Cloning of two hexokinase isoenzyme sequences from Drosophila melanogaster

Hexokinase coding DM1 and DM2 sequences were obtained from genomic DNA of a Drosophila melanogaster cell line by PCR amplification strategy. Both the sequences were found to encode an enzyme with a molecular weight of 50,000 Da. Amino acid sequence alignment of DM1 and DM2 shows approximately 45% homology with yeast and human hexokinases. The sequences also indicated the presence of conserved amino acid residues and motifs that are present in mammalian hexokinases and are involved in the binding of different substrates. Southern blot analysis suggests that the D. melanogaster genome contain a single copy of DM1 and DM2 sequences. Northern analysis indicates DM1 is expressed as more than one transcript in adult as well as in the D.Mel2 cell line. DM2 is expressed as a single transcript in adult flies. Expression levels for DM1 and DM2 encoded message were found to be similar in different stages of development as seen by RT-PCR. The biotechnological significance of these sequences in metabolic engineering of cells is discussed.