The effects of multiple ancestral residues on the Thermus thermophilus 3-isopropylmalate dehydrogenase.
Previously, we showed that mutants of Thermus thermophilus 3-isopropylmalate dehydrogenase (IPMDH) each containing a residue (ancestral residue) that had been predicted to exist in a postulated common ancestor protein often have greater thermal stabilities than does the contemporary wild-type enzyme. In this study, the combined effects of multiple ancestral residues were analyzed. Two mutants, containing multiple mutations, Sup3mut (Val181Thr/Pro324Thr/Ala335Glu) and Sup4mut (Leu134Asn/Val181Thr/Pro324Thr/Ala335Glu) were constructed and show greater thermal stabilities than the wild-type and single-point mutant IPMDHs do. Most of the mutants have similar or improved catalytic efficiencies at 70 degrees C when compared with the wild-type IPMDH.
Watanabe
Keiko
K
Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Yamagishi
Akihiko
A
D050539:3-Isopropylmalate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D004789:Enzyme Activation; D004795:Enzyme Stability; D007521:Isocitrate Dehydrogenase / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011489:Protein Denaturation; D016415:Sequence Alignment; D016963:Thermus thermophilus / Q000201:enzymology*; D013997:Time Factors
D000596:Amino Acids; D007521:Isocitrate Dehydrogenase; D050539:3-Isopropylmalate Dehydrogenase