Characterization of the Glycogen Branching Enzyme from Pectobacterium carotovorum subsp carotovorum LY34

Abstract

A branching enzyme (EC 2.4.1.18) gene was isolated from Pectobacterium carotovorum subsp. carotovorum LY34. The branching enzyme gene, glgB, consists of an open reading frame (ORF) of 2,178 bp encoding a protein of 725 amino acids (calculated molecular weight of 83,891 Da). The ORF of the glgB gene starts with an ATG codon and ends with a TAA stop codon 3 bp upstream of glgX. The deduced amino acid sequence of GlgB has 40 to 95% similarity to known bacterial branching enzyme sequences. The enzyme is most similar to GlgB of Escherichia coli and contains the four regions conserved in the alpha-amylase family. The enzyme GlgB was purified and the molecular weight of the enzyme is estimated to be about 84 kDa. The glycogen branching enzyme is optimally active at pH 7 and 40 degrees C.