Gene Encoding and Bioinformatics Analysis of Protein Structure of β-Galactosidase from Sunn Pest, Eurygaster integriceps Putton

Aims: To identify the partial sequence of beta-galactosidase (EC 3.2.1.23) enzyme of sunn pest, Eurygaster integriceps Putton (Hemiptera: Scutelleridae), which is a key pest of wheat and barley in the wide area of the world and its relationship with other creatures.
Place and Duration of Study: Department of Plant Protection, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran, and Department of Entomology, Science and Reaserch Branch, Islamic Azad University, Tehran, Iran. Between March 2012 and July 2013.
Methodology: A part of β-galactosidase (βgal) gene was isolated from E. integriceps (designated as Ei-βgal-JQ889818), containing 328 bp. Nucleotide sequences were translated into 109 amino acids by translation tools. Twenty-six beta-galactosidase protein sequences from twenty-seven insect species, two animal samples including human and mouse, two bacteria samples including Escherichia coli and Synechococcus sp. and a sample of plants including Arabidopsis thaliana were aligned. Homology search was done by BLAST to identify the most similar protein sequences to Ei-βgal-JQ889818.
Results: Protein structure analysis revealed that the deduced Ei-βgal-JQ889818 had extensive homology with other insect βgals and contained two catalytic domains of βgals. The predicted 3-D model of Ei-βgal-JQ889818 has a typical spatial structure of βgals and is partly similar to βgals. Phylogenetic tree analysis of Ei-βgal-JQ889818 showed that there is a close relationship among Arabidopsis thaliana, Acyrthosiphun pisum and Mus musculus.
Conclusion: Accordingly, βgals should be functional proteins involved in the biosynthesis of lactose and are derived from a common ancestor. This research will lead us to know more about the role of βgal as a digestive enzyme through its phylogenetic relationship.