A novel chloride channel in Vicia faba guard cell vacuoles activated by the serine/threonine kinase, CDPK.

Published

Journal Article

Calcium-Dependent Protein Kinases (CDPKs) in higher plants contain a C-terminal calmodulin-like regulatory domain. Little is known regarding physiological CDPK targets. Both kinase activity and multiple Ca2+-dependent signaling pathways have been implicated in the control of stomatal guard cell movements. To determine whether CDPK or other protein kinases could have a role in guard cell signaling, purified and recombinant kinases were applied to Vicia faba guard cell vacuoles during patch-clamp experiments. CDPK activated novel vacuolar chloride (VCL) and malate conductances in guard cells. Activation was dependent on both Ca2+ and ATP. Furthermore, VCL activation occurred in the absence of Ca2+ using a Ca2+-independent, constitutively active, CDPK* mutant. Protein kinase A showed weaker activation (22% as compared with CDPK). Current reversals in whole vacuole recordings shifted with the Nernst potential for Cl-and vanished in glutamate. Single channel recordings showed a CDPK-activated 34 +/- 5 pS Cl- channel. VCL channels were activated at physiological potentials enabling Cl- uptake into vacuoles. VCL channels may provide a previously unidentified, but necessary, pathway for anion uptake into vacuoles required for stomatal opening. CDPK-activated VCL currents were also observed in red beet vacuoles suggesting that these channels may provide a more general mechanism for kinase-dependent anion uptake.

Full Text

Duke Authors

Cited Authors

  • Pei, ZM; Ward, JM; Harper, JF; Schroeder, JI

Published Date

  • December 1996

Published In

Volume / Issue

  • 15 / 23

Start / End Page

  • 6564 - 6574

PubMed ID

  • 8978683

Pubmed Central ID

  • 8978683

Electronic International Standard Serial Number (EISSN)

  • 1460-2075

International Standard Serial Number (ISSN)

  • 0261-4189

Digital Object Identifier (DOI)

  • 10.1002/j.1460-2075.1996.tb01047.x

Language

  • eng