Molecular signals switch off genetic limitations
Researchers from FOM Institute AMOLF have demonstrated that genetic limitations in organisms can be switched on and off by molecules in their environment. Consequently the evolutionary development of an organism can suddenly stop. In other cases, an organism whose evolution has stagnated can suddenly compete again in the evolutionary race. The findings contribute to a better understanding of the evolutionary history and to map the possible future of the evolutionary process. The study was published on 27 June 2013 in PLoS Genetics.
Organisms can improve themselves by means of evolution, but there are limitations to this improvement. For example, evolution can never break the laws of physics. In addition, evolutionary progress comes to a standstill if the 'next step' requires a rare combination of mutations.
Molecular signals
Research in the group of Prof.dr.ir. Sander Tans has now demonstrated that molecular signals can strongly influence such genetic limitations. An example of a molecular signal is a sugar present in an organism's environment. The sugar can bind to a protein of the organism. This can change the shape of the protein to the extent that its functioning can be influenced by mutations in new ways that were not previously possible. As a result, a protein and organism that had come to an evolutionary standstill can once again participate in the evolutionary rat race. The converse is also possible – a molecule that binds to a protein can put an end to an evolutionary spurt of this protein.
Experimental approach
The researchers developed an entirely new approach for the study. Previously it was already possible to follow natural evolution for a period of time, for example by growing bacteria in a test-tube. However such a method only reveals what happens and not the reasons why.
The FOM researchers therefore artificially constructed the relevant genetic variants of the E. coli lac-suppressor protein that can bind to lactose. This suppressor protein detects lactose in its environment. If no lactose is present the protein changes shape and will consequently suppress the production of lactose-degrading enzymes. The researchers determined the growth potential of the E. coli bacteria with and without lactose in the environment. The measurements formed a multidimensional 'map' of the relationship between the molecular signal, the growth potential and the genetic variations as a consequence of mutations. The map illustrated the switching on and off of genetic limitations by the molecular signal.
The study helps to provide a better understanding of the evolutionary process in terms of both its history and its future. In addition, the discovery is important for gaining a better understanding of the evolution of antibiotic resistance, for example.
Reference
Environmental dependence of genetic constraint, Marjon G. J. de Vos, Frank J. Poelwijk, Nicholas Battich, Ndika Tanyi and Sander J. Tans. PLoS Genetics, June 2013.
Contact
Prof.dr.ir. Sander Tans, +31 (0) 20 754 71 00.
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