title: Acquisition of selenium tolerance by a selenium non-accumulating Astragalus species via selection.
abstract: Selection of cultured cells of the selenium sensitive and non-accumulating Astragalus cicer for tolerance to stepwise increasing concentrations of selenite in the medium lead to a variant able to grow at 75 microM selenite. The Se-tolerant culture synthesized a selenocysteine methyltransferase immunologically related but not identical to that of the accumulating A. bisulcatus species and produced Se-methyl-selenocysteine in vivo. Re-cultivation in selenium-free medium lead to breakdown of tolerance and the disappearance of the methyltransferase from cellular proteins. The results prove that the non-accumulating species A. cicer has the cryptic capacity for synthesis of a selenocysteine methyltransferase and also demonstrate that synthesis of the organoselenium compounds in Se-accumulating plants are contributing to selenium tolerance.
authors.affiliation: Lehrstuhl für Mikrobiologie, Universität München, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Böck
authors.forename: B
authors.initials: B
authors.lastname: Neuhierl
mesh_terms: D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D015180:Electrophoresis, Gel, Two-Dimensional; D004790:Enzyme Induction; D007526:Isoelectric Point; D008745:Methylation / Q000187:drug effects; D008780:Methyltransferases / Q000096:biosynthesis; D016566:Organoselenium Compounds / Q000378:metabolism; D059828:Plant Cells; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D012641:Selection, Genetic; D012643:Selenium / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology / Q000633:toxicity; D017279:Selenocysteine / Q000031:analogs & derivatives; D018038:Sodium Selenite / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D013997:Time Factors
chemical_list: D016566:Organoselenium Compounds; D010940:Plant Proteins; D017279:Selenocysteine; D008780:Methyltransferases; C100751:selenocysteine methyltransferase; D012643:Selenium; D018038:Sodium Selenite; D003545:Cysteine; C002979:selenomethylselenocysteine