1XXU

Crystal Structure of AhpE from Mycrobacterium tuberculosis, a 1-Cys peroxiredoxin

Summary for 1XXU

• Entry DOI: 10.2210/pdb1xxu/pdb
• Related: 1xvw
• Descriptor: Hypothetical protein Rv2238c/MT2298 (2 entities in total)
• Functional Keywords: 1-cys peroxiredoxin, thioredoxin fold, structural genomics, psi, protein structure initiative, tb structural genomics consortium, tbsgc, oxidoreductase
• Biological source: Mycobacterium tuberculosis
• Total number of polymer chains: 4
• Total formula weight: 67335.80

Authors

Li, S.,Peterson, N.A.,Kim, M.Y.,Kim, C.Y.,Hung, L.W.,Yu, M.,Lekin, T.,Segelke, B.W.,Lott, J.S.,Baker, E.N.,TB Structural Genomics Consortium (TBSGC) (deposition date: 2004-11-08, release date: 2005-02-22, Last modification date: 2023-10-25)

Primary citation

Li, S.,Peterson, N.A.,Kim, M.Y.,Kim, C.Y.,Hung, L.W.,Yu, M.,Lekin, T.,Segelke, B.W.,Lott, J.S.,Baker, E.N.
Crystal Structure of AhpE from Mycobacterium tuberculosis, a 1-Cys Peroxiredoxin
J.Mol.Biol., 346:1035-1046, 2005

PubMed Abstract: All living systems require protection against the damaging effects of reactive oxygen species. The genome of Mycobacterium tuberculosis, the cause of TB, encodes a number of peroxidases that are thought to be active against organic and inorganic peroxides, and are likely to play a key role in the ability of this organism to survive within the phagosomes of macrophages. The open reading frame Rv2238c in M.tuberculosis encodes a 153-residue protein AhpE, which is a peroxidase of the 1-Cys peroxiredoxin (Prx) family. The crystal structure of AhpE, determined at 1.87 A resolution (R(cryst)=0.179, R(free)=0.210), reveals a compact single-domain protein with a thioredoxin fold. AhpE forms both dimers and octamers; a tightly-associated dimer and a ring-like octamer, generated by crystallographic 4-fold symmetry. In this native structure, the active site Cys45 is in its oxidized, sulfenic acid (S-O-H) state. A second crystal form of AhpE, obtained after soaking in sodium bromide and refined at 1.90 A resolution (R(cryst)=0.242, R(free)=0.286), reveals the reduced structure. In this structure, a conformational change in an external loop, in two of the four molecules in the asymmetric unit, allows Arg116 to stabilise the Cys45 thiolate ion, and concomitantly closes a surface channel. This channel is identified as the likely binding site for a physiological reductant, and the conformational change is inferred to be important for the reaction cycle of AhpE.

PubMed: 15701515
DOI: 10.1016/j.jmb.2004.12.046

Experimental method

X-RAY DIFFRACTION (1.9 Å)