Selenocysteine

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Selenocysteine

August Böck, University of Munich, Munich, Germany

Published online: May 2005

DOI: 10.1038/npg.els.0003891

Full Article on Wiley Online Library

Abstract
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References

The trace element selenium is present in the form of selenocysteine in selected proteins of organisms from all three lines of descent. Selenocysteine incorporation is DNA-encoded, determined by the UGA codon, and occurs via a unique mechanism representing an expansion of the genetic code.

Keywords: selenoproteins; SelB; selenocysteyl-tRNA; SECIS; recoding

References
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	Stadtman TC (1996) Selenocysteine. Annual Review of Biochemistry 65: 83–100.
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Further Reading
	book Atkins JF, Böck A, Matsufuji S and Gesteland RF (1999) "Dynamics of the genetic code". In: Gesteland RF, Cech TR, Atkins JF (eds). The RNA World, 2nd edn, pp. 637–673. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press.
	book Hatfield DL (ed.) (2001) Selenium. Its Molecular Biology and Role in Human Health. Boston: Kluwer Academic.
	book Hüttenhofer A and Böck A (1998) "RNA structures involved in selenoprotein synthesis". In: Simons RW and Grunberg-Manago M (eds) RNA Structure and Function, pp. 603–638. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press.
	Low SC and Berry MJ (1996) Knowing when not to stop: selenocysteine incorporation in eukaryotes. Trends in Biochemical Sciences 21: 203–208.
	Stadtman TC (1996) Selenocysteine. Annual Review of Biochemistry 65: 83–100.

Article Title:	Selenocysteine
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	Figure 1. Cloverleaf structures of selenocysteine tRNAs from E. coli, M. jannaschii and humans. Novel tertiary interactions are indicated by bold arrows. Positions conserved in all elongator tRNAs are circled; positions deviating from the consensus are boxed (Sturchler et al., 1993; Baron and Böck, 1995).
	Figure 2. Interactions of SelB with ligands. Domains I, II and III are homologous to those from EF-Tu and interact with guanine nucleotides and selenocysteyl-tRNA; domain IVb binds the SECIS element. Binding of the charged tRNA confers on SelB a conformation with a higher affinity for the SECIS structure. This form of SelB is able to interact with the ribosome, induce GTP hydrolysis and release the charged tRNA. The isolated domain IVb has the same affinity for the SelB protein as the whole-length protein carrying the tRNA. Numbers give the equilibrium constants as determined by stopped-flow analysis (Thanbichler; Böck, 2001).
	Figure 3. Model of the function of the SECIS element in selenocysteine insertion by bacteria (Baron and Böck, 1995) and eukarya (Tujebajeva et al., 2000).

Selenocysteine

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