Role of isozyme group-specific sequence 4 in the isozyme-specific properties of human aldolase C.
To assess which regions of the aldolase C molecule are required for exhibiting isozyme-specific kinetic properties, we have constructed nine chimeric enzymes of human aldolases A and C. Kinetic studies of these chimeric enzymes revealed that aldolase C absolutely required its own isozyme group-specific sequences (IGS), particularly IGS-4, for exhibiting the characteristics of aldolase C which differ significantly from those of isozymes A and B (Kusakabe T, Motoki K, Hori K. Human aldolase C: characterization of the recombinant enzyme expressed in Escherichia coli. J Biochem (Tokyo) 1994;115:1172-7). Whereas human aldolases A and B required their own isozyme group-specific sequences-1 and -4 (IGS-1 and -4) as the main determinants of isozyme-specific kinetic properties (Motoki K, Kitajima Y, Hori K. Isozyme-specific modules on human aldolase A molecule. J Biol Chem 1993;268:1677-83; Kusakabe T, Motoki K, Sugimoto Y, Takasaki Y, Hori K. Human aldolase B: liver-specific properties of the isoenzyme depend on type B isozyme group-specific sequence. Prot. Eng. 1994;7:1387-93), the present studies indicate that the IGS-1 is principally substitutable between aldolases A and C. The kinetic data also suggests that the connector-2 (amino acid residues 243-306) may modulate the interaction of IGS units with the alpha/beta barrel of the aldolase molecule.
Kusakabe
T
T
Department of Biochemistry, Saga Medical School, Japan. kusakabe@agr.kyushu-u.ac.jp
Motoki
K
K
Sugimoto
Y
Y
Hori
K
K
D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D005634:Fructose-Bisphosphate Aldolase