4MAB

Resolving Cys to Ala variant of Salmonella Alkyl Hydroperoxide Reductase C in its substrate-ready conformation

Summary for 4MAB

• Entry DOI: 10.2210/pdb4mab/pdb
• Related: 4MA9
• Descriptor: Alkyl hydroperoxide reductase subunit C, POTASSIUM ION, GLYCEROL, ... (5 entities in total)
• Functional Keywords: thioredoxin fold, prx1, prx, resolving cys mutant, peroxidase, peroxiredoxin, oxidoreductase
• Biological source: Salmonella enterica subsp. enterica serovar Typhimurium
• Total number of polymer chains: 5
• Total formula weight: 103566.74

Authors

Perkins, A.,Nelson, K.J.,Williams, J.R.,Poole, L.B.,Karplus, P.A. (deposition date: 2013-08-15, release date: 2013-11-20, Last modification date: 2023-09-20)

Primary citation

Perkins, A.,Nelson, K.J.,Williams, J.R.,Parsonage, D.,Poole, L.B.,Karplus, P.A.
The sensitive balance between the fully folded and locally unfolded conformations of a model peroxiredoxin.
Biochemistry, 52:8708-8721, 2013

PubMed Abstract: To reduce peroxides, peroxiredoxins (Prxs) require a key "peroxidatic" Cys that, in a substrate-ready fully folded (FF) conformation, is oxidized to sulfenic acid and then, after a local unfolding (LU) of the active site, forms a disulfide bond with a second "resolving" Cys. For Salmonella typhimurium alkyl hydroperoxide reductase C (StAhpC) and some other Prxs, the FF structure is only known for a peroxidatic Cys→Ser variant, which may not accurately represent the wild-type enzyme. Here, we obtain the structure of authentic reduced wild-type StAhpC by dithiothreitol treatment of disulfide form crystals that fortuitously accommodate both the LU and FF conformations. The unique environment of one molecule in the crystal reveals a thermodynamic linkage between the folding of the active site loop and C-terminal regions, and comparisons with the Ser variant show structural and mobility differences from which we infer that the Cys→Ser mutation stabilizes the FF active site. A structure for the C165A variant (a resolving Cys to Ala mutant) in the same crystal form reveals that this mutation destabilizes the folding of the C-terminal region. These structures prove that subtle modifications to Prx structures can substantially influence enzymatic properties. We also present a simple thermodynamic framework for understanding the various mixtures of FF and LU conformations seen in these structures. On the basis of this framework, we rationalize how physiologically relevant regulatory post-translational modifications may modulate activity, and we propose a nonconventional strategy for designing selective Prx inhibitors.

PubMed: 24175952
DOI: 10.1021/bi4011573

Experimental method

X-RAY DIFFRACTION (1.9 Å)