Enzymes
| UniProtKB help_outline | 2,269 proteins |
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Reaction participants Show >> << Hide
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Namehelp_outline
O-phospho-L-seryl-tRNASec
Identifier
RHEA-COMP:9947
Reactive part
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- Name help_outline 3'-(O-phosphonato-L-seryl)adenylyl group Identifier CHEBI:78551 Charge -2 Formula C13H17N6O11P2 SMILEShelp_outline Nc1ncnc2n(cnc12)[C@@H]1O[C@H](COP([O-])(-*)=O)[C@@H](OC(=O)[C@@H]([NH3+])COP([O-])([O-])=O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 4 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline selenophosphate Identifier CHEBI:16144 Charge -3 Formula O3PSe InChIKeyhelp_outline JRPHGDYSKGJTKZ-UHFFFAOYSA-K SMILEShelp_outline [O-]P([O-])([O-])=[Se] 2D coordinates Mol file for the small molecule Search links Involved in 9 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O Identifier CHEBI:15377 (CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,337 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Namehelp_outline
L-selenocysteinyl-tRNASec
Identifier
RHEA-COMP:9743
Reactive part
help_outline
- Name help_outline 3'-(L-selenocysteinyl)adenylyl group Identifier CHEBI:78573 Charge -1 Formula C13H17N6O7PSe SMILEShelp_outline N[C@@H](C[SeH])C(=O)O[C@H]1[C@@H](O)[C@@H](O[C@@H]1COP([O-])(-*)=O)n1cnc2c(N)ncnc12 2D coordinates Mol file for the small molecule Search links Involved in 2 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline phosphate Identifier CHEBI:43474 Charge -2 Formula HO4P InChIKeyhelp_outline NBIIXXVUZAFLBC-UHFFFAOYSA-L SMILEShelp_outline OP([O-])([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 1,020 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:25041 | RHEA:25042 | RHEA:25043 | RHEA:25044 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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The human SepSecS-tRNASec complex reveals the mechanism of selenocysteine formation.
Palioura S., Sherrer R.L., Steitz T.A., Soll D., Simonovic M.
Selenocysteine is the only genetically encoded amino acid in humans whose biosynthesis occurs on its cognate transfer RNA (tRNA). O-Phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS) catalyzes the final step of selenocysteine formation by a poorly understood tRNA-dependent mechanism. The cr ... >> More
Selenocysteine is the only genetically encoded amino acid in humans whose biosynthesis occurs on its cognate transfer RNA (tRNA). O-Phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS) catalyzes the final step of selenocysteine formation by a poorly understood tRNA-dependent mechanism. The crystal structure of human tRNA(Sec) in complex with SepSecS, phosphoserine, and thiophosphate, together with in vivo and in vitro enzyme assays, supports a pyridoxal phosphate-dependent mechanism of Sec-tRNA(Sec) formation. Two tRNA(Sec) molecules, with a fold distinct from other canonical tRNAs, bind to each SepSecS tetramer through their 13-base pair acceptor-TPsiC arm (where Psi indicates pseudouridine). The tRNA binding is likely to induce a conformational change in the enzyme's active site that allows a phosphoserine covalently attached to tRNA(Sec), but not free phosphoserine, to be oriented properly for the reaction to occur. << Less
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RNA-dependent conversion of phosphoserine forms selenocysteine in eukaryotes and archaea.
Yuan J., Palioura S., Salazar J.C., Su D., O'Donoghue P., Hohn M.J., Cardoso A.M., Whitman W.B., Soell D.
The trace element selenium is found in proteins as selenocysteine (Sec), the 21st amino acid to participate in ribosome-mediated translation. The substrate for ribosomal protein synthesis is selenocysteinyl-tRNA(Sec). Its biosynthesis from seryl-tRNA(Sec) has been established for bacteria, but the ... >> More
The trace element selenium is found in proteins as selenocysteine (Sec), the 21st amino acid to participate in ribosome-mediated translation. The substrate for ribosomal protein synthesis is selenocysteinyl-tRNA(Sec). Its biosynthesis from seryl-tRNA(Sec) has been established for bacteria, but the mechanism of conversion from Ser-tRNA(Sec) remained unresolved for archaea and eukarya. Here, we provide evidence for a different route present in these domains of life that requires the tRNA(Sec)-dependent conversion of O-phosphoserine (Sep) to Sec. In this two-step pathway, O-phosphoseryl-tRNA(Sec) kinase (PSTK) converts Ser-tRNA(Sec) to Sep-tRNA(Sec). This misacylated tRNA is the obligatory precursor for a Sep-tRNA:Sec-tRNA synthase (SepSecS); this protein was previously annotated as SLA/LP. The human and archaeal SepSecS genes complement in vivo an Escherichia coli Sec synthase (SelA) deletion strain. Furthermore, purified recombinant SepSecS converts Sep-tRNA(Sec) into Sec-tRNA(Sec) in vitro in the presence of sodium selenite and purified recombinant E. coli selenophosphate synthetase (SelD). Phylogenetic arguments suggest that Sec decoding was present in the last universal common ancestor. SepSecS and PSTK coevolved with the archaeal and eukaryotic lineages, but the history of PSTK is marked by several horizontal gene transfer events, including transfer to non-Sec-decoding Cyanobacteria and fungi. << Less
Proc. Natl. Acad. Sci. U.S.A. 103:18923-18927(2006) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.