Cloning and characterization of the glycogen branching enzyme gene existing in tandem with the glycogen debranching enzyme from Pectobacterium chrysanthemi PY35

Abstract

The glycogen branching enzyme gene ( glgB) from Pectobacterium chrysanthemi PY35 was cloned, sequenced, and expressed in Escherichia coli. The glgB gene consisted of an open reading frame of 2196 bp encoding a protein of 731 amino acids (calculated molecular weight of 83,859 Da). The glgB gene is upstream of glgX and the ORF starts the ATG initiation codon and ends with the TGA stop codon at 2 bp upstream of glgX. The enzyme was 43–69% sequence identical with other glycogen branching enzymes. The enzyme is the most similar to GlgB of E. coli and contained the four regions conserved among the α-amylase family. The glycogen branching enzyme (GlgB) was purified and the molecular weight of the enzyme was estimated to be 84 kDa by SDS–PAGE. The glycogen branching enzyme was optimally active at pH 7 and 30 °C.