Discovery and Characterization of a Thermostable and Highly Halotolerant GH5 Cellulase from an Icelandic Hot Spring Isolate

• Published in: PloS one 2016-01, Vol.11 (1), p.e0146454
• Main Authors: Zarafeta, Dimitra, Kissas, Dimitrios, Sayer, Christopher, Gudbergsdottir, Sóley R, Ladoukakis, Efthymios, Isupov, Michail N, Chatziioannou, Aristotelis, Peng, Xu, Littlechild, Jennifer A, Skretas, Georgios, Kolisis, Fragiskos N
• Format: Article
• Language: English
• Subjects: Archaea; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Biochemical characteristics; Biochemistry; Bioinformatics; Biology; Biotechnology; Catalytic Domain; Cell culture; Cellulase; Cellulase - chemistry; Cellulase - genetics; Cellulose; Cellulose - chemistry; Chemical engineering; Chemistry; Chlorides - chemistry; Crystallography; Crystallography, X-Ray; Deoxyribonucleic acid; DNA; Environmental science; Enzyme Stability; Enzymes; Genomes; Glycoside hydrolase; Hot springs; Hot Springs - microbiology; Hot Temperature; Hydrogen-Ion Concentration; Hydrolase; Hydrolases; Iceland; Identification and classification; Kinetics; Laboratories; Metal concentrations; Metal ions; Models, Molecular; Pharmaceutical sciences; Properties; Proteins; Salinity tolerance; Salt Tolerance; Substrate Specificity; Sugar; Thermal stability; Thermoanaerobacter - enzymology; Thermoanaerobacter - genetics; X-ray crystallography
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0146454

With the ultimate goal of identifying robust cellulases for industrial biocatalytic conversions, we have isolated and characterized a new thermostable and very halotolerant GH5 cellulase. This new enzyme, termed CelDZ1, was identified by bioinformatic analysis from the genome of a polysaccharide-enrichment culture isolate, initiated from material collected from an Icelandic hot spring. Biochemical characterization of CelDZ1 revealed that it is a glycoside hydrolase with optimal activity at 70°C and pH 5.0 that exhibits good thermostability, high halotolerance at near-saturating salt concentrations, and resistance towards metal ions and other denaturing agents. X-ray crystallography of the new enzyme showed that CelDZ1 is the first reported cellulase structure that lacks the defined sugar-binding 2 subsite and revealed structural features which provide potential explanations of its biochemical characteristics.