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Wang Z, Chu Y, Li Q, Han X, Zhao L, Zhang H, Cai K, Zhang X, Wang X, Qin Y, Fan E. A minimum functional form of the Escherichia coli BAM complex constituted by BamADE assembles outer membrane proteins in vitro. J Biol Chem 2024; 300:107324. [PMID: 38677515 PMCID: PMC11130730 DOI: 10.1016/j.jbc.2024.107324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 04/18/2024] [Indexed: 04/29/2024] Open
Abstract
The biogenesis of outer membrane proteins is mediated by the β-barrel assembly machinery (BAM), which is a heteropentomeric complex composed of five proteins named BamA-E in Escherichia coli. Despite great progress in the BAM structural analysis, the molecular details of BAM-mediated processes as well as the exact function of each BAM component during OMP assembly are still not fully understood. To enable a distinguishment of the function of each BAM component, it is the aim of the present work to examine and identify the effective minimum form of the E. coli BAM complex by use of a well-defined reconstitution strategy based on a previously developed versatile assay. Our data demonstrate that BamADE is the core BAM component and constitutes a minimum functional form for OMP assembly in E. coli, which can be stimulated by BamB and BamC. While BamB and BamC have a redundant function based on the minimum form, both together seem to cooperate with each other to substitute for the function of the missing BamD or BamE. Moreover, the BamAE470K mutant also requires the function of BamD and BamE to assemble OMPs in vitro, which vice verse suggests that BamADE are the effective minimum functional form of the E. coli BAM complex.
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Affiliation(s)
- Zhe Wang
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Yindi Chu
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Qingrong Li
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Xiaochen Han
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Leyi Zhao
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Hanqing Zhang
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Kun Cai
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Xuyan Zhang
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Xingyuan Wang
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Youcai Qin
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Enguo Fan
- Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China; School of Medicine, Linyi University, Linyi, China.
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2
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Gopinath A, Rath T, Morgner N, Joseph B. Lateral gating mechanism and plasticity of the β-barrel assembly machinery complex in micelles and Escherichia coli. PNAS NEXUS 2024; 3:pgae019. [PMID: 38312222 PMCID: PMC10833450 DOI: 10.1093/pnasnexus/pgae019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 01/08/2024] [Indexed: 02/06/2024]
Abstract
The β-barrel assembly machinery (BAM) mediates the folding and insertion of the majority of outer membrane proteins (OMPs) in gram-negative bacteria. BAM is a penta-heterooligomeric complex consisting of the central β-barrel BamA and four interacting lipoproteins BamB, C, D, and E. The conformational switching of BamA between inward-open (IO) and lateral-open (LO) conformations is required for substrate recognition and folding. However, the mechanism for the lateral gating or how the structural details observed in vitro correspond with the cellular environment remains elusive. In this study, we addressed these questions by characterizing the conformational heterogeneity of BamAB, BamACDE, and BamABCDE complexes in detergent micelles and/or Escherichia coli using pulsed dipolar electron spin resonance spectroscopy (PDS). We show that the binding of BamB does not induce any visible changes in BamA, and the BamAB complex exists in the IO conformation. The BamCDE complex induces an IO to LO transition through a coordinated movement along the BamA barrel. However, the extracellular loop 6 (L6) is unaffected by the presence of lipoproteins and exhibits large segmental dynamics extending to the exit pore. PDS experiments with the BamABCDE complex in intact E. coli confirmed the dynamic behavior of both the lateral gate and the L6 in the native environment. Our results demonstrate that the BamCDE complex plays a key role in the function by regulating lateral gating in BamA.
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Affiliation(s)
- Aathira Gopinath
- Department of Physics, Freie Universität Berlin, Berlin, 14195, Germany
- Institute of Biophysics, Goethe Universität Frankfurt, Frankfurt, 60438, Germany
| | - Tobias Rath
- Institute of Physical and Theoretical Chemistry, Goethe Universität Frankfurt, Frankfurt, 60438, Germany
| | - Nina Morgner
- Institute of Physical and Theoretical Chemistry, Goethe Universität Frankfurt, Frankfurt, 60438, Germany
| | - Benesh Joseph
- Department of Physics, Freie Universität Berlin, Berlin, 14195, Germany
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3
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Germany EM, Thewasano N, Imai K, Maruno Y, Bamert RS, Stubenrauch CJ, Dunstan RA, Ding Y, Nakajima Y, Lai X, Webb CT, Hidaka K, Tan KS, Shen H, Lithgow T, Shiota T. Dual recognition of multiple signals in bacterial outer membrane proteins enhances assembly and maintains membrane integrity. eLife 2024; 12:RP90274. [PMID: 38226797 PMCID: PMC10945584 DOI: 10.7554/elife.90274] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024] Open
Abstract
Outer membrane proteins (OMPs) are essential components of the outer membrane of Gram-negative bacteria. In terms of protein targeting and assembly, the current dogma holds that a 'β-signal' imprinted in the final β-strand of the OMP engages the β-barrel assembly machinery (BAM) complex to initiate membrane insertion and assembly of the OMP into the outer membrane. Here, we revealed an additional rule that signals equivalent to the β-signal are repeated in other, internal β-strands within bacterial OMPs, by peptidomimetic and mutational analysis. The internal signal is needed to promote the efficiency of the assembly reaction of these OMPs. BamD, an essential subunit of the BAM complex, recognizes the internal signal and the β-signal, arranging several β-strands and partial folding for rapid OMP assembly. The internal signal-BamD ordering system is not essential for bacterial viability but is necessary to retain the integrity of the outer membrane against antibiotics and other environmental insults.
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Affiliation(s)
- Edward M Germany
- Frontier Science Research Center, University of MiyazakiMiyazakiJapan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazakiJapan
| | - Nakajohn Thewasano
- Frontier Science Research Center, University of MiyazakiMiyazakiJapan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazakiJapan
| | - Kenichiro Imai
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)TokyoJapan
| | - Yuki Maruno
- Frontier Science Research Center, University of MiyazakiMiyazakiJapan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazakiJapan
| | - Rebecca S Bamert
- Centre to Impact AMR, Monash UniversityClaytonAustralia
- Infection Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash UniversityClaytonAustralia
| | - Christopher J Stubenrauch
- Centre to Impact AMR, Monash UniversityClaytonAustralia
- Infection Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash UniversityClaytonAustralia
| | - Rhys A Dunstan
- Centre to Impact AMR, Monash UniversityClaytonAustralia
- Infection Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash UniversityClaytonAustralia
| | - Yue Ding
- Department of Materials Science and Engineering, Monash UniversityClaytonAustralia
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash UniversityClaytonAustralia
| | - Yukari Nakajima
- Frontier Science Research Center, University of MiyazakiMiyazakiJapan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazakiJapan
| | - XiangFeng Lai
- Department of Materials Science and Engineering, Monash UniversityClaytonAustralia
| | - Chaille T Webb
- Centre to Impact AMR, Monash UniversityClaytonAustralia
- Infection Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash UniversityClaytonAustralia
| | - Kentaro Hidaka
- Frontier Science Research Center, University of MiyazakiMiyazakiJapan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazakiJapan
| | - Kher Shing Tan
- Centre to Impact AMR, Monash UniversityClaytonAustralia
- Infection Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash UniversityClaytonAustralia
| | - Hsinhui Shen
- Department of Materials Science and Engineering, Monash UniversityClaytonAustralia
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash UniversityClaytonAustralia
| | - Trevor Lithgow
- Centre to Impact AMR, Monash UniversityClaytonAustralia
- Infection Program, Biomedicine Discovery Institute, and Department of Microbiology, Monash UniversityClaytonAustralia
| | - Takuya Shiota
- Frontier Science Research Center, University of MiyazakiMiyazakiJapan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazakiJapan
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4
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Storek KM, Sun D, Rutherford ST. Inhibitors targeting BamA in gram-negative bacteria. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119609. [PMID: 37852326 DOI: 10.1016/j.bbamcr.2023.119609] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/08/2023] [Accepted: 09/19/2023] [Indexed: 10/20/2023]
Abstract
Antibiotic resistance has led to an increase in the number of patient hospitalizations and deaths. The situation for gram-negative bacteria is especially dire as the last new class of antibiotics active against these bacteria was introduced to the clinic over 60 years ago, thus there is an immediate unmet need for new antibiotic classes able to overcome resistance. The outer membrane, a unique and essential structure in gram-negative bacteria, contains multiple potential antibacterial targets including BamA, an outer membrane protein that folds and inserts transmembrane β-barrel proteins. BamA is essential and conserved, and its outer membrane location eliminates a barrier that molecules must overcome to access this target. Recently, antibacterial small molecules, natural products, peptides, and antibodies that inhibit BamA activity have been reported, validating the druggability of this target and generating potential leads for antibiotic development. This review will describe these BamA inhibitors, highlight their key attributes, and identify challenges with this potential target.
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Affiliation(s)
- Kelly M Storek
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, USA
| | - Dawei Sun
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA
| | - Steven T Rutherford
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, USA.
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5
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Miano A, Rychel K, Lezia A, Sastry A, Palsson B, Hasty J. High-resolution temporal profiling of E. coli transcriptional response. Nat Commun 2023; 14:7606. [PMID: 37993418 PMCID: PMC10665441 DOI: 10.1038/s41467-023-43173-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 11/02/2023] [Indexed: 11/24/2023] Open
Abstract
Understanding how cells dynamically adapt to their environment is a primary focus of biology research. Temporal information about cellular behavior is often limited by both small numbers of data time-points and the methods used to analyze this data. Here, we apply unsupervised machine learning to a data set containing the activity of 1805 native promoters in E. coli measured every 10 minutes in a high-throughput microfluidic device via fluorescence time-lapse microscopy. Specifically, this data set reveals E. coli transcriptome dynamics when exposed to different heavy metal ions. We use a bioinformatics pipeline based on Independent Component Analysis (ICA) to generate insights and hypotheses from this data. We discovered three primary, time-dependent stages of promoter activation to heavy metal stress (fast, intermediate, and steady). Furthermore, we uncovered a global strategy E. coli uses to reallocate resources from stress-related promoters to growth-related promoters following exposure to heavy metal stress.
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Affiliation(s)
- Arianna Miano
- Department of Bioengineering, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA.
| | - Kevin Rychel
- Department of Bioengineering, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
| | - Andrew Lezia
- Department of Bioengineering, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
| | - Anand Sastry
- Department of Bioengineering, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
| | - Bernhard Palsson
- Department of Bioengineering, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs, Lyngby, Denmark
| | - Jeff Hasty
- Department of Bioengineering, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
- Department of Molecular Biology, School of Biological Sciences, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
- Synthetic Biology Institute, University of California San Diego, 9500 Gliman Dr, La Jolla, CA, USA
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6
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Rath P, Hermann A, Schaefer R, Agustoni E, Vonach JM, Siegrist M, Miscenic C, Tschumi A, Roth D, Bieniossek C, Hiller S. High-throughput screening of BAM inhibitors in native membrane environment. Nat Commun 2023; 14:5648. [PMID: 37704632 PMCID: PMC10499997 DOI: 10.1038/s41467-023-41445-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 09/02/2023] [Indexed: 09/15/2023] Open
Abstract
The outer membrane insertase of Gram-negative bacteria, BAM, is a key target for urgently needed novel antibiotics. Functional reconstitutions of BAM have so far been limited to synthetic membranes and with low throughput capacity for inhibitor screening. Here, we describe a BAM functional assay in native membrane environment capable of high-throughput screening. This is achieved by employing outer membrane vesicles (OMVs) to present BAM directly in native membranes. Refolding of the model substrate OmpT by BAM was possible from the chaperones SurA and Skp, with the required SurA concentration three times higher than Skp. In the OMVs, the antibiotic darobactin had a tenfold higher potency than in synthetic membranes, highlighting the need for native conditions in antibiotics development. The assay is successfully miniaturized for 1536-well plates and upscaled using large scale fermentation, resulting in high-throughput capacities to screen large commercial compound libraries. Our OMV-based assay thus lays the basis for discovery, hit validation and lead expansion of antibiotics targeting BAM.
