Phosphorylation influences water and ion channel function of AtPIP2;1. (17th August 2020)

• Record Type: Journal Article
• Authors: Qiu, Jiaen; McGaughey, Samantha A.; Groszmann, Michael; Tyerman, Stephen D.; Byrt, Caitlin S.
• Is Part Of: Plant, cell and environment. Volume 43:Number 10(2020)
• Page Start: 2428
• Page End: 2442
• Publication Date: 2020-08-17
• Subjects: aquaporin -- Arabidopsis -- gating -- NSCC -- osmotic stress -- potassium -- regulation -- salt stress -- sodium transport -- trafficking; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.13851
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: The phosphorylation state of two serine residues within the C‐terminal domain of AtPIP2;1 (S280, S283) regulates its plasma membrane localization in response to salt and osmotic stress. Here, we investigated whether the phosphorylation state of S280 and S283 also influence AtPIP2;1 facilitated water and cation transport. A series of single and double S280 and S283 phosphomimic and phosphonull AtPIP2;1 mutants were tested in heterologous systems. In Xenopus laevis oocytes, phosphomimic mutants AtPIP2;1 S280D, S283D, and S280D/S283D had significantly greater ion conductance for Na + and K +, whereas the S280A single phosphonull mutant had greater water permeability. We observed a phosphorylation‐dependent inverse relationship between AtPIP2;1 water and ion transport with a 10‐fold change in both. The results revealed that phosphorylation of S280 and S283 influences the preferential facilitation of ion or water transport by AtPIP2;1. The results also hint that other regulatory sites play roles that are yet to be elucidated. Expression of the AtPIP2;1 phosphorylation mutants in Saccharomyces cerevisiae confirmed that phosphorylation influences plasma membrane localization, and revealed higher Na + accumulation for S280A and S283D mutants. Collectively, the results show that phosphorylation in the C‐terminal domain of AtPIP2;1 influences its subcellular localization and cation transport capacity. Abstract : Salt‐stress associated changes in the phosphorylation state of Arabidopsis dual water‐ion permeable aquaporin AtPIP2;1 influence its channel function. Testing in a heterologous system revealed a phosphorylation‐mimic dependent inverse relationship between AtPIP2;1 water and ion channel function.