Experiment turns up the heat on natural selection, reveals new details of an evolutionary mechanism
Scientists in Munich report evidence that high concentrations of the molecular "chaperone" proteins GroEL and GroES -- intracellular machines that can stabilize folding proteins under stress -- play a critical role in increasing the maximum temperature at which E. coli bacteria can grow. Massively and permanently elevated levels of the GroE proteins were found in bacteria adapted, step-wise over a period of years, for growth at 48.5 degrees C. This genomic change persisted for more than 600 generations, and molecular analyses ruled out other mechanisms that might account for the increase in heat resistance. The researchers' findings, published in the June 18 edition of the Journal of Biological Chemistry, have important implications for both fundamental evolutionary studies and biotechnology applications.