Crystal structure of the 100 kDa arsenite oxidase from Alcaligenes faecalis in two crystal forms at 1.64 Å and 2.03 Å

Paul J. Ellis, Thomas Conrads, Russ Hille, Peter Kuhn*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

281 Scopus citations


Background: Arsenite oxidase from Alcaligenes faecalis NCIB 8687 is a molybdenum/iron protein involved in the detoxification of arsenic. It is induced by the presence of AsO2- (arsenite) and functions to oxidize AsIIIO2-, which binds to essential sulfhydryl groups of proteins and dithiols, to the relatively less toxic AsVO43- (arsenate) prior to methylation. Results: Using a combination of multiple isomorphous replacement with anomalous scattering (MIRAS) and multiple-wavelength anomalous dispersion (MAD) methods, the crystal structure of arsenite oxidase was determined to 2.03 Å in a P21 crystal form with two molecules in the asymmetric unit and to 1.64 Å in a P1 crystal form with four molecules in the asymmetric unit. Arsenite oxidase consists of a large subunit of 825 residues and a small subunit of approximately 134 residues. The large subunit contains a Mo site, consisting of a Mo atom bound to two pterin cofactors, and a [3Fe-4S] cluster. The small subunit contains a Rieske-type [2Fe-2S] site. Conclusions: The large subunit of arsenite oxidase is similar to other members of the dimethylsulfoxide (DMSO) reductase family of molybdenum enzymes, particularly the dissimilatory periplasmic nitrate reductase from Desulfovibrio desulfuricans, but is unique in having no covalent bond between the polypeptide and the Mo atom. The small subunit has no counterpart among known Mo protein structures but is homologous to the Rieske [2Fe-2S] protein domain of the cytochrome bc1 and cytochrome b6f complexes and to the Rieske domain of naphthalene 1,2-dioxygenase.

Original languageEnglish
Pages (from-to)125-132
Number of pages8
Issue number2
StatePublished - 2001
Externally publishedYes


  • Arsenite oxidase
  • Crystal structure
  • Molybdopterin cofactor
  • Multiwavelength anomalous dispersion
  • [2Fe-2S] cluster
  • [3Fe-4S] cluster


Dive into the research topics of 'Crystal structure of the 100 kDa arsenite oxidase from Alcaligenes faecalis in two crystal forms at 1.64 Å and 2.03 Å'. Together they form a unique fingerprint.

Cite this