EVOLUTIONARY OPTIMIZATION OF LOW TEMPERATURE ACTIVITY IN HYPERTHERMOPHILIC GLUCOKINASES

Seyedeh Shirin Kamalaldinezabadi¹ and Brian G. Miller^{1, 2}

1 Institute of Molecular Biophysics, Florida State University, Tallahassee FL, USA

2 Department of Chemistry and Biochemistry, Florida State University, Tallahassee FL, USA

Proteins experience functionally important motions across a range of timescales spanning more than 12 orders of magnitude. The question of how evolution tailors protein dynamics for optimal function over such a large temporal window remains unanswered. To address this question, we are: (1) using directed evolution to maximize the activity of two homologous hyperthermophilic glucokinases at low temperature, and (2) investigating the dynamic consequences of this evolutionary process. Here, we present the results of experiments in which error-prone PCR is coupled with an in vivo genetic selection system to identify variants with elevated enzymatic activity at 30˚C. We also describe preliminary investigations into the structural, functional and dynamic attributes of the starting catalysts and the evolved variants. The results of our study are expected to provide fundamental insight into the types of motions that are required for optimal function and the number of distinct mutational trajectories capable of overcoming the dynamic dysfunction of hyperthermophilic proteins at low temperature.