title: Heterologous expression and characterization of a novel thermo-halotolerant endoglucanase Cel5H from Dictyoglomus thermophilum.
abstract: A novel β-1,4-endoglucanase gene was cloned from Dictyoglomus thermophilum, designated as Cel5H for being a member of glycoside hydrolase family 5. The purified recombinant endoglucanase showed high hydrolytic activities on carboxylmethyl cellulose with a broad optimal temperature of 50-85°C and an optimal pH of 5.0. Furthermore, this enzyme was highly thermostable with a half-life of 336 h at 70°C and retained more than 80% of the initial activity after 135 days incubation at 50°C. To enhance the performance of the thermophilic endoglucanase, chimeric enzymes containing Cel5H and syncretic cellulose binding module (CBM) were constructed. The results showed that all the CBMs were effective. In addition, Cel5H was highly tolerant against high salt concentration and distinguished from salt-tolerant bacteria since it was independent of high salt concentration. Three-dimensional structure of Cel5H was developed by homology modeling methods and surface electrostatic analysis was performed.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology,130 Meilong Road, Shanghai 200237, China.
authors.forename: Runrun
authors.initials: R
authors.lastname: Shi
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Li
authors.forename: Qin
authors.initials: Q
authors.lastname: Ye
authors.forename: Jianhe
authors.initials: J
authors.lastname: Xu
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology*; D001483:Base Sequence; D002480:Cellulase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D006358:Hot Temperature; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D002480:Cellulase
keywords: Cellulose binding module; Endoglucanase; Halo-tolerance; Homology modeling; Thermostability