1xxu
From Proteopedia
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==Overview== | ==Overview== | ||
| - | All living systems require protection against the damaging effects of | + | 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. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Peroxidase]] | [[Category: Peroxidase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Baker, E | + | [[Category: Baker, E N.]] |
| - | [[Category: Hung, L | + | [[Category: Hung, L W.]] |
| - | [[Category: Kim, C | + | [[Category: Kim, C Y.]] |
| - | [[Category: Kim, M | + | [[Category: Kim, M Y.]] |
[[Category: Lekin, T.]] | [[Category: Lekin, T.]] | ||
[[Category: Li, S.]] | [[Category: Li, S.]] | ||
| - | [[Category: Lott, J | + | [[Category: Lott, J S.]] |
| - | [[Category: Peterson, N | + | [[Category: Peterson, N A.]] |
| - | [[Category: Segelke, B | + | [[Category: Segelke, B W.]] |
| - | [[Category: TBSGC, TB | + | [[Category: TBSGC, TB Structural Genomics Consortium.]] |
[[Category: Yu, M.]] | [[Category: Yu, M.]] | ||
[[Category: 1-cys peroxiredoxin]] | [[Category: 1-cys peroxiredoxin]] | ||
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[[Category: thioredoxin fold]] | [[Category: thioredoxin fold]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:59:44 2008'' |
Revision as of 13:59, 21 February 2008
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Crystal Structure of AhpE from Mycrobacterium tuberculosis, a 1-Cys peroxiredoxin
Overview
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.
About this Structure
1XXU is a Single protein structure of sequence from Mycobacterium tuberculosis. Active as Peroxidase, with EC number 1.11.1.7 Full crystallographic information is available from OCA.
Reference
Crystal Structure of AhpE from Mycobacterium tuberculosis, a 1-Cys peroxiredoxin., Li S, Peterson NA, Kim MY, Kim CY, Hung LW, Yu M, Lekin T, Segelke BW, Lott JS, Baker EN, J Mol Biol. 2005 Mar 4;346(4):1035-46. Epub 2005 Jan 25. PMID:15701515
Page seeded by OCA on Thu Feb 21 15:59:44 2008
Categories: Mycobacterium tuberculosis | Peroxidase | Single protein | Baker, E N. | Hung, L W. | Kim, C Y. | Kim, M Y. | Lekin, T. | Li, S. | Lott, J S. | Peterson, N A. | Segelke, B W. | TBSGC, TB Structural Genomics Consortium. | Yu, M. | 1-cys peroxiredoxin | Protein structure initiative | Psi | Structural genomics | Tb structural genomics consortium | Tbsgc | Thioredoxin fold
