Identification of a novel esterase from the thermophilic bacterium Geobacillus thermodenitrificans NG80-2

• Published in: Extremophiles : life under extreme conditions 2019-07, Vol.23 (4), p.407-419
• Main Authors: Curci, Nicola, Strazzulli, Andrea, De Lise, Federica, Iacono, Roberta, Maurelli, Luisa, Dal Piaz, Fabrizio, Cobucci-Ponzano, Beatrice, Moracci, Marco
• Format: Article
• Language: English
• Subjects: 12th International Congress on Extremophiles; Bacteria; Biochemistry; Biomedical and Life Sciences; Biotechnology; Cofactors; Dithiothreitol; Enterobactin; Enzymatic activity; Enzyme activity; Enzymes; Esterase; Esterases; Esters; Geobacillus thermodenitrificans; Iron; Life Sciences; Microbial Ecology; Microbiology; n-Hexane; Organic solvents; Original Paper; Phylogeny; Recombinants; Siderophores; Space life sciences; Specificity; Substrate specificity; Substrates; Uptake
• ISSN: 1431-0651; 1433-4909
• DOI: 10.1007/s00792-019-01093-9

In the framework of the discovery of new thermophilic enzymes of potential biotechnological interest, we embarked in the characterization of a new thermophilic esterase from the thermophilic bacterium Geobacillus thermodenitrificans . The phylogenetic analysis of the GTNG_0744 esterase indicated that the sequence belongs to the enterochelin/enterobactin esterase group, which have never been recognized as a family in the lipases/esterase classification. These enzymes catalyze the last step in the acquisition of environmental Fe 3+ through siderophore hydrolysis. In silico analysis revealed, for the first time, that the machinery for the uptake of siderophores is present in G. thermodenitrificans . The purified recombinant enzyme, EstGtA3, showed different substrate specificity from known enterochelin/enterobactin esterases, recognizing short chain esters with a higher specificity constant for 4-NP caprylate. The enzyme does not require cofactors for its activity, is active in the pH range 7.0–8.5, has highest activity at 60 °C and is 100% stable when incubated for 16 h at 55 °C. DTT, β-mercaptoethanol and Triton X-100 have an activating effect on the enzymatic activity. Organic solvents have in general a negative effect on the enzyme, but n-hexane is a strong activator up to 150, making EstGtA3 a good candidate for applications in biotechnology.