title: Differential regulation of serine acetyltransferase is involved in nickel hyperaccumulation in Thlaspi goesingense.
abstract: When growing in its native habitat, Thlaspi goesingense can hyperaccumulate 1.2% of its shoot dry weight as nickel. We reported previously that both constitutively elevated activity of serine acetyltransferase (SAT) and concentration of glutathione (GSH) are involved in the ability of T. goesingense to tolerate nickel. A feature of SAT is its feedback inhibition by L-cysteine. To understand the role of this regulation of SAT by Cys on GSH-mediated nickel tolerance in T. goesingense, we characterized the enzymatic properties of SATs from T. goesingense. We demonstrate that all three isoforms of SAT in T. goesingense are insensitive to inhibition by Cys. Further, two amino acids (proline and alanine) in the C-terminal region of the cytosolic SAT (SAT-c) from T. goesingense are responsible for converting the enzyme from a Cys-sensitive to a Cys-insensitive form. Furthermore, the Cys-insensitive isoform of SAT-c confers elevated resistance to nickel when expressed in Escherichia coli and Arabidopsis thaliana, supporting a role for altered regulation of SAT by Cys in nickel tolerance in T. goesingense.
authors.affiliation: Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: GunNam
authors.initials: G
authors.lastname: Na
authors.forename: David E
authors.initials: DE
authors.lastname: Salt
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D003545:Cysteine / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism* / Q000633:toxicity; D018087:Plastids / Q000201:enzymology; D011110:Polymorphism, Genetic; D017434:Protein Structure, Tertiary; D051050:Serine O-Acetyltransferase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D031227:Thlaspi / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009532:Nickel; D051050:Serine O-Acetyltransferase; D003545:Cysteine