembly of these proteins into the corresponding OM is in each case facilitated by a dedicated protein complex that contains a highly conserved central β-barrel protein termed BamA/YaeT/Omp85 in Gram-negative bacteria and Tob55/Sam50 in mitochondria. However, little is known about the exact mechanism by which these complexes mediate the integration of β-barrel precursors into the lipid bilayer. Interestingly, previous studies showed that during evolution, these complexes retained the ability to functionally assemble β-barrel proteins from different origins. In this review we summarize the current knowledge on the biogenesis pathway of β-barrel proteins in Gram-negative bacteria, mitochondria and chloroplasts and focus on the commonalities and divergences that evolved between the different β-barrel assembly machineries.
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ulrich
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany. Electronic address: doron.rapaport@uni-tuebingen.de.
authors.forename: Doron
authors.initials: D
authors.lastname: Rapaport
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D005075:Biological Evolution; D060365:Chloroplast Proteins / Q000737:chemistry / Q000378:metabolism*; D002736:Chloroplasts / Q000737:chemistry / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000737:chemistry / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D011487:Protein Conformation; D055503:Protein Multimerization
chemical_list: D001425:Bacterial Outer Membrane Proteins; D060365:Chloroplast Proteins; D024101:Mitochondrial Proteins
keywords: BAM complex; BamA; Periplasmic chaperones; TOB complex; Tob55; β-Barrel proteins