Format

Send to

Choose Destination
Plant Cell. 2016 Feb;28(2):568-82. doi: 10.1105/tpc.15.00637. Epub 2016 Jan 13.

Reconstitution of CO2 Regulation of SLAC1 Anion Channel and Function of CO2-Permeable PIP2;1 Aquaporin as CARBONIC ANHYDRASE4 Interactor.

Author information

1
Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116.
2
Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116 College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China huhh@mail.hzau.edu.cn jischroeder@ucsd.edu.
3
Department of Physiology and Biophysics, Case Western Reserve University, Ohio 44106.
4
College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
5
Physics Department, University of California San Diego, La Jolla, California 92093.
6
Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116 huhh@mail.hzau.edu.cn jischroeder@ucsd.edu.

Abstract

Dark respiration causes an increase in leaf CO2 concentration (Ci), and the continuing increases in atmospheric [CO2] further increases Ci. Elevated leaf CO2 concentration causes stomatal pores to close. Here, we demonstrate that high intracellular CO2/HCO3 (-) enhances currents mediated by the Arabidopsis thaliana guard cell S-type anion channel SLAC1 upon coexpression of any one of the Arabidopsis protein kinases OST1, CPK6, or CPK23 in Xenopus laevis oocytes. Split-ubiquitin screening identified the PIP2;1 aquaporin as an interactor of the βCA4 carbonic anhydrase, which was confirmed in split luciferase, bimolecular fluorescence complementation, and coimmunoprecipitation experiments. PIP2;1 exhibited CO2 permeability. Mutation of PIP2;1 in planta alone was insufficient to impair CO2- and abscisic acid-induced stomatal closing, likely due to redundancy. Interestingly, coexpression of βCA4 and PIP2;1 with OST1-SLAC1 or CPK6/23-SLAC1 in oocytes enabled extracellular CO2 enhancement of SLAC1 anion channel activity. An inactive PIP2;1 point mutation was identified that abrogated water and CO2 permeability and extracellular CO2 regulation of SLAC1 activity. These findings identify the CO2-permeable PIP2;1 as key interactor of βCA4 and demonstrate functional reconstitution of extracellular CO2 signaling to ion channel regulation upon coexpression of PIP2;1, βCA4, SLAC1, and protein kinases. These data further implicate SLAC1 as a bicarbonate-responsive protein contributing to CO2 regulation of S-type anion channels.

PMID:
26764375
PMCID:
PMC4790870
DOI:
10.1105/tpc.15.00637
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center