Mutant AhpC peroxiredoxins suppress thiol-disulfide redox deficiencies and acquire deglutathionylating activity.
The bacterial peroxiredoxin AhpC, a cysteine-dependent peroxidase, can be converted through a single amino acid insertion to a disulfide reductase, AhpC*, active in the glutathione and glutaredoxin pathway. Here we show that, whereas AhpC* is inactive as a peroxidase, other point mutants in AhpC can confer the in vivo disulfide reductase activity without abrogating peroxidase activity. Moreover, AhpC* and several point mutants tested in vitro exhibit an enhanced reductase activity toward mixed disulfides between glutathione and glutaredoxin (Grx-S-SG), consistent with the in vivo requirements for these components. Remarkably, this Grx-S-SG reductase activity relies not on the peroxidatic cysteine but rather on the resolving cysteine that plays only a secondary role in the peroxidase mechanism. Furthermore, putative conformational changes, which impart this unusual Grx-S-SG reductase activity, are transmissible across subunits. Thus, AhpC and potentially other peroxiredoxins in this widespread family can elaborate a new reductase function that alleviates disulfide stress.
Yamamoto
Yuji
Y
Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Ritz
Dani
D
Planson
Anne-Gaëlle
AG
Jönsson
Thomas J
TJ
Faulkner
Melinda J
MJ
Boyd
Dana
D
Beckwith
Jon
J
Poole
Leslie B
LB
D019943:Amino Acid Substitution; D003545:Cysteine / Q000378:metabolism; D019281:Dimerization; D004220:Disulfides / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D054477:Glutaredoxins / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008958:Models, Molecular; D016254:Mutagenesis, Insertional; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D054464:Peroxiredoxins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D017354:Point Mutation; D011487:Protein Conformation; D021122:Protein Subunits; D013379:Substrate Specificity; D018911:Trinucleotide Repeats
D004220:Disulfides; D029968:Escherichia coli Proteins; D054477:Glutaredoxins; D021122:Protein Subunits; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D054464:Peroxiredoxins; C515937:ahpC protein, E coli; D005978:Glutathione; D003545:Cysteine