The cyclic nucleotide-gated calmodulin-binding channel AtCNGC10 localizes to the plasma membrane and influences numerous growth responses and starch accumulation in Arabidopsis thaliana.
Cyclic nucleotide gated channels (CNGCs) that are regulated by calmodulin (CaM) have been shown to play essential roles in signal transduction, metabolism, and growth in animals. By contrast, very little is known about the subcellular location and the function of these channels in plants. Here we report on the effects of antisense suppression of the expression of AtCNGC10, a putative K+ channel, and the immunolocalization of the protein using an AtCNGC10-specific antiserum. In Arabidopsis thaliana leaves, AtCNGC10 was localized to the plasma membrane of mesophyll and parenchyma cells. Antisense AtCNGC10 plants had 40% of the AtCNGC10 mRNA levels and virtually undetectable protein levels relative to wild type plants. Antisense expression of AtCNGC10 did not affect the mRNA levels of AtCNGC13, the most closely related CNGC family member in the genome. Relative to wild type Columbia, antisense AtCNGC10 plants flowered 10 days earlier, and had a 25% reduction in leaf surface area, thickness and palisade parenchyma cell length. Their roots responded more slowly to gravitropic changes and the chloroplasts accumulated more starch. We propose that AtCNGC10, through interactions with CaM and cGMP, modulates cellular K+ balance across the plasma membrane, and that perturbations of this K+ gradient affect numerous growth and developmental processes.
Borsics
Tamás
T
Department of Molecular Biosciences and Bioengineering, University of Hawaii, 1955 East-West Road, Agsciences 218, Honolulu, HI 96822, USA.
Webb
David
D
Andeme-Ondzighi
Christine
C
Staehelin
L Andrew
LA
Christopher
David A
DA
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure; D054815:Cyclic Nucleotide-Gated Cation Channels; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D016253:Microscopy, Immunoelectron; D018515:Plant Leaves / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D013213:Starch / Q000378:metabolism*; D013997:Time Factors
D029681:Arabidopsis Proteins; D002147:Calmodulin; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D013213:Starch