Nucleotide sequence of the melA gene, Coding for α-galactosidase inEscherichia coliK-12

Abstract
Mellbiose uptake and hydrolysis in E.coli Is performed by the MelB and MelA proteins, respectively. We report the cloning and sequencing of the melA gene. The nucleotlde sequence data showed that melA codes for a 450 amlno acid long protein with a molecular weight of 50.6 kd. The sequence data also supported the assumption that the mel locus forms an operon with melA in proximal position. A comparison of MelA with α -galactosidase proteins from yeast and human origin showed that these proteins have only limited homology, the yeast and human proteins being more related. However, regions common to all three proteins were found Indicating sequences that might comprise the active site of α-galactosidase.