The unique tRNASec and its role in selenocysteine biosynthesis

Amino Acids. 2018 Sep;50(9):1145-1167. doi: 10.1007/s00726-018-2595-6. Epub 2018 Jun 12.

Abstract

Selenium (Se) is an essential trace element for several organisms and is mostly present in proteins as L-selenocysteine (Sec or U). Sec is synthesized on its L-seryl-tRNASec to produce Sec-tRNASec molecules by a dedicated selenocysteine synthesis machinery and incorporated into selenoproteins at specified in-frame UGA codons. UGA-Sec insertion is signaled by an mRNA stem-loop structure called the SElenoCysteine Insertion Sequence (SECIS). tRNASec transcription regulation and folding have been described showing its importance to Sec biosynthesis. Here, we discuss structural aspects of Sec-tRNASec and its role in Sec biosynthesis as well as Sec incorporation into selenoproteins. Defects in the Sec biosynthesis or incorporation pathway have been correlated with pathological conditions.

Keywords: Sec; Sec–tRNASec; Selenocysteine; Selenoprotein.

Publication types

  • Review

MeSH terms

  • Animals
  • Codon, Terminator / chemistry
  • Codon, Terminator / genetics
  • Codon, Terminator / metabolism
  • Humans
  • Protein Biosynthesis
  • RNA, Messenger / chemistry
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Transfer, Cys / chemistry
  • RNA, Transfer, Cys / genetics*
  • RNA, Transfer, Cys / metabolism
  • Selenocysteine / biosynthesis*
  • Selenocysteine / genetics

Substances

  • Codon, Terminator
  • RNA, Messenger
  • RNA, Transfer, Cys
  • Selenocysteine