Cloning and characterization of a thermostable glutathione reductase from a psychrophilic Arctic bacterium Sphingomonas sp
ABSTRACT Glutathione reductase is an important oxidoreductase that helps maintain redox homeostasis by catalyzing the conversion of glutathione disulfide to glutathione using NADPH as a cofactor. In this study, we cloned and characterized a glutathione reductase (hereafter referred to as SpGR) from...
Published in: | FEMS Microbiology Letters |
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Main Authors: | , , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Oxford University Press (OUP)
2019
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Subjects: | |
Online Access: | http://dx.doi.org/10.1093/femsle/fnz218 http://academic.oup.com/femsle/advance-article-pdf/doi/10.1093/femsle/fnz218/30194884/fnz218.pdf https://academic.oup.com/femsle/article-pdf/366/18/fnz218/42816832/fnz218.pdf |
Summary: | ABSTRACT Glutathione reductase is an important oxidoreductase that helps maintain redox homeostasis by catalyzing the conversion of glutathione disulfide to glutathione using NADPH as a cofactor. In this study, we cloned and characterized a glutathione reductase (hereafter referred to as SpGR) from Sphingomonas sp. PAMC 26621, an Arctic bacterium. SpGR comprises 449 amino acids, and functions as a dimer. Surprisingly, SpGR exhibits characteristics of thermophilic enzymes, showing optimum activity at 60°C and thermal stability up to 70°C with ∼50% residual activity at 70°C for 2 h. The amino acid composition analysis of SpGR showed a 1.9-fold higher Arg content (6%) and a 2.7-fold lower Lys/Arg ratio (0.75) compared to the Arg content (3.15%) and the Lys/Arg ratio (2.01) of known psychrophilic glutathione reductases. SpGR also exhibits its activity at 4°C, and circular dichroism and fluorescence spectroscopy results indicate that SpGR maintains its secondary and tertiary structures within the temperature range of 4–70°C. Taken together, the results of this study indicate that despite its origin from a psychrophilic bacterium, SpGR has high thermal stability. Our study provides an insight into the role of glutathione reductase in maintaining the reducing power of an Arctic bacterium in a broad range of temperatures. |
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