Faculty Opinions recommendation of Translocation of phospholipids is facilitated by a subset of membrane-spanning proteins of the bacterial cytoplasmic membrane.

2003 ◽  
Author(s):  
Bradley Smith
Keyword(s):  
Cytoplasmic Membrane ◽  
Membrane Spanning

FtsL, an Essential Cytoplasmic Membrane Protein Involved in Cell Division in Escherichia coli

1992 ◽  
Vol 174 (23) ◽  
pp. 7717-7728 ◽  
Author(s):  
Luz-Maria Guzman ◽  
James J. Barondess ◽  
Jon Beckwith
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Membrane Protein ◽  
Cytoplasmic Membrane ◽  
Topological Analysis ◽  
Growth Conditions ◽  
Bacterial Cell Division ◽  
Leucine Zippers ◽  
Protein Dimerization ◽  
Membrane Spanning

We have identified a gene involved in bacterial cell division, located immediately upstream of the ftsI gene in the min 2 region of the Escherichia coli chromosome. This gene, which we named ftsL , was detected through characterization of Tn phoA insertions in a plasmid containing this chromosomal region. Tn phoA topological analysis and fractionation of alkaline phosphatase fusion proteins indicated that the ftsL gene product is a 13.6-kDa cytoplasmic membrane protein with a cytoplasmic amino terminus, a single membrane-spanning segment, and a periplasmic carboxy terminus. The ftsL gene is essential for cell growth and division. A null mutation in ftsL resulted in inhibition of cell division, formation of long, nonseptate filaments, ultimate cessation of growth, and lysis. Under certain growth conditions, depletion of FtsL or expression of the largest ftsL-phoA fusion produced a variety of cell morphologies, including Y-shaped bacteria, indicating a possible general weakening of the cell wall. The FtsL protein is estimated to be present at about 20 to 40 copies per cell. The periplasmic domain of the protein displays a sequence with features characteristic of leucine zippers, which are involved in protein dimerization.

scholarly journals AnkB, a Periplasmic Ankyrin-Like Protein inPseudomonas aeruginosa, Is Required for Optimal Catalase B (KatB) Activity and Resistance to Hydrogen Peroxide

2000 ◽  
Vol 182 (16) ◽  
pp. 4545-4556 ◽  
Author(s):  
Michael L. Howell ◽  
Eyad Alsabbagh ◽  
Ju-Fang Ma ◽  
Urs A. Ochsner ◽  
Martin G. Klotz ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hydrogen Peroxide ◽  
Cytoplasmic Membrane ◽  
Membrane Vesicles ◽  
Gene Encoding ◽  
Rnase Protection ◽  
C Terminus ◽  
Hydrophobic Amino Acids ◽  
Increased Sensitivity ◽  
Membrane Spanning

ABSTRACT In this study, we have cloned the ankB gene, encoding an ankyrin-like protein in Pseudomonas aeruginosa. TheankB gene is composed of 549 bp encoding a protein of 183 amino acids that possesses four 33-amino-acid ankyrin repeats that are a hallmark of erythrocyte and brain ankyrins. The location ofankB is 57 bp downstream of katB, encoding a hydrogen peroxide-inducible catalase, KatB. Monomeric AnkB is a 19.4-kDa protein with a pI of 5.5 that possesses 22 primarily hydrophobic amino acids at residues 3 to 25, predicting an inner-membrane-spanning motif with the N terminus in the cytoplasm and the C terminus in the periplasm. Such an orientation in the cytoplasmic membrane and, ultimately, periplasmic space was confirmed using AnkB-BlaM and AnkB-PhoA protein fusions. Circular dichroism analysis of recombinant AnkB minus its signal peptide revealed a secondary structure that is ∼65% α-helical. RNase protection and KatB- and AnkB-LacZ translational fusion analyses indicated that katBand ankB are part of a small operon whose transcription is induced dramatically by H2O2, and controlled by the global transactivator OxyR. Interestingly, unlike the spherical nature of ankyrin-deficient erythrocytes, the cellular morphology of anankB mutant was identical to that of wild-type bacteria, yet the mutant produced more membrane vesicles. The mutant also exhibited a fourfold reduction in KatB activity and increased sensitivity to H2O2, phenotypes that could be complemented in trans by a plasmid constitutively expressing ankB. Our results suggest that AnkB may form an antioxidant scaffolding with KatB in the periplasm at the cytoplasmic membrane, thus providing a protective lattice work for optimal H2O2 detoxification.

scholarly journals Role of TonB1 in Pyoverdine-Mediated Signaling in Pseudomonas aeruginosa

2009 ◽  
Vol 191 (18) ◽  
pp. 5634-5640 ◽  
Author(s):  
Matt Shirley ◽  
Iain L. Lamont
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Sigma Factor ◽  
Phenylacetic Acid ◽  
Cytoplasmic Membrane ◽  
Receptor Protein ◽  
Wild Type ◽  
Membrane Spanning ◽  
Signaling Process

