Biochemical and structural characterization of a novel halotolerant cellulase from soil metagenome

Abstract

Cellulase catalyzes the hydrolysis of β-1,4-linkages of cellulose to produce industrially relevant monomeric subunits. Cellulases find their applications in pulp and paper, laundry, food and feed, textile, brewing industry and in biofuel production. These industries always have great demand for cellulases that can work efficiently even in harsh conditions such as high salt, heat, and acidic environments. While, cellulases with high thermal and acidic stability are already in use, existence of a high halotolerant cellulase is still elusive. Here, we report a novel cellulase Cel5R, obtained from soil metagenome that shows high halotolerance and thermal stability. The biochemical and functional characterization of Cel5R revealed its endoglucanase activity and high halostability. In addition, the crystal structure of Cel5R determined at 2.2 Å resolution reveals a large number of acidic residues on the surface of the protein that contribute to the halophilic nature of this enzyme. Moreover, we demonstrate that the four free and non-conserved cysteine residues (C65, C90, C231 and C273) contributes to the thermal stability of Cel5R by alanine scanning experiments. Thus, the newly identified endoglucanase Cel5R is a promising candidate for various industrial applications.

Substrate-Induced Response in Biogas Process Performance and Microbial Community Relates Back to Inoculum Source

“…Members of this genus have been found at various relative abundances in other anaerobic digesters and also in other anaerobic environments, such as cow manure, wetlands, sludge from alkali-hydrolyzed rice straw, and plant residues in irrigated rice-field soil [ 47 , 48 , 49 , 50 , 51 , 52 ]. The genus Paludibacter was recently also suggested as a potential cellulose degrader [ 51 , 53 ].…”

Understanding High-Salt and Cold Adaptation of a Polyextremophilic Enzyme

“…Halophily was evidenced by a highly negatively charged surface [ 14 , 20 , 29 ]. The negatively charged surface residues coordinate hydrated ions and therefore form a highly ordered solvation shell, which prevents aggregation and increases protein solubility [ 15 , 25 , 74 , 75 ]. Additionally, halophilic proteins have a reduced overall hydrophobicity to prevent aggregation and retain structural flexibility at high salt concentrations [ 76 ].…”

Identification and characterization of a novel alkalistable and salt‐tolerant esterase from the deep‐sea hydrothermal vent of the East Pacific Rise

“…Metagenomics, a cultivation‐independent method, provides a way to discover new functional genes in both cultured and uncultured microorganisms. Since the potential of functional metagenomics was first discovered by Rondon, Raffel, Goodman, & Handelsman (), various enzymes such as carboxylesterase (Alcaide, Stogios, et al., ; Alcaide, Tchigvintsev, et al., ; Popovic et al., ), beta‐glycosidase (Matsuzawa & Yaoi, ), cellulase (Garg et al., ; Zhao et al., ) and chitinase (Berini et al., ) have been identified using metagenomic screening.…”