Article
Microbiology
Sunyia Hussain, Janine H. Peterson, Harris D. Bernstein
Summary: The assembly of trimeric porins involves a stepwise process that requires the presence of the Bam complex and LPS. The interaction with LPS is not only essential for trimerization but also for the productive insertion of individual subunits into the lipid bilayer.
Article
Microbiology
Xu Wang, Janine H. Peterson, Harris D. Bernstein
Summary: This study identified two parallel mechanisms for the assembly of outer membrane proteins in Gram-negative bacteria, involving the beta signal and SurA. It challenges the view that periplasmic chaperones are redundant, suggesting they have specialized roles in OMP targeting and quality control.
Review
Infectious Diseases
Claire Overly Cottom, Robert Stephenson, Lindsey Wilson, Nicholas Noinaj
Summary: The emergence of multidrug resistance in bacterial pathogens poses a global threat to human health, but the discovery of new antibiotics has not kept pace with this alarming trend. Recent approaches to antibiotic discovery have expanded to target essential surface receptors and protein complexes, including the beta-barrel assembly machinery (BAM) responsible for the biogenesis of outer membrane proteins in Gram-negative bacteria. In this review, we highlight the importance of BAM as a promising therapeutic target and discuss recent studies on compounds and vaccines targeting BAM across various bacteria, sparking ongoing research and interest in BAM for combating multidrug resistance.
Review
Microbiology
Matthew Thomas Doyle, Harris D. Bernstein
Summary: The Omp85 protein superfamily is a group of proteins found in the outer membrane of gram-negative bacteria and bacterial-origin eukaryotic organelles. These proteins are involved in both membrane insertion and translocation of proteins across the outer membrane. Recent studies have uncovered new insights into the functions of these proteins, particularly the well-studied member BamA, which is essential for bacterial barrel assembly and has potential implications for antibiotic development.
ANNUAL REVIEW OF MICROBIOLOGY
(2022)
Article
Biochemistry & Molecular Biology
Xiaoyu Chen, Yue Ding, Rebecca S. Bamert, Anton P. Le Brun, Anthony P. Duff, Chun-Ming Wu, Hsien-Yi Hsu, Takuya Shiota, Trevor Lithgow, Hsin-Hui Shen
Summary: Researchers reconstituted each subunit of the Gram-negative bacteria BAM complex into a biomimetic membrane to study their interactions and structural changes. They found that binding of BamE or a BamDE dimer to BamA induced conformational changes, and addition of an unfolded substrate protein extended the length of POTRA domains as part of the mechanism for protein folding into the membrane.
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
(2021)
Review
Biochemistry & Molecular Biology
Karl Lundquist, Evan Billings, Maxine Bi, James Wellnitz, Nicholas Noinaj
Summary: Gram-negative bacteria, mitochondria, and chloroplasts all have outer membranes populated with a type of beta-barrel outer-membrane protein. These proteins play crucial roles in maintaining the viability of their hosts, and recent studies have made significant progress in understanding the biogenesis of these proteins. The structural and functional advancements in the beta-barrel assembly machinery and sorting and assembly machinery provide new insights into the budding mechanism of beta OMPs in these organelles.
MOLECULAR MICROBIOLOGY
(2021)
Article
Biochemistry & Molecular Biology
Simen Hermansen, David Ryoo, Marcella Orwick-Rydmark, Athanasios Saragliadis, James C. Gumbart, Dirk Linke
Summary: The outer membrane of Gram-negative bacteria acts as an additional diffusion barrier for solutes and nutrients. Outer membrane proteins (OMPs) with large loops protruding into the extracellular environment have potential applications in biotechnology and therapy. This study quantifies the effects of loop insertions on OMP folding and stability using the small outer membrane protein OmpX as a model system. The results show that the length and hydrophobicity of insertions affect OMP folding, and different constructs can fold both in vitro and in their native environment. These findings will improve the design and efficiency of recombinant OMPs.
FRONTIERS IN MOLECULAR BIOSCIENCES
(2022)
Article
Biochemistry & Molecular Biology
Dung T. Huynh, Wouter S. P. Jong, Gregory M. Koningstein, Peter van Ulsen, Joen Luirink
Summary: Ct-MOMP, a promising subunit-based vaccine candidate, is difficult to express in its native structure in E. coli outer membrane. Co-expression of the Bam complex improved the expression and localization of recombinant Ct-MOMP, leading to correct folding and assembly into a beta-barrel conformation at the cell surface.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Multidisciplinary Sciences
Ashton N. Combs, Thomas J. Silhavy
Summary: This study reveals a novel role for the periplasmic chaperone Skp in the folding of outer membrane proteins (OMPs) in gram-negative bacteria. Skp removes membrane-integration-defective OMP substrates from the beta-barrel assembly machine (Bam) complex, allowing for clearance of stalled Bam-OMP complexes. Furthermore, Skp acts as an adaptor protein to facilitate the degradation of defective OMP substrates by the periplasmic protease DegP. These findings highlight the importance of Skp in ensuring efficient beta-barrel folding.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Biochemistry & Molecular Biology
Yindi Chu, Zhe Wang, Sebastian Weigold, Derrick Norrell, Enguo Fan
Summary: Research shows that a single TtOmp85 protein can replace the collective function of the five subunits constituting the E. coli BAM, providing new insights into the search for the primitive form of a functional BAM.
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Paul White, Samuel F. Haysom, Matthew G. Iadanza, Anna J. Higgins, Jonathan M. Machin, James M. Whitehouse, Jim E. Horne, Bob Schiffrin, Charlotte Carpenter-Platt, Antonio N. Calabrese, Kelly M. Storek, Steven T. Rutherford, David J. Brockwell, Neil A. Ranson, Sheena E. Radford
Summary: The study elucidates the roles of BAM structure and lipid dynamics in OMP folding, showing that both factors are crucial for efficient OMP assembly.
NATURE COMMUNICATIONS
(2021)
Article
Microbiology
Wei He, Gangjin Yu, Tianpeng Li, Ling Bai, Yuanyuan Yang, Zixiao Xue, Yonghao Pang, Dana Reichmann, Sebastian Hiller, Lichun He, Maili Liu, Shu Quan
Summary: Our research demonstrates the role of the periplasmic chaperone Spy in maintaining the homeostasis of certain outer membrane proteins (OMPs). Spy utilizes a unique chaperone mechanism to bind OmpX, allowing it to form a partially folded beta-strand secondary structure in a dynamic exchange of conformations. This mechanism differs from that of other E. coli periplasmic chaperones such as Skp and SurA, highlighting the differences in the mechanisms of ATP-independent chaperones.
Article
Multidisciplinary Sciences
Eve E. Weatherill, Monifa A. Fahie, David P. Marshall, Rachel A. Andvig, Matthew R. Cheetham, Min Chen, Mark Wallace
Summary: Compared to globular proteins, the folding and insertion of beta-barrel membrane proteins are slow but rapid, occurring within seconds upon arrival at the membrane interface. This combination of infrequent yet fast folding events resolves the apparent contradiction between slow ensemble kinetics and typical biomolecular folding timescales.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Biotechnology & Applied Microbiology
Trang H. Phan, Coen Kuijl, Dung T. Huynh, Wouter S. P. Jong, Joen Luirink, Peter van Ulsen
Summary: The overproduction of the BAM complex has been found to increase the surface display of difficult-to-secrete chimeras, not only for monomeric autotransporter fusions but also for fusions to trimeric autotransporters. This beneficial effect suggests that overproduction of BAM might be an attractive strategy to improve the production of recombinant autotransporter constructs.
MICROBIAL CELL FACTORIES
(2021)
Review
Biochemistry & Molecular Biology
Qian Xu, Min Guo, Feiyuan Yu
Summary: The outer membrane of Gram-negative bacteria is closely related to their pathogenicity and drug resistance, and outer membrane proteins (OMPs) play important biological roles. The beta-barrel assembly machinery (BAM) complex is essential for the correct folding and insertion of OMPs into the outer membrane, allowing them to perform various functions. Abnormalities in the BAM complex can lead to OMP folding obstruction, affecting outer membrane function and leading to bacterial death. Due to its significant role in OMP biogenesis, the BAM complex has become an attractive target for the development of new antibacterial drugs. This article summarizes the structure and function of the BAM complex and reviews the latest research progress on antibacterial drugs targeting BAM, providing a new perspective for antibiotic development.
Article
Chemistry, Multidisciplinary
Frederick A. Rubino, Aurelio Mollo, Sujeet Kumar, Emily K. Butler, Natividad Ruiz, Suzanne Walker, Daniel E. Kahne
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2020)
Article
Biochemistry & Molecular Biology
Emily A. Lundstedt, Brent W. Simpson, Natividad Ruiz
MOLECULAR MICROBIOLOGY
(2020)
Article
Multidisciplinary Sciences
Elizabeth M. Hart, Meera Gupta, Martin Wuehr, Thomas J. Silhavy
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2020)
Editorial Material
Microbiology
Thomas J. Silhavy
JOURNAL OF BACTERIOLOGY
(2021)
Article
Microbiology
Elizabeth M. Hart, Thomas J. Silhavy
JOURNAL OF BACTERIOLOGY
(2020)
Editorial Material
Microbiology
Thomas J. Silhavy
JOURNAL OF BACTERIOLOGY
(2021)
Article
Biology
Fangyu Liu, James Lee, Jue Chen
Summary: The ATP-binding cassette (ABC) transporter family is diverse and contains thousands of members. ABCA4 is a eukaryotic importer that transports retinal and removes toxic retinoids, mutations in which lead to impaired vision. Despite years of study, the molecular mechanism of ABCA4 remains unknown.
Review
Microbiology
Jiawei Sun, Steven T. Rutherford, Thomas J. Silhavy, Kerwyn Casey Huang
Summary: This review discusses the emerging physical and mechanical properties of the Gram-negative outer membrane, revealing a more expansive and versatile role in cellular physiology and viability. Recent studies have uncovered key molecular factors and interactions through experimental and computational research, while advancements in microfluidics and microscopy have contributed to a better understanding of the structural, rheological, and mechanical properties of the outer membrane. These findings suggest broader connections between cellular structure and physiology, with future prospects for elucidating the implications of outer membrane construction for cellular fitness and survival.
NATURE REVIEWS MICROBIOLOGY
(2022)
Article
Multidisciplinary Sciences
Georgina Benn, Irina Mikheyeva, Patrick George Inns, Joel C. Forster, Nikola Ojkic, Christian Bortolini, Maxim G. Ryadnov, Colin Kleanthous, Thomas J. Silhavy, Bart W. Hoogenboom
Summary: Using atomic force microscopy, the organization of the outer membrane of gram-negative bacteria, particularly E. coli, was revealed. The main outer-membrane protein OmpF forms a static network interspersed with barren patches of LPS, contributing to the integrity of the membrane. Destabilization of the outer membrane correlates with bacterial sensitivity to harsh environments.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Multidisciplinary Sciences
Ashton N. Combs, Thomas J. Silhavy
Summary: This study reveals a novel role for the periplasmic chaperone Skp in the folding of outer membrane proteins (OMPs) in gram-negative bacteria. Skp removes membrane-integration-defective OMP substrates from the beta-barrel assembly machine (Bam) complex, allowing for clearance of stalled Bam-OMP complexes. Furthermore, Skp acts as an adaptor protein to facilitate the degradation of defective OMP substrates by the periplasmic protease DegP. These findings highlight the importance of Skp in ensuring efficient beta-barrel folding.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Review
Microbiology
Natividad Ruiz, Thomas J. Silhavy
Summary: Escherichia coli, as a well-studied organism, has played a significant role in the development of biochemical genetics and molecular biology. Its suitability for biochemical and genetic research, along with the conservation of processes found in complex organisms, contributed to its selection as a model organism.
JOURNAL OF BACTERIOLOGY
(2022)
Article
Multidisciplinary Sciences
Randi L. Guest, Michael J. Lee, Wei Wang, Thomas J. Silhavy
Summary: The outer membrane of Gram-negative bacteria is unique and important for its structural and functional characteristics. The lipid asymmetry creates mechanical strength and lowers membrane permeability. The Mla pathway is responsible for removing mislocalized glycerophospholipids from the outer membrane. Pseudomonas aeruginosa has two proteins, PA2800 and PA3239, of the MlaA family.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Multidisciplinary Sciences
Irina V. Mikheyeva, Jiawei Sun, Kerwyn Casey Huang, Thomas J. Silhavy
Summary: This study demonstrates that loss of BamD in Escherichia coli leads to reduction in outer membrane proteins (OMPs), weakening the outer membrane and altering cell shape. This results in outer membrane rupture in spent medium. In response to the loss of OMPs, phospholipids flip into the outer leaflet, creating tension between the membrane leaflets and contributing to membrane rupture. Suppressor mutations that halt phospholipid removal prevent rupture but do not restore membrane stiffness or normal cell shape, suggesting a possible connection between outer membrane stiffness and cell shape.
NATURE COMMUNICATIONS
(2023)
Letter
Multidisciplinary Sciences
Georgina Benn, Thomas J. Silhavy, Colin Kleanthous, Bart W. Hoogenboom
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Kathryn A. Macgillivray, Siu Lung Ng, Sophia Wiesenfeld, Randi L. Guest, Tahrima Jubery, Thomas J. Silhavy, William C. Ratcliff, Brian K. Hammer
Summary: The study reveals that populations of Escherichia coli, when subjected to T6SS attack by Vibrio cholerae, evolved to better survive the attack through two convergently evolved pathways. However, these mutations come with trade-offs, reducing cellular growth rates and increasing susceptibility to antibiotics and elevated pH.