ABSTRACT Pyoverdines are siderophores secreted by Pseudomonas aeruginosa. Uptake of ferripyoverdine in P. aeruginosa PAO1 occurs via the FpvA receptor protein and requires the energy-transducing protein TonB1. Interaction of (ferri)pyoverdine with FpvA activates pyoverdine gene expression in a signaling process involving the cytoplasmic-membrane-spanning anti-sigma factor FpvR and the sigma factor PvdS. Here, we show that mutation of a region of FpvA that interacts with TonB1 (the TonB box) prevents this signaling process, as well as inhibiting bacterial growth in the presence of the iron-chelating compound ethylenediamine-di(o-hydroxy-phenylacetic acid). Signaling via wild-type FpvA was also eliminated in strains lacking TonB1 but was unaffected in strains lacking either (or both) of two other TonB proteins in P. aeruginosa, TonB2 and TonB3. An absence of pyoverdine-mediated signaling corresponded with proteolysis of PvdS. These data show that interactions between FpvA and TonB1 are required for (ferri)pyoverdine signal transduction, as well as for ferripyoverdine transport, consistent with a mechanistic link between the signaling and transport functions of FpvA.

Rewiring photosynthesis: engineering wrong-way electron transfer in the purple bacterial reaction centre

2005 ◽  
Vol 33 (4) ◽  
pp. 851-857 ◽  
Author(s):  
M.C. Wakeham ◽  
M.R. Jones
Keyword(s):  
Electron Transfer ◽  
Cytoplasmic Membrane ◽  
Functional Asymmetry ◽  
Site Directed Mutagenesis ◽  
Transfer Reactions ◽  
Reaction Centre ◽  
The Subject ◽  
Membrane Spanning ◽  
Equivalent Electron ◽  
Kinetics Of

The purple bacterial reaction centre uses light energy to separate charge across the cytoplasmic membrane, reducing ubiquinone and oxidizing a c-type cytochrome. The protein possesses a macroscopic structural two-fold symmetry but displays a strong functional asymmetry, with only one of two available membrane-spanning branches of cofactors (the so-called A-branch) being used to catalyse photochemical charge separation. The factors underlying this functional asymmetry have been the subject of study for many years but are still not fully understood. Site-directed mutagenesis has been partially successful in rerouting electron transfer along the normally inactive B-branch, allowing comparison of the kinetics of equivalent electron transfer reactions on the two branches. Both the primary and secondary electron transfer steps on the B-branch appear to be considerably slower than their A-branch counterparts. The effectiveness of different mutations in rerouting electron transfer along the B-branch of cofactors is discussed.

scholarly journals Translocation of Phospholipids Is Facilitated by a Subset of Membrane-spanning Proteins of the Bacterial Cytoplasmic Membrane

2003 ◽  
Vol 278 (27) ◽  
pp. 24586-24593 ◽  
Author(s):  
Matthijs A. Kol ◽  
Annemieke van Dalen ◽  
Anton I. P. M. de Kroon ◽  
Ben de Kruijff
Keyword(s):  
Cytoplasmic Membrane ◽  
Membrane Spanning

scholarly journals Characterization of Transmembrane Segments 3, 4, and 5 of MalF by Mutational Analysis

2001 ◽  
Vol 183 (1) ◽  
pp. 375-381 ◽  
Author(s):  
Angelika Steinke ◽  
Sandra Grau ◽  
Amy Davidson ◽  
Eckhard Hofmann ◽  
Michael Ehrmann
Keyword(s):  
Structural Model ◽  
Cytoplasmic Membrane ◽  
Mutational Analysis ◽  
Point Mutations ◽  
Transport Channel ◽  
Transmembrane Segments ◽  
Maltose Transporter ◽  
Membrane Spanning ◽  
Membrane Components

ABSTRACT MalF and MalG are the cytoplasmic membrane components of the binding protein-dependent ATP binding cassette maltose transporter inEscherichia coli. They are thought to form the transport channel and are thus of critical importance for the mechanism of transport. To study the contributions of individual transmembrane segments of MalF, we isolated 27 point mutations in membrane-spanning segments 3, 4, and 5. These data complement a previous study, which described the mutagenesis of membrane-spanning segments 6, 7, and 8. While most of the isolated mutations appear to cause assembly defects, L323Q in helix 5 could interfere more directly with substrate specificity. The phenotypes and locations of the mutations are consistent with a previously postulated structural model of MalF.

Effect of piperacillin on morphology and viability of gram-negative bacteria

1984 ◽  
Vol 42 ◽  
pp. 218-219
Author(s):  
R. H. Liss
Keyword(s):  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Drug Binding ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Drug Induced ◽  
Penicillin Binding Proteins ◽  
Lactam Antibiotic ◽  
Drug Free ◽  
Tube Dilution

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.

