title: RNA-dependent cysteine biosynthesis in archaea.
abstract: Several methanogenic archaea lack cysteinyl-transfer RNA (tRNA) synthetase (CysRS), the essential enzyme that provides Cys-tRNA(Cys) for translation in most organisms. Partial purification of the corresponding activity from Methanocaldococcus jannaschii indicated that tRNA(Cys) becomes acylated with O-phosphoserine (Sep) but not with cysteine. Further analyses identified a class II-type O-phosphoseryl-tRNA synthetase (SepRS) and Sep-tRNA:Cys-tRNA synthase (SepCysS). SepRS specifically forms Sep-tRNA(Cys), which is then converted to Cys-tRNA(Cys) by SepCysS. Comparative genomic analyses suggest that this pathway, encoded in all organisms lacking CysRS, can also act as the sole route for cysteine biosynthesis. This was proven for Methanococcus maripaludis, where deletion of the SepRS-encoding gene resulted in cysteine auxotrophy. As the conversions of Sep-tRNA to Cys-tRNA or to selenocysteinyl-tRNA are chemically analogous, the catalytic activity of SepCysS provides a means by which both cysteine and selenocysteine may have originally been added to the genetic code.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
authors.forename: Anselm
authors.initials: A
authors.lastname: Sauerwald
authors.forename: Wenhong
authors.initials: W
authors.lastname: Zhu
authors.forename: Tiffany A
authors.initials: TA
authors.lastname: Major
authors.forename: Hervé
authors.initials: H
authors.lastname: Roy
authors.forename: Sotiria
authors.initials: S
authors.lastname: Palioura
authors.forename: Dieter
authors.initials: D
authors.lastname: Jahn
authors.forename: William B
authors.initials: WB
authors.lastname: Whitman
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: Michael
authors.initials: M
authors.lastname: Ibba
authors.forename: Dieter
authors.initials: D
authors.lastname: Söll
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001105:Archaea / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000096:biosynthesis*; D017015:Methanococcales / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D017017:Methanococcus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010768:Phosphoserine / Q000378:metabolism; D019642:RNA, Archaeal / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012350:RNA, Transfer, Cys / Q000378:metabolism
chemical_list: D019642:RNA, Archaeal; D012346:RNA, Transfer, Amino Acyl; D012350:RNA, Transfer, Cys; D010768:Phosphoserine; D000255:Adenosine Triphosphate; D000604:Amino Acyl-tRNA Synthetases; C019975:cysteinyl-tRNA synthetase; D003545:Cysteine