ENGINEERING THE XENOBIOTIC SUBSTRATE SPECIFICITY OF SWEET ORANGE TAU GLUTATHIONE S-TRANSFERASE

Glutathione S-transferases (GSTs) are a versatile group of enzymes widely distributed in nature and involved in cellular detoxification processes.
In a previous study we isolated from sweet orange leaves two GST genes, namely GSTU1 and GSTU2 (Lo Piero et al., 2009). The encoded proteins differ only for three amino acids all of them included in the C-terminal domain of the enzymes (R89P, E117K, I172V). In order to understand the significance of the single mismatched residues between U1 and U2 (R89P, E117K and I172V, respectively) site-directed mutagenesis experiments were undertaken to generate several mutate enzymes.
Among the mutate enzymes, GST-RKV, obtained by the substitution R89P upon the isoform GSTU2, showed extremely high catalytic efficiency towards GSH and pronounced ability to conjugate GSH to the alkyl halide 4-nitrophenethyl bromide, a molecule of toxicological interest in view of its occurrence as environmental pollutant.
Due to these features GST-RKV exhibits great potential for the development of germplasm with novel favourable traits.

II International Symposium on Citrus Biotechnology

A.R. Lo Piero, I. Puglisi, V. Mercurio, G. Petrone

sweet orange, tau class GST, detoxifying enzyme, site-directed mutagenesis

https://doi.org/10.17660/ActaHortic.2011.892.17