3C71: Structure Of A Resa Variant With A Dsba-like Active Site Motif (cphc)

The thiol-disulfide oxidoreductase ResA from Bacillus subtilis fulfils a reductive role in cytochrome c maturation. The pK(a) values for the CEPC (one-letter code) active-site cysteine residues of ResA are unusual for thioredoxin-like proteins in that they are both high (>8) and within 0.5 unit of each other. To determine the contribution of the inter-cysteine dipeptide of ResA to its redox and acid-base properties, three variants (CPPC, CEHC and CPHC) were generated representing a stepwise conversion into the active-site sequence of the high-potential DsbA protein from Escherichia coli. The substitutions resulted in large decreases in the pK(a) values of both the active-site cysteine residues: in CPHC (DsbA-type) ResA, DeltapK(a) values of -2.5 were measured for both cysteine residues. Increases in midpoint reduction potentials were also observed, although these were comparatively small: CPHC (DsbA-type) ResA exhibited an increase of +40 mV compared with the wild-type protein. Unfolding studies revealed that, despite the observed differences in the properties of the reduced proteins, changes in stability were largely confined to the oxidized state. High-resolution structures of two of the variants (CEHC and CPHC ResA) in their reduced states were determined and are discussed in terms of the observed changes in properties. Finally, the in vivo functional properties of CEHC ResA are shown to be significantly affected compared with those of the wild-type protein.
PDB ID: 3C71Download
MMDB ID: 66018
PDB Deposition Date: 2008/2/6
Updated in MMDB: 2016/12
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 3C71: monomeric; determined by author and by software (PISA)
Molecular Components in 3C71
Label Count Molecule
Protein (1 molecule)
Thiol-disulfide Oxidoreductase Resa(Gene symbol: resA)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

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