title: Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress.
abstract: During waterlogging and the associated oxygen deprivation stress, plants respond by the induction of adaptive programs, including the redirected expression of gene networks toward the synthesis of core hypoxia-response proteins. Among these core response proteins in Arabidopsis (Arabidopsis thaliana) is the calcium sensor CML38, a protein related to regulator of gene silencing calmodulin-like proteins (rgsCaMs). CML38 transcripts are up-regulated more than 300-fold in roots within 6 h of hypoxia treatment. Transfer DNA insertional mutants of CML38 show an enhanced sensitivity to hypoxia stress, with lowered survival and more severe inhibition of root and shoot growth. By using yellow fluorescent protein (YFP) translational fusions, CML38 protein was found to be localized to cytosolic granule structures similar in morphology to hypoxia-induced stress granules. Immunoprecipitation of CML38 from the roots of hypoxia-challenged transgenic plants harboring CML38pro::CML38:YFP followed by liquid chromatography-tandem mass spectrometry analysis revealed the presence of protein targets associated with messenger RNA ribonucleoprotein (mRNP) complexes including stress granules, which are known to accumulate as messenger RNA storage and triage centers during hypoxia. This finding is further supported by the colocalization of CML38 with the mRNP stress granule marker RNA Binding Protein 47 (RBP47) upon cotransfection of Nicotiana benthamiana leaves. Ruthenium Red treatment results in the loss of CML38 signal in cytosolic granules, suggesting that calcium is necessary for stress granule association. These results confirm that CML38 is a core hypoxia response calcium sensor protein and suggest that it serves as a potential calcium signaling target within stress granules and other mRNPs that accumulate during flooding stress responses.
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology (A.L., W.C.C., C.M., D.M.R.) and Program in Genome Science and Technology (T.L., D.M.R.), University of Tennessee, Knoxville, Tennessee 37996.
authors.forename: Ansul
authors.identifier: http://orcid.org/0000-0003-2264-2701
authors.initials: A
authors.lastname: Lokdarshi
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology (A.L., W.C.C., C.M., D.M.R.) and Program in Genome Science and Technology (T.L., D.M.R.), University of Tennessee, Knoxville, Tennessee 37996.
authors.forename: W Craig
authors.identifier: http://orcid.org/0000-0001-7968-6276
authors.initials: WC
authors.lastname: Conner
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology (A.L., W.C.C., C.M., D.M.R.) and Program in Genome Science and Technology (T.L., D.M.R.), University of Tennessee, Knoxville, Tennessee 37996.
authors.forename: Carlee
authors.initials: C
authors.lastname: McClintock
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology (A.L., W.C.C., C.M., D.M.R.) and Program in Genome Science and Technology (T.L., D.M.R.), University of Tennessee, Knoxville, Tennessee 37996.
authors.forename: Tian
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Biochemistry and Cellular and Molecular Biology (A.L., W.C.C., C.M., D.M.R.) and Program in Genome Science and Technology (T.L., D.M.R.), University of Tennessee, Knoxville, Tennessee 37996 drobert2@utk.edu.
authors.forename: Daniel M
authors.identifier: http://orcid.org/0000-0002-0780-7056
authors.initials: DM
authors.lastname: Roberts
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D046912:Multiprotein Complexes / Q000378:metabolism*; D016254:Mutagenesis, Insertional / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010100:Oxygen; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D012430:Ruthenium Red / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014026:Nicotiana / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C522736:CML38 protein, Arabidopsis; D002147:Calmodulin; D004269:DNA, Bacterial; D046912:Multiprotein Complexes; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C036483:T-DNA; D012430:Ruthenium Red; D010100:Oxygen; D002118:Calcium