Specially bred Escherichia coli bacteria (here: electron micrograph of thin sections) can withstand temperatures of 48.5 degrees. However, they grow slower than their ancestors. Image: Jeannette Winter / TU Munich
Reading aloud With the production of heat protection proteins, bacteria adapt to higher temperatures. However, the protection costs strength: the microorganisms grow slower. A research team from the Technical University of Munich (TUM) found this out when, through breeding, it got used to the bacterium Escherichia coli for survival at temperatures above 48.5 degrees Celsius? 11.5 degrees more than the usual feel-good temperature. The microbes produce the protein GroE when heated. This in turn stabilizes other proteins that lose their shape at high temperatures. The intestinal bacterium Escherichia coli is one of the most important workhorses of biotechnology. It replicates rapidly and produces insulin as well as many other pharmaceutically important substances. Normally, the bacterium feels most comfortable at 37 degrees Celsius. Higher temperatures cause stress to the organism, temperatures above 46 degrees Celsius are already deadly. The scientists have now studied on Escherichia coli bacteria how organisms adapt to higher temperatures through evolution.

The researchers around winter biochemist Escherichia coli have gradually grown through evolution over several years, a higher heat resistance: the bacteria now grow at temperatures of 48.5 degrees Celsius. Here, however, a natural limit seems to exist for the organism. Compared to the ancestors, the heat-resistant bacteria already contained the protein GroE known as heat protection in 16-fold higher concentrations under normal conditions. However, the heat resistance has its price: Since the organism carries changes in the genome due to the constant stress and puts a lot of energy into the production of heat protection proteins, it grows overall slower than its ancestors.

GroE belongs to the so-called chaperones: These proteins help freshly produced proteins to fold correctly. Each protein consists of a long chain of amino acids. Only through artistic folding into a three-dimensional structure does it become the functioning protein. In the case of the bacterium Escherichia coli, GroE solidified proteins that become unstable at higher temperatures and returned them to their functional form. "The ability of heat-resistant bacteria to produce significantly higher levels of GroE is a critical factor in survivability under these conditions, " explains Jeannette Winter.

The study also provides clues as to how organisms adapt to changing environmental conditions. This could open up new avenues for the targeted breeding of organisms for specific tasks: "These are not only bacteria for the production of pharmaceutically interesting proteins, but also, for example, bacteria that can break down environmental toxins under harsh environmental conditions, " explains Winter. display

Jeannette Winter (Technical University of Munich) et al .: Journal of Biological Chemistry, doi: 10.1074 / bjc.M110.103374 ddp / science.de? Rochus Rademacher

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