scholarly journals CryoEM structure of the outer membrane secretin channel pIV from the f1 filamentous bacteriophage

2021 ◽  
Author(s):  
Rebecca Conners ◽  
Mathew McLaren ◽  
Urszula Lapinska ◽  
Kelly Sanders ◽  
M Rhia L Stone ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Filamentous Bacteriophage ◽  
Cryo Electron Microscopy ◽  
Channel Opening ◽  
Filamentous Bacteriophages ◽  
Gated Channel ◽  
Model Channel ◽  
Bacterial Outer Membrane ◽  
Similarities And Differences

The Ff family of filamentous bacteriophages infect gram-negative bacteria, but do not cause lysis of their host cell. Instead, new virions are extruded via the phage-encoded pIV protein, which has homology with bacterial secretins. Here, we have determined the structure of pIV from the f1 filamentous bacteriophage at 2.7 A resolution by cryo-electron microscopy, the first near-atomic structure of a phage secretin. Fifteen f1 pIV monomers assemble to form a gated channel in the bacterial outer membrane, with associated soluble domains projecting into the periplasm. We model channel opening and propose a mechanism for phage-mediated gate movement. By single-cell microfluidics experiments, we demonstrate the potential for secretins such as pIV to be used as adjuvants to increase the uptake and efficacy of antibiotics in bacteria. Finally, we compare the f1 pIV structure to its homologues to reveal similarities and differences between phage and bacterial secretins.

scholarly journals CryoEM structure of the outer membrane secretin channel pIV from the f1 filamentous bacteriophage

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rebecca Conners ◽  
Mathew McLaren ◽  
Urszula Łapińska ◽  
Kelly Sanders ◽  
M. Rhia L. Stone ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Filamentous Bacteriophage ◽  
Cryo Electron Microscopy ◽  
Channel Opening ◽  
Filamentous Bacteriophages ◽  
Gated Channel ◽  
Model Channel ◽  
Bacterial Outer Membrane ◽  
Similarities And Differences

AbstractThe Ff family of filamentous bacteriophages infect gram-negative bacteria, but do not cause lysis of their host cell. Instead, new virions are extruded via the phage-encoded pIV protein, which has homology with bacterial secretins. Here, we determine the structure of pIV from the f1 filamentous bacteriophage at 2.7 Å resolution by cryo-electron microscopy, the first near-atomic structure of a phage secretin. Fifteen f1 pIV subunits assemble to form a gated channel in the bacterial outer membrane, with associated soluble domains projecting into the periplasm. We model channel opening and propose a mechanism for phage egress. By single-cell microfluidics experiments, we demonstrate the potential for secretins such as pIV to be used as adjuvants to increase the uptake and efficacy of antibiotics in bacteria. Finally, we compare the f1 pIV structure to its homologues to reveal similarities and differences between phage and bacterial secretins.

scholarly journals Dynamic interaction of fluoroquinolones with magnesium ions monitored using bacterial outer membrane nanopores

2020 ◽  
Vol 11 (38) ◽  
pp. 10344-10353
Author(s):  
Jiajun Wang ◽  
Jigneshkumar Dahyabhai Prajapati ◽  
Ulrich Kleinekathöfer ◽  
Mathias Winterhalter
Keyword(s):  
Outer Membrane ◽  
Divalent Cations ◽  
Dynamic Interaction ◽  
Gram Negative Bacteria ◽  
Magnesium Ions ◽  
Gram Negative ◽  
Bacterial Outer Membrane

Divalent cations alter the translocation of antibiotic molecules through the Gram-negative bacteria outer membrane nanopores.

