Levels of major proteins of Escherichia coli during growth at different temperatures.

The adaptation of Escherichia coli B/r to temperature was studied by measuring the levels of 133 proteins (comprising 70% of the cell's protein mass) during balanced growth in rich medium at seven temperatures from 13.5 to 46 degrees C. The growth rate of this strain in either rich or minimal medium varies as a simple function of temperature with an Arrhenius constant of approximately 13,500 cal (ca. 56,500 J) per mol from 23 to 37 degrees C, the so-called normal range; above and below this range the growth rate decreases sharply. Analysis of the detailed results indicates that (i) metabolic coordination within the normal (Arrhenius) range is largely achieved by modulation of enzyme activity rather than amount; (ii) the restricted growth that occurs outside this range is accompanied by marked changes in the levels of most of these proteins; (iii) a few proteins are thermometer-like in varying simply with temperature over the whole temperature range irrespective of the influence of temperature on cell growth; and (iv) the temperature response of half of the proteins can be predicted from current information on their metabolic role or from their variation in level in different media at 37 degrees C.