Structure of an N-terminally truncated selenophosphate synthetase fromAquifex aeolicus

Abstract

PDB Reference: selenophosphate synthetase, 2zau, r2zausf.Selenophosphate synthetase (SPS) catalyzes the activation of selenide with ATP to synthesize selenophosphate, the reactive selenium donor for biosyntheses of both the 21st amino acid selenocysteine and 2-selenouridine nucleotides in tRNA anticodons. The crystal structure of an N-terminally (25 residues) truncated fragment of SPS (SPS-ÁN) from Aquifex aeolicus has been determined at 2.0 Å resolution. The structure revealed SPS to be a two-domain / protein, with domain folds that are homologous to those of PurMsuperfamily proteins. In the crystal, six monomers of SPS-ÁN form a hexamer of 204 kDa, whereas the molecular weight estimated by ultracentrifugation was $63 kDa, which is comparable to the calculated weight of the dimer (68 kDa).

Structure of Selenophosphate Synthetase Essential for Selenium Incorporation into Proteins and RNAs

“…A phosphate ion is observed at the same site in the SPS-ΔN structure. 24 In the SPS·AMPCPP structure, Gly12 on the N-terminal mobile loop in the closed conformation (subunit A) occupies the pocket, although the excess electron density suggests partial occupancy by a phosphate ion (not shown). The phosphate/sulfate position is ∼ 16.5 Å away from the γ-phosphate group of AMPCPP.…”

“…The crystal structures of SPS and that complexed with adenosine 5′-(α,β-methylene) triphosphate (AMPCPP) (SPS·AMPCPP) were solved by molecular replacement method and refined to 1.98 and 2.1 Å resolutions, respectively ( Table 1). The coordinates of the N-terminally (25-residue) truncated SPS fragment (SPS-ΔN) [Protein Data Bank (PDB) ID 2ZAU], which we reported previously, 24 were used as search model. The space groups differ between the apo SPS and SPS·AMPCPP crystals.…”

Structural Insights into the Catalytic Mechanism of Escherichia coli Selenophosphate Synthetase

“…The crystal structures of SPS from Aquifex aeolicus (AaSPS) (17,28), both native and complexed with AMPCPP (␣,␤-methyleneadenosine 5=-triphosphate, a nonhydrolyzable ATP analogue), were recently reported. The AaSPS crystal structures provided the first view of the overall structure of SPS, as well as the molecular details of the catalytic machinery of SPS and its interaction with the ATP analogue AMPCPP.…”

Crystallization and preliminary X-ray diffraction analysis of selenophosphate synthetases fromTrypanosoma bruceiandLeishmania major

“…The first reported SPS structure from the thermophilic A. aeolicus was also obtained as an N-terminally truncated fragment (Matsumoto et al, 2008). The selenophosphate synthetases possess a flexible N-terminal region owing to the Gly-rich loop (Itoh et al, 2009).…”

“…Crystal structures have been reported of Aquifex aeolicus SPS (AaSPS; 27 and 29% amino-acid sequence identity to TbSPS2 and LmSPS2, respectively) in the apo form and in complex with the nonhydrolyzable AMPCPP (,-methyleneadenosine 5 0 -triphosphate) (Matsumoto et al, 2008;Itoh et al, 2009). For human SPS1 (HsSPS1; 42% amino-acid sequence identity to both TbSPS2 and LmSPS2), structures of complexes with AMPCPP, ADP and P i products have been reported (Wang et al, 2009).…”