Nucleotide Sequence of a Paenibacillus Endoglucanase Gene and Characterization of the Recombinant Enzyme

Abstract

An endoglucanase gene of Paenibacillus sp. strain KSM-N546 was cloned and sequenced. The gene for the endoglucanase (Egl-546H) had an open reading frame of 1710 bp that encoded a putative signal sequence (37 amino acids) and mature enzyme (533 amino acids: 61,348 Da). The mature enzyme was most homologous to a cellulase of Geobacillus sp. Y412MC10 with 68% identity. The optimal pH and temperature of the recombinant enzyme for degrading carboxymethyl cellulose (CMC) were around pH 5.3 and 40°C, respectively. The enzyme efficiently degraded CMC and lichenan as well as glucomannan. It was crystallized with a rod shape by a hanging drop vapor-diffusion method. Egl-546H is comprised of two conserved domains, a glycosyl hydrolase family 5 domain and a DUF291 domain of unknown function. Several mutant proteins deleted of a DUF291-like domain were produced by Escherichia coli as inclusion bodies with no enzymatic activity.