Can a gene mutation make bacteria better at surviving extreme heat?

Details

The grpE gene of Escherichia coli is essential for bacteriophage lambda DNA replication and is also necessary for the bacterial host’s RNA and DNA synthesis at high temperature.

In a laboratory experiment, researchers compared an E. coli grpE mutant with wild-type bacteria and a grpE+ revertant under heat exposure, and also compared the mutant’s sensitivity to H2O2 and UV with that of the wild-type. The grpE mutant was substantially more resistant to 50°C heat treatment than the wild-type.

After a 42°C heat shock lasting 15 min, both the wild-type and the grpE mutant became more resistant to heat—that is, they became thermotolerant. The grpE+ revertant behaved similarly to the wild-type: it was more sensitive to heat than the grpE mutant.

The grpE mutant had the same sensitivity to hydrogen peroxide (H2O2) and ultraviolet radiation (UV) as the wild-type. This implies that the benefit of the grpE mutation was specific to heat exposure, rather than extending to H2O2 or UV exposure.

Heat-shock protein synthesis occurred sooner in the grpE mutant than in the wild-type, indicating that the E. coli grpE gene may influence regulation of the heat-shock response.