Crystal structures of thermally stable adenylate kinase mutants designed by local structural entropy optimization and structure-guided mutagenesis

Thermally stable proteins are desirable in many industrial and laboratory settings, and numerous approaches have been developed to redesign proteins for higher thermal stability. Here, we report the crystal structures of two thermally stable adenylate kinase (AK) mutants that were designed by applying a combination of local structural entropy (LSE) optimization and structure-guided mutagenesis. Structure-guided mutagenesis resulted in stabilizing interactions connecting distant regions of the LSEoptimized AK sequence. This demonstrates the feasibility and importance of simultaneous optimization of local and global features in protein thermal stabilization. An additional AK mutant showed that small changes in side-chain configuration can greatly impact thermal stability.