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Literature summary for 2.7.9.3 extracted from

  • Itoh, Y.; Sekine, S.I.; Matsumoto, E.; Akasaka, R.; Takemoto, C.; Shirouzu, M.; Yokoyama, S.
    Structure of selenophosphate synthetase essential for selenium incorporation into proteins and RNAs (2008), J. Mol. Biol., 385, 1456-1469.
    View publication on PubMed

Cloned(Commentary)

Cloned (Comment) Organism
expression of trigger factor-fused SPS2 in Escherichia coli Aquifex aeolicus

Crystallization (Commentary)

Crystallization (Comment) Organism
SPS2 free or with bound alpha/beta-methylene ATP, X-ray diffraction structure determination and analysis at 1.98-2.1 A resolution, molecular replacement Aquifex aeolicus

Protein Variants

Protein Variants Comment Organism
C13S site-directed mutagenesis, inactive mutant, the activity cannot be recovered by the NifS-like protein Aquifex aeolicus
C17S site-directed mutagenesis, inactive mutant, the activity can be recovered by the NifS-like protein Aquifex aeolicus
K16A site-directed mutagenesis, inactive mutant Aquifex aeolicus
N79A site-directed mutagenesis, the mutation enhances the ATP consumption by about 3fold compared to the wild-type enzyme Aquifex aeolicus

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ ATP binding, metal binding, and the formation of their binding sites are interdependent, Thr221 and Gly222 are involved in metal binding Aquifex aeolicus

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
ATP + selenide + H2O Aquifex aeolicus Sec replaces the catalytically essential Cys residue, SPS is strictly conserved in the organisms that utilize Sec and/or selenouridine AMP + selenophosphate + phosphate
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additional information Aquifex aeolicus SPS orthologs, SPS1 and SPS2, exist, and SPS2 is the one that synthesizes selenophosphate, while SPS1 does not ?
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?

Organism

Organism UniProt Comment Textmining
Aquifex aeolicus O67139 gene selD
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Purification (Commentary)

Purification (Comment) Organism
recombinant trigger factor-fused SPS2 from Escherichia coli, during purification, the N-terminal trigger factor portion is removed by proteolysis with thrombin, and the final SPS protein comprises the full-length SPS region, residues 1-336, and nine extra N-terminal residues, GSGGIEGRH, which are derived from the linker Aquifex aeolicus

Reaction

Reaction Comment Organism Reaction ID
ATP + selenide + H2O = AMP + selenophosphate + phosphate SPS catalyzes the exchange of the ATP gamma-phosphate group in the absence of selenide, suggesting that the beta-gamma-phosphate bond, but not the alpha-beta-phosphate bond, could be the initial cleavage site, formation of a phosphorylated enzyme intermediate, catalytic mechanism, overview Aquifex aeolicus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ATP + selenide + H2O Sec replaces the catalytically essential Cys residue, SPS is strictly conserved in the organisms that utilize Sec and/or selenouridine Aquifex aeolicus AMP + selenophosphate + phosphate
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?
ATP + selenide + H2O the phosphate moiety of selenophosphate is derived from the ATP gamma-phosphate group, while the orthophosphate is from the beta-phosphate group. Although Thr221 is not essential for the reaction, it contributes to the enzyme activity, probably by interacting with the ATP gamma-phosphate group and a water molecule. Sec/Cys13 and Lys16 are essential for the SPS catalysis. Thr221 and Gly222 interact with the gamma-phosphate group of ATP Aquifex aeolicus AMP + selenophosphate + phosphate
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?
additional information SPS orthologs, SPS1 and SPS2, exist, and SPS2 is the one that synthesizes selenophosphate, while SPS1 does not Aquifex aeolicus ?
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?

Synonyms

Synonyms Comment Organism
More SPS belongs to the PurM superfamily Aquifex aeolicus
selenophosphate synthase
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Aquifex aeolicus
SPS
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Aquifex aeolicus

Cofactor

Cofactor Comment Organism Structure
alpha,beta-methylene ATP i.e. MPCPP, binding structure, overview Aquifex aeolicus
ATP the ATP-binding site is formed at the subunit interface of the homodimer. Four Asp residues coordinate four metal ions to bind the phosphate groups of AMPCPP. In the free SPS structure, the two loop regions in the ATP-binding site are not ordered, and no enzyme-associated metal is observed. This suggests that ATP binding, metal binding, and the formation of their binding sites are interdependent, Thr221 and Gly222 interact with the gamma-phosphate group of ATP Aquifex aeolicus