Localized structural effects of electrostatic interactions in a thermostable enzyme.
The sequence and resolved structure of thermotrophic isopropylmalate dehydrogenase (IPMDH) and a related protein, mesotrophic isocitrate dehydrogenase (IDH), were compared emphasizing clusters of charged residues identified from X-ray crystallographic studies (Wallon, G., Kryger, G., Lovett, S. T., Oshima, T., Ringe, D., and Petsko, G. A. (1997) J. Mol. Biol. 266, 1016-1031). Mesotrophic isocitrate dehydrogenase was used for comparison because crystallographic data for a mesotrophic form of IPMDH was not available in the database. The structural features in the region of these clusters were compared and localized conformational differences were found in the thermotroph compared to the mesotroph. Because the overall topology of the two proteins is similar, it was concluded that these localized structural differences induced by electrostatic interactions between charged residues in the thermotrophic enzyme were responsible for the enhanced thermal stability of proteins from thermotroph.
Rhode
D J
DJ
Department of Biochemistry, University of Tennessee, 858 Madison Avenue, Memphis, Tennessee, 38163, USA.
Martin
B L
BL
D050539:3-Isopropylmalate Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000737:chemistry*; D000595:Amino Acid Sequence; D004795:Enzyme Stability; D007521:Isocitrate Dehydrogenase / Q000737:chemistry*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
D000429:Alcohol Oxidoreductases; D007521:Isocitrate Dehydrogenase; D050539:3-Isopropylmalate Dehydrogenase