Comparative surface and ultrastructural views of methylotrophic bacteria by TEM, STEM, SE, and freeze-etch electron microscopy.

1987 ◽  
Vol 45 ◽  
pp. 792-793
Author(s):  
T.A. Fassel ◽  
M.J. Schaller ◽  
M.E. Lidstrom ◽  
C.C. Remsen
Keyword(s):  
Cytoplasmic Membrane ◽  
Structural Features ◽  
Methylotrophic Bacteria ◽  
Type I ◽  
Type Ii ◽  
Membrane Complex ◽  
Oxidation Of Methane ◽  
Methane Oxidizing Bacteria ◽  
Wall Structures ◽  
Methylomonas Albus

Methylotrophic bacteria play an Important role in the environment in the oxidation of methane and methanol. Extensive intracytoplasmic membranes (ICM) have been associated with the oxidation processes in methylotrophs and chemolithotrophic bacteria. Classification on the basis of ICM arrangement distinguishes 2 types of methylotrophs. Bundles or vesicular stacks of ICM located away from the cytoplasmic membrane and extending into the cytoplasm are present in Type I methylotrophs. In Type II methylotrophs, the ICM form pairs of peripheral membranes located parallel to the cytoplasmic membrane. Complex cell wall structures of tightly packed cup-shaped subunits have been described in strains of marine and freshwater phototrophic sulfur bacteria and several strains of methane oxidizing bacteria. We examined the ultrastructure of the methylotrophs with particular view of the ICM and surface structural features, between representatives of the Type I Methylomonas albus (BG8), and Type II Methylosinus trichosporium (OB-36).

Calcium ion imaging in plant cells

1993 ◽  
Vol 51 ◽  
pp. 132-133
Author(s):  
Peter K. Hepler ◽  
Dale A. Callaham
Keyword(s):  
Plant Cell Wall ◽  
Cytoplasmic Membrane ◽  
Fluorescent Dyes ◽  
Free Acid ◽  
Methyl Esters ◽  
Free Calcium ◽  
Local Concentration ◽  
Ion Imaging ◽  
Membrane Compartments ◽  
Free Acid Form

Calcium ions (Ca) participate in many signal transduction processes, and for that reason it is important to determine where these ions are located within the living cell, and when and to what extent they change their local concentration. Of the different Ca-specific indicators, the fluorescent dyes, developed by Grynkiewicz et al. (1), have proved most efficacious, however, their use on plants has met with several problems (2). First, the dyes as acetoxy-methyl esters are often cleaved by extracellular esterases in the plant cell wall, and thus they do not enter the cell. Second, if the dye crosses the plasma membrane it may continue into non-cytoplasmic membrane compartments. Third, even if cleaved by esterases in the cytoplasm, or introduced as the free acid into the cytoplasmic compartment, the dyes often become quickly sequestered into vacuoles and organelles, or extruded from the cell. Finally, the free acid form of the dye readily complexes with proteins reducing its ability to detect free calcium. All these problems lead to an erroneous measurement of calcium (2).

IMPACT OF SORBITOL- INDUCED OSMOTIC STRESS ON SOME BIOCHEMICAL TRAITS OF POTATO IN VITRO

2020 ◽  
Vol 51 (4) ◽  
pp. 1038-1047
Author(s):  
Mawia & et al.
Keyword(s):  
Ascorbic Acid ◽  
Osmotic Stress ◽  
Cytoplasmic Membrane ◽  
Genotypic Variation ◽  
Membrane Damage ◽  
Membrane Integrity ◽  
Culture Collection ◽  
Nutritive Medium ◽  
Starting Point

This study had as principal objective identification of osmotic-tolerant potato genotypes by using "in vitro" tissue culture and sorbitol as a stimulating agent, to induce water stress, which was added to the  culture nutritive medium in different concentration (0,50, 110, 220, 330 and 440 mM).  The starting point was represented by plantlets culture collection, belonging to eleven potato genotypes: Barcelona, Nectar, Alison, Jelly, Malice, Nazca, Toronto, Farida, Fabulla, Colomba and Spunta. Plantlets were multiplied between two internodes to obtain microcuttings (in sterile condition), which were inoculated on medium. Sorbitol-induced osmotic stress caused a significant reduction in the ascorbic acid, while the concentration of proline, H2O2 and solutes leakage increased compared with the control. Increased the proline content prevented lipid peroxidation, which played a pivotal role in the maintenance of membrane integrity under osmotic stress conditions. The extent of the cytoplasmic membrane damage depends on osmotic stress severity and the genotypic variation in the maintenance of membranes stability was highly associated with the ability of producing more amounts of osmoprotectants (proline) and the non-enzymic antioxidant ascorbic acid in response to osmotic stress level. The results showed that the genotypes Jelly, Nectar, Allison, Toronto, and Colomba are classified as highly osmotic stress tolerant genotypes, while the genotypes Nazca and Farida are classified as osmotic stress susceptible ones.

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