title: Structures and analysis of highly homologous psychrophilic, mesophilic, and thermophilic adenylate kinases.
abstract: The crystal structures of adenylate kinases from the psychrophile Bacillus globisporus and the mesophile Bacillus subtilis have been solved and compared with that from the thermophile Bacillus stearothermophilus. This is the first example we know of where a trio of protein structures has been solved that have the same number of amino acids and a high level of identity (66-74%) and yet come from organisms with different operating temperatures. The enzymes were characterized for their own thermal denaturation and inactivation, and they exhibited the same temperature preferences as their source organisms. The structures of the three highly homologous, dynamic proteins with different temperature-activity profiles provide an opportunity to explore a molecular mechanism of cold and heat adaptation. Their analysis suggests that the maintenance of the balance between stability and flexibility is crucial for proteins to function at their environmental temperatures, and it is achieved by the modification of intramolecular interactions in the process of temperature adaptation.
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Euiyoung
authors.initials: E
authors.lastname: Bae
authors.forename: George N
authors.initials: GN
authors.lastname: Phillips
mesh_terms: D000263:Adenylate Kinase / Q000737:chemistry*; D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology; D001412:Bacillus subtilis / Q000201:enzymology; D002152:Calorimetry, Differential Scanning; D003001:Cloning, Molecular; D003080:Cold Temperature; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000378:metabolism; D001411:Geobacillus stearothermophilus / Q000201:enzymology; D006358:Hot Temperature; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013696:Temperature; D015032:Zinc / Q000737:chemistry
chemical_list: D000263:Adenylate Kinase; D015032:Zinc