Crystal structures of Fe2+ dioxygenase superoxo, alkylperoxo, and bound product intermediates.
We report the structures of three intermediates in the O2 activation and insertion reactions of an extradiol ring-cleaving dioxygenase. A crystal of Fe2+-containing homoprotocatechuate 2,3-dioxygenase was soaked in the slow substrate 4-nitrocatechol in a low O2 atmosphere. The x-ray crystal structure shows that three different intermediates reside in different subunits of a single homotetrameric enzyme molecule. One of these is the key substrate-alkylperoxo-Fe2+ intermediate, which has been predicted, but not structurally characterized, in an oxygenase. The intermediates define the major chemical steps of the dioxygenase mechanism and point to a general mechanistic strategy for the diverse 2-His-1-carboxylate enzyme family.
Kovaleva
Elena G
EG
Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
Lipscomb
John D
JD
D001665:Binding Sites; D001951:Brevibacterium / Q000201:enzymology*; D002384:Catalysis; D002396:Catechols / Q000737:chemistry / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D049308:Dioxygenases / Q000737:chemistry* / Q000378:metabolism*; D005290:Ferric Compounds / Q000737:chemistry* / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D013481:Superoxides / Q000737:chemistry
D002396:Catechols; D005290:Ferric Compounds; D005296:Ferrous Compounds; D008024:Ligands; D021122:Protein Subunits; D013481:Superoxides; D049308:Dioxygenases; C020055:3,4-dihydroxyphenylacetate 2,3-dioxygenase; D010100:Oxygen; C001833:4-nitrocatechol