In:
Acta Crystallographica Section D Biological Crystallography, International Union of Crystallography (IUCr), Vol. 55, No. 4 ( 1999-04-01), p. 921-924
Abstract:
The arsenical resistance ( ars ) operon of the Escherichia coli plasmid R773 encodes a system for the active extrusion from cells of the toxic oxyanions arsenite (As III O_{2}^{-}) and antimonite (Sb III O_{2}^{-}) via an ATP-driven pump. The arsA and arsB genes of the operon encode the catalytic subunit (ATPase) and the membrane subunit of the pump, respectively. The arsC gene codes for a reductase that converts arsenate (As V O_{4}^{3-}) to arsenite, thus extending bacterial resistance to the pentavalent state of arsenic. Crystals diffracting beyond 2.0 Å were obtained for the catalytic subunit of the pump (ArsA). These crystals belong to space group I 222, with unit-cell parameters a ≃ 73, b ≃ 76, c ≃ 223 Å. A single molecule of ArsA, composed of two homologous halves, occupies the asymmetric unit of the I 222 crystals with a predicted solvent content of 46%. Self-rotation function analysis suggests, however, that ArsA adopts a molecular packing corresponding to point group 422. One possible explanation of this result is that the two homologous halves of ArsA are related by a twofold axis of local symmetry and that the two halves of a `pseudo'-tetramer are related by a crystallographic twofold axis.
Type of Medium:
Online Resource
ISSN:
0907-4449
DOI:
10.1107/S0907444999000256
Language:
Unknown
Publisher:
International Union of Crystallography (IUCr)
Publication Date:
1999
detail.hit.zdb_id:
2968623-4
SSG:
12
SSG:
13
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