title: Distinct genetic code expansion strategies for selenocysteine and pyrrolysine are reflected in different aminoacyl-tRNA formation systems.
abstract: Selenocysteine and pyrrolysine, known as the 21st and 22nd amino acids, are directly inserted into growing polypeptides during translation. Selenocysteine is synthesized via a tRNA-dependent pathway and decodes UGA (opal) codons. The incorporation of selenocysteine requires the concerted action of specific RNA and protein elements. In contrast, pyrrolysine is ligated directly to tRNA(Pyl) and inserted into proteins in response to UAG (amber) codons without the need for complex re-coding machinery. Here we review the latest updates on the structure and mechanisms of molecules involved in Sec-tRNA(Sec) and Pyl-tRNA(Pyl) formation as well as the distribution of the Pyl-decoding trait.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA. jing.yuan@yale.edu
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.forename: Patrick
authors.initials: P
authors.lastname: O'Donoghue
authors.forename: Alex
authors.initials: A
authors.lastname: Ambrogelly
authors.forename: Sarath
authors.initials: S
authors.lastname: Gundllapalli
authors.forename: R Lynn
authors.initials: RL
authors.lastname: Sherrer
authors.forename: Sotiria
authors.initials: S
authors.lastname: Palioura
authors.forename: Miljan
authors.initials: M
authors.lastname: Simonović
authors.forename: Dieter
authors.initials: D
authors.lastname: Söll
mesh_terms: D018388:Codon, Terminator / Q000235:genetics; D005815:Genetic Code; D008239:Lysine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D017279:Selenocysteine / Q000096:biosynthesis / Q000235:genetics*; D046249:Transfer RNA Aminoacylation
chemical_list: D018388:Codon, Terminator; D012346:RNA, Transfer, Amino Acyl; C112705:selenocysteinyl-tRNA; D017279:Selenocysteine; C456839:pyrrolysine; D008239:Lysine