We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. In stationary-phase cells, an unexpected and more complex picture emerged. These kinks effectively reduce the surface area accessible to other fatty acid chains, weakening Van der Waals interactions. It is also possible that despite sonication in buffer, the phospholipids in our preparations were not fully hydrated, which would also have increased their melting temperature. Submission, Review, & Publication Processes, Role of Membrane Fluidity in Pressure Resistance of Escherichia coli NCTC 8164, Copyright © 2002 American Society for Microbiology. This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. The position of the peak maximum (Tm) on the temperature axis indicates the temperature at which the excess specific heat absorbed by the system is at a maximum. 6b). The calorimetric studies of Jackson and Cronan (19) showed that the phase transition of membrane phospholipids of E. coli was completed below the temperature of growth, whereas we found that the midpoint of membrane lipid melting occurred around the growth temperature. Am. Print. 1978 Dec;136(3):1027-36. doi: 10.1128/JB.136.3.1027-1036.1978. This transition is driven by the conversion of the bulk membrane lipid phase to the gel state, but it is less cooperative and occurs at lower temperatures than the bulk lipid transition. The Tm was directly related to the growth temperature (Fig. Lipids can exist in a number of phases, which are summarized below. COVID-19 is an emerging, rapidly evolving situation. (45) examined the relationship between pressure inactivation of stationary-phase cells of L. plantarum and inactivation of the multidrug transporter HorA. Mahajan S, Lewis RN, George R, Sykes BD, McElhaney RN. If enough other exposed proteins are nearby, this can result in a hydrophobic effect-mediated protein aggregation event, as displayed in, Factors Affecting Lipid Phase Transitions. Biological membranes are primarily composed of phospholipids—a diverse class of compounds composed of a hydrophilic head group covalently attached to a pair of hydrophobic fatty acids. As the membrane enters its lipid phase transition, ATPase activity begins to fall off more rapidly than it does above the transition. Ritz et al. The results suggest that the familial "biphasic linear" Arrhenius plots reported for many membrane enzymes and transport systems may, in fact, have more complex shapes, analysis of which can furnish useful information about the behavior of the enzyme molecule or transport system in its membrane environment. Pressure causes closer packing of the hydrocarbon chains of phospholipids and in this sense has an effect similar to cooling. Journal of Microbiology & Biology Education, Microbiology and Molecular Biology Reviews. While these bilayers tend to exist in a fluid phase under physiological conditions, their component phospholipids can undergo phase transitions under the correct environmental conditions. We suggest instead that the physiological changes that occur as cells enter the stationary phase have an overriding effect on pressure resistance that is independent of membrane fluidity. the highest fluidity at 37"C, induce the highest biological activities; smooth (S) form lipopolysaccharide and free lipid A with their higher transition temperatures, i.e. Raghunathan, V. A., and John Katsaras. Our results showing that resistance of E. coli NCTC 8164 decreases between 30 and 10°C are consistent with this previous finding. Pressure may be envisioned to have an irreversible effect on membrane proteins in one of two ways: either the proteins could be denatured in situ or they might be squeezed out of the membrane as a result of closer packing of membrane phospholipids. We further examined the relationship between membrane fluidity and pressure resistance of exponential- and stationary-phase cells by varying the temperature of pressure treatment, on the assumption that membrane fluidity during pressure treatment would tend to increase with increasing ambient temperature. Stronger Van der Waals interactions lead to tighter, more ordered lipid packing, impeding lateral movement across the surface of the membrane. This is consistent with the observations of Mejía et al. 7, pressure resistance in both exponential- and stationary-phase cells increased with increasing temperatures of pressure treatment (between 10 and ca. Effect of temperature of pressurization on pressure resistance of E. coli NCTC 8164. J Bioenerg Biomembr. Phase separation between lipids surrounding integral membrane proteins can briefly expose the hydrophobic residues of the middle of the protein to water. Membrane fluidity and pressure resistance.To assess the relationship among growth temperature, the FI, and the melting behavior of membrane lipids, total phospholipids were extracted from stationary-phase cells grown at different temperatures and analyzed by DSC. The reason why more-fluid membranes are less susceptible to pressure damage is not immediately obvious. The result is a “liquid ordered phase” with solid-like qualities similar to the gel phase without sacrificing the high rate of lateral diffusion attainable in the liquid-disordered phase. Membrane lipid physical state and modulation of the Na+,Mg2+-ATPase activity in Acholeplasma laidlawii B. Physiological role and membrane lipid modulation of the membrane-bound (Mg2+, na+)-adenosine triphosphatase activity in Acholeplasma laidlawii. Thank you for sharing this Applied and Environmental Microbiology article. J Bacteriol. Proc Natl Acad Sci U S A. For example for DPPC, transition temperature is 41 oC and below that temperature, Lets say at RT, it will be in gel phase which leads precipitations. This leads to increasing Tm’s with increasing chain length, as shown in Figure \(\PageIndex{1}\). With regard to the effect of temperature during treatment, many authors have reported a broad optimum temperature for resistance between approximately 20 to 30°C (9, 23, 42). Characterization of sodium transport in Acholeplasma laidlawii B cells and in lipid vesicles containing purified A. laidlawii (Na+-Mg2+)-ATPase by using nuclear magnetic resonance spectroscopy and 22Na tracer techniques. 14 May 2015. . This site needs JavaScript to work properly. The melting point of UFA is lower than that of SFA, and the general effect of the incorporation of more UFA in the membrane is a decrease in the phase transition temperature (2). However, other changes not necessarily related to envelope composition may also affect pressure resistance, so further work is needed to clarify this. J Bacteriol. (21) reported that cells of Listeria monocytogenes and Yarrowia lipolytica treated at the end of exponential phase were more resistant to high-pressure homogenization when grown at lower temperatures. As heat is increased, the membrane makes a sharp transition from a rigid state to a more fluid state. This results in the formation of patches of long, saturated, gel-phase lipids in the membrane.  |  Note: Transition temperatures for natural products are typically not available in the literature. The growth temperatures were chosen to produce cells with large differences in membrane fatty acid composition, i.e., 10°C for exponential-phase cells and 37°C for stationary-phase cells. National Center for Biotechnology Information, Unable to load your collection due to an error, Unable to load your delegates due to an error. Thus, in stationary-phase cells, treatment temperature affects resistance in a manner similar to its effect on exponential-phase cells but this effect is superimposed on the independent but much larger effects of stationary-phase adaptation (discussed below) that are expressed most strongly in cells grown at 30 to 37°C (Fig. Phase transitions and permeability changes in dry membranes during rehydration. Temperatures above a lipid’s Tm will transition lipids to a liquid phase, while colder temperatures will cause a transition to a solid-like phase. The decrease in pressure resistance of exponential-phase cells that occurred with increasing growth temperature is in agreement with the observations of Smelt et al. It is not clear which particular adaptations are important, but the acquisition of a more resilient cell envelope appears to be critical, because the cytoplasmic membranes of stationary-phase cells are much less susceptible to disruption by pressure than those of exponential-phase cells and the resistance of the stationary-phase membrane to pressure-induced permeabilization was related to rpoS status (5, 32). 2016 Nov 22;11:6229-6238. doi: 10.2147/IJN.S112835. Growth temperature and pressure resistance.Exponential- and stationary-phase cells showed unexpected differences in the way that growth temperature affected pressure resistance.


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