BamA β16C strand and periplasmic turns are critical for outer membrane protein insertion and assembly
- 21 November 2017
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 474 (23), 3951-3961
- https://doi.org/10.1042/bcj20170636
Abstract
Outer membrane (OM) β-barrel proteins play important roles in importing nutrients, exporting wastes and conducting signals in Gram-negative bacteria, mitochondria and chloroplasts. The outer membrane proteins (OMPs) are inserted and assembled into the OM by OMP85 family proteins. In Escherichia coli, the β-barrel assembly machinery (BAM) contains four lipoproteins such as BamB, BamC, BamD and BamE, and one OMP BamA, forming a ‘top hat’-like structure. Structural and functional studies of the E. coli BAM machinery have revealed that the rotation of periplasmic ring may trigger the barrel β1C–β6C scissor-like movement that promote the unfolded OMP insertion without using ATP. Here, we report the BamA C-terminal barrel structure of Salmonella enterica Typhimurium str. LT2 and functional assays, which reveal that the BamA's C-terminal residue Trp, the β16C strand of the barrel and the periplasmic turns are critical for the functionality of BamA. These findings indicate that the unique β16C strand and the periplasmic turns of BamA are important for the outer membrane insertion and assembly. The periplasmic turns might mediate the rotation of the periplasmic ring to the scissor-like movement of BamA β1C–β6C, triggering the OMP insertion. These results are important for understanding the OMP insertion in Gram-negative bacteria, as well as in mitochondria and chloroplasts.This publication has 44 references indexed in Scilit:
- Evolution and targeting of Omp85 homologs in the chloroplast outer envelope membraneFrontiers in Plant Science, 2014
- A comprehensive analysis of the Omp85/TpsB protein superfamily structural diversity, taxonomic occurrence, and evolutionFrontiers in Microbiology, 2014
- Evolution of the β-barrel assembly machineryTrends in Microbiology, 2012
- Assembly of outer-membrane proteins in bacteria and mitochondriaMicrobiology, 2010
- Conserved Properties of Polypeptide Transport-associated (POTRA) Domains Derived from Cyanobacterial Omp85Online Journal of Public Health Informatics, 2010
- Omp85 from the Thermophilic Cyanobacterium Thermosynechococcus elongatus Differs from Proteobacterial Omp85 in Structure and Domain CompositionOnline Journal of Public Health Informatics, 2010
- Biogenesis of β-barrel membrane proteins in bacteria and eukaryotes: evolutionary conservation and divergenceCellular and Molecular Life Sciences, 2009
- Membrane protein architects: the role of the BAM complex in outer membrane protein assemblyNature Reviews Microbiology, 2009
- Structure and Function of an Essential Component of the Outer Membrane Protein Assembly MachineScience, 2007
- Identification of a Multicomponent Complex Required for Outer Membrane Biogenesis in Escherichia coliCell, 2005