Isozyme-specific modules on human aldolase A molecule. Isozyme group-specific sequences 1 and 4 are required for showing characteristics as aldolase A.
Vertebrate aldolase molecules bear at least four stretches of isozyme group-specific sequences (referred to as IGS). The IGSs of the type A isozyme are known to endow the aldolase molecules with some characteristics typical of A. In order to locate the type A regions, 4 chimeric enzymes were constructed between human aldolases A and B and 5 mutant enzymes with single or double mutations in the IGS-1 region. Among engineered proteins, the chimeric enzymes bearing the type A IGS-1 to -4 (BABA34-108:306-363) and the IGS-1 and -4 (BABA34-55:306-363) exhibited similarities to isozyme A in many respects. On the other hand, neither chimeric enzyme bearing the type A IGS-1 to -3 (BAB34-108) nor that bearing the IGS-1 alone (BAB34-55) exhibited properties as isozyme A. Four mutant aldolases A (carrying single mutation in the IGS-1 region) maintained the original activity as A. Similarly, the BA306 chimera with the type B-->A substitution at positions 41 and 45 (BA306 N41K:R45S) failed to exhibit the A-like properties although the activities toward Fru-1,6-P2 and Fru-1-P significantly increased. Conclusively, the type A IGS-1, together with the IGS-4, act as indispensable modules in determining the characteristic properties of human aldolase A.
Motoki
K
K
Department of Biochemistry, Saga Medical School, Japan.
Kitajima
Y
Y
Hori
K
K
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry* / Q000235:genetics; D005635:Fructosediphosphates / Q000378:metabolism; D005636:Fructosephosphates / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D014169:Transformation, Bacterial
D000911:Antibodies, Monoclonal; D005635:Fructosediphosphates; D005636:Fructosephosphates; D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; C032284:fructose-1-phosphate; D005634:Fructose-Bisphosphate Aldolase; C029063:fructose-1,6-diphosphate