Corynebacterium diphtheriae methionine sulfoxide reductase a exploits a unique mycothiol redox relay mechanism.
Methionine sulfoxide reductases are conserved enzymes that reduce oxidized methionines in proteins and play a pivotal role in cellular redox signaling. We have unraveled the redox relay mechanisms of methionine sulfoxide reductase A of the pathogen Corynebacterium diphtheriae (Cd-MsrA) and shown that this enzyme is coupled to two independent redox relay pathways. Steady-state kinetics combined with mass spectrometry of Cd-MsrA mutants give a view of the essential cysteine residues for catalysis. Cd-MsrA combines a nucleophilic cysteine sulfenylation reaction with an intramolecular disulfide bond cascade linked to the thioredoxin pathway. Within this cascade, the oxidative equivalents are transferred to the surface of the protein while releasing the reduced substrate. Alternatively, MsrA catalyzes methionine sulfoxide reduction linked to the mycothiol/mycoredoxin-1 pathway. After the nucleophilic cysteine sulfenylation reaction, MsrA forms a mixed disulfide with mycothiol, which is transferred via a thiol disulfide relay mechanism to a second cysteine for reduction by mycoredoxin-1. With x-ray crystallography, we visualize two essential intermediates of the thioredoxin relay mechanism and a cacodylate molecule mimicking the substrate interactions in the active site. The interplay of both redox pathways in redox signaling regulation forms the basis for further research into the oxidative stress response of this pathogen.
From the Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, 1050 Brussels, Belgium, the Brussels Center for Redox Biology, 1050 Brussels, Belgium, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium, and.
Maria-Armineh
MA
Tossounian
From the Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, 1050 Brussels, Belgium, the Brussels Center for Redox Biology, 1050 Brussels, Belgium, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium, and.
Brandán
B
Pedre
From the Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, 1050 Brussels, Belgium, the Brussels Center for Redox Biology, 1050 Brussels, Belgium, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium, and.
Khadija
K
Wahni
From the Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, 1050 Brussels, Belgium, the Brussels Center for Redox Biology, 1050 Brussels, Belgium, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium, and.
Huriye
H
Erdogan
the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium.
Didier
D
Vertommen
From the Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, 1050 Brussels, Belgium, the Brussels Center for Redox Biology, 1050 Brussels, Belgium, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium, and Inge.VanMolle@vib-vub.be.
Inge
I
Van Molle
From the Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, 1050 Brussels, Belgium, the Brussels Center for Redox Biology, 1050 Brussels, Belgium, Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium, and joris.messens@vib-vub.be.
Joris
J
Messens
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D003353:Corynebacterium diphtheriae / Q000201:enzymology*; D003545:Cysteine / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism; D006020:Glycopeptides / Q000378:metabolism*; D007294:Inositol / Q000378:metabolism*; D008715:Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D051150:Methionine Sulfoxide Reductases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism
D004220:Disulfides; D006020:Glycopeptides; C089265:mycothiol; D007294:Inositol; D013879:Thioredoxins; D008715:Methionine; D010088:Oxidoreductases; C121837:mycothione reductase; D013880:Thioredoxin-Disulfide Reductase; D051150:Methionine Sulfoxide Reductases; D003545:Cysteine; C013111:methionine sulfoxide
Disulfide; Enzyme Mechanism; Kinetics; Oxidation-Reduction (Redox); Redox; Redox Regulation; Thiol; Thiol-Disulfide Exchange; X-ray Crystallography