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Affiliation(s)
- Parthasarathi Rath
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Adrian Hermann
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Ramona Schaefer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Elia Agustoni
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Jean-Marie Vonach
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Martin Siegrist
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Christian Miscenic
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Andreas Tschumi
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Doris Roth
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Christoph Bieniossek
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland.
| | - Sebastian Hiller
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland.
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7
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Kumar S, Konovalova A. BamE directly interacts with BamA and BamD coordinating their functions. Mol Microbiol 2023; 120:397-407. [PMID: 37455652 PMCID: PMC10528117 DOI: 10.1111/mmi.15127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/18/2023]
Abstract
The β-barrel assembly machinery (Bam) complex facilitates the assembly of outer membrane proteins (OMPs) in gram-negative bacteria. The Bam complex is conserved and essential for bacterial viability and consists of five subunits, BamA-E. BamA is the transmembrane component, and its β-barrel domain opens laterally to allow folding and insertion of incoming OMPs. The remaining components are regulatory, among which only BamD is essential. Previous studies suggested that BamB regulates BamA directly, while BamE and BamC serve as BamD regulators. However, specific molecular details of their functions remain unknown. Our previous research demonstrated that BamE plays a specialized role in assembling the complex between the lipoprotein RcsF and its OMP partners, required for the Regulator of Capsule Synthesis (Rcs) stress response. Here, we used RcsF/OmpA as a model substrate to investigate BamE function. Our results challenge the current view that BamE only serves as a BamD regulator. We show that BamE also directly interacts with BamA. BamE interaction with both BamA and BamD is important for function. Our genetic and biochemical analysis shows that BamE stabilizes the Bam complex and promotes bidirectional signaling interaction between BamA and BamD. This BamE function becomes essential when direct BamA/BamD communication is impeded.
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Affiliation(s)
- Santosh Kumar
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
| | - Anna Konovalova
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, USA
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8
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Devlin T, Fleming PJ, Loza N, Fleming KG. Generation of unfolded outer membrane protein ensembles defined by hydrodynamic properties. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:415-425. [PMID: 36899114 DOI: 10.1007/s00249-023-01639-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/23/2023] [Accepted: 02/20/2023] [Indexed: 03/12/2023]
Abstract
Outer membrane proteins (OMPs) must exist as an unfolded ensemble while interacting with a chaperone network in the periplasm of Gram-negative bacteria. Here, we developed a method to model unfolded OMP (uOMP) conformational ensembles using the experimental properties of two well-studied OMPs. The overall sizes and shapes of the unfolded ensembles in the absence of a denaturant were experimentally defined by measuring the sedimentation coefficient as a function of urea concentration. We used these data to model a full range of unfolded conformations by parameterizing a targeted coarse-grained simulation protocol. The ensemble members were further refined by short molecular dynamics simulations to reflect proper torsion angles. The final conformational ensembles have polymer properties different from unfolded soluble and intrinsically disordered proteins and reveal inherent differences in the unfolded states that necessitate further investigation. Building these uOMP ensembles advances the understanding of OMP biogenesis and provides essential information for interpreting structures of uOMP-chaperone complexes.
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Affiliation(s)
- Taylor Devlin
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Patrick J Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Nicole Loza
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Karen G Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA.
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9
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Thewasano N, Germany EM, Maruno Y, Nakajima Y, Shiota T. Categorization of Escherichia coli Outer Membrane Proteins by Dependence on Accessory Proteins of the β-barrel Assembly Machinery Complex. J Biol Chem 2023:104821. [PMID: 37196764 PMCID: PMC10300371 DOI: 10.1016/j.jbc.2023.104821] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 04/20/2023] [Accepted: 05/08/2023] [Indexed: 05/19/2023] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is populated by various outer membrane proteins (OMPs) that fold into a unique β-barrel transmembrane domain. Most OMPs are assembled into the OM by the β-barrel assembly machinery (BAM) complex. In Escherichia coli, the BAM complex is composed of two essential proteins (BamA and BamD) and three non-essential accessory proteins (BamB, BamC, and BamE). The currently proposed molecular mechanisms of the BAM complex involve only essential subunits, with the function of the accessory proteins remaining largely unknown. Here, we compared the accessory protein requirements for the assembly of seven different OMPs, 8- to 22-stranded, by our in vitro reconstitution assay using an E. coli mid-density membrane (EMM). BamE was responsible for the full efficiency of the assembly of all tested OMPs, as it enhanced the stability of essential subunit binding. BamB increased the assembly efficiency of more than 16-stranded OMPs, whereas BamC was not required for the assembly of any tested OMPs. Our categorization of the requirements of BAM complex accessory proteins in the assembly of substrate OMPs enables us to identify potential targets for the development of new antibiotics.
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Affiliation(s)
- Nakajohn Thewasano
- Organization for Promotion of Tenure Track, University of Miyazaki, Nishi 1-1 Gakuen Kibanadai, Miyazaki, 889-2192, Japan; Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Edward M Germany
- Organization for Promotion of Tenure Track, University of Miyazaki, Nishi 1-1 Gakuen Kibanadai, Miyazaki, 889-2192, Japan; Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Yuki Maruno
- Organization for Promotion of Tenure Track, University of Miyazaki, Nishi 1-1 Gakuen Kibanadai, Miyazaki, 889-2192, Japan; Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Yukari Nakajima
- Organization for Promotion of Tenure Track, University of Miyazaki, Nishi 1-1 Gakuen Kibanadai, Miyazaki, 889-2192, Japan; Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Takuya Shiota
- Organization for Promotion of Tenure Track, University of Miyazaki, Nishi 1-1 Gakuen Kibanadai, Miyazaki, 889-2192, Japan; Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
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10
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Devlin T, Marx DC, Roskopf MA, Bubb QR, Plummer AM, Fleming KG. FkpA enhances membrane protein folding using an extensive interaction surface. Protein Sci 2023; 32:e4592. [PMID: 36775935 PMCID: PMC10031210 DOI: 10.1002/pro.4592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/17/2023] [Accepted: 02/07/2023] [Indexed: 02/14/2023]
Abstract
Outer membrane protein (OMP) biogenesis in gram-negative bacteria is managed by a network of periplasmic chaperones that includes SurA, Skp, and FkpA. These chaperones bind unfolded OMPs (uOMPs) in dynamic conformational ensembles to suppress aggregation, facilitate diffusion across the periplasm, and enhance folding. FkpA primarily responds to heat-shock stress, but its mechanism is comparatively understudied. To determine FkpA chaperone function in the context of OMP folding, we monitored the folding of three OMPs and found that FkpA, unlike other periplasmic chaperones, increases the folded yield but decreases the folding rate of OMPs. The results indicate that FkpA behaves as a chaperone and not as a folding catalyst to influence the OMP folding trajectory. Consistent with the folding assay results, FkpA binds all three uOMPs as determined by sedimentation velocity (SV) and photo-crosslinking experiments. We determine the binding affinity between FkpA and uOmpA171 by globally fitting SV titrations and find it to be intermediate between the known affinities of Skp and SurA for uOMP clients. Notably, complex formation steeply depends on the urea concentration, suggesting an extensive binding interface. Initial characterizations of the complex using photo-crosslinking indicate that the binding interface spans the entire FkpA molecule. In contrast to prior findings, folding and binding experiments performed using subdomain constructs of FkpA demonstrate that the full-length chaperone is required for full activity. Together these results support that FkpA has a distinct and direct effect on OMP folding that it achieves by utilizing an extensive chaperone-client interface to tightly bind clients.
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Affiliation(s)
- Taylor Devlin
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Dagan C. Marx
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Michaela A. Roskopf
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Quenton R. Bubb
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Ashlee M. Plummer
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Karen G. Fleming
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
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11
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Akshay SD, Nayak S, Deekshit VK, Rohit A, Maiti B. Differential expression of outer membrane proteins and quinolone resistance determining region mutations can lead to ciprofloxacin resistance in Salmonella Typhi. Arch Microbiol 2023; 205:136. [PMID: 36961627 DOI: 10.1007/s00203-023-03485-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 01/17/2023] [Accepted: 03/13/2023] [Indexed: 03/25/2023]
Abstract
Multi-drug resistance in Salmonella Typhi remains a public health concern globally. This study aimed to investigate the function of quinolone resistance determining region (QRDR) of gyrA and parC in ciprofloxacin (CIP) resistant isolates and examine the differential expression of outer membrane proteins (OMPs) on exposure to sub-lethal concentrations of CIP in S. Typhi. The CIP-resistant isolates were screened for mutations in the QRDR and analyzed for bacterial growth. Furthermore, major OMPs encoding genes such as ompF, lamB, yaeT, tolC, ompS1, and phoE were examined for differential expression under the sub-lethal concentrations of CIP by real-time PCR and SDS-PAGE. Notably, our study has shown a single-point mutation in gyrA at codon 83 (Ser83-tyrosine and Ser83-phenylalanine), also the rare amino acid substitution in parC gene at codon 80 (Glu80-glycine) in CIP-resistant isolates. Additionally, CIP-resistant isolates showed moderate growth compared to susceptible isolates. Although most of the OMP-encoding genes (tolC, ompS1, and phoE) showed some degree of upregulation, a significant level of upregulation (p < 0.05) was observed only for yaeT. However, ompF and lamB genes were down-regulated compared to CIP-susceptible isolates. Whereas OMPs profiling using SDS-PAGE did not show any changes in the banding pattern. These results provide valuable information on the QRDR mutation, and the difference in the growth, and expression of OMP-encoding genes in resistant and susceptible isolates of S. Typhi. This further provides insight into the involvement of QRDR mutation and OMPs associated with CIP resistance in S. Typhi.
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Affiliation(s)
- Sadanand Dangari Akshay
- Division of Infectious Diseases, Nitte (Deemed to Be University), Nitte University Centre for Science Education and Research (NUCSER), Paneer Campus, Deralakatte, Mangalore, 575018, India
| | - Srajana Nayak
- Division of Infectious Diseases, Nitte (Deemed to Be University), Nitte University Centre for Science Education and Research (NUCSER), Paneer Campus, Deralakatte, Mangalore, 575018, India
| | - Vijaya Kumar Deekshit
- Division of Infectious Diseases, Nitte (Deemed to Be University), Nitte University Centre for Science Education and Research (NUCSER), Paneer Campus, Deralakatte, Mangalore, 575018, India
| | - Anusha Rohit
- Division of Infectious Diseases, Nitte (Deemed to Be University), Nitte University Centre for Science Education and Research (NUCSER), Paneer Campus, Deralakatte, Mangalore, 575018, India
- Department of Microbiology, The Madras Medical Mission, 4-A, Dr, Mogappair, Chennai, Tamil Nadu, 600037, India
| | - Biswajit Maiti
- Division of Infectious Diseases, Nitte (Deemed to Be University), Nitte University Centre for Science Education and Research (NUCSER), Paneer Campus, Deralakatte, Mangalore, 575018, India.
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12
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Miller RD, Iinishi A, Modaresi SM, Yoo BK, Curtis TD, Lariviere PJ, Liang L, Son S, Nicolau S, Bargabos R, Morrissette M, Gates MF, Pitt N, Jakob RP, Rath P, Maier T, Malyutin AG, Kaiser JT, Niles S, Karavas B, Ghiglieri M, Bowman SEJ, Rees DC, Hiller S, Lewis K. Computational identification of a systemic antibiotic for gram-negative bacteria. Nat Microbiol 2022; 7:1661-1672. [PMID: 36163500 PMCID: PMC10155127 DOI: 10.1038/s41564-022-01227-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 08/05/2022] [Indexed: 12/14/2022]
Abstract
Discovery of antibiotics acting against Gram-negative species is uniquely challenging due to their restrictive penetration barrier. BamA, which inserts proteins into the outer membrane, is an attractive target due to its surface location. Darobactins produced by Photorhabdus, a nematode gut microbiome symbiont, target BamA. We reasoned that a computational search for genes only distantly related to the darobactin operon may lead to novel compounds. Following this clue, we identified dynobactin A, a novel peptide antibiotic from Photorhabdus australis containing two unlinked rings. Dynobactin is structurally unrelated to darobactins, but also targets BamA. Based on a BamA-dynobactin co-crystal structure and a BAM-complex-dynobactin cryo-EM structure, we show that dynobactin binds to the BamA lateral gate, uniquely protruding into its β-barrel lumen. Dynobactin showed efficacy in a mouse systemic Escherichia coli infection. This study demonstrates the utility of computational approaches to antibiotic discovery and suggests that dynobactin is a promising lead for drug development.