Epitope mapping of monoclonal antibodies specific for the directly cross-linkedmeso-diaminopimelic acid peptidoglycan found in the anaerobic beer spoilage bacteriumPectinatus cerevisiiphilus

1999 ◽  
Vol 45 (9) ◽  
pp. 779-785 ◽  
Author(s):  
Barry Ziola ◽  
Sheryl L Gares ◽  
Brandene Lorrain ◽  
Lori Gee ◽  
W M Ingledew ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Outer Membrane ◽  
Epitope Mapping ◽  
Sodium Dodecyl ◽  
Diaminopimelic Acid ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Spoilage Bacteria ◽  
Beer Spoilage ◽  
Bacterial Outer Membrane

Nineteen monoclonal antibodies (Mabs) were isolated based on reactivity with disrupted Pectinatus cerevisiiphilus cells. All of the Mabs reacted with cells from which the outer membrane had been stripped by incubation with sodium dodecyl sulphate, suggesting the peptidoglycan (PG) layer was involved in binding. Mab reactivity with purified PG confirmed this. Epitope mapping revealed the Mabs in total recognize four binding sites on the PG. Mabs specific for each of the four sites also bound strongly to disrupted Pectinatus frisingensis, Selenomonas lacticifix, Zymophilus paucivorans, and Zymophilus raffinosivorans cells, but weakly to disrupted Megasphaera cerevisiae cells. No antibody reactivity was seen with disrupted cells of 11 other species of Gram-negative bacteria. These results confirm that a common PG structure is used by several species of anaerobic Gram-negative beer spoilage bacteria. These results also indicate that PG-specific Mabs can be used to rapidly detect a range of anaerobic Gram-negative beer spoilage bacteria, provided the bacterial outer membrane is first removed to allow antibody binding.Key words: beer spoilage, epitope mapping, monoclonal antibodies, Pectinatus, peptidoglycan.

scholarly journals Inter-membrane association of the Sec and BAM translocons for bacterial outer-membrane biogenesis

2019 ◽  
Author(s):  
Sara Alvira ◽  
Daniel W. Watkins ◽  
Lucy Troman ◽  
William J. Allen ◽  
James Lorriman ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Conformational Changes ◽  
Major Constituent ◽  
Gram Negative Bacteria ◽  
Surface Adhesion ◽  
Core Complex ◽  
Inner Membrane ◽  
Bacterial Outer Membrane ◽  
Periplasmic Chaperones ◽  
Outer Membrane Biogenesis

SUMMARYThe outer-membrane of Gram-negative bacteria is critical for surface adhesion, pathogenicity, antibiotic resistance and survival. The major constituent – hydrophobic β-barrel Outer-Membrane Proteins (OMPs) – are secreted across the inner-membrane through the Sec-translocon for delivery to periplasmic chaperones e.g. SurA, which prevent aggregation. OMPs are then offloaded to the β-Barrel Assembly Machinery (BAM) in the outer-membrane for insertion and folding. We show the Holo-TransLocon (HTL: an assembly of the protein-channel core-complex SecYEG, the ancillary sub-complex SecDF, and the membrane ‘insertase’ YidC) contacts SurA and BAM through periplasmic domains of SecDF and YidC, ensuring efficient OMP maturation. Our results show the trans-membrane proton-motive-force (PMF) acts at distinct stages of protein secretion: for SecA-driven translocation across the inner-membrane through SecYEG; and to communicate conformational changes via SecDF to the BAM machinery. The latter presumably ensures efficient passage of OMPs. These interactions provide insights of inter-membrane organisation, the importance of which is becoming increasingly apparent.

scholarly journals Assembly and Channel Opening of Outer Membrane Protein in Tripartite Drug Efflux Pumps of Gram-negative Bacteria

2012 ◽  
Vol 287 (15) ◽  
pp. 11740-11750 ◽  
Author(s):  
Yongbin Xu ◽  
Arne Moeller ◽  
So-Young Jun ◽  
Minho Le ◽  
Bo-Young Yoon ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Membrane Fusion Protein ◽  
Docking Model ◽  
Channel Opening

