title: Neutron scattering reveals the dynamic basis of protein adaptation to extreme temperature.
abstract: To explore protein adaptation to extremely high temperatures, two parameters related to macromolecular dynamics, the mean square atomic fluctuation and structural resilience, expressed as a mean force constant, were measured by neutron scattering for hyperthermophilic malate dehydrogenase from Methanococcus jannaschii and a mesophilic homologue, lactate dehydrogenase from Oryctolagus cunniculus (rabbit) muscle. The root mean square fluctuations, defining flexibility, were found to be similar for both enzymes (1.5 A) at their optimal activity temperature. Resilience values, defining structural rigidity, are higher by an order of magnitude for the high temperature-adapted protein (0.15 Newtons/meter for O. cunniculus lactate dehydrogenase and 1.5 Newtons/meter for M. jannaschii malate dehydrogenase). Thermoadaptation appears to have been achieved by evolution through selection of appropriate structural rigidity in order to preserve specific protein structure while allowing the conformational flexibility required for activity.
authors.affiliation: Institut de Biologie Structurale Commissariat à l'Energie Atomique-CNRS-Université Joseph Fourier, 38027 Grenoble, France.
authors.forename: Moeava
authors.initials: M
authors.lastname: Tehei
authors.forename: Dominique
authors.initials: D
authors.lastname: Madern
authors.forename: Bruno
authors.initials: B
authors.lastname: Franzetti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zaccai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D004795:Enzyme Stability; D006358:Hot Temperature; D006860:Hydrogen Bonding; D007770:L-Lactate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D017017:Methanococcus / Q000201:enzymology; D008958:Models, Molecular; D009132:Muscles / Q000201:enzymology; D009502:Neutrons; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D011817:Rabbits; D013057:Spectrum Analysis / Q000379:methods*; D013816:Thermodynamics
chemical_list: D011506:Proteins; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase