Molecular Machines that Facilitate Bacterial Outer Membrane Protein Biogenesis

• Published in: Annual review of biochemistry Vol. 93; no. 1; pp. 211 - 231
• Main Authors: Doyle, Matthew Thomas, Bernstein, Harris D
• Format: Journal Article
• Language: English
• Published: United States Annual Reviews 01.08.2024; Annual Reviews, Inc
• Subjects: Assembly machines; Bacteria; Bacterial Outer Membrane - metabolism; Bacterial Outer Membrane Proteins - chemistry; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - metabolism; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gram-negative bacteria; Gram-Negative Bacteria - genetics; Gram-Negative Bacteria - metabolism; holotranslocon; membrane protein folding; membrane protein integration; Membranes; Models, Molecular; Molecular Chaperones - chemistry; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Molecular machines; Outer membrane proteins; Periplasm - metabolism; periplasmic chaperones; Periplasmic space; Protein Folding; Protein Transport; Proteins; SEC Translocation Channels - chemistry; SEC Translocation Channels - genetics; SEC Translocation Channels - metabolism; β-barrel assembly machine; β-barrel assembly machine; holotranslocon; outer membrane proteins; periplasmic chaperones; membrane protein integration; membrane protein folding
• ISSN: 0066-4154; 1545-4509; 1545-4509
• DOI: 10.1146/annurev-biochem-030122-033754

Almost all outer membrane proteins (OMPs) in Gram-negative bacteria contain a β-barrel domain that spans the outer membrane (OM). To reach the OM, OMPs must be translocated across the inner membrane by the Sec machinery, transported across the crowded periplasmic space through the assistance of molecular chaperones, and finally assembled (folded and inserted into the OM) by the β-barrel assembly machine. In this review, we discuss how considerable new insights into the contributions of these factors to OMP biogenesis have emerged in recent years through the development of novel experimental, computational, and predictive methods. In addition, we describe recent evidence that molecular machines that were thought to function independently might interact to form dynamic intermembrane supercomplexes. Finally, we discuss new results that suggest that OMPs are inserted primarily near the middle of the cell and packed into supramolecular structures (OMP islands) that are distributed throughout the OM.