Universität zu Köln

Arjune, Sita, Schwarz, Guenter ORCID: 0000-0002-2118-9338 and Belaidi, Abdel A. (2015). Involvement of the Cys-Tyr cofactor on iron binding in the active site of human cysteine dioxygenase. Amino Acids, 47 (1). S. 55 - 64. WIEN: SPRINGER WIEN. ISSN 1438-2199

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Abstract

Sulfur metabolism has gained increasing medical interest over the last years. In particular, cysteine dioxygenase (CDO) has been recognized as a potential marker in oncology due to its altered gene expression in various cancer types. Human CDO is a non-heme iron-dependent enzyme, which catalyzes the irreversible oxidation of cysteine to cysteine sulfinic acid, which is further metabolized to taurine or pyruvate and sulfate. Several studies have reported a unique post-translational modification of human CDO consisting of a cross-link between cysteine 93 and tyrosine 157 (Cys-Tyr), which increases catalytic efficiency in a substrate-dependent manner. However, the reaction mechanism by which the Cys-Tyr cofactor increases catalytic efficiency remains unclear. In this study, steady-state kinetics were determined for wild type CDO and two different variants being either impaired or saturated with the Cys-Tyr cofactor. Cofactor formation in CDO resulted in an approximately fivefold increase in k (cat) and tenfold increase in k (cat)/K (m) over the cofactor-free CDO variant. Furthermore, iron titration experiments revealed an 18-fold decrease in K (d) of iron upon cross-link formation. This finding suggests a structural role of the Cys-Tyr cofactor in coordinating the ferrous iron in the active site of CDO in accordance with the previously postulated reaction mechanism of human CDO. Finally, we identified product-based inhibition and alpha-ketoglutarate and glutarate as CDO inhibitors using a simplified well plate-based activity assay. This assay can be used for high-throughput identification of additional inhibitors, which may contribute to understand the functional importance of CDO in sulfur amino acid metabolism and related diseases.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Arjune, Sita UNSPECIFIED UNSPECIFIED UNSPECIFIED Schwarz, Guenter UNSPECIFIED orcid.org/0000-0002-2118-9338 UNSPECIFIED Belaidi, Abdel A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-417890
DOI:	10.1007/s00726-014-1843-7
Journal or Publication Title:	Amino Acids
Volume:	47
Number:	1
Page Range:	S. 55 - 64
Date:	2015
Publisher:	SPRINGER WIEN
Place of Publication:	WIEN
ISSN:	1438-2199
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Biochemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CONTAINING AMINO-ACIDS; GLUTATHIONE SYNTHESIS; IN-VIVO; METABOLISM; RAT; ENZYMES; PURIFICATION; BIOGENESIS; DEFICIENCY; PARKINSONS Multiple languages Biochemistry & Molecular Biology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/41789