Identification of the Selenoprotein S Positive UGA Recoding (SPUR) element and its position-dependent activity.

Selenoproteins are a unique class of proteins that contain the 21 amino acid, selenocysteine (Sec). Addition of Sec into a protein is achieved by recoding of the UGA stop codon. All 25 mammalian selenoprotein mRNAs possess a 3' UTR stem-loop structure, the Selenocysteine Insertion Sequence (SECIS), which is required for Sec incorporation.

Identification and Characterization of Proteins that Bind to Selenoprotein 3' UTRs.

This chapter explains the use of RNase-assisted RNA chromatography. RNA affinity chromatography is a powerful technique that is used to isolate and identify proteins that bind to a specific RNA ligand. The RNA of interest is attached to beads before protein lysates are passed over the column.

Selenoprotein Gene Nomenclature.

The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4, and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine sulfoxide reductase B1), and SEPHS2 (selenophosphate synthetase 2).

Characterization of the UGA-recoding and SECIS-binding activities of SECIS-binding protein 2.

Selenium, a micronutrient, is primarily incorporated into human physiology as selenocysteine (Sec). The 25 Sec-containing proteins in humans are known as selenoproteins. Their synthesis depends on the translational recoding of the UGA stop codon to allow Sec insertion.

Impaired selenoprotein expression in brain triggers striatal neuronal loss leading to co-ordination defects in mice.

Secisbp2 [SECIS (selenocysteine insertion sequence)-binding protein 2] binds to SECIS elements located in the 3'-UTR region of eukaryotic selenoprotein mRNAs. It facilitates the incorporation of the rare amino acid selenocysteine in response to UGA codons. Inactivation of Secisbp2 in hepatocytes greatly reduced selenoprotein levels.

Secisbp2 is essential for embryonic development and enhances selenoprotein expression.

Aims: The selenocysteine insertion sequence (SECIS)-binding protein 2 (Secisbp2) binds to SECIS elements located in the 3'-untranslated region of eukaryotic selenoprotein mRNAs. Selenoproteins contain the rare amino acid selenocysteine (Sec). Mutations in SECISBP2 in humans lead to reduced selenoprotein expression thereby affecting thyroid hormone-dependent growth and differentiation processes.

Identification of nucleotides and amino acids that mediate the interaction between ribosomal protein L30 and the SECIS element.

Background: Ribosomal protein L30 belongs to the L7Ae family of RNA-binding proteins, which recognize diverse targets. L30 binds to kink-turn motifs in the 28S ribosomal RNA, L30 pre-mRNA, and mature L30 mRNA. L30 has a noncanonical function as a component of the UGA recoding machinery that incorporates selenocysteine (Sec) into selenoproteins during translation.

Alternative transcripts and 3'UTR elements govern the incorporation of selenocysteine into selenoprotein S.

Selenoprotein S (SelS) is a 189 amino acid trans-membrane protein that plays an important yet undefined role in the unfolded protein response. It has been proposed that SelS may function as a reductase, with the penultimate selenocysteine (Sec(188)) residue participating in a selenosulfide bond with cysteine (Cys(174)). Cotranslational incorporation of Sec into SelS depends on the recoding of the UGA codon, which requires a Selenocysteine Insertion Sequence (SECIS) element in the 3'UTR of the transcript.

Identification of a signature motif for the eIF4a3-SECIS interaction.

eIF4a3, a DEAD-box protein family member, is a component of the exon junction complex which assembles on spliced mRNAs. The protein also acts as a transcript-selective translational repressor of selenoprotein synthesis during selenium deficiency. Selenocysteine (Sec) incorporation into selenoproteins requires a Sec Insertion Sequence (SECIS) element in the 3' untranslated region.

Nucleolin binds to a subset of selenoprotein mRNAs and regulates their expression.

Selenium, an essential trace element, is incorporated into selenoproteins as selenocysteine (Sec), the 21st amino acid. In order to synthesize selenoproteins, a translational reprogramming event must occur since Sec is encoded by the UGA stop codon. In mammals, the recoding of UGA as Sec depends on the selenocysteine insertion sequence (SECIS) element, a stem-loop structure in the 3' untranslated region of the transcript.

Eukaryotic initiation factor 4a3 is a selenium-regulated RNA-binding protein that selectively inhibits selenocysteine incorporation.

The synthesis of selenoproteins requires the translational recoding of the UGA stop codon as selenocysteine. During selenium deficiency, there is a hierarchy of selenoprotein expression, with certain selenoproteins synthesized at the expense of others. The mechanism by which the limiting selenocysteine incorporation machinery is preferentially utilized to maintain the expression of essential selenoproteins has not been elucidated.

Novel structural determinants in human SECIS elements modulate the translational recoding of UGA as selenocysteine.

The selenocysteine insertion sequence (SECIS) element directs the translational recoding of UGA as selenocysteine. In eukaryotes, the SECIS is located downstream of the UGA codon in the 3'-UTR of the selenoprotein mRNA. Despite poor sequence conservation, all SECIS elements form a similar stem-loop structure containing a putative kink-turn motif.

Known turnover and translation regulatory RNA-binding proteins interact with the 3' UTR of SECIS-binding protein 2.

The human selenoproteome is composed of approximately 25 selenoproteins, which cotranslationally incorporate selenocysteine, the 21st amino acid. Selenoprotein expression requires an unusual translation mechanism, as selenocysteine is encoded by the UGA stop codon. SECIS-binding protein 2 (SBP2) is an essential component of the selenocysteine insertion machinery.

Altered RNA binding activity underlies abnormal thyroid hormone metabolism linked to a mutation in selenocysteine insertion sequence-binding protein 2.

The expression of selenoproteins requires the translational recoding of the UGA stop codon to selenocysteine. In eukaryotes, this requires an RNA stem loop structure in the 3'-untranslated region, termed a selenocysteine insertion sequence (SECIS), and SECIS-binding protein 2 (SBP2). This study implicates SBP2 in dictating the hierarchy of selenoprotein expression, because it is the first to show that SBP2 distinguishes between SECIS elements in vitro.

Ribosomal protein L30 is a component of the UGA-selenocysteine recoding machinery in eukaryotes.

The translational recoding of UGA as selenocysteine (Sec) is directed by a SECIS element in the 3' untranslated region (UTR) of eukaryotic selenoprotein mRNAs. The selenocysteine insertion sequence (SECIS) contains two essential tandem sheared G.A pairs that bind SECIS-binding protein 2 (SBP2), which recruits a selenocysteine-specific elongation factor and Sec-tRNA(Sec) to the ribosome.

Noncanonical function of glutamyl-prolyl-tRNA synthetase: gene-specific silencing of translation.

Aminoacyl tRNA synthetases (ARS) catalyze the ligation of amino acids to cognate tRNAs. Chordate ARSs have evolved distinctive features absent from ancestral forms, including compartmentalization in a multisynthetase complex (MSC), noncatalytic peptide appendages, and ancillary functions unrelated to aminoacylation. Here, we show that glutamyl-prolyl-tRNA synthetase (GluProRS), a bifunctional ARS of the MSC, has a regulated, noncanonical activity that blocks synthesis of a specific protein.

Isolation of an mRNA-binding protein involved in C-to-U editing.

This chapter describes the technique of RNA affinity chromatography, which is a powerful approach for isolating RNA-binding proteins. This method takes advantage of the fact that sequence-specific RNA-binding proteins often bind their targets with high affinity. Here we outline a protocol for purifying Apobec-1 complementation factor (ACF), the RNA-binding subunit of the apolipoprotein-B (apo-B) mRNA-editing enzyme.

Finding needles in a haystack. In silico identification of eukaryotic selenoprotein genes.

identification of eukaryotic selenoprotein genes

Mechanism and regulation of selenoprotein synthesis.

Selenium is an essential trace element that is incorporated into proteins as selenocysteine (Sec), the twenty-first amino acid. Sec is encoded by a UGA codon in the selenoprotein mRNA. The decoding of UGA as Sec requires the reprogramming of translation because UGA is normally read as a stop codon.

Identification of domains in apobec-1 complementation factor required for RNA binding and apolipoprotein-B mRNA editing.

The C-to-U editing of apolipoprotein-B (apo-B) mRNA is catalyzed by an enzyme complex that recognizes an 11-nt mooring sequence downstream of the editing site. A minimal holoenzyme that edits apo-B mRNA in vitro has been defined. This complex contains apobec-1, the catalytic subunit, and apobec-1 complementation factor (ACF), the RNA-binding subunit that binds to the mooring sequence.