Nematode selenoproteome: The use of the selenocysteine insertion system to decode one codon in an animal genome?

Kalin Taskov, Charles Chapple, Gregory V. Kryukov, Sergi Castellano, Alexey V. Lobanov, Konstantin V. Korotkov, Roderic Guigó, Vadim N. Gladyshev

Research output: Contribution to journalArticlepeer-review

71 Scopus citations

Abstract

Selenocysteine (Sec) is co-translationally inserted into selenoproteins in response to codon UGA with the help of the selenocysteine insertion sequence (SECIS) element. The number of selenoproteins in animals varies, with humans having 25 and mice having 24 selenoproteins. To date, however, only one selenoprotein, thioredoxin reductase, has been detected in Caenorhabditis elegans, and this enzyme contains only one Sec. Here, we characterize the selenoproteomes of C.elegans and Caenorhabditis briggsae with three independent algorithms, one searching for pairs of homologous nematode SECIS elements, another searching for Cys- or Sec-containing homologs of potential nematode selenoprotein genes and the third identifying Sec-containing homologs of annotated nematode proteins. These methods suggest that thioredoxin reductase is the only Sec-containing protein in the C.elegans and C.briggsae genomes. In contrast, we identified additional selenoproteins in other nematodes. Assuming that Sec insertion mechanisms are conserved between nematodes and other eukaryotes, the data suggest that nematode selenoproteomes were reduced during evolution, and that in an extreme reduction case Sec insertion systems probably decode only a single UGA codon in C.elegans and C.briggsae genomes. In addition, all detected genes had a rare form of SECIS element containing a guanosine in place of a conserved adenosine present in most other SECIS structures, suggesting that in organisms with small selenoproteomes SECIS elements may change rapidly.

Original languageEnglish
Pages (from-to)2227-2238
Number of pages12
JournalNucleic Acids Research
Volume33
Issue number7
DOIs
StatePublished - 2005

Bibliographical note

Funding Information:
This study was supported by NIH grants GM061603 and GM065204 and by grant BIO2000-1358-C02-02 from Plan Nacional de I+D (Spain). Funding to pay the Open Access publication charges for this article was provided by GM061603.

ASJC Scopus subject areas

  • Genetics

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