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Affiliation(s)
- Ryan D Miller
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Akira Iinishi
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | | | - Byung-Kuk Yoo
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Thomas D Curtis
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Patrick J Lariviere
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Libang Liang
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Sangkeun Son
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Samantha Nicolau
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Rachel Bargabos
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Madeleine Morrissette
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Michael F Gates
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Norman Pitt
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | | | | | - Timm Maier
- Biozentrum, University of Basel, Basel, Switzerland
| | - Andrey G Malyutin
- Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Jens T Kaiser
- Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Samantha Niles
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Blake Karavas
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Meghan Ghiglieri
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Sarah E J Bowman
- National Crystallization Center, Hauptman-Woodward Medical Research Institute, Buffalo, NY, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| | | | - Kim Lewis
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA.
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13
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Abstract
Several antibacterial compounds have recently been discovered that potentially inhibit the activity of BamA, an essential subunit of a heterooligomer (the barrel assembly machinery or BAM) that assembles outer membrane proteins (OMPs) in Gram-negative bacteria, but their mode of action is unclear. To address this issue, we examined the effect of three inhibitors on the biogenesis of a model E. coli OMP (EspP) in vivo. We found that darobactin potently inhibited the interaction of a conserved C-terminal sequence motif (the “β signal”) with BamA, but had no effect on assembly if added at a postbinding stage. In contrast, Polyphor peptide 7 and MRL-494 inhibited both binding and at least one later step of assembly. Taken together with previous studies that analyzed the binding of darobactin and Polyphor peptide 7 to BamA in vitro, our results strongly suggest that the two compounds inhibit BAM function by distinct competitive and allosteric mechanisms. In addition to providing insights into the properties of the antibacterial compounds, our results also provide direct experimental evidence that supports a model in which the binding of the β signal to BamA initiates the membrane insertion of OMPs.
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14
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Kuo KM, Ryoo D, Lundquist K, Gumbart JC. Modeling intermediates of BamA folding an outer membrane protein. Biophys J 2022; 121:3242-3252. [PMID: 35927955 PMCID: PMC9463690 DOI: 10.1016/j.bpj.2022.07.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/03/2022] [Accepted: 07/21/2022] [Indexed: 11/16/2022] Open
Abstract
BamA, the core component of the β-barrel assembly machinery complex, is an integral outer-membrane protein (OMP) in Gram-negative bacteria that catalyzes the folding and insertion of OMPs. A key feature of BamA relevant to its function is a lateral gate between its first and last β-strands. Opening of this lateral gate is one of the first steps in the asymmetric-hybrid-barrel model of BamA function. In this study, multiple hybrid-barrel folding intermediates of BamA and a substrate OMP, EspP, were constructed and simulated to better understand the model's physical consequences. The hybrid-barrel intermediates consisted of the BamA β-barrel and its POTRA5 domain and either one, two, three, four, five, or six β-hairpins of EspP. The simulation results support an asymmetric-hybrid-barrel model in which the BamA N-terminal β-strand forms stronger interactions with the substrate OMP than the C-terminal β-strand. A consistent "B"-shaped conformation of the final folding intermediate was observed, and the shape of the substrate β-barrel within the hybrid matched the shape of the fully folded substrate. Upon further investigation, inward-facing glycines were found at sharp bends within the hybrid and fully folded β-barrels. Together, the data suggest an influence of sequence on shape of the substrate barrel throughout the OMP folding process and of the fully folded OMP.
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Affiliation(s)
- Katie M Kuo
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia
| | - David Ryoo
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, Georgia
| | - Karl Lundquist
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, Indiana
| | - James C Gumbart
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia; School of Physics, Georgia Institute of Technology, Atlanta, Georgia.
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15
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Overexpression of the Bam Complex Improves the Production of Chlamydia trachomatis MOMP in the E. coli Outer Membrane. Int J Mol Sci 2022; 23:ijms23137393. [PMID: 35806397 PMCID: PMC9266984 DOI: 10.3390/ijms23137393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 06/29/2022] [Accepted: 06/29/2022] [Indexed: 02/07/2023] Open
Abstract
A licensed Chlamydia trachomatis (Ct) vaccine is not yet available. Recombinant Chlamydia trachomatis major outer membrane protein (Ct-MOMP), the most abundant constituent of the chlamydial outer membrane complex, is considered the most attractive candidate for subunit-based vaccine formulations. Unfortunately, Ct-MOMP is difficult to express in its native structure in the E. coli outer membrane (OM). Here, by co-expression of the Bam complex, we improved the expression and localization of recombinant Ct-MOMP in the E. coli OM. Under these conditions, recombinant Ct-MOMP appeared to assemble into a β-barrel conformation and express domains at the cell surface indicative of correct folding. The data indicate that limited availability of the Bam complex can be a bottleneck for the production of heterologous OM vaccine antigens, information that is also relevant for strategies aimed at producing recombinant OMV-based vaccines.
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16
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Dynamic interplay between the periplasmic chaperone SurA and the BAM complex in outer membrane protein folding. Commun Biol 2022; 5:560. [PMID: 35676411 PMCID: PMC9177699 DOI: 10.1038/s42003-022-03502-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 05/18/2022] [Indexed: 12/12/2022] Open
Abstract
Correct folding of outer membrane proteins (OMPs) into the outer membrane of Gram-negative bacteria depends on delivery of unfolded OMPs to the β-barrel assembly machinery (BAM). How unfolded substrates are presented to BAM remains elusive, but the major OMP chaperone SurA is proposed to play a key role. Here, we have used hydrogen deuterium exchange mass spectrometry (HDX-MS), crosslinking, in vitro folding and binding assays and computational modelling to show that the core domain of SurA and one of its two PPIase domains are key to the SurA-BAM interaction and are required for maximal catalysis of OMP folding. We reveal that binding causes changes in BAM and SurA conformation and/or dynamics distal to the sites of binding, including at the BamA β1-β16 seam. We propose a model for OMP biogenesis in which SurA plays a crucial role in OMP delivery and primes BAM to accept substrates for folding. Interaction of the outer membrane protein (OMP) chaperone SurA and the OMP folding catalyst BAM results in changes in the conformational ensembles of both species, suggesting a mechanism for delivery of OMPs to BAM in Gram-negative bacteria.
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17
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Mamou G, Corona F, Cohen-Khait R, Housden NG, Yeung V, Sun D, Sridhar P, Pazos M, Knowles TJ, Kleanthous C, Vollmer W. Peptidoglycan maturation controls outer membrane protein assembly. Nature 2022; 606:953-959. [PMID: 35705811 PMCID: PMC9242858 DOI: 10.1038/s41586-022-04834-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 05/05/2022] [Indexed: 11/12/2022]
Abstract
Linkages between the outer membrane of Gram-negative bacteria and the peptidoglycan layer are crucial for the maintenance of cellular integrity and enable survival in challenging environments1–5. The function of the outer membrane is dependent on outer membrane proteins (OMPs), which are inserted into the membrane by the β-barrel assembly machine6,7 (BAM). Growing Escherichia coli cells segregate old OMPs towards the poles by a process known as binary partitioning, the basis of which is unknown8. Here we demonstrate that peptidoglycan underpins the spatiotemporal organization of OMPs. Mature, tetrapeptide-rich peptidoglycan binds to BAM components and suppresses OMP foldase activity. Nascent peptidoglycan, which is enriched in pentapeptides and concentrated at septa9, associates with BAM poorly and has little effect on its activity, leading to preferential insertion of OMPs at division sites. The synchronization of OMP biogenesis with cell wall growth results in the binary partitioning of OMPs as cells divide. Our study reveals that Gram-negative bacteria coordinate the assembly of two major cell envelope layers by rendering OMP biogenesis responsive to peptidoglycan maturation, a potential vulnerability that could be exploited in future antibiotic design. Peptidoglycan stem peptides in the Gram-negative bacterial cell wall regulate the insertion of essential outer membrane proteins, thus representing a potential target for antibiotic design.
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Affiliation(s)
- Gideon Mamou
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Federico Corona
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.,Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ruth Cohen-Khait
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Nicholas G Housden
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Vivian Yeung
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK
| | - Dawei Sun
- Structural Biology, Genentech, South San Francisco, CA, USA
| | - Pooja Sridhar
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Manuel Pazos
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.,Department of Molecular Biology, Center of Molecular Biology 'Severo Ochoa' (UAM-CSIC), Autonomous University of Madrid, Madrid, Spain
| | | | - Colin Kleanthous
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford, UK.
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.
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18
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Doyle MT, Bernstein HD. Function of the Omp85 Superfamily of Outer Membrane Protein Assembly Factors and Polypeptide Transporters. Annu Rev Microbiol 2022; 76:259-279. [PMID: 35650668 DOI: 10.1146/annurev-micro-033021-023719] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Omp85 protein superfamily is found in the outer membrane (OM) of all gram-negative bacteria and eukaryotic organelles of bacterial origin. Members of the family catalyze both the membrane insertion of β-barrel proteins and the translocation of proteins across the OM. Although the mechanism(s) by which these proteins function is unclear, striking new insights have emerged from recent biochemical and structural studies. In this review we discuss the entire Omp85 superfamily but focus on the function of the best-studied member, BamA, which is an essential and highly conserved component of the bacterial barrel assembly machinery (BAM). Because BamA has multiple functions that overlap with those of other Omp85 proteins, it is likely the prototypical member of the Omp85 superfamily. Furthermore, BamA has become a protein of great interest because of the recent discovery of small-molecule inhibitors that potentially represent an important new class of antibiotics. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Matthew Thomas Doyle
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA; ,
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA; ,
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19
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Huynh MS, Hooda Y, Li YR, Jagielnicki M, Lai CCL, Moraes TF. Reconstitution of surface lipoprotein translocation through the slam translocon. eLife 2022; 11:72822. [PMID: 35475756 PMCID: PMC9090332 DOI: 10.7554/elife.72822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Surface lipoproteins (SLPs) are peripherally attached to the outer leaflet of the outer membrane in many Gram-negative bacteria, playing significant roles in nutrient acquisition and immune evasion in the host. While the factors that are involved in the synthesis and delivery of SLPs in the inner membrane are well characterized, the molecular machinery required for the movement of SLPs to the surface are still not fully elucidated. In this study, we investigated the translocation of a SLP TbpB through a Slam1-dependent pathway. Using purified components, we developed an in vitro translocation assay where unfolded TbpB is transported through Slam1-containing proteoliposomes, confirming Slam1 as an outer membrane translocon. While looking to identify factors to increase translocation efficiency, we discovered the periplasmic chaperone Skp interacted with TbpB in the periplasm of Escherichia coli. The presence of Skp was found to increase the translocation efficiency of TbpB in the reconstituted translocation assays. A knockout of Skp in Neisseria meningitidis revealed that Skp is essential for functional translocation of TbpB to the bacterial surface. Taken together, we propose a pathway for surface destined lipoproteins, where Skp acts as a holdase for Slam-mediated TbpB translocation across the outer membrane.
