9Y0Q

Crystal structure of Escherichia coli DsbA C33A mutant in complex with a peptide derived from LptD - Binding mode II

Summary for 9Y0Q

• Entry DOI: 10.2210/pdb9y0q/pdb
• Descriptor: Thiol:disulfide interchange protein DsbA, Peptide from LPS-assembly protein LptD, GLYCEROL, ... (4 entities in total)
• Functional Keywords: thiol oxidase mutant, bacterial foldase, thioredoxin fold, complex, oxidoreductase
• Biological source: Escherichia coli; More
• Total number of polymer chains: 2
• Total formula weight: 22546.59

Authors

Cunliffe, T.R.,Heras, B.,Paxman, J.J. (deposition date: 2025-08-28, release date: 2026-03-25, Last modification date: 2026-04-29)

Primary citation

Cunliffe, T.,Wang, G.,Penning, S.,Subedi, P.,Totsika, M.,Paxman, J.J.,Heras, B.
A universal cis-proline lock defines catalysis in thioredoxin-fold enzymes.
Commun Biol, 2026

PubMed Abstract: Thioredoxin-fold oxidoreductases drive oxidative protein folding and redox homeostasis across all domains of life. They catalyse thiol-disulfide exchange in diverse substrates, yet how they reconcile catalytic precision with substrate diversity remains unclear. Here we show, using high-resolution structures and functional analyses of the Escherichia coli oxidoreductase DsbA, that a conserved cis-proline loop adjacent to the catalytic Cys-Pro-His-Cys motif serves as a universal catalytic lock. The loop positions the substrate cysteine in a right-handed disulfide geometry optimal for exchange, while surrounding surfaces accommodate sequence variation. Substitution of the cis-proline abolishes turnover, whereas mutation of the preceding glycine preserves geometry but reduces efficiency. Comparative structural analyses demonstrate that this cis-proline-dependent hydrogen-bonding scaffold is conserved across thioredoxins, protein disulfide isomerases, peroxiredoxins and bacterial Dsb proteins. This conserved mechanism explains how catalytic fidelity is maintained while enabling substrate versatility and provides a foundation for enzyme engineering and therapeutic development.

PubMed: 41981106
DOI: 10.1038/s42003-026-10010-8

Experimental method

X-RAY DIFFRACTION (1.47 Å)