EVOLUTION:
Heat Shock Protein Mutes Genetic Changes
Elizabeth Pennisi
In the 26 November issue of Nature, cell biologists report findings that may help explain one of the mysteries of evolution, namely how closely related organisms can come to look and act quite differently, often in a short period of time. The researchers' work suggests that the fruit fly genome contains a hidden reservoir of small mutations. Normally, these mutations are masked by HSP90, one of the so-called heat shock proteins that bind to other proteins to protect them against stresses such as high temperatures and also help newly made proteins fold correctly. But when HSP90 is out of commission, as may happen when the organism is stressed, it can no longer stabilize the proteins made by the mutant genes and keep them working properly, and the mutations are revealed. Usually, they alter physical traits in harmful ways but may in some cases produce changes that help the organism adapt to the stress.
