Antibodies to the CFTR modulate the turgor pressure of guard cell protoplasts via slow anion channels

• Published in: FEBS letters 2001-04, Vol.494 (1), p.15-18
• Main Authors: Leonhardt, Nathalie, Bazin, Ingrid, Richaud, Pierre, Marin, Elena, Vavasseur, Alain, Forestier, Cyrille
• Format: Article
• Language: English
• Subjects: ABC, ATP-binding cassette; Animals; Anion channel; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - metabolism; ATP-binding cassette protein; BSA, bovine serum albumin; CFTR, cystic fibrosis transmembrane conductance regulator; Cystic fibrosis transmembrane conductance regulator; Cystic Fibrosis Transmembrane Conductance Regulator - immunology; GCPs, guard cell protoplasts; Guard cell; Humans; Ion Channels - metabolism; Ion Channels - physiology; Peptides - metabolism; Plant Proteins - metabolism; Plant Proteins - physiology; Protoplasts - metabolism; Protoplasts - physiology; PVDF, polyvinylidene difluoride; Rosales; SUR, sulfonylurea receptor; Vicia faba
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(01)02289-X

The plasma membrane guard cell slow anion channel is a key element at the basis of water loss control in plants allowing prolonged osmolite efflux necessary for stomatal closure. This channel has been extensively studied by electrophysiological approaches but its molecular identification is still lacking. Recently, we described that this channel was sharing some similarities with the mammalian ATP-binding cassette protein, cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel [Leonhardt, N. et al. (1999) Plant Cell 11, 1141–1151]. Here, using the patch-clamp technique and a bioassay, consisting in the observation of the change in guard cell protoplasts volume, we demonstrated that a functional antibody raised against the mammalian CFTR prevented ABA-induced guard cell protoplasts shrinking and partially inhibited the slow anion current. Moreover, this antibody immunoprecipitated a polypeptide from guard cell protein extracts and immunolabeled stomata in Vicia faba leaf sections. These results indicate that the guard cell slow anion channel is, or is closely controlled by a polypeptide, exhibiting one epitope shared with the mammalian CFTR.