loading page

Phosphorylation influences water and ion channel function of AtPIP2;1
  • +2
  • Jiaen Qiu,
  • Samantha McGaughey,
  • Michael Groszmann,
  • Steve Tyerman,
  • Caitlin Byrt
Jiaen Qiu
University of Adelaide
Author Profile
Samantha McGaughey
Australian National University
Author Profile
Michael Groszmann
Australian National University
Author Profile
Steve Tyerman
University of Adelaide
Author Profile
Caitlin Byrt
Australian National University
Author Profile

Peer review status:UNDER REVIEW

22 May 2020Submitted to Plant, Cell & Environment
22 May 2020Submission Checks Completed
22 May 2020Assigned to Editor
22 May 2020Reviewer(s) Assigned
13 Jun 2020Review(s) Completed, Editorial Evaluation Pending
09 Jul 20201st Revision Received
09 Jul 2020Submission Checks Completed
09 Jul 2020Assigned to Editor
09 Jul 2020Review(s) Completed, Editorial Evaluation Pending

Abstract

The phosphorylation states of two serine residues within the C-terminal domain of AtPIP2;1 (S280, S283) regulate its trafficking to the plasma membrane in response to salt and osmotic stress. Here we investigated whether the phosphorylation states of S280 and S283 also influence AtPIP2;1 facilitated water and cation transport. A series of single and double S280 and S283 phospho-mimic and -deficient AtPIP2;1 mutants were tested in heterologous systems. In Xenopus laevis oocytes, phospho-mimic mutants AtPIP2;1 S280D, S283D and S280D/S283D, had significantly greater ion conductance for Na+ and K+, whereas the S280A single and S280A/S283A double mutants, had greater water permeability. A phospho-mimic-dependent inverse relationship between AtPIP2;1 water and ion transport with a 10-fold change in both was observed. These results revealed that phosphorylation of S280 and S283 influences the preferential facilitation between ion and water permeability by AtPIP2;1. The results also hint at other sites playing a role that are yet to be elucidated. Expression of the phospho-mimic AtPIP2;1 mutants in Saccharomyces cerevisiae, confirmed that phosphorylation influences plasma membrane localisation, and revealed higher Na+ accumulation for S280A and S283D. Collectively, the results show that phosphorylation in the C-terminal domain of AtPIP2;1 influences its subcellular localisation and cation transport capacity.