Characterization of selenium-containing tRNAGlu from Clostridium sticklandii.
A selenium-containing tRNA from Clostridium sticklandii has been shown to be an isoaccepting tRNAGlu (W.-M. Ching and T. C. Stadtman (1982) Proc. Natl. Acad. Sci. USA 79, 374-377). Not only is this tRNAGlu one of the most abundant selenium-containing tRNA species but it is also the major glutamate isoacceptor in this organism. The selenonucleoside, which is located at the first position of the anticodon, was identified as 5-methylaminomethyl-2-selenouridine (A. J. Wittwer, L. Tsai, W.-M. Ching, and T. C. Stadt (1984) Biochemistry 23, 4650-4655). Other modified nucleosides present in this tRNA include 4-thiouridine, pseudouridine, ribothymidine, modified guanosine, and two different modified adenosines. When this seleno-tRNAGlu is incubated in 1.0 M Tris X HCl, pH 8.5, partial deselenization occurs. Moreover, treatment with cyanogen bromide almost completely removes the selenium. The presence of selenium in this tRNAGlu is essential for its enzymatic acylation with glutamate. This seleno-tRNAGlu recognizes both GAA and GAG codons. However, at 10 mM magnesium, which is near the physiological range, the GAA codon is slightly favored. In a cell free translation system, the acylated seleno-tRNAGlu is a very active glutamate donor.
W M
WM
Ching
D001426:Bacterial Proteins / Q000096:biosynthesis; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D003013:Clostridium / Q000235:genetics*; D003062:Codon; D009705:Nucleosides / Q000032:analysis; D012329:RNA, Bacterial / Q000502:physiology*; D012343:RNA, Transfer / Q000502:physiology*; D012346:RNA, Transfer, Amino Acyl / Q000502:physiology*; D012270:Ribosomes / Q000378:metabolism; D012643:Selenium / Q000502:physiology*
D001426:Bacterial Proteins; D003062:Codon; D009705:Nucleosides; D012329:RNA, Bacterial; D012346:RNA, Transfer, Amino Acyl; C366009:seleno-tRNA; D012343:RNA, Transfer; D012643:Selenium