Dataset Information

A novel stem loop control element-dependent UGA read-through system without translational selenocysteine incorporation in Drosophila.

ABSTRACT: Translational read-through of the UGA stop codon is an evolutionarily conserved feature that most prominently represents the basis of selenoprotein biosynthesis. It requires a specific cis-acting stem loop control element, termed SECIS, which is located in the 3'-untranslated region of eukaryotic selenoprotein mRNAs. In a search for novel factors underlying the SECIS-directed UGA read-through process, we identified an evolutionary conserved GTPase-activating protein, termed GAPsec. We show that the activity of the Drosophila GAPsec (dGAPsec) is necessary to support SECIS-dependent UGA read-through activity in flies and the mouse homolog mGAPsec in mice tissue culture cells. However, selenoprotein biosynthesis is not impaired in flies that lack dGAPsec activity. The results indicate that GAPsec is part of a novel SECIS-dependent translational read-through system that does not involve selenocysteine incorporation.

SUBMITTER: Hirosawa-Takamori M

PROVIDER: S-EPMC2626620 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A novel stem loop control element-dependent UGA read-through system without translational selenocysteine incorporation in Drosophila.

Hirosawa-Takamori Mitsuko M Ossipov Dmitri D Novoselov Sergey V SV Turanov Anton A AA Zhang Yan Y Gladyshev Vadim N VN Krol Alain A Vorbrüggen Gerd G Jäckle Herbert H

FASEB journal : official publication of the Federation of American Societies for Experimental Biology 20080904 1

Translational read-through of the UGA stop codon is an evolutionarily conserved feature that most prominently represents the basis of selenoprotein biosynthesis. It requires a specific cis-acting stem loop control element, termed SECIS, which is located in the 3'-untranslated region of eukaryotic selenoprotein mRNAs. In a search for novel factors underlying the SECIS-directed UGA read-through process, we identified an evolutionary conserved GTPase-activating protein, termed GAPsec. We show that ...[more]

PMID: 18772345

Similar Datasets

Project description:The formate dehydrogenases (Fdh) Fdh-O, Fdh-N, and Fdh-H, are the only proteins in Escherichia coli that incorporate selenocysteine at a specific position by decoding a UGA codon. However, an excess of selenium can lead to toxicity through misincorporation of selenocysteine into proteins. To determine whether selenocysteine substitutes for cysteine, we grew Escherichia coli in the presence of excess sodium selenite. The respiratory Fdh-N and Fdh-O enzymes, along with nitrate reductase (Nar) were co-purified from wild type strain MC4100 after anaerobic growth with nitrate and either 2 µM or 100 µM selenite. Mass spectrometric analysis of the catalytic subunits of both Fdhs identified the UGA-specified selenocysteine residue and revealed incorporation of additional, 'non-specific' selenocysteinyl residues, which always replaced particular cysteinyl residues. Although variable, their incorporation was not random and was independent of the selenite concentration used. Notably, these cysteines are likely to be non-essential for catalysis and they do not coordinate the iron-sulfur cluster. The remaining cysteinyl residues that could be identified were never substituted by selenocysteine. Selenomethionine was never observed in our analyses. Non-random substitution of particular cysteinyl residues was also noted in the electron-transferring subunit of both Fdhs as well as in the subunits of the Nar enzyme. Nar isolated from an E. coli selC mutant also showed a similar selenocysteine incorporation pattern to the wild-type indicating that non-specific selenocysteine incorporation was independent of the specific selenocysteine pathway. Thus, selenide replaces sulfide in the biosynthesis of cysteine and misacylated selenocysteyl-tRNA(Cys) decodes either UGU or UGC codons, which usually specify cysteine. Nevertheless, not every UGU or UGC codon was decoded as selenocysteine. Together, our results suggest that a degree of misincorporation of selenocysteine into enzymes through replacement of particular, non-essential cysteines, is tolerated and this might act as a buffering system to cope with excessive intracellular selenium.

Dataset Information

A novel stem loop control element-dependent UGA read-through system without translational selenocysteine incorporation in Drosophila.

Publications

A novel stem loop control element-dependent UGA read-through system without translational selenocysteine incorporation in Drosophila.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets