AtPFA-DSP3, an atypical dual-specificity protein tyrosine phosphatase, affects salt stress response by modulating MPK3 and MPK6 activity.

Abstract

Protein phosphorylation, especially serine/threonine and tyrosine phosphorylation, plays significant roles in signaling during plant growth and development as well as plant responses to biotic or abiotic stresses. Dual-specificity protein tyrosine phosphatases dephosphorylate components of these signaling pathways. Here, we report that an atypical dual-specificity protein tyrosine phosphatase, AtPFA-DSP3 (DSP3), negatively affects the response of plants to high-salt conditions. A DSP3 loss-of-function mutant showed reduced sensitivity to salt treatment. DSP3 was primarily localized in nuclei and was degraded during salt treatment. Compared to wild-type, the level of ROS was lower in the dsp3 mutant and higher in plants ectopically expressing DSP3, indicating that higher DSP3 level was associated with increased ROS production. DSP3 interacted with and dephosphorylated MPK3 and MPK6. Genetic analyses of a dsp3mpk3 double mutant revealed that DSP3 s effect on salt stress depends on MPK3. Moreover, the phosphatase activity of DSP3 was required for its role in salt signaling. These results indicate that DSP3 is a negative regulator of salt responses in Arabidopsis by directly modulating the accumulation of phosphorylated MPK3 and MPK6. This article is protected by copyright. All rights reserved.