1xvw

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Crystal Structure of AhpE from Mycobacterium 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

1XVW is a Single protein structure of sequence from Mycobacterium tuberculosis. 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

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