Pseudouridine, the fifth-most abundant nucleoside in RNA, is not metabolized in mammals, but is excreted intact in urine. The purpose of the present work was to search for an enzyme that would dephosphorylate pseudouridine 5′-phosphate, a potential intermediate in RNA degradation. We show that human erythrocytes contain a pseudouridine-5′-phosphatase displaying a Km ≤ 1 μM for its substrate. The activity of the partially purified enzyme was dependent on Mg2+, and was inhibited by Ca2+ and vanadate, suggesting that it belonged to the ‘haloacid dehalogenase’ family of phosphatases. Its low molecular mass (26 kDa) suggested that this phosphatase could correspond to the protein encoded by the HDHD1 (haloacid dehalogenase-like hydrolase domain-containing 1) gene, present next to the STS (steroid sulfatase) gene on human chromosome Xp22. Purified human recombinant HDHD1 dephosphorylated pseudouridine 5′-phosphate with a kcat of 1.6 s−1, a Km of 0.3 μM and a catalytic efficiency at least 1000-fold higher than that on which it acted on other phosphate esters, including 5′-UMP. The molecular identity of pseudouridine-5′-phosphatase was confirmed by the finding that its activity was negligible (<10% of controls) in extracts of B-cell lymphoblasts or erythrocytes from X-linked ichthyosis patients harbouring a combined deletion of the STS gene (the X-linked ichthyosis gene) and the HDHD1 gene. Furthermore, pseudouridine-5′-phosphatase activity was 1.5-fold higher in erythrocytes from women compared with men, in agreement with the HDHD1 gene undergoing only partial inactivation in females. In conclusion, HDHD1 is a phosphatase specifically involved in dephosphorylation of a modified nucleotide present in RNA.
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Research Article|
September 28 2010
HDHD1, which is often deleted in X-linked ichthyosis, encodes a pseudouridine-5′-phosphatase
Alice Preumont;
Alice Preumont
1de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium
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Rim Rzem;
Rim Rzem
1de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium
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Didier Vertommen;
Didier Vertommen
1de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium
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Emile Van Schaftingen
Emile Van Schaftingen
1
1de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium
1To whom correspondence should be addressed (email emile.vanschaftingen@uclouvain.be).
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Publisher: Portland Press Ltd
Received:
January 29 2010
Revision Received:
August 17 2010
Accepted:
August 20 2010
Accepted Manuscript online:
August 20 2010
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2010 Biochemical Society
2010
Biochem J (2010) 431 (2): 237–244.
Article history
Received:
January 29 2010
Revision Received:
August 17 2010
Accepted:
August 20 2010
Accepted Manuscript online:
August 20 2010
Citation
Alice Preumont, Rim Rzem, Didier Vertommen, Emile Van Schaftingen; HDHD1, which is often deleted in X-linked ichthyosis, encodes a pseudouridine-5′-phosphatase. Biochem J 15 October 2010; 431 (2): 237–244. doi: https://doi.org/10.1042/BJ20100174
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