Cellodextrin Phosphorylase from Clostridium thermocellum YM4 Strain Expressed in Escherichia coli.

Abstract

A cellodextrin phosphorylase (CDP) gene was cloned from Clostridium thermocellum YM4 strain by using a PCR cloning method. The nucleotide sequence of the gene contained an open reading frame of 2952 by encoding a polypeptide of 984 amino acid residues. The deduced protein sequence was very close to that of CDP from C. thermocellum ATCC 27405 (92% identity) but not so similar to that of CDP from C. stercorarium (20%). The recombinant CDP phosphorolyzed cellooligosaccharides larger than cellotriose and utilized cellooligosaccharides larger than cellobiose as the acceptor molecule. The enzyme was stable up to 60°C and showed highest activity at pH 7.5.