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Affiliation(s)
- Minh Sang Huynh
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Yogesh Hooda
- MRC Laboratory of Molecular Biology, University of Cambridge, Cambridge, United Kingdom
| | - Yuzi Raina Li
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | | | | | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, Canada
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20
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Plasticity within the barrel domain of BamA mediates a hybrid-barrel mechanism by BAM. Nat Commun 2021; 12:7131. [PMID: 34880256 PMCID: PMC8655018 DOI: 10.1038/s41467-021-27449-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 11/22/2021] [Indexed: 12/26/2022] Open
Abstract
In Gram-negative bacteria, the biogenesis of β-barrel outer membrane proteins is mediated by the β-barrel assembly machinery (BAM). The mechanism employed by BAM is complex and so far- incompletely understood. Here, we report the structures of BAM in nanodiscs, prepared using polar lipids and native membranes, where we observe an outward-open state. Mutations in the barrel domain of BamA reveal that plasticity in BAM is essential, particularly along the lateral seam of the barrel domain, which is further supported by molecular dynamics simulations that show conformational dynamics in BAM are modulated by the accessory proteins. We also report the structure of BAM in complex with EspP, which reveals an early folding intermediate where EspP threads from the underside of BAM and incorporates into the barrel domain of BamA, supporting a hybrid-barrel budding mechanism in which the substrate is folded into the membrane sequentially rather than as a single unit.
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21
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Hall SCL, Clifton LA, Sridhar P, Hardy DJ, Wotherspoon P, Wright J, Whitehouse J, Gamage N, Laxton CS, Hatton C, Hughes GW, Jeeves M, Knowles TJ. Surface-tethered planar membranes containing the β-barrel assembly machinery: a platform for investigating bacterial outer membrane protein folding. Biophys J 2021; 120:5295-5308. [PMID: 34757080 PMCID: PMC8715194 DOI: 10.1016/j.bpj.2021.10.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 09/06/2021] [Accepted: 10/26/2021] [Indexed: 11/16/2022] Open
Abstract
The outer membrane of Gram-negative bacteria presents a robust physicochemical barrier protecting the cell from both the natural environment and acting as the first line of defense against antimicrobial materials. The proteins situated within the outer membrane are responsible for a range of biological functions including controlling influx and efflux. These outer membrane proteins (OMPs) are ultimately inserted and folded within the membrane by the β-barrel assembly machine (Bam) complex. The precise mechanism by which the Bam complex folds and inserts OMPs remains unclear. Here, we have developed a platform for investigating Bam-mediated OMP insertion. By derivatizing a gold surface with a copper-chelating self-assembled monolayer, we were able to assemble a planar system containing the complete Bam complex reconstituted within a phospholipid bilayer. Structural characterization of this interfacial protein-tethered bilayer by polarized neutron reflectometry revealed distinct regions consistent with known high-resolution models of the Bam complex. Additionally, by monitoring changes of mass associated with OMP insertion by quartz crystal microbalance with dissipation monitoring, we were able to demonstrate the functionality of this system by inserting two diverse OMPs within the membrane, pertactin, and OmpT. This platform has promising application in investigating the mechanism of Bam-mediated OMP insertion, in addition to OMP function and activity within a phospholipid bilayer environment.
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Affiliation(s)
- Stephen C L Hall
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom
| | - Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom
| | - Pooja Sridhar
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - David J Hardy
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Peter Wotherspoon
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Jack Wright
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - James Whitehouse
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Nadisha Gamage
- Membrane Protein Laboratory, Diamond Light Source, Harwell Science & Innovation Campus, Oxfordshire, United Kingdom
| | - Claire S Laxton
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Caitlin Hatton
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Gareth W Hughes
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Mark Jeeves
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Timothy J Knowles
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
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22
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Ritzmann N, Manioglu S, Hiller S, Müller DJ. Monitoring the antibiotic darobactin modulating the β-barrel assembly factor BamA. Structure 2021; 30:350-359.e3. [PMID: 34875215 DOI: 10.1016/j.str.2021.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/30/2021] [Accepted: 11/11/2021] [Indexed: 12/15/2022]
Abstract
The β-barrel assembly machinery (BAM) complex is an essential component of Escherichia coli that inserts and folds outer membrane proteins (OMPs). The natural antibiotic compound darobactin inhibits BamA, the central unit of BAM. Here, we employ dynamic single-molecule force spectroscopy (SMFS) to better understand the structure-function relationship of BamA and its inhibition by darobactin. The five N-terminal polypeptide transport (POTRA) domains show low mechanical, kinetic, and energetic stabilities. In contrast, the structural region linking the POTRA domains to the transmembrane β-barrel exposes the highest mechanical stiffness and lowest kinetic stability within BamA, thus indicating a mechano-functional role. Within the β-barrel, the four N-terminal β-hairpins H1-H4 expose the highest mechanical stabilities and stiffnesses, while the four C-terminal β-hairpins H5-H6 show lower stabilities and higher flexibilities. This asymmetry within the β-barrel suggests that substrates funneling into the lateral gate formed by β-hairpins H1 and H8 can force the flexible C-terminal β-hairpins to change conformations.
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Affiliation(s)
- Noah Ritzmann
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Selen Manioglu
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Sebastian Hiller
- Biozentrum, University of Basel, Spitalstrasse 41, 4056 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, 4058 Basel, Switzerland.
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23
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The Escherichia coli Outer Membrane β-Barrel Assembly Machinery (BAM) Crosstalks with the Divisome. Int J Mol Sci 2021; 22:ijms222212101. [PMID: 34829983 PMCID: PMC8620860 DOI: 10.3390/ijms222212101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/29/2021] [Accepted: 11/05/2021] [Indexed: 01/25/2023] Open
Abstract
The BAM is a macromolecular machine responsible for the folding and the insertion of integral proteins into the outer membrane of diderm Gram-negative bacteria. In Escherichia coli, it consists of a transmembrane β-barrel subunit, BamA, and four outer membrane lipoproteins (BamB-E). Using BAM-specific antibodies, in E. coli cells, the complex is shown to localize in the lateral wall in foci. The machinery was shown to be enriched at midcell with specific cell cycle timing. The inhibition of septation by aztreonam did not alter the BAM midcell localization substantially. Furthermore, the absence of late cell division proteins at midcell did not impact BAM timing or localization. These results imply that the BAM enrichment at the site of constriction does not require an active cell division machinery. Expression of the Tre1 toxin, which impairs the FtsZ filamentation and therefore midcell localization, resulted in the complete loss of BAM midcell enrichment. A similar effect was observed for YidC, which is involved in the membrane insertion of cell division proteins in the inner membrane. The presence of the Z-ring is needed for preseptal peptidoglycan (PG) synthesis. As BAM was shown to be embedded in the PG layer, it is possible that BAM is inserted preferentially simultaneously with de novo PG synthesis to facilitate the insertion of OMPs in the newly synthesized outer membrane.
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Abstract
Gram-negative bacteria have a multicomponent and constitutively active periplasmic chaperone system to ensure the quality control of their outer membrane proteins (OMPs). Recently, OMPs have been identified as a new class of vulnerable targets for antibiotic development, and therefore a comprehensive understanding of OMP quality control network components will be critical for discovering antimicrobials. Here, we demonstrate that the periplasmic chaperone Spy protects certain OMPs against protein-unfolding stress and can functionally compensate for other periplasmic chaperones, namely Skp and FkpA, in the Escherichia coli K-12 MG1655 strain. After extensive in vivo genetic experiments for functional characterization of Spy, we use nuclear magnetic resonance and circular dichroism spectroscopy to elucidate the mechanism by which Spy binds and folds two different OMPs. Along with holding OMP substrates in a dynamic conformational ensemble, Spy binding enables OmpX to form a partially folded β-strand secondary structure. The bound OMP experiences temperature-dependent conformational exchange within the chaperone, pointing to a multitude of local dynamics. Our findings thus deepen the understanding of functional compensation among periplasmic chaperones during OMP biogenesis and will promote the development of innovative antimicrobials against pathogenic Gram-negative bacteria.
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Abstract
Many integral membrane proteins form oligomeric complexes, but the assembly of these structures is poorly understood. Here, we show that the assembly of OmpC, a trimeric porin that resides in the Escherichia coli outer membrane (OM), can be reconstituted in vitro. Although we observed the insertion of both urea-denatured and in vitro-synthesized OmpC into pure lipid vesicles at physiological pH, the protein assembled only into dead-end dimers. In contrast, in vitro-synthesized OmpC was inserted into proteoliposomes that contained the barrel assembly machinery (Bam) complex, a conserved heterooligomer that catalyzes protein integration into the bacterial OM, and folded into heat-stable trimers by passing through a short-lived dimeric intermediate. Interestingly, complete OmpC assembly was also dependent on the addition of lipopolysaccharide (LPS), a glycolipid located exclusively in the OM. Our results strongly suggest that trimeric porins form through a stepwise process that requires the integration of the protein into the OM in an assembly-competent state. Furthermore, our results provide surprising evidence that interaction with LPS is required not only for trimerization but also for the productive insertion of individual subunits into the lipid bilayer.
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Steenhuis M, Corona F, ten Hagen-Jongman CM, Vollmer W, Lambin D, Selhorst P, Klaassen H, Versele M, Chaltin P, Luirink J. Combining Cell Envelope Stress Reporter Assays in a Screening Approach to Identify BAM Complex Inhibitors. ACS Infect Dis 2021; 7:2250-2263. [PMID: 34125508 PMCID: PMC8369490 DOI: 10.1021/acsinfecdis.0c00728] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Indexed: 12/11/2022]
Abstract
The development of new antibiotics is particularly problematic in Gram-negative bacteria due to the presence of the outer membrane (OM), which serves as a permeability barrier. Recently, the β-barrel assembly machine (BAM), located in the OM and responsible for β-barrel type OM protein (OMP) assembly, has been validated as a novel target for antibiotics. Here, we identified potential BAM complex inhibitors using a screening approach that reports on cell envelope σE and Rcs stress in Escherichia coli. Screening a library consisting of 316 953 compounds yielded five compounds that induced σE and Rcs stress responses, while not inducing the intracellular heat-shock response. Two of the five compounds (compounds 2 and 14) showed the characteristics of known BAM complex inhibitors: synergy with OMP biogenesis mutants, decrease in the abundance of various OMPs, and loss of OM integrity. Importantly, compound 2 also inhibited BAM-dependent OMP folding in an in vitro refolding assay using purified BAM complex reconstituted in proteoliposomes.
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Affiliation(s)
- Maurice Steenhuis
- Department
of Molecular Microbiology, Amsterdam Institute
of Molecular and Life Sciences (AIMMS), Vrije Universiteit, De Boelelaan 1085, 1081HV Amsterdam, The Netherlands
| | - Federico Corona
- Centre
for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle
upon Tyne NE2 4HH, United
Kingdom
| | - Corinne M. ten Hagen-Jongman
- Department
of Molecular Microbiology, Amsterdam Institute
of Molecular and Life Sciences (AIMMS), Vrije Universiteit, De Boelelaan 1085, 1081HV Amsterdam, The Netherlands
| | - Waldemar Vollmer
- Centre
for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle
upon Tyne NE2 4HH, United
Kingdom
| | - Dominique Lambin
- Centre
for Innovation and Stimulation of Drug Discovery (CISTIM), Gaston Geenslaan 2, B-3001 Leuven, Belgium
| | - Philippe Selhorst
- Centre
for Innovation and Stimulation of Drug Discovery (CISTIM), Gaston Geenslaan 2, B-3001 Leuven, Belgium
| | - Hugo Klaassen
- Centre
for Innovation and Stimulation of Drug Discovery (CISTIM), Gaston Geenslaan 2, B-3001 Leuven, Belgium
| | - Matthias Versele
- Centre
for Innovation and Stimulation of Drug Discovery (CISTIM), Gaston Geenslaan 2, B-3001 Leuven, Belgium
| | - Patrick Chaltin
- Center
for Drug Design and Development (CD3), KU
Leuven R&D, Waaistraat 6, B-3000 Leuven, Belgium
| | - Joen Luirink
- Department
of Molecular Microbiology, Amsterdam Institute
of Molecular and Life Sciences (AIMMS), Vrije Universiteit, De Boelelaan 1085, 1081HV Amsterdam, The Netherlands
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Zhao L, Tao J, Huang Y, Zhu K, Du Y, Hao D, Liu H, Zhang R, Ma G. Tailored nanodisc immobilization for one-step purification and reconstitution of cytochrome P450: A tool for membrane proteins' hard cases. J Sep Sci 2021; 44:3429-3440. [PMID: 34313005 DOI: 10.1002/jssc.202100284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/25/2021] [Accepted: 07/19/2021] [Indexed: 11/07/2022]
Abstract
A novel nanodisc-based immobilization method was developed for high-efficient purification and reconstitution of cytochrome P450 in one step. Using membrane scaffold protein containing a histidine tag, charged-nanodiscs were prepared in the form of self-assembly of lipid-protein nanoparticles. Their properties including the particle diameter and its distribution and Zeta potential were controlled well by adjusting molar ratios of phospholipids to membrane scaffold protein. At an optimum lipid-to-membrane scaffold protein molar ratio of 60:1, uniformly regular-shaped and discoidal nanodiscs with an average particle diameter of 10 nm and Zeta potential of -19 mV were obtained. They can be well fractionated by size exclusion chromatography. Charged-nanodiscs were successfully immobilized onto Ni-chelating microspheres via histidine tags with a density of 6.6 mg membrane scaffold protein/mL gel. After being packed in a column, chromatography studies demonstrated that this nanodisc-immobilized chromatographic medium had a specific binding to cytochrome P450 in rat liver microsome. Nanodiscs containing cytochrome P450 can be furthermore eluted from the column with a diameter of about 87.0 nm and height of about 8.0 nm, respectively. The purity of cytochrome P450 after purification increased 25 folds strikingly. This nanodisc-immobilized chromatography method is promising for the one-step purification and reconstitution of membrane protein.
