Fatty acid profile of Escherichia coli during the heat-shock response.
The possible changes in the fatty acid profile of Escharichia coli during heat-shock have been investigated. Bacteria growing in steady-state at 30 degrees C were subjected to an abrupt temperature upshift to 45 degrees C and held at the high temperature for various periods of time in order to elicit the heat-shock response. Fatty acid compositions of lipids extracted from samples taken at different times after the temperature upshift, as well as from cultures in steady-state at 30 and 45 degrees C, were determined by gas-chromatography. It has been found that the total unsaturates to total saturates ratio decreases gradually during heat-shock and that 30 min after the temperature jump, the reduction is equivalent to 57% of the difference between ratios corresponding to steady-state cultures at 30 and 45 degrees C. Consistent with this remodeling of lipid acyl chains, there is a decrease in the excimerization rate of the fluidity probe dipyrenylpropane incorporated into sonicated E. coli lipid extracts. Such modifications occur within the time-span of the heat-shock response, as judged from our previous measurements of the kinetics of change in heat-shock proteins induction ratio. Together, these results indicate that the control of membrane fluidity during the heat-shock response can be accounted for, at least in part, by an important change in the fatty acid composition of Escherichia coli lipids.
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Dept. Biochemistry, Centro de Investigación y de Estudios Avanzados del I. P. N., A. P., México, D. F.
Gómez-Eichelmann
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MC
Fernández
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MS
D004926:Escherichia coli / Q000737:chemistry*; D005227:Fatty Acids / Q000502:physiology*; D018869:Heat-Shock Response / Q000502:physiology*; D015233:Models, Statistical; D013696:Temperature; D013997:Time Factors
D005227:Fatty Acids