Identification of conserved promoter elements for aldB and isozyme specific residues in aldolase B

The comparison of three complete aldolase B genes-including known and putat ive regulatory elements-is presented. The third aldolase B gene was provide d by the complete aldB gene sequence (14803 bp) encoding the rabbit aldolas e B isozyme. The promoter sequence alignment included the nonmammalian chic ken aldolase B gene and confirms the promoter sequence conservation of thos e elements where trans-factor binding has been demonstrated in rat aldB. Mo reover, the alignment reveals conserved sequences that may represent previo usly unidentified promoter elements that are present in all aldBs or specif ically in the mammalian aldB promoters. One remarkable feature is a poly-pu rine segment found between the CAAT and TATA elements. In the mammalian pro moters, this is exclusively a 9-10 bp poly-dA stretch. The avian promoter h as an additional stretch of eight dG-bases immediately upstream of the poly -dA. Alignment of a portion of intron 1 of the chicken, human, and rabbit a ldB genes reveals conserved sequences that are likely candidates for a repo rted positive activation sequence. In addition, the amino acid sequences of all eight known aldolase B isozymes is compared to the other vertebrate al dolases. A. number of aldolase B-specific residues are identified that clus ter in the carboxyl-portion of the sequence. With the exception of residue C268, these residues are not found near the active site, although, they are likely to be responsible for the substrate specificity of aldolase B. (C) 1999 Elsevier Science Inc. All rights reserved.