A novel coiled-coil protein co-localizes and interacts with a calcium-dependent protein kinase in the common ice plant during low-humidity stress.
McCPK1 (Mesembryanthemum crystallinum calcium-dependent protein kinase 1) mRNA expression is induced transiently by salinity and water deficit stress and also McCPK1 undergoes dynamic subcellular localization changes in response to these same stresses. Here we have confirmed that low humidity is capable of causing a drastic change in McCPK1's subcellular localization. We attempted to elucidate this phenomenon by isolating components likely to be involved in this process. McCAP1 (M. crystallinum CDPK adapter protein 1) was cloned in a yeast two-hybrid screen with a constitutively active McCPK1 as bait. We show that McCPK1 and McCAP1 can interact in the yeast two-hybrid system, in vitro, and in vivo as demonstrated by coimmunoprecipitation experiments from plant extracts. However, McCAP1 does not appear to be a substrate for McCPK1. DsRed-McCAP1 and EGFP-McCPK1 fusions colocalize in epidermal cells of ice plants exposed to low humidity. McCAP1 is homologous to a family of proteins in Arabidopsis with no known function. Computational threading analysis suggests that McCAP1 is likely to be an intermediate filament protein of the cytoskeleton.
Patharkar
O Rahul
OR
Department of Molecular Biology, Massachusetts General Hospital, Wellman 11, Boston, MA 02114, USA.
Cushman
John C
JC
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002466:Cell Nucleolus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006813:Humidity; D047468:Immunoprecipitation; D035723:Mesembryanthemum / Q000235:genetics* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D017871:Calcium-Calmodulin-Dependent Protein Kinases
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D005982:Glutathione Transferase; D049452:Green Fluorescent Proteins; D010940:Plant Proteins; D011494:Protein Kinases; D011993:Recombinant Fusion Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases