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Overproduction of selenocysteine tRNA in Chinese hamster ovary cells following transfection of the mouse tRNA[Ser]Sec gene

Published online by Cambridge University Press:  01 November 1998

MOHAMED E. MOUSTAFA ,
MUHAMMAD A. EL-SAADANI ,
KAMAL M. KANDEEL ,
DAVID B. MANSUR ,
BYEONG JAE LEE ,
DOLPH L. HATFIELD  and
ALAN M. DIAMOND
MOHAMED E. MOUSTAFA
Affiliation:
Section on the Molecular Biology of Selenium, Basic Research Laboratory, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
MUHAMMAD A. EL-SAADANI
Affiliation:
Department of Biochemistry, Faculty of Science, Alexandria University, Alexandria, Egypt
KAMAL M. KANDEEL
Affiliation:
Department of Biochemistry, Faculty of Science, Alexandria University, Alexandria, Egypt
DAVID B. MANSUR
Affiliation:
Department of Human Nutrition and Dietetics, University of Illinois at Chicago, Chicago, Illinois 60612-7256, USA
BYEONG JAE LEE
Affiliation:
Laboratory of Molecular Genetics, Institute for Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Korea
DOLPH L. HATFIELD
Affiliation:
Section on the Molecular Biology of Selenium, Basic Research Laboratory, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
ALAN M. DIAMOND
Affiliation:
Department of Human Nutrition and Dietetics, University of Illinois at Chicago, Chicago, Illinois 60612-7256, USA
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Abstract

Selenocysteine insertion during selenoprotein biosynthesis begins with the aminoacylation of selenocysteine tRNA[Ser]Sec with serine, the conversion of the serine moiety to selenocysteine, and the recognition of specific UGA codons within the mRNA. Selenocysteine tRNA[Ser]Sec exists as two major forms, differing by methylation of the ribose portion of the nucleotide at the wobble position of the anticodon. The levels and relative distribution of these two forms of the tRNA are influenced by selenium in mammalian cells and tissues. We have generated Chinese hamster ovary cells that exhibit increased levels of tRNA[Ser]Sec following transfection of the mouse tRNA[Ser]Sec gene. The levels of selenocysteine tRNA[Ser]Sec in transfectants increased proportionally to the number of stably integrated copies of the tRNA[Ser]Sec gene. Although we were able to generate transfectants overproducing tRNA[Ser]Sec by as much as tenfold, the additional tRNA was principally retained in the unmethylated form. Selenium supplementation could not significantly affect the relative distributions of the two major selenocysteine tRNA[Ser]Sec isoacceptors. In addition, increased levels of tRNA[Ser]Sec did not result in measurable alterations in the levels of selenoproteins, including glutathione peroxidase.

Keywords

glutathione peroxidasemethylationseleniumselenoprotein
Type
Research Article
Information
RNA , Volume 4 , Issue 11 , November 1998 , pp. 1436 - 1443
Copyright
© 1998 RNA Society

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