Diversity and functional plasticity of eukaryotic selenoproteins: Identification and characterization of the SelJ family
- Sergi Castellano*,†,
- Alexey V. Lobanov‡,
- Charles Chapple*,
- Sergey V. Novoselov‡,
- Mario Albrecht§,
- Deame Hua‡,
- Alain Lescure¶,
- Thomas Lengauer§,
- Alain Krol¶,
- Vadim N. Gladyshev‡, and
- Roderic Guigó*
- *Grup de Recerca en Informàtica Biomèdica, Institut Municipal d'Investigació Mèdica, Universitat Pompeu Fabra and Centre de Regulació Genòmica, Carrer del Doctor Aiguader 80, 08003 Barcelona, Spain; ‡Department of Biochemistry, University of Nebraska, Lincoln, NE 65588; §Max Planck Institute for Informatics, Stuhlsatzenhausweg 85, 66123 Saarbrücken, Germany; and ¶Institut de Biologie Moléculaire et Cellulaire, 15 Rue René Descartes, 67084 Strasbourg Cedex, France
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Edited by Philip P. Green, University of Washington School of Medicine, Seattle, WA, and approved September 22, 2005 (received for review June 19, 2005)
Abstract
Selenoproteins are a diverse group of proteins that contain selenocysteine (Sec), the 21st amino acid. In the genetic code, UGA serves as a termination signal and a Sec codon. This dual role has precluded the automatic annotation of selenoproteins. Recent advances in the computational identification of selenoprotein genes have provided a first glimpse of the size, functions, and phylogenetic diversity of eukaryotic selenoproteomes. Here, we describe the identification of a selenoprotein family named SelJ. In contrast to known selenoproteins, SelJ appears to be restricted to actinopterygian fishes and sea urchin, with Cys homologues only found in cnidarians. SelJ shows significant similarity to the jellyfish J1-crystallins and with them constitutes a distinct subfamily within the large family of ADP-ribosylation enzymes. Consistent with its potential role as a structural crystallin, SelJ has preferential and homogeneous expression in the eye lens in early stages of zebrafish development. A structural role for SelJ would be in contrast to the majority of known selenoenzymes. The unusually highly restricted phylogenetic distribution of SelJ, its specialization, and the comparative analysis of eukaryotic selenoproteomes reveal the diversity and functional plasticity of selenoproteins and point to a mosaic evolution of the use of Sec in proteins.
Footnotes
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↵ † To whom correspondence should be sent at the present address: Department of Molecular Biology and Genetics, Cornell University, 101 Biotechnology Building, Ithaca, NY 14853. E-mail: sc464{at}cornell.edu.
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Author contributions: S.C., A.V.L., M.A., A.L., T.L., A.K., V.N.G., and R.G. designed research; S.C., A.V.L., C.C., S.V.N., M.A., D.H., and A.L. performed research; S.C. and M.A. analyzed data; and S.C., M.A., V.N.G., and R.G. wrote the paper.
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Conflict of interest statement: No conflicts declared.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviations: Sec, selenocysteine; SECIS, Sec insertion sequence; ARH, ADP-ribosylglycohydrolase; mjARH, ARH from Methanococcus jannaschii.
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See Commentary on page 16123.
- Copyright © 2005, The National Academy of Sciences
