title: Selenocysteine tRNA identification in the model organisms Dictyostelium discoideum and Tetrahymena thermophila.
abstract: Characterizing Sec tRNAs that decode UGA provides one of the most direct and easiest means of determining whether an organism possesses the ability to insert selenocysteine (Sec) into protein. Herein, we used a combination of two techniques, computational to identify Sec tRNA genes and RT-PCR to sequence the gene products, to unequivocally demonstrate that two widely studied, model protozoans, Dictyostelium discoideum and Tetrahymena thermophila, encode Sec tRNA in their genomes. The advantage of using both procedures is that computationally we could easily detect potential Sec tRNA genes and then confirm by sequencing that the Sec tRNA was present in the tRNA population, and thus the identified gene was not a pseudogene. Sec tRNAs from both organisms decode UGA. T. thermophila Sec tRNA, like all other sequenced Sec tRNAs, is 90 nucleotides in length, while that from D. discoideum is 91 nucleotides long making it the longest eukaryotic sequenced to date. Evolutionary analyses of known Sec tRNAs reveal the two forms identified herein are the most divergent eukaryotic Sec tRNAs thus far sequenced.
authors.affiliation: Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Shrimali
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Lobanov
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Xu
authors.forename: Mahadev
authors.initials: M
authors.lastname: Rao
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Carlson
authors.forename: Dana C
authors.initials: DC
authors.lastname: Mahadeo
authors.forename: Carole A
authors.initials: CA
authors.lastname: Parent
authors.forename: Vadim N
authors.initials: VN
authors.lastname: Gladyshev
authors.forename: Dolph L
authors.initials: DL
authors.lastname: Hatfield
mesh_terms: D000818:Animals; D001483:Base Sequence; D019295:Computational Biology; D019992:Databases as Topic; D004023:Dictyostelium / Q000378:metabolism*; D016678:Genome; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D012343:RNA, Transfer / Q000737:chemistry; D012345:RNA, Transfer, Amino Acid-Specific / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012984:Software; D013045:Species Specificity; D016808:Tetrahymena thermophila / Q000378:metabolism
chemical_list: D012345:RNA, Transfer, Amino Acid-Specific; C036928:tRNA, selenocysteine-; D012343:RNA, Transfer