title: Responses of plant calmodulin to endocytosis induced by rare earth elements.
abstract: The wide application of rare earth elements (REEs) have led to their diffusion and accumulation in the environment. The activation of endocytosis is the primary response of plant cells to REEs. Calmodulin (CaM), as an important substance in calcium (Ca) signaling systems, regulating almost all of the physiological activities in plants, such as cellular metabolism, cell growth and division. However, the response of CaM to endocytosis activated by REEs remains unknown. By using immunofluorescence labeling and a confocal laser scanning microscope, we found that trivalent lanthanum [La(III)], an REE ion, affected the expression of CaM in endocytosis. Using circular dichroism, X-ray photoelectron spectroscopy and computer simulations, we demonstrated that a low concentration of La(III) could interact with extracellular CaM by electrostatic attraction and was then bound to two Ca-binding sites of CaM, making the molecular structure more compact and orderly, whereas a high concentration of La(III) could be coordinated with cytoplasmic CaM or bound to other Ca-binding sites, making the molecular structure more loose and disorderly. Our results provide a reference for revealing the action mechanisms of REEs in plant cells.
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, PR China; State Key Laboratory of Food Science and Technology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Wang
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, PR China.
authors.forename: Mengzhu
authors.initials: M
authors.lastname: Cheng
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, PR China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Chu
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, PR China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, PR China; Department of Chemistry, University of British Columbia, Vancouver V6T 1Z4, British Columbia, Canada.
authors.forename: David D Y
authors.initials: DDY
authors.lastname: Chen
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, PR China. Electronic address: huangxiaohuanjnu@yahoo.com.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China. Electronic address: qingzhou510@yahoo.com.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D031215:Armoracia / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D003198:Computer Simulation; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D008674:Metals, Rare Earth / Q000494:pharmacology*; D018613:Microscopy, Confocal; D008958:Models, Molecular; D056951:Photoelectron Spectroscopy; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D018521:Plant Physiological Phenomena / Q000187:drug effects*; D011487:Protein Conformation
chemical_list: D002147:Calmodulin; D008674:Metals, Rare Earth
keywords: Calmodulin; Endocytosis; Lanthanum; Molecular basis