CAENORHABDITIS-ELEGANS HAS 2 ISOZYMIC FORMS, CE-1 AND CE-2, OF FRUCTOSE-1,6-BISPHOSPHATE ALDOLASE WHICH ARE ENCODED BY DIFFERENT GENES

Two distinct types of cDNAs for fructose-1,6-bisphosphate (FBP) aldola se, Ce-1 and Ce-2, have been isolated from nematode Caenorhabditis ele gans, and the respective recombinant aldolase isozymes, CE-1 and CE2, have been purified and characterized. The Ce-1 and Ce-2 are 1282 and 1 248 bp in total length, respectively, and both have an open reading fr ame of 1098 bp, which encodes 366 amino acid residues. The entire amin o acid sequences deduced from Ce-1 and Ce-2 show a high degree of iden tity to one another and to those of vertebrate and invertebrate aldola ses. The highest sequence diversity was found in the carboxyl-terminal region that corresponds to one of the isozyme group-specific sequence s of vertebrate aldolase isozymes that play a role in determining isoz yme-specific functions. Southern blot analysis suggests that CE-1 and CE-2 are encoded by different genes. Concerning general or kinetic pro perties, CE-2 is quite different from CE-1. CE-1 exhibits unique chara cteristics which are not identical to any aldolase isozymes previously reported, whereas CE-2 is similar to vertebrate aldolase C. These res ults suggest that CE-2 might preserve the properties of a progenitor a ldolase with a moderate preference for FBP over fructose 1-phosphate ( F1P) as a substrate, whereas CE-1 evolved to act as an intrinsic enzym e that exhibits a much broader substrate specificity than does CE-2. ( C) 1997 Academic Press.