Escherichia coli membrane composition

Lindblom, G., Oradd, G., Rilfors, L. and Morein, S. (2002) Regulation of lipid composition in Acholeplasma laidlawii and Escherichia coli membranes NMR studies of lipid lateral diffusion at different growth temperatures. Biochemistry 41, 11512-11515. 

The earliest general model of adaptation to temperature in membrane lipids focused on the physical state ( static order or viscosity [= 1 / fluidity ]) of the bilayer. The finding that the physical state of membrane lipids from Escherichia coli cultured at different temperatures was similar at the different growth temperatures led to the homeoviscous adaptation hypothesis, which states that lipid composition is modified during thermal acclimation to facilitate retention of a relatively stable membrane physical state (Sinensky, 1974). At the outset of any discussion of homeoviscous adaptation, it is important to examine carefully what is meant by physical state (or the related terms static order, viscosity, and fluidity ). In such an analysis, one must also consider the physical methods that are used to make such measurements—and the limitations of these techniques. 

Yuk, H.G. and Marshall, D.L. 2005. Influence of acetic, citric and lactic acids on Escherichia coli 0157 H7 membrane lipid composition, verotoxin secretion, and acid resistance in simulated gastric fluid. Journal of Food Protection 68 673-679. 

Temperature also affects the activity of QACs against Pseudomonas aeruginosa and Escherichia coli. Tests of 18 proprietary disinfectant products used in the food industry showed that their activity decreased as the temperature was decreased from 20° to 10°C [27], This may be related to temperature-induced changes in QAC critical micelle concentration. Alternatively, changes in microbial membrane fluidity may be responsible for the observed changes. More such data with well-defined QAC composition and extended temperature ranges are needed to understand the correlation between temperature and antimicrobial activity of QACs. 

Incubations with Cloned, Expressed Enzymes Individual UGT enzymes have been expressed in a wide variety of systems including insect cells (Supersomes or Baculosomes), Escherichia coli, yeast, and mammalian cells. Zakim and Dannenberg have demonstrated that the lipid membrane composition can influence activity (Zakim, 1992). There tends to be excellent protein expression insect cells transfected with baculovirus, but when activity is measured compared to mammalian cells systems, there appears to be significant amounts of inactive protein due to either poor membrane insertion or improper folding (lack of chaperones ). Bacteria do not have an ER, but alteration of the signal sequence results in active membrane bound preparations. Yeast and mammalian cells such as HEK293 or V79 cells have a more typical membrane environment and may be preferable for expression of ER proteins. 

The polymer efficiently permeabilises anionic vesicles with compositions which mimic those of bacterial membranes. The polymer binds to anionic phospholipid vesicles but not zwitterionic vesicles, which causes phase separation in anionic phospholipid mixtures, clustering the negative charge. The polymer permeabilises the outer membrane of Escherichia coli ML-35p in a biphasic manner low polymer concentrations permeabilise the inner membrane of Escherichia coli ML-35p, whereas high concentrations of the polymer can block the active transport of or onitrophenyl-P-n-galactoside in wild-type Escherichia coli K12 [17]. 

Ulrich AK, de Mendoza D, Garwin JL, Cronan JE. Genetic and biochemical analyses of Escherichia coli mutants altered in the temperature-dependent regulation of membrane lipid composition. J Bacteriol 1983 154 221-230. 

Mavis, R. D., and Vagelos, P. R., 1972, The effect of phospholipid fatty acid composition on membranous enzymes in Escherichia coli, ]. Biol. Chem. 247 652. 

Utilizations of hybrid/composite membranes can also be found for ultrafiltration membranes toward protein separation "" and functionalized polyelectrolyte capsules using filamentous Escherichia coli cells, " which will further extend the application fields for functionalized hybrid/composite membranes. 

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