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The Arabidopsis HAL2 ‐like gene family includes a novel sodium‐sensitive phosphatase
Author(s) -
GilMascarell Rosario,
LópezCoronado José M.,
Bellés José M.,
Serrano Ramón,
Rodríguez Pedro L.
Publication year - 1999
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1999.00385.x
Subject(s) - phosphatase , arabidopsis , yeast , biochemistry , arabidopsis thaliana , mutant , chemistry , polyphosphate , alkaline phosphatase , inositol , microbiology and biotechnology , biology , gene , enzyme , phosphate , receptor
Summary The yeastHAL2gene encodes a lithium‐ and sodium‐sensitive phosphatase that hydrolyses 3′‐phosphoadenosine‐5′‐phosphate (PAP). Salt toxicity in yeast results from Hal2 inhibition and accumulation of PAP, which inhibits sulphate assimilation and RNA processing. We have investigated whether the model plantArabidopsis thalianacontains sodium‐sensitive PAP phosphatases. TheArabidopsis HAL2‐like gene family is composed of three members:AtAHLandAtSAL2, characterized in the present work, and the previously identifiedAtSAL1. TheAtAHLandAtSAL2cDNAs complement the auxotrophy for methionine of the yeasthal2mutant and the recombinant proteins catalyse the conversion of PAP to AMP in a Mg 2+ ‐dependent reaction sensitive to inhibition by Ca 2+ and Li + . The PAP phosphatase activity of AtAHL is sensitive to physiological concentrations of Na + , whereas the activities of AtSAL1 and AtSAL2 are not. Another important difference is that AtAHL is very specific for PAP while AtSAL1 and AtSAL2 also act as inositol polyphosphate 1‐phosphatases. AtAHL constitutes a novel type of sodium‐sensitive PAP phosphatase which could act co‐ordinately with plant sulphotransferases and serve as target of salt toxicity in plants.