Temperature and Protein Evolution
Temperature affects protein function by altering molecular interactions in native protein structures. As a result, natural selection favors proteins of certain amino acid sequences that preserve efficient protein functions in a particular thermal environment. But, how many proteins must adapt to temperature? Much work has shown this type of temperature adaptation within a certain class of enzymes called dehydrogenases. We have broadened this study of functional temperature adaptation by comparing enzyme kinetics among a diverse set of orthologous enzymes in the cold-adapted mussel Mytilus trossulus and the warm-adapted mussel Mytilus galloprovincialis. We have found that rates of temperature adaptation are variable among different classes of enzymes, and that relatively small numbers of amino acid substitutions cause large differences in the thermal sensitivity of enzyme function. Our results support the hypothesis that temperature adaptation at the protein level is largely dependent on the effects of temperature on protein structure-function relationships.
Mytilus mussels are interesting in the context of temperature adaptation because the differences in temperature between the native environments of these two species constitute a few to several degrees Celsius, which are the same as the temperature increases predicted by models of global warming. Therefore, by studying temperature adaptation in this system we can gain insights into how ectotherms may adapt to climate change.
Mytilus mussels are interesting in the context of temperature adaptation because the differences in temperature between the native environments of these two species constitute a few to several degrees Celsius, which are the same as the temperature increases predicted by models of global warming. Therefore, by studying temperature adaptation in this system we can gain insights into how ectotherms may adapt to climate change.