An extended active-site motif controls the reactivity of the thioredoxin fold.
Proteins belonging to the thioredoxin (Trx) superfamily are abundant in all organisms. They share the same structural features, arranged in a seemingly simple fold, but they perform a multitude of functions in oxidative protein folding and electron transfer pathways. We use the C-terminal domain of the unique transmembrane reductant conductor DsbD as a model for an in-depth analysis of the factors controlling the reactivity of the Trx fold. We employ NMR spectroscopy, x-ray crystallography, mutagenesis, in vivo functional experiments applied to DsbD, and a comparative sequence analysis of Trx-fold proteins to determine the effect of residues in the vicinity of the active site on the ionization of the key nucleophilic cysteine of the -CXXC- motif. We show that the function and reactivity of Trx-fold proteins depend critically on the electrostatic features imposed by an extended active-site motif.
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom and.
Despoina A I
DA
Mavridou
Emmanuel
E
Saridakis
Paraskevi
P
Kritsiligkou
Erin C
EC
Mozley
Stuart J
SJ
Ferguson
Christina
C
Redfield
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013879:Thioredoxins / Q000737:chemistry*
D029968:Escherichia coli Proteins; D013879:Thioredoxins; D010088:Oxidoreductases; C094848:DsbD electron transport protein, E coli
DsbD; Electrostatics; NMR; Oxidase; Reductase; Thiol-Disulfide Exchange; Thioredoxin; Thioredoxin Fold; X-ray Crystallography; pKa Values