PROSITE documentation PDOC00493
Bacterial ring hydroxylating dioxygenases alpha-subunit signature


Bacterial ring hydroxylating dioxygenases are multicomponent enzymatic complexes composed of a hydroxylase component and an electron transfer component. The hydroxylase component is itself composed of two subunits: an α-subunit of about 50 Kd, and a β-subunit of about 20 Kd. The electron transfer component is either composed of two subunits: a ferredoxin and a ferredoxin reductase or by a single bifunctional ferredoxin/reductase subunit.

The α-subunit of hydroxylase components are evolutionary related [1]. The currently known members of this family are listed below.

  • Benzene 1,2-dioxygenase (EC (gene bnzA) from Pseudomonas putida.
  • phthalate 4,5-dioxygenase (EC (gene pht3) from Pseudomonas.
  • Benzoate 1,2-dioxygenase (EC (gene benA) from Acinetobacter calcoaceticus.
  • Naphthalene 1,2-dioxygenase (EC (gene ndoC) from Pseudomonas.
  • 3-chlorobenzoate-3,4-dioxygenase (EC 1.14.12-.-) (gene cbaA) from Alcaligenes.
  • Biphenyl dioxygenase (EC 1.14.99.-) (gene bphA) from Pseudomonas.
  • Toluate 1,2-dioxygenase (EC 1.14.12.-) (gene xylX) from Pseudomonas putida.
  • Toluene 2,3-dioxygenase (EC 1.14.12.-) (gene todC1) from Pseudomonas putida.

The α-subunit of the hydroxylase components bind both a 2Fe-2S type iron-sulfur center and an iron atom. There is, in the N-terminal section of these proteins, a conserved region of 24 residues which contains two cysteines and two histidines which have been shown [2] to be involved in the binding of the iron-sulfur center. We have used this region has a signature pattern.

Expert(s) to contact by email:

Harayama S.

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

RING_HYDROXYL_ALPHA, PS00570; Bacterial ring hydroxylating dioxygenases alpha-subunit signature  (PATTERN)


1AuthorsNeidle E.L. Hartnett C. Ornston L.N. Bairoch A. Rekik M. Harayama S.
TitleNucleotide sequences of the Acinetobacter calcoaceticus benABC genes for benzoate 1,2-dioxygenase reveal evolutionary relationships among multicomponent oxygenases.
SourceJ. Bacteriol. 173:5385-5395(1991).
PubMed ID1885518

2AuthorsKauppi B. Lee K. Carredano E. Parales R.E. Gibson D.T. Eklund H. Ramaswamy S.
TitleStructure of an aromatic-ring-hydroxylating dioxygenase-naphthalene 1,2-dioxygenase.
SourceStructure 6:571-586(1998).
PubMed ID9634695

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