The gain-of-function allele <i>bamA</i> <sub> <i>E470K</i> </sub> bypasses the essential requirement for BamD in β-barrel outer membrane protein assembly
Elizabeth M. Hart, Meera Gupta, Martin Wühr, Thomas J. Silhavy
Abstract
Significance The assembly of β-barrel outer membrane proteins (OMPs) is broadly conserved in diderm bacteria as well as in mitochondria and chloroplasts. The β-barrel assembly machine (BAM), which assembles OMPs into the outer membrane of gram-negative microbes, contains two essential proteins, BamA and BamD. Here we identify a genetic background in which BamD is nonessential, indicating that BamD does not function in OMP catalysis, but rather plays a regulatory role in OMP assembly. BamD is not conserved in the complexes that assemble OMPs in chloroplasts and mitochondria, likely because these organelles, unlike bacteria, inhabit a carefully controlled cytoplasmic environment.
Topics & Concepts
BamaBacterial outer membraneOrganelleBarrel (horology)ChloroplastBiologyCytoplasmBacteriaFunction (biology)Cell biologyMembrane proteinMembraneGeneticsEscherichia coliGeneComposite materialMaterials scienceGenomics and Phylogenetic StudiesProtein Structure and DynamicsRNA and protein synthesis mechanisms