Phytochelatins (PCs) and metallothioneins (MTs) are the two major heavy metal chelating peptides in eukaryotes. We report here on the identification of a biosynthetically inactive pseudo-phytochelatin synthase enzyme (TtpsiPCS) in the ciliate Tetrahymena thermophila, the first of this kind (pseudo-PCS) to be described in eukaryotes. TtpsiPCS which resembles a true PCS at the N-terminal region, while it is most divergent in its Cys-poor C-terminal region, was found to be up-regulated under cadmium stress conditions. However, only glutathione (GSH) hydrolysis products, but not PCs, could be detected in extracts from Cd-treated cells. The latter feature is reminiscent of pseudo-PCS enzymes recently identified in cyanobacteria, which are also biosynthetically inactive, but capable to hydrolyze GSH.

A pseudo-phytochelatin synthase in the ciliated protozoan Tetrahymena thermophila / Amaro, F; Ruotolo, Roberta; MARTÍN GONZÁLEZ, A; Faccini, A; Ottonello, Simone; Gutiérrez, Jc. - In: COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C. TOXICOLOGY & PHARMACOLOGY. - ISSN 1532-0456. - 149:(2009), pp. 598-604. [10.1016/j.cbpc.2009.01.002]

A pseudo-phytochelatin synthase in the ciliated protozoan Tetrahymena thermophila

RUOTOLO, Roberta;OTTONELLO, Simone;
2009

Abstract

Phytochelatins (PCs) and metallothioneins (MTs) are the two major heavy metal chelating peptides in eukaryotes. We report here on the identification of a biosynthetically inactive pseudo-phytochelatin synthase enzyme (TtpsiPCS) in the ciliate Tetrahymena thermophila, the first of this kind (pseudo-PCS) to be described in eukaryotes. TtpsiPCS which resembles a true PCS at the N-terminal region, while it is most divergent in its Cys-poor C-terminal region, was found to be up-regulated under cadmium stress conditions. However, only glutathione (GSH) hydrolysis products, but not PCs, could be detected in extracts from Cd-treated cells. The latter feature is reminiscent of pseudo-PCS enzymes recently identified in cyanobacteria, which are also biosynthetically inactive, but capable to hydrolyze GSH.
A pseudo-phytochelatin synthase in the ciliated protozoan Tetrahymena thermophila / Amaro, F; Ruotolo, Roberta; MARTÍN GONZÁLEZ, A; Faccini, A; Ottonello, Simone; Gutiérrez, Jc. - In: COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C. TOXICOLOGY & PHARMACOLOGY. - ISSN 1532-0456. - 149:(2009), pp. 598-604. [10.1016/j.cbpc.2009.01.002]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2283525
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