Transport across the outer membrane ofEscherichia coli K12 via the FhuA receptor is regulated by the TonB protein of the cytoplasmic membrane

1989 ◽  
Vol 217 (2-3) ◽  
pp. 378-383 ◽  
Author(s):  
Harald Schöffler ◽  
Volkmar Braum
Keyword(s):  
Outer Membrane ◽  
Cytoplasmic Membrane ◽  
Ofescherichia Coli ◽  
Tonb Protein

scholarly journals Lipoprotein Sorting Signals Evaluated as the LolA-dependent Release of Lipoproteins from the Cytoplasmic Membrane ofEscherichia coli

2001 ◽  
Vol 276 (50) ◽  
pp. 47690-47694 ◽  
Author(s):  
Makiko Terada ◽  
Toshiro Kuroda ◽  
Shin-ichi Matsuyama ◽  
Hajime Tokuda
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Cytoplasmic Membrane ◽  
Fatty Acyl ◽  
Ofescherichia Coli ◽  
Membrane Localization ◽  
Inner Membrane ◽  
Sorting Signals ◽  
Acyl Chains ◽  
Retention Signal

Escherichia colilipoproteins are anchored to either the inner or outer membrane through fatty acyl chains covalently attached to an N-terminal cysteine. Aspartate at position 2 functions to retain lipoproteins in the inner membrane, although the retention is perturbed depending on the residue at position 3. We previously revealed that LolCDE and LolA play critical roles in this lipoprotein sorting. To clarify the sorting signals, the LolA-dependent release of lipoprotein derivatives having various residues at positions 2 and 3 was examined in spheroplasts. When the residue at position 3 was serine, only aspartate at position 2 caused the retention of lipoproteins in spheroplasts. We then examined the release of derivatives having aspartate at position 2 and various residues at position 3. Strong inner membrane retention occurred with a limited number of species of residues at position 3. These residues were present at position 3 of native lipoproteins having aspartate at position 2, whereas residues that inhibited the retention were not. It was also found that a strong inner membrane retention signal having residues other than aspartate at position 2 could be formed through the combination of the residues at positions 2 and 3. These results indicate that the inner membrane localization of native lipoproteins is ensured by the use of a limited number of strong inner membrane retention signals.

scholarly journals Pyoverdine-Mediated Iron Uptake in Pseudomonas aeruginosa: the Tat System Is Required for PvdN but Not for FpvA Transport

2006 ◽  
Vol 188 (9) ◽  
pp. 3317-3323 ◽  
Author(s):  
Romé Voulhoux ◽  
Alain Filloux ◽  
Isabelle J. Schalk
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Cytoplasmic Membrane ◽  
Signal Sequence ◽  
Iron Release ◽  
Outer Membrane Receptor ◽  
Uptake Pathway ◽  
Uptake Process ◽  
Tat System

ABSTRACT Under iron-limiting conditions, Pseudomonas aeruginosa PAO1 secretes a fluorescent siderophore called pyoverdine (Pvd). After chelating iron, this ferric siderophore is transported back into the cells via the outer membrane receptor FpvA. The Pvd-dependent iron uptake pathway requires several essential genes involved in both the synthesis of Pvd and the uptake of ferric Pvd inside the cell. A previous study describing the global phenotype of a tat-deficient P. aeruginosa strain showed that the defect in Pvd-mediated iron uptake was due to the Tat-dependent export of proteins involved in Pvd biogenesis and ferric Pvd uptake (U. Ochsner, A. Snyder, A. I. Vasil, and M. L. Vasil, Proc. Natl. Acad. Sci. USA 99:8312-8317, 2002). Using biochemical and biophysical tools, we showed that despite its predicted Tat signal sequence, FpvA is correctly located in the outer membrane of a tat mutant and is fully functional for all steps of the iron uptake process (ferric Pvd uptake and recycling of Pvd on FpvA after iron release). However, in the tat mutant, no Pvd was produced. This suggested that a key element in the Pvd biogenesis pathway must be exported to the periplasm by the Tat pathway. We located PvdN, a still unknown but essential component in Pvd biogenesis, at the periplasmic side of the cytoplasmic membrane and showed that its export is Tat dependent. Our results further support the idea that a critical step of the Pvd biogenesis pathway involving PvdN occurs at the periplasmic side of the cytoplasmic membrane.

scholarly journals Membrane fusion during phage lysis

2015 ◽  
Vol 112 (17) ◽  
pp. 5497-5502 ◽  
Author(s):  
Manoj Rajaure ◽  
Joel Berry ◽  
Rohit Kongari ◽  
Jesse Cahill ◽  
Ry Young
Keyword(s):  
Membrane Fusion ◽  
Outer Membrane ◽  
Cytoplasmic Membrane ◽  
Bacterial Host ◽  
Inner Membrane ◽  
Gram Negative ◽  
Encoded Proteins ◽  
Coliphage Lambda ◽  
Necessary And Sufficient

In general, phages cause lysis of the bacterial host to effect release of the progeny virions. Until recently, it was thought that degradation of the peptidoglycan (PG) was necessary and sufficient for osmotic bursting of the cell. Recently, we have shown that in Gram-negative hosts, phage lysis also requires the disruption of the outer membrane (OM). This is accomplished by spanins, which are phage-encoded proteins that connect the cytoplasmic membrane (inner membrane, IM) and the OM. The mechanism by which the spanins destroy the OM is unknown. Here we show that the spanins of the paradigm coliphage lambda mediate efficient membrane fusion. This supports the notion that the last step of lysis is the fusion of the IM and OM. Moreover, data are provided indicating that spanin-mediated fusion is regulated by the meshwork of the PG, thus coupling fusion to murein degradation by the phage endolysin. Because endolysin function requires the formation of μm-scale holes by the phage holin, the lysis pathway is seen to require dramatic dynamics on the part of the OM and IM, as well as destruction of the PG.

scholarly journals Mechanism of Bactericidal Activity of Microcin L inEscherichia coliandSalmonella enterica

2010 ◽  
Vol 55 (3) ◽  
pp. 997-1007 ◽  
Author(s):  
Natacha Morin ◽  
Isabelle Lanneluc ◽  
Nathalie Connil ◽  
Marie Cottenceau ◽  
Anne Marie Pons ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Bactericidal Activity ◽  
Salmonella Enterica ◽  
Cytoplasmic Membrane ◽  
Genetic System ◽  
Proton Motive Force ◽  
Motive Force ◽  
Membrane Properties ◽  
Outer Membrane Receptor ◽  
E Coli

ABSTRACTFor the first time, the mechanism of action of microcin L (MccL) was investigated in live bacteria. MccL is a gene-encoded peptide produced byEscherichia coliLR05 that exhibits a strong antibacterial activity against relatedEnterobacteriaceae, includingSalmonella entericaserovars Typhimurium and Enteritidis. We first subcloned the MccL genetic system to remove the sequences not involved in MccL production. We then optimized the MccL purification procedure to obtain large amounts of purified microcin to investigate its antimicrobial and membrane properties. We showed that MccL did not induce outer membrane permeabilization, which indicated that MccL did not use this way to kill the sensitive cell or to enter into it. Using a set ofE. coliandSalmonella entericamutants lacking iron-siderophore receptors, we demonstrated that the MccL uptake required the outer membrane receptor Cir. Moreover, the MccL bactericidal activity was shown to depend on the TonB protein that transduces the proton-motive force of the cytoplasmic membrane to transport iron-siderophore complexes across the outer membrane. Using carbonyl cyanide 3-chlorophenylhydrazone, which is known to fully dissipate the proton-motive force, we proved that the proton-motive force was required for the bactericidal activity of MccL onE. coli. In addition, we showed that a primary target of MccL could be the cytoplasmic membrane: a high level of MccL disrupted the inner membrane potential ofE. colicells. However, no permeabilization of the membrane was detected.

