title: N-terminal truncation of the variable subunit stabilizes spinach ferredoxin:thioredoxin reductase.
abstract: The variable subunit of spinach ferredoxin:thioredoxin reductase (FTR) has an extended N-terminus compared to FTRs from other sources and this was proposed to contribute to the instability of the protein. We constructed two N-terminal truncation mutants of recombinant FTR by removing 16 or 24 residues from the variable subunit. The mutant proteins are readily expressed and show half-saturation values (S(0.5)) for ferredoxin and thioredoxin f comparable to WT. However, truncation increases significantly their stability. Using the stabilized FTR an exposed Cys on its thioredoxin contact surface could be substituted without altering its properties, whereas the replacement of an active site Cys by Ser completely destabilized the protein.
authors.affiliation: Laboratoire de Biochimie Végétale, Université de Neuchâtel, Rue Emile Argand 11, CH-2007, Neuchâtel, Switzerland.
authors.forename: W
authors.initials: W
authors.lastname: Manieri
authors.forename: L
authors.initials: L
authors.lastname: Franchini
authors.forename: L
authors.initials: L
authors.lastname: Raeber
authors.forename: S
authors.initials: S
authors.lastname: Dai
authors.forename: A-L
authors.initials: AL
authors.lastname: Stritt-Etter
authors.forename: P
authors.initials: P
authors.lastname: Schürmann
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites / Q000235:genetics; D004795:Enzyme Stability / Q000235:genetics*; D007506:Iron-Sulfur Proteins; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics*; D016415:Sequence Alignment; D017384:Sequence Deletion; D018724:Spinacia oleracea / Q000201:enzymology*
chemical_list: D007506:Iron-Sulfur Proteins; D021122:Protein Subunits; D010088:Oxidoreductases; C021588:ferredoxin-thioredoxin reductase