Phosphatase Subfamily Acr2

Phosphatase Classification: Superfamily Cys-based II: Family CDC25: Subfamily Acr2

Prokaryotes and eukaryotes use arsenate reductases of distinct folds. E. coli uses ArsC, which belongs to Superfamily Cys-based III, the same as LMWPTP and SSU72. Eukaryotes, particularly fungi, plants and protists, may use ACR2 which have the same fold as CDC25 [1]. However, knocking out ACR2 does not affect arsenic redox status in Arabidopsis thaliana and Saccharomyces cerevisiae , which implies the existence of other arsenate reductase(s) in plants and yeast [2].

Arc2 in eukaryotes

Saccharomyces cerevisiae. Overexpressed in E. coli, ARR2, the ACR2 gene of Saccharomyces cerevisiae, was shown to exhibit arsenate reductase activity and complement the arsenate-sensitive phenotype of an ArsC deletion in E. coli [1, 3, 4]. The Cx5R motif is required for its catalytic activity as arsenate reductase [5].

Arabidopsis thaliana. Acr2 of Arabidopsis thaliana was initially characterized as a phosphatase, given the evidences: i) protein structure solved by NMR [6], ii) recombinant expression in E. coli shows tyrosine phosphatase activity towards artificial substrate [7], and iii) overexpression in fission yeast function suggests it is a mitotic accelerator [8]. It has been suggested to play a role in arsenate reduction [9, 10, 11]. However, knocking out ACR2 does not affect arsenic redox status in Arabidopsis thaliana and Saccharomyces cerevisiae [2].

Pteris vittata (fern). The ACR2 of "Pteris vittata" (PvACR2) can suppress the arsenate sensitivity and arsenic hyperaccumulation phenotypes of yeast (Saccharomyces cerevisiae) lacking the arsenate reductase gene ACR2 [11, 12]. However, PvACR2 is unique in that the arginine of catalytic motif Cx5R, previously shown to be essential for phosphatase and reductase activity, is replaced with a serine.

Chlamydomonas reinhardtii (green alga). Chlamydomonas reinhardtii has two Acr2s. One of them complement the arsenate-sensitive phenotype of an ArsC deletion in E. coli [13]

Reference

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