Gram-negative bacteria are capable of expelling diverse xenobiotic substances from within the cell by use of three-component efflux pumps in which the energy-activated inner membrane transporter is connected to the outer membrane channel protein via the membrane fusion protein. In this work, we describe the crystal structure of the membrane fusion protein MexA from the Pseudomonas aeruginosa MexAB-OprM pump in the hexameric ring arrangement. Electron microscopy study on the chimeric complex of MexA and the outer membrane protein OprM reveals that MexA makes a tip-to-tip interaction with OprM, which suggests a docking model for MexA and OprM. This docking model agrees well with genetic results and depicts detailed interactions. Opening of the OprM channel is accompanied by the simultaneous exposure of a protein structure resembling a six-bladed cogwheel, which intermeshes with the complementary cogwheel structure in the MexA hexamer. Taken together, we suggest an assembly and channel opening model for the MexAB-OprM pump. This study provides a better understanding of multidrug resistance in Gram-negative bacteria.

scholarly journals Defining key roles for auxiliary proteins in an ABC transporter that maintains bacterial outer membrane lipid asymmetry

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Shuhua Thong ◽  
Bilge Ercan ◽  
Federico Torta ◽  
Zhen Yang Fong ◽  
Hui Yi Alvina Wong ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Abc Transporter ◽  
Hydrolytic Activity ◽  
Membrane Lipid ◽  
Permeability Barrier ◽  
Gram Negative Bacteria ◽  
Lipid Asymmetry ◽  
Selective Permeability ◽  
Complex Functions ◽  
Bacterial Outer Membrane

In Gram-negative bacteria, lipid asymmetry is critical for the function of the outer membrane (OM) as a selective permeability barrier, but how it is established and maintained is poorly understood. Here, we characterize a non-canonical ATP-binding cassette (ABC) transporter in Escherichia coli that provides energy for maintaining OM lipid asymmetry via the transport of aberrantly localized phospholipids (PLs) from the OM to the inner membrane (IM). We establish that the transporter comprises canonical components, MlaF and MlaE, and auxiliary proteins, MlaD and MlaB, of previously unknown functions. We further demonstrate that MlaD forms extremely stable hexamers within the complex, functions in substrate binding with strong affinity for PLs, and modulates ATP hydrolytic activity. In addition, MlaB plays critical roles in both the assembly and activity of the transporter. Our work provides mechanistic insights into how the MlaFEDB complex participates in ensuring active retrograde PL transport to maintain OM lipid asymmetry.

scholarly journals Pal stabilises the bacterial outer membrane during constriction by a mobilisation-and-capture mechanism

2019 ◽  
Author(s):  
Joanna Szczepaniak ◽  
Peter Holmes ◽  
Karthik Rajasekar ◽  
Renata Kaminska ◽  
Firdaus Samsudin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Outer Membrane Lipoprotein ◽  
Capture Mechanism ◽  
Dividing Cells ◽  
Bacterial Outer Membrane ◽  
Membrane Lipoprotein ◽  
Inner Membrane Protein

SummaryCoordination of outer membrane constriction with septation is critical to faithful division in Gram-negative bacteria and vital to the barrier function of the membrane. Recent studies suggest this coordination is through the active accumulation of the peptidoglycan-binding outer membrane lipoprotein Pal at division sites by the Tol system, but the mechanism is unknown. Here, we show that Pal accumulation at Escherichia coli division sites is a consequence of three key functions of the Tol system. First, Tol mobilises Pal molecules in dividing cells, which otherwise diffuse very slowly due to their binding of the cell wall. Second, Tol actively captures mobilised Pal molecules and deposits them at the division septum. Third, the active capture mechanism is analogous to that used by the inner membrane protein TonB to dislodge the plug domains of outer membrane TonB-dependent nutrient transporters. We conclude that outer membrane constriction is coordinated with cell division by active mobilisation-and-capture of Pal at division septa by the Tol system.

