CHARACTERIZATION OF A MAIZE CDNA THAT COMPLEMENTS AN ENOLASE-DEFICIENT MUTANT OF ESCHERICHIA-COLI

A cDNA encoding maize enolase (2-phospho-D-glycerate hydrolase) was purified by functional genetic complementation using an enolase deficient mutant of Escherichia coli, DF261. This cDNA, pZM245, was characterized by restriction mapping and DNA sequence analysis. The cDNA contained an open reading frame encoding a protein of 446 amino acids with a high degree of similarity to enolase sequences from other organisms (72% identity to yeast enolase and 82% identity to human enolase). The pZM245 contains a correctly positioned consensus prokaryotic translation initiation sequence. The specific activity of enolase in maize increases to about twice its initial level after 48 hours of anaerobiosis. Northern-blot analysis showed a five-fold anaerobic induction in enolase mRNA, while heat shock or cold shock increased enolase mRNA levels only slightly. Southern-blot analysis of maize genomic DNA indicated that there is one copy of the pZM245 hybridizing sequence per haploid genome in maize.