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Affiliation(s)
- Lan Zhao
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China
| | - Jiaoli Tao
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China.,School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing, P. R. China
| | - Yongdong Huang
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China
| | - Kai Zhu
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China
| | - Yuxiang Du
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China.,School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing, P. R. China
| | - Dongxia Hao
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China
| | - Hongying Liu
- School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing, P. R. China
| | - Rongyue Zhang
- Department of Applied Chemistry, Beijing Institute of Petrochemical Technology, Beijing, P. R. China
| | - Guanghui Ma
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P. R. China.,School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, P. R. China
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28
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Hawley KL, Montezuma-Rusca JM, Delgado KN, Singh N, Uversky VN, Caimano MJ, Radolf JD, Luthra A. Structural Modeling of the Treponema pallidum Outer Membrane Protein Repertoire: a Road Map for Deconvolution of Syphilis Pathogenesis and Development of a Syphilis Vaccine. J Bacteriol 2021; 203:e0008221. [PMID: 33972353 PMCID: PMC8407342 DOI: 10.1128/jb.00082-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/27/2021] [Indexed: 01/11/2023] Open
Abstract
Treponema pallidum, an obligate human pathogen, has an outer membrane (OM) whose physical properties, ultrastructure, and composition differ markedly from those of phylogenetically distant Gram-negative bacteria. We developed structural models for the outer membrane protein (OMP) repertoire (OMPeome) of T. pallidum Nichols using solved Gram-negative structures, computational tools, and small-angle X-ray scattering (SAXS) of selected recombinant periplasmic domains. The T. pallidum "OMPeome" harbors two "stand-alone" proteins (BamA and LptD) involved in OM biogenesis and four paralogous families involved in the influx/efflux of small molecules: 8-stranded β-barrels, long-chain-fatty-acid transporters (FadLs), OM factors (OMFs) for efflux pumps, and T. pallidum repeat proteins (Tprs). BamA (TP0326), the central component of a β-barrel assembly machine (BAM)/translocation and assembly module (TAM) hybrid, possesses a highly flexible polypeptide-transport-associated (POTRA) 1-5 arm predicted to interact with TamB (TP0325). TP0515, an LptD ortholog, contains a novel, unstructured C-terminal domain that models inside the β-barrel. T. pallidum has four 8-stranded β-barrels, each containing positively charged extracellular loops that could contribute to pathogenesis. Three of five FadL-like orthologs have a novel α-helical, presumptively periplasmic C-terminal extension. SAXS and structural modeling further supported the bipartite membrane topology and tridomain architecture of full-length members of the Tpr family. T. pallidum's two efflux pumps presumably extrude noxious small molecules via four coexpressed OMFs with variably charged tunnels. For BamA, LptD, and OMFs, we modeled the molecular machines that deliver their substrates into the OM or external milieu. The spirochete's extended families of OM transporters collectively confer a broad capacity for nutrient uptake. The models also furnish a structural road map for vaccine development. IMPORTANCE The unusual outer membrane (OM) of T. pallidum, the syphilis spirochete, is the ultrastructural basis for its well-recognized capacity for invasiveness, immune evasion, and persistence. In recent years, we have made considerable progress in identifying T. pallidum's repertoire of OMPs. Here, we developed three-dimensional (3D) models for the T. pallidum Nichols OMPeome using structural modeling, bioinformatics, and solution scattering. The OM contains three families of OMP transporters, an OMP family involved in the extrusion of noxious molecules, and two "stand-alone" proteins involved in OM biogenesis. This work represents a major advance toward elucidating host-pathogen interactions during syphilis; understanding how T. pallidum, an extreme auxotroph, obtains a wide array of biomolecules from its obligate human host; and developing a vaccine with global efficacy.
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Affiliation(s)
- Kelly L. Hawley
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Division of Infectious Diseases and Immunology, Connecticut Children’s, Hartford, Connecticut, USA
| | - Jairo M. Montezuma-Rusca
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Division of Infectious Diseases, UConn Health, Farmington, Connecticut, USA
| | | | - Navreeta Singh
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Melissa J. Caimano
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Justin D. Radolf
- Department of Pediatrics, UConn Health, Farmington, Connecticut, USA
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
- Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA
- Department of Immunology, UConn Health, Farmington, Connecticut, USA
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, Connecticut, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
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29
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Shim J, Zhou C, Gong T, Iserlis DA, Linjawi HA, Wong M, Pan T, Tan C. Building protein networks in synthetic systems from the bottom-up. Biotechnol Adv 2021; 49:107753. [PMID: 33857631 PMCID: PMC9558565 DOI: 10.1016/j.biotechadv.2021.107753] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/18/2021] [Accepted: 04/06/2021] [Indexed: 01/01/2023]
Abstract
The recent development of synthetic biology has expanded the capability to design and construct protein networks outside of living cells from the bottom-up. The new capability has enabled us to assemble protein networks for the basic study of cellular pathways, expression of proteins outside cells, and building tissue materials. Furthermore, the integration of natural and synthetic protein networks has enabled new functions of synthetic or artificial cells. Here, we review the underlying technologies for assembling protein networks in liposomes, water-in-oil droplets, and biomaterials from the bottom-up. We cover the recent applications of protein networks in biological transduction pathways, energy self-supplying systems, cellular environmental sensors, and cell-free protein scaffolds. We also review new technologies for assembling protein networks, including multiprotein purification methods, high-throughput assay screen platforms, and controllable fusion of liposomes. Finally, we present existing challenges towards building protein networks that rival the complexity and dynamic response akin to natural systems. This review addresses the gap in our understanding of synthetic and natural protein networks. It presents a vision towards developing smart and resilient protein networks for various biomedical applications.
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Affiliation(s)
- Jiyoung Shim
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Chuqing Zhou
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Ting Gong
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Dasha Aleksandra Iserlis
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Hamad Abdullah Linjawi
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Matthew Wong
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Tingrui Pan
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America; Suzhou Institute for Advanced Research, University of Science and Technology, Suzhou, China.
| | - Cheemeng Tan
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America.
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30
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Lee J, Song WJ. Folding of Circularly Permuted and Split Outer Membrane Protein F via Electrostatic Interactions with Terminal Residues. Biochemistry 2021; 60:1787-1796. [PMID: 34060805 DOI: 10.1021/acs.biochem.1c00195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane proteins are essential targets in drug design, biosensing, and catalysis. In this study, we explored the folding of engineered outer membrane protein F (OmpF), an abundant and functional β-barrel protein expressed in Gram-negative bacteria. We carried out circular permutation, splitting and self-complementation, and point mutation. The folding efficiency and kinetic analyses demonstrated that the N- and C-terminal residues of OmpF played critical roles in folding via electrostatic interactions with lipid headgroups. Our results indicate that native porins without charged terminal residues may be tightly downregulated to retain the integrity of the outer membrane, and this modification may facilitate the insertion and folding of modified membrane proteins under in vitro and in vivo conditions for various applications.
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Affiliation(s)
- Jaewon Lee
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Woon Ju Song
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
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31
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Dautin N. Folding Control in the Path of Type 5 Secretion. Toxins (Basel) 2021; 13:341. [PMID: 34064645 PMCID: PMC8151025 DOI: 10.3390/toxins13050341] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 12/17/2022] Open
Abstract
The type 5 secretion system (T5SS) is one of the more widespread secretion systems in Gram-negative bacteria. Proteins secreted by the T5SS are functionally diverse (toxins, adhesins, enzymes) and include numerous virulence factors. Mechanistically, the T5SS has long been considered the simplest of secretion systems, due to the paucity of proteins required for its functioning. Still, despite more than two decades of study, the exact process by which T5SS substrates attain their final destination and correct conformation is not totally deciphered. Moreover, the recent addition of new sub-families to the T5SS raises additional questions about this secretion mechanism. Central to the understanding of type 5 secretion is the question of protein folding, which needs to be carefully controlled in each of the bacterial cell compartments these proteins cross. Here, the biogenesis of proteins secreted by the Type 5 secretion system is discussed, with a focus on the various factors preventing or promoting protein folding during biogenesis.
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Affiliation(s)
- Nathalie Dautin
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Université de Paris, LBPC-PM, CNRS, UMR7099, 75005 Paris, France;
- Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild pour le Développement de la Recherche Scientifique, 75005 Paris, France
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32
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Wang X, Peterson JH, Bernstein HD. Bacterial Outer Membrane Proteins Are Targeted to the Bam Complex by Two Parallel Mechanisms. mBio 2021; 12:e00597-21. [PMID: 33947759 PMCID: PMC8262991 DOI: 10.1128/mbio.00597-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 03/12/2021] [Indexed: 01/23/2023] Open
Abstract
Membrane proteins that are integrated into the outer membrane of Gram-negative bacteria typically contain a unique "β barrel" structure that serves as a membrane spanning segment. A conserved "β signal" motif is located at the C terminus of the β barrel of many outer membrane proteins (OMPs), but the function of this sequence is unclear. We found that mutations in the β signal slightly delayed the assembly of three model Escherichia coli OMPs by reducing their affinity for the barrel assembly machinery (Bam) complex, a heterooligomer that catalyzes β barrel insertion, and led to the degradation of a fraction of the protein in the periplasm. Interestingly, the absence of the periplasmic chaperone SurA amplified the effect of the mutations and caused the complete degradation of the mutant proteins. In contrast, the absence of another periplasmic chaperone (Skp) suppressed the effect of the mutations and considerably enhanced the efficiency of assembly. Our results reveal the existence of two parallel OMP targeting mechanisms that rely on a cis-acting peptide (the β signal) and a trans-acting factor (SurA), respectively. Our results also challenge the long-standing view that periplasmic chaperones are redundant and provide evidence that they have specialized functions.IMPORTANCE Proteins that are embedded in the outer membrane of Gram-negative bacteria (OMPs) play an important role in protecting the cell from harmful chemicals. OMPs share a common architecture and often contain a conserved sequence motif (β motif) of unknown function. Although OMPs are escorted to the outer membrane by proteins called chaperones, the exact function of the chaperones is also unclear. Here, we show that the β motif and the chaperone SurA both target OMPs to the β barrel insertion machinery in the outer membrane. In contrast, the chaperone Skp delivers unintegrated OMPs to protein degradation complexes. Our results challenge the long-standing view that chaperones are functionally redundant and strongly suggest that they have specialized roles in OMP targeting and quality control.
