scholarly journals A method for measuring the outer membrane-permeability of .BETA.-lactam antibiotics in gram-negative bacteria.

1977 ◽  
Vol 30 (12) ◽  
pp. 1134-1136 ◽  
Author(s):  
TETSUO SAWAI ◽  
KIYOTAKA MATSUBA ◽  
SABURO YAMAGISHI
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Beta Lactam ◽  
Gram Negative ◽  
Beta Lactam Antibiotics ◽  
Outer Membrane Permeability

scholarly journals Outer Membrane Permeability of Cyanobacterium Synechocystis sp. Strain PCC 6803: Studies of Passive Diffusion of Small Organic Nutrients Reveal the Absence of Classical Porins and Intrinsically Low Permeability

2017 ◽  
Vol 199 (19) ◽  
Author(s):  
Hikaru Kowata ◽  
Saeko Tochigi ◽  
Hideyuki Takahashi ◽  
Seiji Kojima
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Inorganic Ions ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Organic Nutrients ◽  
Outer Membrane Permeability ◽  
Pcc 6803

ABSTRACT The outer membrane of heterotrophic Gram-negative bacteria plays the role of a selective permeability barrier that prevents the influx of toxic compounds while allowing the nonspecific passage of small hydrophilic nutrients through porin channels. Compared with heterotrophic Gram-negative bacteria, the outer membrane properties of cyanobacteria, which are Gram-negative photoautotrophs, are not clearly understood. In this study, using small carbohydrates, amino acids, and inorganic ions as permeation probes, we determined the outer membrane permeability of Synechocystis sp. strain PCC 6803 in intact cells and in proteoliposomes reconstituted with outer membrane proteins. The permeability of this cyanobacterium was >20-fold lower than that of Escherichia coli. The predominant outer membrane proteins Slr1841, Slr1908, and Slr0042 were not permeable to organic nutrients and allowed only the passage of inorganic ions. Only the less abundant outer membrane protein Slr1270, a homolog of the E. coli export channel TolC, was permeable to organic solutes. The activity of Slr1270 as a channel was verified in a recombinant Slr1270-producing E. coli outer membrane. The lack of putative porins and the low outer membrane permeability appear to suit the cyanobacterial autotrophic lifestyle; the highly impermeable outer membrane would be advantageous to cellular survival by protecting the cell from toxic compounds, especially when the cellular physiology is not dependent on the uptake of organic nutrients. IMPORTANCE Because the outer membrane of Gram-negative bacteria affects the flux rates for various substances into and out of the cell, its permeability is closely associated with cellular physiology. The outer membrane properties of cyanobacteria, which are photoautotrophic Gram-negative bacteria, are not clearly understood. Here, we examined the outer membrane of Synechocystis sp. strain PCC 6803. We revealed that it is relatively permeable to inorganic ions but is markedly less permeable to organic nutrients, with >20-fold lower permeability than the outer membrane of Escherichia coli. Such permeability appears to fit the cyanobacterial lifestyle, in which the diffusion pathway for inorganic solutes may suffice to sustain the autotrophic physiology, illustrating a link between outer membrane permeability and the cellular lifestyle.

scholarly journals The outer membrane permeability of gram-negative bacteria

FEBS Letters ◽  
1979 ◽  
Vol 106 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Masao Tokunaga ◽  
Hiroko Tokunaga ◽  
Taiji Nakae
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Outer Membrane Permeability

scholarly journals The bacterial outer-membrane permeability of .BETA.-lactam antibiotics.

1979 ◽  
Vol 32 (1) ◽  
pp. 59-65 ◽  
Author(s):  
TETSUO SAWAI ◽  
KIYOTAKA MATSUBA ◽  
ATSUSHI TAMURA ◽  
SABURO YAMAGISHI
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Beta Lactam ◽  
Beta Lactam Antibiotics ◽  
Bacterial Outer Membrane ◽  
Outer Membrane Permeability

scholarly journals Phospholipid retention in the absence of asymmetry strengthens the outer membrane permeability barrier to last-resort antibiotics

2018 ◽  
Vol 115 (36) ◽  
pp. E8518-E8527 ◽  
Author(s):  
Matthew J. Powers ◽  
M. Stephen Trent
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Lipid A ◽  
Permeability Barrier ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Outer Leaflet ◽  
Two Factors ◽  
Evolution Experiment ◽  
Outer Membrane Permeability

The outer membrane of Gram-negative bacteria is a critical barrier that prevents entry of noxious compounds. Integral to this functionality is the presence of lipopolysaccharide (LPS) or lipooligosaccharide (LOS), a molecule that is located exclusively in the outer leaflet of the outer membrane. Its lipid anchor, lipid A, is a glycolipid whose hydrophobicity and net negative charge are primarily responsible for the robustness of the membrane. Because of this, lipid A is a hallmark of Gram-negative physiology and is generally essential for survival. Rare exceptions have been described, includingAcinetobacter baumannii, which can survive in the absence of lipid A, albeit with significant growth and membrane permeability defects. Here, we show by an evolution experiment that LOS-deficientA. baumanniican rapidly improve fitness over the course of only 120 generations. We identified two factors which negatively contribute to fitness in the absence of LOS, Mla and PldA. These proteins are involved in glycerophospholipid transport (Mla) and lipid degradation (PldA); both are active only on mislocalized, surface-exposed glycerophospholipids. Elimination of these two mechanisms was sufficient to cause a drastic fitness improvement in LOS-deficientA. baumannii. The LOS-deficient double mutant grows as robustly as LOS-positive wild-type bacteria while remaining resistant to the last-resort polymyxin antibiotics. These data provide strong biological evidence for the directionality of Mla-mediated glycerophospholipid transport in Gram-negative bacteria and furthers our knowledge of asymmetry-maintenance mechanisms in the context of the outer membrane barrier.

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