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In biology, the SECIS element (SECIS: selenocysteine insertion sequence) is an RNA element around 60 nucleotides in length that adopts a stem-loop structure.1 This structural motif (pattern of nucleotides) directs the cell to translate UGA codons as selenocysteines. (UGA is normally a stop codon.) SECIS elements are thus a fundamental aspect of selenoproteins, which are proteins that include one or more selenocysteine residues.
In bacteria the SECIS element appears soon after the UGA codon it affects. In archaea and eukaryotes, it occurs in the 3' UTR of an mRNA, and can cause multiple UGA codons within the mRNA to code for selenocysteine. One archaeal SECIS element, in Methanococcus, is located in the 5' UTR.
The SECIS element appears defined by sequence characteristics, i.e. particular nucleotides tend to be at particular positions in it, and a characteristic secondary structure. The secondary structure is the result of base-pairing of complementary RNA nucleotides, and causes a hairpin-like structure. The eukaryotic SECIS element includes non-canonical A-G base pairs, which are uncommon in nature, but are critically important to correct SECIS element function. Although the eukaryotic, archaeal and bacterial SECIS elements each share a general hairpin structure, they are not alignable, e.g. a scheme to recognize eukaryotic SECIS elements will not be able to recognize archaeal SECIS elements.
In bioinformatics, several computer programs have been created that search for SECIS elements within a genome sequence, based on the sequence and secondary structure characteristics of SECIS elements. These programs have been used in searches for novel selenoproteins.2
Species distribution
The SECIS element is found in a wide variety of eukaryotes, prokaryotes and viruses.3456
References
- ^ Walczak, R; Westhof E, Carbon P, Krol A (1996). "A novel RNA structural motif in the selenocysteine insertion element of eukaryotic selenoprotein mRNAs". RNA 2: 367–379. PMID 8634917.
- ^ Lambert, A; Lescure A, Gautheret D (2002). "A survey of metazoan selenocysteine insertion sequences". Biochimie 84: 953–959. doi:. PMID 12458087.
- ^ Mix H, Lobanov AV, Gladyshev VN (2007). "SECIS elements in the coding regions of selenoprotein transcripts are functional in higher eukaryotes". Nucleic Acids Res. 35 (2): 414–23. doi:. PMID 17169995.
- ^ Cassago A, Rodrigues EM, Prieto EL, et al (2006). "Identification of Leishmania selenoproteins and SECIS element". Mol. Biochem. Parasitol. 149 (2): 128–34. doi:. PMID 16766053.
- ^ Mourier T, Pain A, Barrell B, Griffiths-Jones S (2005). "A selenocysteine tRNA and SECIS element in Plasmodium falciparum". RNA 11 (2): 119–22. doi:. PMID 15659354.
- ^ Lambert A, Lescure A, Gautheret D (2002). "A survey of metazoan selenocysteine insertion sequences". Biochimie 84 (9): 953–9. doi:. PMID 12458087.
- G. V. Kryukov, S. Castellano, S. V. Novoselov, A. V. Lobanov, O. Zehtab, R. Guigó, and V. N. Gladyshev (2003). "Characterization of mammalian selenoproteomes". Science 300 (5624): 1439–1443. doi:. PMID 12775843.
- Gregory V. Kryukov and Vadim N. Gladyshev (2004). "The prokaryotic selenoproteome". EMBO Rep 5 (5): 538–543. doi:. PMID 15105824.
- Alain Krol (2002). "Evolutionarily different RNA motifs and RNA-protein complexes to achieve selenoprotein synthesis". Biochimie 84 (8): 765–774. doi:. PMID 12457564.
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- This page was last modified on 22 September 2008, at 04:23.
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