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Affiliation(s)
- Xu Wang
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Janine H Peterson
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
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33
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Diederichs KA, Buchanan SK, Botos I. Building Better Barrels - β-barrel Biogenesis and Insertion in Bacteria and Mitochondria. J Mol Biol 2021; 433:166894. [PMID: 33639212 PMCID: PMC8292188 DOI: 10.1016/j.jmb.2021.166894] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 01/20/2023]
Abstract
β-barrel proteins are folded and inserted into outer membranes by multi-subunit protein complexes that are conserved across different types of outer membranes. In Gram-negative bacteria this complex is the barrel-assembly machinery (BAM), in mitochondria it is the sorting and assembly machinery (SAM) complex, and in chloroplasts it is the outer envelope protein Oep80. Mitochondrial β-barrel precursor proteins are translocated from the cytoplasm to the intermembrane space by the translocase of the outer membrane (TOM) complex, and stabilized by molecular chaperones before interaction with the assembly machinery. Outer membrane bacterial BamA interacts with four periplasmic accessory proteins, whereas mitochondrial Sam50 interacts with two cytoplasmic accessory proteins. Despite these major architectural differences between BAM and SAM complexes, their core proteins, BamA and Sam50, seem to function the same way. Based on the new SAM complex structures, we propose that the mitochondrial β-barrel folding mechanism follows the budding model with barrel-switching aiding in the release of new barrels. We also built a new molecular model for Tom22 interacting with Sam37 to identify regions that could mediate TOM-SAM supercomplex formation.
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Affiliation(s)
- Kathryn A Diederichs
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Susan K Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Istvan Botos
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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34
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Chen X, Ding Y, Bamert RS, Le Brun AP, Duff AP, Wu CM, Hsu HY, Shiota T, Lithgow T, Shen HH. Substrate-dependent arrangements of the subunits of the BAM complex determined by neutron reflectometry. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183587. [PMID: 33639106 DOI: 10.1016/j.bbamem.2021.183587] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 02/09/2021] [Accepted: 02/17/2021] [Indexed: 12/22/2022]
Abstract
In Gram-negative bacteria, the β-barrel assembly machinery (BAM) complex catalyses the assembly of β-barrel proteins into the outer membrane, and is composed of five subunits: BamA, BamB, BamC, BamD and BamE. Once assembled, - β-barrel proteins can be involved in various functions including uptake of nutrients, export of toxins and mediating host-pathogen interactions, but the precise mechanism by which these ubiquitous and often essential β-barrel proteins are assembled is yet to be established. In order to determine the relative positions of BAM subunits in the membrane environment we reconstituted each subunit into a biomimetic membrane, characterizing their interaction and structural changes by Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) and neutron reflectometry. Our results suggested that the binding of BamE, or a BamDE dimer, to BamA induced conformational changes in the polypeptide transported-associated (POTRA) domains of BamA, but that BamB or BamD alone did not promote any such changes. As monitored by neutron reflectometry, addition of an unfolded substrate protein extended the length of POTRA domains further away from the membrane interface as part of the mechanism whereby the substrate protein was folded into the membrane.
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Affiliation(s)
- Xiaoyu Chen
- Department of Materials Science & Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Yue Ding
- Department of Materials Science & Engineering, Monash University, Clayton, VIC 3800, Australia; Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - Rebecca S Bamert
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Anthony P Duff
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Chun-Ming Wu
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia; National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Hsien-Yi Hsu
- School of Energy and Environment & Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, PR China; Shenzhen Research Institute of City University of Hong Kong, Shenzhen 518057, PR China
| | - Takuya Shiota
- Institute for Tenure Track Promotion, Organization for Promotion of Career Management, University of Miyazaki, Miyazaki, Japan
| | - Trevor Lithgow
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia.
| | - Hsin-Hui Shen
- Department of Materials Science & Engineering, Monash University, Clayton, VIC 3800, Australia; Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
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35
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Rooke JL, Icke C, Wells TJ, Rossiter AE, Browning DF, Morris FC, Leo JC, Schütz MS, Autenrieth IB, Cunningham AF, Linke D, Henderson IR. BamA and BamD Are Essential for the Secretion of Trimeric Autotransporter Adhesins. Front Microbiol 2021; 12:628879. [PMID: 33708185 PMCID: PMC7940764 DOI: 10.3389/fmicb.2021.628879] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/26/2021] [Indexed: 12/14/2022] Open
Abstract
The BAM complex in Escherichia coli is composed of five proteins, BamA-E. BamA and BamD are essential for cell viability and are required for the assembly of β-barrel outer membrane proteins. Consequently, BamA and BamD are indispensable for secretion via the classical autotransporter pathway (Type 5a secretion). In contrast, BamB, BamC, and BamE are not required for the biogenesis of classical autotransporters. Recently, we demonstrated that TamA, a homologue of BamA, and its partner protein TamB, were required for efficient secretion of proteins via the classical autotransporter pathway. The trimeric autotransporters are a subset of the Type 5-secreted proteins. Unlike the classical autotransporters, they are composed of three identical polypeptide chains which must be assembled together to allow secretion of their cognate passenger domains. In contrast to the classical autotransporters, the role of the Bam and Tam complex components in the biogenesis of the trimeric autotransporters has not been investigated fully. Here, using the Salmonella enterica trimeric autotransporter SadA and the structurally similar YadA protein of Yersinia spp., we identify the importance of BamA and BamD in the biogenesis of the trimeric autotransporters and reveal that BamB, BamC, BamE, TamA and TamB are not required for secretion of functional passenger domain on the cell surface. Importance The secretion of trimeric autotransporters (TAA's) has yet to be fully understood. Here we show that efficient secretion of TAAs requires the BamA and D proteins, but does not require BamB, C or E. In contrast to classical autotransporter secretion, neither trimeric autotransporter tested required TamA or B proteins to be functionally secreted.
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Affiliation(s)
- Jessica L Rooke
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Christopher Icke
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Timothy J Wells
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia.,The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Amanda E Rossiter
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Douglas F Browning
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Faye C Morris
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Jack C Leo
- Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom.,Department of Biosciences, University of Oslo, Oslo, Norway
| | - Monika S Schütz
- Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Ingo B Autenrieth
- Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Adam F Cunningham
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Dirk Linke
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Ian R Henderson
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
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36
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Tomasek D, Kahne D. The assembly of β-barrel outer membrane proteins. Curr Opin Microbiol 2021; 60:16-23. [PMID: 33561734 DOI: 10.1016/j.mib.2021.01.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/17/2021] [Accepted: 01/22/2021] [Indexed: 01/21/2023]
Abstract
The outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts contain β-barrel integral membrane proteins. In bacteria, the five-protein β-barrel assembly machine (Bam) accelerates the folding and membrane integration of these proteins. The central component of the machine, BamA, contains a β-barrel domain that can adopt a lateral-open state with its N-terminal and C-terminal β-strands unpaired. Recently, strategies have been developed to capture β-barrel folding intermediates on the Bam complex. Biochemical and structural studies provide support for a model in which substrates assemble at the lateral opening of BamA. In this model, the N-terminal β-strand of BamA captures the C-terminal β-strand of substrates by hydrogen bonding to allow their directional folding and subsequent release into the membrane.
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Affiliation(s)
- David Tomasek
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Daniel Kahne
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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37
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Bryant JA, Morris FC, Knowles TJ, Maderbocus R, Heinz E, Boelter G, Alodaini D, Colyer A, Wotherspoon PJ, Staunton KA, Jeeves M, Browning DF, Sevastsyanovich YR, Wells TJ, Rossiter AE, Bavro VN, Sridhar P, Ward DG, Chong ZS, Goodall EC, Icke C, Teo AC, Chng SS, Roper DI, Lithgow T, Cunningham AF, Banzhaf M, Overduin M, Henderson IR. Structure of dual BON-domain protein DolP identifies phospholipid binding as a new mechanism for protein localisation. eLife 2020; 9:62614. [PMID: 33315009 PMCID: PMC7806268 DOI: 10.7554/elife.62614] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/11/2020] [Indexed: 12/16/2022] Open
Abstract
The Gram-negative outer-membrane envelops the bacterium and functions as a permeability barrier against antibiotics, detergents, and environmental stresses. Some virulence factors serve to maintain the integrity of the outer membrane, including DolP (formerly YraP) a protein of unresolved structure and function. Here, we reveal DolP is a lipoprotein functionally conserved amongst Gram-negative bacteria and that loss of DolP increases membrane fluidity. We present the NMR solution structure for Escherichia coli DolP, which is composed of two BON domains that form an interconnected opposing pair. The C-terminal BON domain binds anionic phospholipids through an extensive membrane:protein interface. This interaction is essential for DolP function and is required for sub-cellular localisation of the protein to the cell division site, providing evidence of subcellular localisation of these phospholipids within the outer membrane. The structure of DolP provides a new target for developing therapies that disrupt the integrity of the bacterial cell envelope.
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Affiliation(s)
- Jack Alfred Bryant
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Faye C Morris
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Timothy J Knowles
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom.,School of Biosciences, University of Birmingham, Edgbaston, United Kingdom
| | - Riyaz Maderbocus
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom.,Institute for Cancer and Genomic Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Eva Heinz
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Australia
| | - Gabriela Boelter
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Dema Alodaini
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Adam Colyer
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Peter J Wotherspoon
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Kara A Staunton
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Mark Jeeves
- Institute for Cancer and Genomic Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Douglas F Browning
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | | | - Timothy J Wells
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Amanda E Rossiter
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Vassiliy N Bavro
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Pooja Sridhar
- School of Biosciences, University of Birmingham, Edgbaston, United Kingdom
| | - Douglas G Ward
- School of Biosciences, University of Birmingham, Edgbaston, United Kingdom
| | - Zhi-Soon Chong
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Emily Ca Goodall
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom.,Institute for Molecular Bioscience, University of Queensland, St. Lucia, Australia
| | - Christopher Icke
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom.,Institute for Molecular Bioscience, University of Queensland, St. Lucia, Australia
| | - Alvin Ck Teo
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore, Singapore.,School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - David I Roper
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Trevor Lithgow
- Infection & Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Australia
| | - Adam F Cunningham
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom.,Institute of Inflammation and Immunotherapy, University of Birmingham, Edgbaston, United Kingdom
| | - Manuel Banzhaf
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom
| | - Michael Overduin
- School of Biosciences, University of Birmingham, Edgbaston, United Kingdom.,Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - Ian R Henderson
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, United Kingdom.,Department of Chemistry, National University of Singapore, Singapore, Singapore
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38
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Boyce JH, Dang B, Ary B, Edmondson Q, Craik CS, DeGrado WF, Seiple IB. Platform to Discover Protease-Activated Antibiotics and Application to Siderophore-Antibiotic Conjugates. J Am Chem Soc 2020; 142:21310-21321. [PMID: 33301681 DOI: 10.1021/jacs.0c06987] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Here we present a platform for discovery of protease-activated prodrugs and apply it to antibiotics that target Gram-negative bacteria. Because cleavable linkers for prodrugs had not been developed for bacterial proteases, we used substrate phage to discover substrates for proteases found in the bacterial periplasm. Rather than focusing on a single protease, we used a periplasmic extract of E. coli to find sequences with the greatest susceptibility to the endogenous mixture of periplasmic proteases. Using a fluorescence assay, candidate sequences were evaluated to identify substrates that release native amine-containing payloads. We next designed conjugates consisting of (1) an N-terminal siderophore to facilitate uptake, (2) a protease-cleavable linker, and (3) an amine-containing antibiotic. Using this strategy, we converted daptomycin-which by itself is active only against Gram-positive bacteria-into an antibiotic capable of targeting Gram-negative Acinetobacter species. We similarly demonstrated siderophore-facilitated delivery of oxazolidinone and macrolide antibiotics into a number of Gram-negative species. These results illustrate this platform's utility for development of protease-activated prodrugs, including Trojan horse antibiotics.
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Affiliation(s)
- Jonathan H Boyce
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States.,Cardiovascular Research Institute, University of California, San Francisco, California 94158, United States
| | - Bobo Dang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China.,Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China.,Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Beatrice Ary
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - Quinn Edmondson
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States.,Cardiovascular Research Institute, University of California, San Francisco, California 94158, United States
| | - Ian B Seiple
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, United States.,Cardiovascular Research Institute, University of California, San Francisco, California 94158, United States
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39
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Lyratzakis A, Valsamidis G, Kanavaki I, Nikolaki A, Rupprecht F, Langer JD, Tsiotis G. Proteomic Characterization of the Pseudomonas sp. Strain phDV1 Response to Monocyclic Aromatic Compounds. Proteomics 2020; 21:e2000003. [PMID: 33108051 DOI: 10.1002/pmic.202000003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 10/13/2020] [Indexed: 11/06/2022]
Abstract
The degradation of aromatic compounds comprises an important step in the removal of pollutants and re-utilization of plastics and other non-biological polymers. Here, Pseudomonas sp. strain phDV1, a gram-negative bacterium that is selected for its ability to degrade aromatic compounds is studied. In order to understand how the aromatic compounds and their degradation products are reintroduced in the metabolism of the bacteria and the systematic/metabolic response of the bacterium to the new carbon source, the proteome of this strain is analyzed in the presence of succinate, phenol, and o-, m-, and p-cresol as the sole carbon source. As a reference proteome, the bacteria are grown in succinate and then compared with the respective proteomes of bacteria grown on phenol and different cresols. In total, 2295 proteins are identified; 1908 proteins are used for quantification between different growth conditions. The carbon source affects the synthesis of enzymes related to aromatic compound degradation and in particular the enzyme involved in the meta-pathway of monocyclic aromatic compounds degradation. In addition, proteins involved in the production of polyhydroxyalkanoate (PHA), an attractive biomaterial, show higher abundance in the presence of monocyclic aromatic compounds. The results provide, for the first time, comprehensive information on the proteome response of this strain to monocyclic aromatic compounds.
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Affiliation(s)
- Alexandros Lyratzakis
- Division of Biochemistry, Department of Chemistry, University of Crete, Voutes, Heraklion, GR-71003, Greece
| | - Giannis Valsamidis
- Division of Biochemistry, Department of Chemistry, University of Crete, Voutes, Heraklion, GR-71003, Greece
| | - Iliana Kanavaki
- Division of Biochemistry, Department of Chemistry, University of Crete, Voutes, Heraklion, GR-71003, Greece
| | - Antigoni Nikolaki
- Division of Biochemistry, Department of Chemistry, University of Crete, Voutes, Heraklion, GR-71003, Greece
| | - Fiona Rupprecht
- Max Planck Institute for Brain Research, Max-von-Laue-Straße 4, Frankfurt am Main, D-60438, Germany.,Max Planck Institute for Biophysics, Max-von-Laue-Straße 3, Frankfurt am Main, D-60438, Germany
| | - Julian D Langer
- Max Planck Institute for Brain Research, Max-von-Laue-Straße 4, Frankfurt am Main, D-60438, Germany.,Max Planck Institute for Biophysics, Max-von-Laue-Straße 3, Frankfurt am Main, D-60438, Germany
| | - Georgios Tsiotis
- Division of Biochemistry, Department of Chemistry, University of Crete, Voutes, Heraklion, GR-71003, Greece
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40
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Liu J, Gumbart JC. Membrane thinning and lateral gating are consistent features of BamA across multiple species. PLoS Comput Biol 2020; 16:e1008355. [PMID: 33112853 PMCID: PMC7652284 DOI: 10.1371/journal.pcbi.1008355] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 11/09/2020] [Accepted: 09/21/2020] [Indexed: 01/09/2023] Open
Abstract
In Gram-negative bacteria, the folding and insertion of β-barrel outer membrane proteins (OMPs) to the outer membrane are mediated by the β-barrel assembly machinery (BAM) complex. Two leading models of this process have been put forth: the hybrid barrel model, which claims that a lateral gate in BamA’s β-barrel can serve as a template for incoming OMPs, and the passive model, which claims that a thinned membrane near the lateral gate of BamA accelerates spontaneous OMP insertion. To examine the key elements of these two models, we have carried out 45.5 μs of equilibrium molecular dynamics simulations of BamA with and without POTRA domains from Escherichia coli, Salmonella enterica, Haemophilus ducreyi and Neisseria gonorrhoeae, together with BamA’s homolog, TamA from E. coli, in their native, species-specific outer membranes. In these equilibrium simulations, we consistently observe membrane thinning near the lateral gate for all proteins. We also see occasional spontaneous lateral gate opening and sliding of the β-strands at the gate interface for N. gonorrhoeae, indicating that the gate is dynamic. An additional 14 μs of free-energy calculations shows that the energy necessary to open the lateral gate in BamA/TamA varies by species, but is always lower than the Omp85 homolog, FhaC. Our combined results suggest OMP insertion utilizes aspects of both the hybrid barrel and passive models. Gram-negative bacteria such as Escherichia coli have a second, outer membrane surrounding them. This outer membrane provides an additional layer of protection, but also presents an additional challenge in its construction, exacerbated by the lack of chemical energy in this region of the bacterial cell. For example, proteins in the outer membrane are inserted via BamA, itself an integral membrane protein. The precise mechanisms by which BamA assists in the insertion process are still unclear. Here, we use extensive simulations in atomistic detail of BamA from multiple species in its native outer membrane environment to shed light on this process. We find that the lateral gate of BamA, a proposed pathway into the membrane, is dynamic, although to a degree varying by species. On the other hand, thinning of the outer membrane near BamA’s lateral gate is observed consistently across all simulations. We conclude that multiple features of BamA contribute to protein insertion into the outer membrane.
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Affiliation(s)
- Jinchan Liu
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Tang Aoqing Honors Program in Science, College of Chemistry, Jilin University, Changchun, Jilin Province, China
| | - James C. Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- * E-mail:
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41
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Functions of the BamBCDE Lipoproteins Revealed by Bypass Mutations in BamA. J Bacteriol 2020; 202:JB.00401-20. [PMID: 32817097 DOI: 10.1128/jb.00401-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/13/2020] [Indexed: 12/27/2022] Open
Abstract
The heteropentomeric β-barrel assembly machine (BAM complex) is responsible for folding and inserting a diverse array of β-barrel outer membrane proteins (OMPs) into the outer membrane (OM) of Gram-negative bacteria. The BAM complex contains two essential proteins, the β-barrel OMP BamA and a lipoprotein BamD, whereas the auxiliary lipoproteins BamBCE are individually nonessential. Here, we identify and characterize three bamA mutations, the E-to-K change at position 470 (bamAE470K ), the A-to-P change at position 496 (bamAA496P ), and the A-to-S change at position 499 (bamAA499S ), that suppress the otherwise lethal ΔbamD, ΔbamB ΔbamC ΔbamE, and ΔbamC ΔbamD ΔbamE mutations. The viability of cells lacking different combinations of BAM complex lipoproteins provides the opportunity to examine the role of the individual proteins in OMP assembly. Results show that, in wild-type cells, BamBCE share a redundant function; at least one of these lipoproteins must be present to allow BamD to coordinate productively with BamA. Besides BamA regulation, BamD shares an additional essential function that is redundant with a second function of BamB. Remarkably, bamAE470K suppresses both, allowing the construction of a BAM complex composed solely of BamAE470K that is able to assemble OMPs in the absence of BamBCDE. This work demonstrates that the BAM complex lipoproteins do not participate in the catalytic folding of OMP substrates but rather function to increase the efficiency of the assembly process by coordinating and regulating the assembly of diverse OMP substrates.IMPORTANCE The folding and insertion of β-barrel outer membrane proteins (OMPs) are conserved processes in mitochondria, chloroplasts, and Gram-negative bacteria. In Gram-negative bacteria, OMPs are assembled into the outer membrane (OM) by the heteropentomeric β-barrel assembly machine (BAM complex). In this study, we probe the function of the individual BAM proteins and how they coordinate assembly of a diverse family of OMPs. Furthermore, we identify a gain-of-function bamA mutant capable of assembling OMPs independently of all four other BAM proteins. This work advances our understanding of OMP assembly and sheds light on how this process is distinct in Gram-negative bacteria.
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42
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Ding Y, Shiota T, Le Brun AP, Dunstan RA, Wang B, Hsu HY, Lithgow T, Shen HH. Characterization of BamA reconstituted into a solid-supported lipid bilayer as a platform for measuring dynamics during substrate protein assembly into the membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183317. [DOI: 10.1016/j.bbamem.2020.183317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/14/2022]
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43
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Horne JE, Brockwell DJ, Radford SE. Role of the lipid bilayer in outer membrane protein folding in Gram-negative bacteria. J Biol Chem 2020; 295:10340-10367. [PMID: 32499369 PMCID: PMC7383365 DOI: 10.1074/jbc.rev120.011473] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/03/2020] [Indexed: 01/09/2023] Open
Abstract
β-Barrel outer membrane proteins (OMPs) represent the major proteinaceous component of the outer membrane (OM) of Gram-negative bacteria. These proteins perform key roles in cell structure and morphology, nutrient acquisition, colonization and invasion, and protection against external toxic threats such as antibiotics. To become functional, OMPs must fold and insert into a crowded and asymmetric OM that lacks much freely accessible lipid. This feat is accomplished in the absence of an external energy source and is thought to be driven by the high thermodynamic stability of folded OMPs in the OM. With such a stable fold, the challenge that bacteria face in assembling OMPs into the OM is how to overcome the initial energy barrier of membrane insertion. In this review, we highlight the roles of the lipid environment and the OM in modulating the OMP-folding landscape and discuss the factors that guide folding in vitro and in vivo We particularly focus on the composition, architecture, and physical properties of the OM and how an understanding of the folding properties of OMPs in vitro can help explain the challenges they encounter during folding in vivo Current models of OMP biogenesis in the cellular environment are still in flux, but the stakes for improving the accuracy of these models are high. OMP folding is an essential process in all Gram-negative bacteria, and considering the looming crisis of widespread microbial drug resistance it is an attractive target. To bring down this vital OMP-supported barrier to antibiotics, we must first understand how bacterial cells build it.
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Affiliation(s)
- Jim E Horne
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - David J Brockwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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44
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Jin F. The transmembrane supercomplex mediating the biogenesis of OMPs in Gram-negative bacteria assumes a circular conformational change upon activation. FEBS Open Bio 2020; 10:1698-1715. [PMID: 32602996 PMCID: PMC7396438 DOI: 10.1002/2211-5463.12922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/15/2020] [Accepted: 06/15/2020] [Indexed: 11/06/2022] Open
Abstract
The cell envelope of Gram-negative bacteria is composed of the inner (plasma) and the outer membrane. In the outer membrane, the outer membrane β-barrel proteins (OMPs) serve multiple functions. They are synthesized in the cytoplasm and finally inserted into the outer membrane through a critical and complex pathway facilitated by many protein factors. Recently, a new model for the biogenesis of OMPs in Gram-negative bacteria was proposed, in which a supercomplex containing multiple proteins spans the inner and outer membrane, to mediate the biogenesis of OMPs. The core part of the transmembrane supercomplex is the inner membrane protein translocon and the outer membrane β-barrel assembly machinery (BAM) complex. Some components of the supercomplex, such as the BamA subunit of the BAM complex, are essential and conserved across species. The other components, for example, the BamB subunit and the primary periplasmic chaperone SurA, are also required for the supercomplex to gain complete function and full efficiency. How BamB and SurA behave in the supercomplex, however, is less well understood. Therefore, the crosstalk between BamA, BamB and SurA was investigated mainly through in vivo protein photo-cross-linking experiments and protein modeling. Moreover, theoretical structures for part of the supercomplex consisting of SurA and the BAM complex were constructed. The modeling data are consistent with the experimental results. The theoretical structures computed in this work provide a more comprehensive view of the mechanism of the supercomplex, demonstrating a circular conformational change of the supercomplex when it is active.
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Affiliation(s)
- Feng Jin
- School of Life Sciences, Peking University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
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45
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Li Y, Zhu X, Zhang J, Lin Y, You X, Chen M, Wang Y, Zhu N, Si S. Identification of a Compound That Inhibits the Growth of Gram-Negative Bacteria by Blocking BamA-BamD Interaction. Front Microbiol 2020; 11:1252. [PMID: 32636816 PMCID: PMC7316895 DOI: 10.3389/fmicb.2020.01252] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/18/2020] [Indexed: 12/31/2022] Open
Abstract
The demand for novel antibiotics is imperative for drug-resistant Gram-negative bacteria which causes diverse intractable infection disease in clinic. Here, a comprehensive screening was implemented to identify potential agents that disrupt the assembly of β-barrel outer-membrane proteins (OMPs) in the outer membrane (OM) of Gram-negative bacteria. The assembly of OMPs requires ubiquitous β-barrel assembly machinery (BAM). Among the five protein subunits in BAM, the interaction between BamA and BamD is essential for the function of this complex. We first established a yeast two-hybrid (Y2H) system to confirm the interaction between BamA and BamD, and then screened agents that specifically disrupt this interaction. From this screen, we identified a compound IMB-H4 that specially blocks BamA–BamD interaction and selectively inhibits the growth of Escherichia coli and other Gram-negative bacteria. Moreover, our results suggest that IMB-H4 disrupts BamA–BamD interaction by binding to BamA. Strikingly, E. coli cells having been treated with IMB-H4 showed impaired OM integrity and decreased the abundance of OMPs. Therefore, an antibacterial agent was identified successfully using Y2H system, and this compound likely blocks the assembly of OMPs by targeting BamA–BamD interaction in Gram-negative bacteria.
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Affiliation(s)
- Yan Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiaohong Zhu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jing Zhang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yuan Lin
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing, China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Minghua Chen
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yanchang Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, United States
| | - Ningyu Zhu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuyi Si
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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46
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Tomasek D, Rawson S, Lee J, Wzorek JS, Harrison SC, Li Z, Kahne D. Structure of a nascent membrane protein as it folds on the BAM complex. Nature 2020; 583:473-478. [PMID: 32528179 PMCID: PMC7367713 DOI: 10.1038/s41586-020-2370-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/25/2020] [Indexed: 11/09/2022]
Abstract
Mitochondria, chloroplasts, and Gram-negative bacteria are encased in a double layer of membranes. The outer membrane contains proteins with a β-barrel structure1,2. β-barrels are sheets of β-strands wrapped into a cylinder with the first strand hydrogen-bonded to the last strand. Conserved multi-subunit molecular machines fold and insert these proteins into the outer membrane3–5. One subunit of the machines is itself a β-barrel protein that plays a central role in folding other β-barrels. In Gram-negative bacteria, the β-barrel assembly machine (Bam) consists of the β-barrel protein BamA and four lipoproteins5–8. To understand how the Bam complex accelerates folding without using exogenous energy (e.g., ATP)9, we trapped folding intermediates on the machine. We report here the structure of the Bam complex folding BamA itself. The BamA catalyst (BamAM, for BamAmachine) forms an asymmetric hybrid β-barrel with the BamA substrate (BamAS). The N-terminal edge of BamAM has an antiparallel hydrogen-bonded interface with the C-terminal edge of BamAS, consistent with previous crosslinking studies10–12; the other edges of BamAM and BamAS are close to each other but curl inward and do not pair. Six hydrogen bonds in a membrane environment make the interface between the two proteins very stable. This stability allows folding but creates a high kinetic barrier to substrate release once folding has finished. Features at each end of the substrate overcome the barrier and promote release by stepwise exchange of hydrogen bonds. This mechanism of substrate-assisted product release explains how the Bam complex can stably associate with the substrate during folding and then turn over rapidly when folding is complete.
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Affiliation(s)
- David Tomasek
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Shaun Rawson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - James Lee
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.,Laboratory of Membrane Biophysics and Biology, The Rockefeller University, New York, NY, USA
| | - Joseph S Wzorek
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.,Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Stephen C Harrison
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Boston, MA, USA.
| | - Zongli Li
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Boston, MA, USA.
| | - Daniel Kahne
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA. .,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA. .,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
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47
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Calabrese AN, Schiffrin B, Watson M, Karamanos TK, Walko M, Humes JR, Horne JE, White P, Wilson AJ, Kalli AC, Tuma R, Ashcroft AE, Brockwell DJ, Radford SE. Inter-domain dynamics in the chaperone SurA and multi-site binding to its outer membrane protein clients. Nat Commun 2020; 11:2155. [PMID: 32358557 PMCID: PMC7195389 DOI: 10.1038/s41467-020-15702-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 03/18/2020] [Indexed: 01/11/2023] Open
Abstract
The periplasmic chaperone SurA plays a key role in outer membrane protein (OMP) biogenesis. E. coli SurA comprises a core domain and two peptidylprolyl isomerase domains (P1 and P2), but its mechanisms of client binding and chaperone function have remained unclear. Here, we use chemical cross-linking, hydrogen-deuterium exchange mass spectrometry, single-molecule FRET and molecular dynamics simulations to map the client binding site(s) on SurA and interrogate the role of conformational dynamics in OMP recognition. We demonstrate that SurA samples an array of conformations in solution in which P2 primarily lies closer to the core/P1 domains than suggested in the SurA crystal structure. OMP binding sites are located primarily in the core domain, and OMP binding results in conformational changes between the core/P1 domains. Together, the results suggest that unfolded OMP substrates bind in a cradle formed between the SurA domains, with structural flexibility between domains assisting OMP recognition, binding and release.
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Affiliation(s)
- Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Bob Schiffrin
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Matthew Watson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Theodoros K Karamanos
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Martin Walko
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Astbury Centre for Structural Molecular Biology, School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Julia R Humes
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Jim E Horne
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Paul White
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Andrew J Wilson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Astbury Centre for Structural Molecular Biology, School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Antreas C Kalli
- Astbury Centre for Structural Molecular Biology and School of Medicine, University of Leeds, Leeds, LS2 9JT, UK
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Alison E Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - David J Brockwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
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48
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Bam complex-mediated assembly of bacterial outer membrane proteins synthesized in an in vitro translation system. Sci Rep 2020; 10:4557. [PMID: 32165713 PMCID: PMC7067875 DOI: 10.1038/s41598-020-61431-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 02/21/2020] [Indexed: 02/01/2023] Open
Abstract
Bacterial outer membrane proteins (OMPs) contain a unique "β barrel" segment that is inserted into the membrane by the barrel assembly machinery (Bam) complex by an unknown mechanism. OMP assembly has been reconstituted in vitro, but assembly reactions have involved the use of urea-denatured protein purified from inclusion bodies. Here we show that the E. coli Bam complex catalyzes the efficient assembly of OMPs synthesized de novo in a coupled in vitro transcription/translation system. Interestingly, the in vitro translated forms of the OMPs we analyzed were assembled more rapidly and were effectively engaged by fewer periplasmic chaperones than their urea-denatured counterparts. Taken together, our results strongly suggest that the mode of production influences the conformational states sampled by OMPs and thereby affects their recognition by both chaperones and the Bam complex. Besides providing insights into OMP biogenesis, our work describes a novel, streamlined method to reconstitute OMP assembly in vitro.
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49
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Imai Y, Meyer KJ, Iinishi A, Favre-Godal Q, Green R, Manuse S, Caboni M, Mori M, Niles S, Ghiglieri M, Honrao C, Ma X, Guo JJ, Makriyannis A, Linares-Otoya L, Böhringer N, Wuisan ZG, Kaur H, Wu R, Mateus A, Typas A, Savitski MM, Espinoza JL, O'Rourke A, Nelson KE, Hiller S, Noinaj N, Schäberle TF, D'Onofrio A, Lewis K. A new antibiotic selectively kills Gram-negative pathogens. Nature 2019; 576:459-464. [PMID: 31747680 PMCID: PMC7188312 DOI: 10.1038/s41586-019-1791-1] [Citation(s) in RCA: 402] [Impact Index Per Article: 80.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 11/08/2019] [Indexed: 11/16/2022]
Abstract
The current need for novel antibiotics is especially acute for
drug-resistant Gram-negative pathogens1,2. These
microorganisms have a highly restrictive permeability barrier, which limits
penetration of most compounds3,4. As a result, the last class of
antibiotics acting against Gram-negative bacteria was developed in the
60s2. We reason that
useful compounds can be found in bacteria that share similar requirements for
antibiotics with humans, and focus on Photorhabdus symbionts of
entomopathogenic nematode microbiomes. Here we report a new antibiotic that we
name darobactin, from a screen of Photorhabdus isolates.
Darobactin is coded by a silent operon with little production under laboratory
conditions, and is ribosomally synthesized. Darobactin has an unusual structure
with two fused rings that form post-translationally. The compound is active
against important Gram-negative pathogens both in vitro and in
animal models of infection. Mutants resistant to darobactin map to BamA, an
essential chaperone and translocator that folds outer membrane proteins. Our
study suggests that bacterial symbionts of animals harbor antibiotics that are
particularly suitable for development into therapeutics.
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Affiliation(s)
- Yu Imai
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Kirsten J Meyer
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Akira Iinishi
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Quentin Favre-Godal
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Robert Green
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Sylvie Manuse
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Mariaelena Caboni
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Miho Mori
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Samantha Niles
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Meghan Ghiglieri
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Chandrashekhar Honrao
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Xiaoyu Ma
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Jason J Guo
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA.,Barnett Institute for Chemical and Biological Analysis, Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA
| | - Alexandros Makriyannis
- Center for Drug Discovery, Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Luis Linares-Otoya
- Institute for Insect Biotechnology, Justus-Liebig-University of Giessen, Giessen, Germany
| | - Nils Böhringer
- Institute for Insect Biotechnology, Justus-Liebig-University of Giessen, Giessen, Germany
| | - Zerlina G Wuisan
- Institute for Insect Biotechnology, Justus-Liebig-University of Giessen, Giessen, Germany
| | - Hundeep Kaur
- Biozentrum, University of Basel, Basel, Switzerland
| | - Runrun Wu
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA.,Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - André Mateus
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Athanasios Typas
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Mikhail M Savitski
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Josh L Espinoza
- Department of Human Biology, J. Craig Venter Institute, La Jolla, CA, USA.,Department of Genomic Medicine, J. Craig Venter Institute, La Jolla, CA, USA
| | - Aubrie O'Rourke
- Department of Human Biology, J. Craig Venter Institute, La Jolla, CA, USA.,Department of Genomic Medicine, J. Craig Venter Institute, La Jolla, CA, USA
| | - Karen E Nelson
- Department of Human Biology, J. Craig Venter Institute, La Jolla, CA, USA.,Department of Genomic Medicine, J. Craig Venter Institute, La Jolla, CA, USA.,Department of Human Biology, J. Craig Venter Institute, Rockville, MD, USA.,Department of Genomic Medicine, J. Craig Venter Institute, Rockville, MD, USA
| | | | - Nicholas Noinaj
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA.,Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Till F Schäberle
- Institute for Insect Biotechnology, Justus-Liebig-University of Giessen, Giessen, Germany.,Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Giessen, Germany.,German Center for Infection Research (DZIF), Partner Site Giessen-Marburg-Langen, Giessen, Germany
| | - Anthony D'Onofrio
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA
| | - Kim Lewis
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, USA.
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50
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Lee J, Tomasek D, Santos TM, May MD, Meuskens I, Kahne D. Formation of a β-barrel membrane protein is catalyzed by the interior surface of the assembly machine protein BamA. eLife 2019; 8:49787. [PMID: 31724945 PMCID: PMC6887485 DOI: 10.7554/elife.49787] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 11/13/2019] [Indexed: 01/02/2023] Open
Abstract
The β-barrel assembly machine (Bam) complex in Gram-negative bacteria and its counterparts in mitochondria and chloroplasts fold and insert outer membrane β-barrel proteins. BamA, an essential component of the complex, is itself a β-barrel and is proposed to play a central role in assembling other barrel substrates. Here, we map the path of substrate insertion by the Bam complex using site-specific crosslinking to understand the molecular mechanisms that control β-barrel folding and release. We find that the C-terminal strand of the substrate is stably held by BamA and that the N-terminal strands of the substrate are assembled inside the BamA β-barrel. Importantly, we identify contacts between the assembling β-sheet and the BamA interior surface that determine the rate of substrate folding. Our results support a model in which the interior wall of BamA acts as a chaperone to catalyze β-barrel assembly.
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Affiliation(s)
- James Lee
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - David Tomasek
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Thiago Ma Santos
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Mary D May
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Ina Meuskens
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Daniel Kahne
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
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