title: In silico and in vivo studies of molecular structures and mechanisms of AtPCS1 protein involved in binding arsenite and/or cadmium in plant cells.
abstract: This paper reports a continuation of our previous research on the phytochelatin synthase1 (PCS1) gene involved in binding and sequestration of heavy metals or metalloids in plant cells. Construction of a 3D structure of the Arabidopsis thaliana PCS1 protein and prediction of gene function by employing iterative implementation of the threading assembly refinement (I-TASSER) revealed that PC ligands (3GC-gamma-glutamylcysteine) and Gln50, Pro53, Ala54, Tyr55, Cys56, Ile102, Gly161, His162, Phe163, Asp204 and Arg211 residues are essential for formation of chelating complex with cadmium (Cd²⁺) or arsenite (AsIII). This finding suggests that the PCS1 protein might be involved in the production of the enzyme phytochelatin synthase, which might in turn bind, localize, store or sequester heavy metals in plant cells. For validation of the in silico results, we included a T-DNA tagged mutant of Arabidopsis thaliana, SAIL_650_C12, (mutation in AtPCS1 gene) in our investigation. Furthermore, using reverse transcriptase PCR we confirmed that the mutant does not express the AtPCS1 gene. Mutant plants of SAIL_650_C12 were exposed to various amounts of cadmium (Cd²⁺) and arsenite (AsIII) and the accumulation of these toxic metals in the plant cells was quantified spectrophotometrically. The levels of Cd²⁺ and AsIII accumulation in the mutant were approximately 2.8 and 1.6 times higher, respectively, than that observed in the wild-type controlled plants. We confirmed that the results obtained in in silico analyses complement those obtained in in vivo experiments.
authors.affiliation: School of Biological Sciences, System Biology Research Center, University of Skövde, PO Box 408, 541 28, Skövde, Sweden.
authors.forename: Noor
authors.initials: N
authors.lastname: Nahar
authors.forename: Aminur
authors.initials: A
authors.lastname: Rahman
authors.forename: Maria
authors.initials: M
authors.lastname: Moś
authors.forename: Tomasz
authors.initials: T
authors.lastname: Warzecha
authors.forename: Sibdas
authors.initials: S
authors.lastname: Ghosh
authors.forename: Khaled
authors.initials: K
authors.lastname: Hossain
authors.forename: Neelu N
authors.initials: NN
authors.lastname: Nawani
authors.forename: Abul
authors.initials: A
authors.lastname: Mandal
mesh_terms: D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018053:Arsenites / Q000378:metabolism* / Q000494:pharmacology; D001665:Binding Sites / Q000235:genetics; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D003198:Computer Simulation; D004151:Dipeptides / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D018053:Arsenites; D004151:Dipeptides; D002104:Cadmium; D019881:Aminoacyltransferases; C502365:AT5G44070 protein, Arabidopsis; C017341:gamma-glutamylcysteine