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Chlamydomonas reinhardtii selenocysteine tRNA[Ser]Sec
Mahadev Rao1, Bradley A Carlson, Sergey V Novoselov
1Section on the Molecular Biology of Selenium, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
Eukaryotic selenocysteine (Sec) protein insertion machinery was thought to be restricted to animals, but the occurrence of both Sec-containing proteins and the Sec insertion system was recently found in Chlamydomonas reinhardtii, a member of the plant kingdom. Herein, we used RT-PCR to determine the sequence of C. reinhardtii Sec tRNA[Ser]Sec, the first non-animal eukaryotic Sec tRNA[Ser]Sec sequence. Like its animal counterpart, it is 90 nucleotides in length, is aminoacylated with serine by seryl-tRNA synthetase, and decodes specifically UGA. Evolutionary analyses of known Sec tRNAs identify the C. reinhardtii form as the most diverged eukaryotic Sec tRNA[Ser]Sec and reveal a common origin for this tRNA in bacteria, archaea, and eukaryotes.