scholarly journals Type V secretion: mechanism(s) of autotransport through the bacterial outer membrane

2012 ◽  
Vol 367 (1592) ◽  
pp. 1088-1101 ◽  
Author(s):  
Jack C. Leo ◽  
Iwan Grin ◽  
Dirk Linke
Keyword(s):  
Outer Membrane ◽  
Polypeptide Chain ◽  
Transmembrane Domain ◽  
Bacterial Virulence ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Bacterial Outer Membrane ◽  
Type V Secretion ◽  
Type V ◽  
Special Case

Autotransport in Gram-negative bacteria denotes the ability of surface-localized proteins to cross the outer membrane (OM) autonomously. Autotransporters perform this task with the help of a β-barrel transmembrane domain localized in the OM. Different classes of autotransporters have been investigated in detail in recent years; classical monomeric but also trimeric autotransporters comprise many important bacterial virulence factors. So do the two-partner secretion systems, which are a special case as the transported protein resides on a different polypeptide chain than the transporter. Despite the great interest in these proteins, the exact mechanism of the transport process remains elusive. Moreover, different periplasmic and OM factors have been identified that play a role in the translocation, making the term ‘autotransport’ debatable. In this review, we compile the wealth of details known on the mechanism of single autotransporters from different classes and organisms, and put them into a bigger perspective. We also discuss recently discovered or rediscovered classes of autotransporters.

scholarly journals Bacterial Outer Membrane Vesicles as a Versatile Tool in Vaccine Research and the Fight against Antimicrobial Resistance

mBio ◽  
2021 ◽  
Author(s):  
Zhuang Zhu ◽  
Fabio Antenucci ◽  
Kasper Rømer Villumsen ◽  
Anders Miki Bojesen
Keyword(s):  
Antimicrobial Resistance ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Gram Negative Bacteria ◽  
Vaccine Research ◽  
Gram Negative ◽  
Versatile Tool ◽  
Bacterial Outer Membrane ◽  
Considerable Range

Gram-negative bacteria include a number of pathogens that cause disease in humans and animals. Although antibiotics are still effective in treating a considerable range of infections caused by Gram-negative bacteria, the alarming increase of antimicrobial resistance (AMR) induced by excessive use of antibiotics has raised global concerns.

scholarly journals Inter-membrane association of the Sec and BAM translocons for bacterial outer-membrane biogenesis

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Sara Alvira ◽  
Daniel W Watkins ◽  
Lucy Troman ◽  
William J Allen ◽  
James S Lorriman ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Conformational Changes ◽  
Major Constituent ◽  
Gram Negative Bacteria ◽  
Surface Adhesion ◽  
Core Complex ◽  
Inner Membrane ◽  
Bacterial Outer Membrane ◽  
Periplasmic Chaperones ◽  
Outer Membrane Biogenesis

The outer-membrane of Gram-negative bacteria is critical for surface adhesion, pathogenicity, antibiotic resistance and survival. The major constituent – hydrophobic β-barrel Outer-Membrane Proteins (OMPs) – are first secreted across the inner-membrane through the Sec-translocon for delivery to periplasmic chaperones, for example SurA, which prevent aggregation. OMPs are then offloaded to the β-Barrel Assembly Machinery (BAM) in the outer-membrane for insertion and folding. We show the Holo-TransLocon (HTL) – an assembly of the protein-channel core-complex SecYEG, the ancillary sub-complex SecDF, and the membrane ‘insertase’ YidC – contacts BAM through periplasmic domains of SecDF and YidC, ensuring efficient OMP maturation. Furthermore, the proton-motive force (PMF) across the inner-membrane acts at distinct stages of protein secretion: (1) SecA-driven translocation through SecYEG and (2) communication of conformational changes via SecDF across the periplasm to BAM. The latter presumably drives efficient passage of OMPs. These interactions provide insights of inter-membrane organisation and communication, the importance of which is becoming increasingly apparent.

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