Integration of the Thylakoid Membrane Protein Cytochromeb6in the Cytoplasmic Membrane ofEscherichia coli†

Biochemistry ◽  
2005 ◽  
Vol 44 (20) ◽  
pp. 7570-7576 ◽  
Author(s):  
Jaroslaw Króliczewski ◽  
Katarzyna Hombek-Urban ◽  
Andrzej Szczepaniak
Keyword(s):  
Membrane Protein ◽  
Thylakoid Membrane ◽  
Cytoplasmic Membrane ◽  
Ofescherichia Coli

scholarly journals The High-Molecular-Weight Cytochrome c Cyc2 of Acidithiobacillus ferrooxidans Is an Outer Membrane Protein

2002 ◽  
Vol 184 (1) ◽  
pp. 313-317 ◽  
Author(s):  
Andrés Yarzábal ◽  
Gaël Brasseur ◽  
Jeanine Ratouchniak ◽  
Karen Lund ◽  
Danielle Lemesle-Meunier ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Outer Membrane ◽  
High Molecular Weight ◽  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Membrane Fraction ◽  
Cytoplasmic Membrane ◽  
Respiratory Pathway ◽  
Membrane Components ◽  
Membrane Level

ABSTRACT A high-molecular-weight c-type cytochrome, Cyc2, and a putative 22-kDa c-type cytochrome were detected in the membrane fraction released during spheroplast formation from Acidithiobacillus ferrooxidans. This fraction was enriched in outer membrane components and devoid of cytoplasmic membrane markers. The genetics, as well as the subcellular localization of Cyc2 at the outer membrane level, therefore make it a prime candidate for the initial electron acceptor in the respiratory pathway between ferrous iron and oxygen.

scholarly journals A small-molecule inhibitor of BamA impervious to efflux and the outer membrane permeability barrier

2019 ◽  
Vol 116 (43) ◽  
pp. 21748-21757 ◽  
Author(s):  
Elizabeth M. Hart ◽  
Angela M. Mitchell ◽  
Anna Konovalova ◽  
Marcin Grabowicz ◽  
Jessica Sheng ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Small Molecule ◽  
Cytoplasmic Membrane ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Permeability Barrier ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Bam Complex ◽  
Induced Aggregation

The development of new antimicrobial drugs is a priority to combat the increasing spread of multidrug-resistant bacteria. This development is especially problematic in gram-negative bacteria due to the outer membrane (OM) permeability barrier and multidrug efflux pumps. Therefore, we screened for compounds that target essential, nonredundant, surface-exposed processes in gram-negative bacteria. We identified a compound, MRL-494, that inhibits assembly of OM proteins (OMPs) by the β-barrel assembly machine (BAM complex). The BAM complex contains one essential surface-exposed protein, BamA. We constructed a bamA mutagenesis library, screened for resistance to MRL-494, and identified the mutation bamAE470K. BamAE470K restores OMP biogenesis in the presence of MRL-494. The mutant protein has both altered conformation and activity, suggesting it could either inhibit MRL-494 binding or allow BamA to function in the presence of MRL-494. By cellular thermal shift assay (CETSA), we determined that MRL-494 stabilizes BamA and BamAE470K from thermally induced aggregation, indicating direct or proximal binding to both BamA and BamAE470K. Thus, it is the altered activity of BamAE470K responsible for resistance to MRL-494. Strikingly, MRL-494 possesses a second mechanism of action that kills gram-positive organisms. In microbes lacking an OM, MRL-494 lethally disrupts the cytoplasmic membrane. We suggest that the compound cannot disrupt the cytoplasmic membrane of gram-negative bacteria because it cannot penetrate the OM. Instead, MRL-494 inhibits OMP biogenesis from outside the OM by targeting BamA. The identification of a small molecule that inhibits OMP biogenesis at the cell surface represents a distinct class of antibacterial agents.

Sign in / Sign up

Export Citation Format

Share Document