RNA-Dependent Cysteine Biosynthesis in Archaea

• Published in: Science (American Association for the Advancement of Science) Vol. 307; no. 5717; pp. 1969 - 1972
• Main Authors: Sauerwald, Anselm, Zhu, Wenhong, Major, Tiffany A, Roy, Hervé, Palioura, Sotiria, Jahn, Dieter, Whitman, William B, Yates, John R, Ibba, Michael, Söll, Dieter
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 25.03.2005; The American Association for the Advancement of Science
• Subjects: Adenosine Triphosphate - metabolism; Amino acids; Amino Acyl-tRNA Synthetases - genetics; Amino Acyl-tRNA Synthetases - isolation & purification; Amino Acyl-tRNA Synthetases - metabolism; Analysis; Archaea; Archaea - enzymology; Archaea - genetics; Archaea - metabolism; Bacteriology; Biochemistry; Biological and medical sciences; Biosynthesis; Cysteine; Cysteine - biosynthesis; Enzymes; Fractions; Fundamental and applied biological sciences. Psychology; Genomes; Genomics; Hydrolysis; Marine; Metabolism. Enzymes; Methanocaldococcus; Methanocaldococcus jannaschii; Methanococcales - enzymology; Methanococcales - genetics; Methanococcales - metabolism; Methanococcus - enzymology; Methanococcus - genetics; Methanococcus - metabolism; Microbiology; Oxidation-Reduction; Phosphoserine - metabolism; Proteins; Ribonucleic acid; RNA; RNA, Archaeal - metabolism; RNA, Transfer, Amino Acyl - metabolism; RNA, Transfer, Cys - metabolism; Scientific Concepts; Transfer RNA; Translation; United States; Sulfur containing aminoacid; Cysteine; Archaeobacteria; Aminoacid; Bacteria; Biosynthesis; Metabolism
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1108329

Several methanogenic archaea lack cysteinyl-transfer RNA (tRNA) synthetase (CysRS), the essential enzyme that provides Cys-tRNA[superscript Cys] for translation in most organisms. Partial purification of the corresponding activity from Methanocaldococcus jannaschii indicated that tRNA[superscript 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[superscript Cys], which is then converted to Cys-tRNA[superscript 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.