PDBsum entry 1a8l

Oxidoreductase

PDB id

1a8l

Contents

			Protein chain

					226 a.a.

			Metals

					_ZN

			Waters ×139

References listed in PDB file

Key reference

Title

A protein disulfide oxidoreductase from the archaeon pyrococcus furiosus contains two thioredoxin fold units.

Authors

B.Ren, G.Tibbelin, D.De pascale, M.Rossi, S.Bartolucci, R.Ladenstein.

Ref.

Nat Struct Biol, 1998, 5, 602-611. [DOI no: 10.1038/862]

PubMed id

9665175

Abstract

Protein disulfide bond formation is a rate limiting step in protein folding and is catalyzed by enzymes belonging to the protein disulfide oxidoreductase superfamily, including protein disulfide isomerase (PDI) in eucarya and DsbA in bacteria. The first high resolution X-ray crystal structure of a protein disulfide oxidoreductase from the hyperthermophilic archaeon Pyrococcus furiosus reveals structural details that suggest a relation to eukaryotic PDI. The protein consists of two homologous structural units with low sequence identity. Each unit contains a thioredoxin fold with a distinct CXXC active site motif. The accessibilities of both active sites are rather different as are, very likely, their redox properties. The protein shows the ability to catalyze the oxidation of dithiols as well as the reduction of disulfide bridges.



	Figure 4. Figure 4. , The final (2F[o] - F[c]) electron density maps at the active site regions of a, the N-unit and b, the C-unit. The conformation of the 14-membered disulfide ring is more relaxed in the C-unit than in the N-unit. The atoms in the C-terminal disulfide have better defined and more spherically shaped electron densities than those in the N-terminal disulfide. Both maps are contoured at the 1.2 level.		Figure 6. Figure 6. Fig 6 a, The coordination geometry of the zinc binding site at the dimer interface. The zinc ion is represented by a green sphere and waters by red spheres. The structural elements in the two monomers are colored in brown and blue respectively. The C-terminal end of helix 1 is distorted by forming a 3[10]-helix. The coordination angles subtended by the zinc and ligated atoms are in the range of 99−117°. b, Ribbon diagram of the pf PDO dimer. The two monomers are colored in brown and blue respectively. The active site disulfides are shown in ball-and-stick representation and colored in yellow. The two zinc ions, which are related by the crystallographic two-fold axis, are shown by green spheres.