Human aldolase B: liver-specific properties of the isozyme depend on type B isozyme group-specific sequences.
A series of chimeric enzymes between two human aldolases A, B or C were constructed to identify the molecular regions responsible for isozyme-specific functions. Chimeras constructed between aldolases A and B were AB34 (an AB chimera connected at position 34), ABA34-306 and ABA212-306 (the ABA chimeras). Those between aldolases B and C are BC243, BC263 and BC306 (the BC chimeras connected at positions as indicated), as well as CB55, CB243, CB263 and CB306 (the CB chimeras connected at positions as indicated), CBC55-263 (a CBC chimera), and BCB55-193, BCB55-306, BCB79-193 and BCB79-306 (the BCB chimeric enzymes). Through the analysis of the properties of these chimeras, it was found that for aldolase B, isozyme B group-specific sequences (IGSs)-1 and -4 were required for exerting type B-specific functions, while the IGSs-2 and -3 enhanced, in collaboration with the IGS-1, the catalytic activity of aldolase B. In addition, the alpha/beta-barrel and the restricted stretches, which were not specified but occupied two distinct regions spanning the amino acid positions 108-137 (designated connector 1) and 243-306 (designated connector 2), were found to be indispensable for showing full catalytic activity of aldolase B.
Kusakabe
T
T
Department of Biochemistry, Saga Medical School, Japan.
Motoki
K
K
Sugimoto
Y
Y
Takasaki
Y
Y
Hori
K
K
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000235:genetics; D005634:Fructose-Bisphosphate Aldolase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D005634:Fructose-Bisphosphate Aldolase