title: Structural features determining thermal adaptation of esterases.
abstract: The adaptation of microorganisms to extreme living temperatures requires the evolution of enzymes with a high catalytic efficiency under these conditions. Such extremophilic enzymes represent valuable tools to study the relationship between protein stability, dynamics and function. Nevertheless, the multiple effects of temperature on the structure and function of enzymes are still poorly understood at the molecular level. Our analysis of four homologous esterases isolated from bacteria living at temperatures ranging from 10°C to 70°C suggested an adaptation route for the modulation of protein thermal properties through the optimization of local flexibility at the protein surface. While the biochemical properties of the recombinant esterases are conserved, their thermal properties have evolved to resemble those of the respective bacterial habitats. Molecular dynamics simulations at temperatures around the optimal temperatures for enzyme catalysis revealed temperature-dependent flexibility of four surface-exposed loops. While the flexibility of some loops increased with raising the temperature and decreased with lowering the temperature, as expected for those loops contributing to the protein stability, other loops showed an increment of flexibility upon lowering and raising the temperature. Preserved flexibility in these regions seems to be important for proper enzyme function. The structural differences of these four loops, distant from the active site, are substantially larger than for the overall protein structure, indicating that amino acid exchanges within these loops occurred more frequently thereby allowing the bacteria to tune atomic interactions for different temperature requirements without interfering with the overall enzyme function.
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-University Duesseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
authors.forename: Filip
authors.initials: F
authors.lastname: Kovacic
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-University Duesseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
authors.forename: Agathe
authors.initials: A
authors.lastname: Mandrysch
authors.affiliation: Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Juelich GmbH, D-52426 Juelich, Germany Department of Physics, Tampere University of Technology, FI-33101 Tampere, Finland.
authors.forename: Chetan
authors.initials: C
authors.lastname: Poojari
authors.affiliation: Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Juelich GmbH, D-52426 Juelich, Germany Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Duesseldorf, D-40225 Düsseldorf, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Strodel
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-University Duesseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Juelich GmbH, D-52426 Juelich, Germany karl-erich.jaeger@fz-juelich.de.
authors.forename: Karl-Erich
authors.initials: KE
authors.lastname: Jaeger
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000737:chemistry / Q000201:enzymology*; D004795:Enzyme Stability; D004950:Esterases / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016415:Sequence Alignment; D013696:Temperature
chemical_list: D004950:Esterases
keywords: esterase; molecular dynamics; psychrophilic, psychrotrophic, mesophilic, thermophilic bacteria; thermophilicity; thermostability