Structure and mechanism of mouse cysteine dioxygenase.

McCoy, Jason G; Bailey, Lucas J; Bitto, Eduard; Bingman, Craig A; Aceti, David J; Fox, Brian G; Phillips, George N · Proc Natl Acad Sci U S A · 2006

basic_science · Level V

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Abstract

Cysteine dioxygenase (CDO) catalyzes the oxidation of l-cysteine to cysteine sulfinic acid. Deficiencies in this enzyme have been linked to autoimmune diseases and neurological disorders. The x-ray crystal structure of CDO from Mus musculus was solved to a nominal resolution of 1.75 Angstroms. The sequence is 91% identical to that of a human homolog. The structure reveals that CDO adopts the typical beta-barrel fold of the cupin superfamily. The NE2 atoms of His-86, -88, and -140 provide the metal binding site. The structure further revealed a covalent linkage between the side chains of Cys-93 and Tyr-157, the cysteine of which is conserved only in eukaryotic proteins. Metal analysis showed that the recombinant enzyme contained a mixture of iron, nickel, and zinc, with increased iron content associated with increased catalytic activity. Details of the predicted active site are used to present and discuss a plausible mechanism of action for the enzyme.

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