Partial gene identification and protein analysis of β-galactosidase from bird cherry-oat aphid

Abstract

Bird cherry-oat aphid, Rhopalosiphum padi L. (Hemiptera: Aphididae) is a key pest of wheat and barley in the wide area of the world. Beta-galactosidase (EC 3.2.1.23) is an important digestive enzyme of R. padi which catalyses the hydrolysis of terminal, non-reducing beta-D-galactose residues in beta-D-galactosides. In this study a part of β-galactosidase (βgal) gene was isolated from R. padi (designated as Rp-βgal-JN835184), which contained 186 nucleotide coding and 62 amino acids. Homology search was done by BLAST in GenBank database. The identified protein sequence was aligned with 33 βgal protein sequences from various insects, two animals including human and mouse, two samples from rice and thale cress and two bacteria samples including Synechococcus sp. and Escherschia coli. Rp-βgal-JN835184 was analysed by computational tools to predict the protein properties, such as molecular mass, isoelectric point, signal peptide, transmembrane domain, secondary and spatial structure. Protein structure analysis revealed the deduced Rp-βgal-JN835184 had extensive homology with insect βgals and other organisms. Phylogenetic analysis of Rp-βgal-JN835184 showed that it has a close relationship with the bacteria, Synechococcus sp. Accordingly, βgals should be functional proteins involved in the biosynthesis of lactose and are derived from a common ancestor.