Datorbaserad analys av enzymers adaption till extrema mijöer
Tidsperiod: 2019-01-01 till 2022-12-31
Projektledare: Johan Åqvist
Budget: 4 043 000 SEK
This project deals with the problem of how enzymes can be shaped by evolution to work under extreme conditions. In particular, we will address cold-adapted enzymes that are able to maintain a high catalytic activity near the freezing point of liquid water. Their main problem is the exponential decay of reaction rates as the temperature is lowered and the thermodynamic solution to this problem appears to be to move part of the activation free energy from enthalpy to entropy. The sequence identity between orthologous enzymes from psychrophiles, mesophiles and thermophiles can be very high, which means that a limited number of mutations suffice to alter both the temperature dependence of the catalyzed reactions and the thermal stability of the protein. The structural and energetic origin of such remarkable adaptation effects is a major unsolved problem that can now be attacked by state-of-the-art computer simulations developed by us. We will examine how both reaction activation parameters and protein stability is affected by mutations that have been fixed by evolution, for several cases of orthologous enzymes where structural information is available. Predictions from such computations will be tested experimentally. Besides psychrophilic enzymes, adaptation to both heat and high salt concentration will also be considered. In a collaborative effort, we will further attempt to characterize psychrophilic ribosomes that appear to show some distinct adaptive features.