Effects of the combined substitutions of amino acid residues on thermal properties of cold-adapted monomeric isocitrate dehydrogenases from psychrophilic bacteria

Extremophiles : Life Under Extreme Conditions
Miyuki Kobayashi, Yasuhiro Takada

Abstract

In the two cold-adapted monomeric isocitrate dehydrogenases from psychrophilic bacteria, Colwellia maris and Colwellia psychrerythraea (CmIDH and CpIDH, respectively), the combined substitutions of amino acid residues between the Leu693, Leu724 and Phe735 residues of CmIDH and the corresponding Phe693, Gln724 and Leu735 residues of CpIDH were introduced by site-directed mutagenesis. A double mutant of CmIDH substituted its Leu724 and Phe735 residues by the corresponding ones of CpIDH, CmL724Q/F735L, and the triple mutant of CpIDH, CpF693L/Q724L/L735F, showed the most decrease and increase of activity, respectively, of each wild-type and its all mutated enzymes. In the case of CmIDH, the substitutions of these three amino acid residues resulted in the decrease of catalytic activity and thermostability for activity, but the combined substitutions of amino acid residues did not necessarily exert additive effects on these properties. On the other hand, similar substitutions in CpIDH had quite opposite effects to CmIDH, and the effects of the combined substitutions were additive. All multiple mutants of CmIDH and CpIDH showed lower and higher catalytic efficiency (k(cat)/K(m)) values than the respective wild-type enzymes. Single and...Continue Reading

References

Aug 1, 1972·Journal of Bacteriology·J Y D'Aoust, D J Kushner
Nov 26, 1998·International Journal of Systematic Bacteriology·I YumotoH Okuyama
Nov 9, 2001·Extremophiles : Life Under Extreme Conditions·L ZecchinonC Gerday
Oct 22, 2003·FEMS Microbiology Letters·Zheng-Xiang WangAlexander Steinbüchel
Jan 19, 2006·Extremophiles : Life Under Extreme Conditions·Shinsuke MakiYasuhiro Takada
Jun 16, 2010·Archives of Microbiology·Shougo MatsuoYasuhiro Takada

Related Concepts

Bacterial Proteins
Enzyme Stability
Isocitrate Dehydrogenase-I
Amino Acid Substitution
Alteromonadaceae
Digestion
Isocitrate Dehydrogenase (NAD+)
Viral Structural Proteins
Mutagenesis Process
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