title: Import inhibition of poly(His) containing chloroplast precursor proteins by Ni2+ ions.
abstract: The precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase (pSS) and a modified pSS containing a C-terminal hexahistidyl tail (pSS(His)6) were imported into isolated Chlamydomonas chloroplasts with comparable efficiency. In the presence of Ni2+ ions the import of pSS(His)6 was inhibited and the precursor bound to the envelope remained protease sensitive, while import of pSS was not affected. Addition of an excess of L-histidine suppressed the inhibition demonstrating that the hexahistidyl-Ni2+ complex was responsible for import inhibition. Inhibition could be observed between about 0.5 and 10 mM Ni2+, depending on the total protein content in the assay. Import incompetent Ni2+ -precursor complexes can be used to study early events in chloroplast protein import.
authors.affiliation: Institut für Biochemie, Universität Bern, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Rothen
authors.forename: M
authors.initials: M
authors.lastname: Thiess
authors.forename: P
authors.initials: P
authors.lastname: Schumann
authors.forename: A
authors.initials: A
authors.lastname: Boschetti
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002696:Chlamydomonas / Q000187:drug effects / Q000378:metabolism; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D006639:Histidine / Q000737:chemistry / Q000235:genetics; D009532:Nickel / Q000494:pharmacology*; D011498:Protein Precursors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*
chemical_list: D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D006639:Histidine; D009532:Nickel; D012273:Ribulose-Bisphosphate Carboxylase