| 1. |
- Škerlová, Jana, et al.
(författare)
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Crystal structures of human PAICS reveal substrate and product binding of an emerging cancer target
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:33, s. 11656-11668
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Tidskriftsartikel (refereegranskat)abstract
- The bifunctional human enzyme phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazolesuccinocarboxamide synthetase (PAICS) catalyzes two essential steps in the de novo purine biosynthesis pathway. PAICS is overexpressed in many cancers and could be a promising target for the development of cancer therapeutics. Here, using gene knockdowns and clonogenic survival and cell viability assays, we demonstrate that PAICS is required for growth and survival of prostate cancer cells. PAICS catalyzes the carboxylation of aminoimidazole ribonucleotide (AIR) and the subsequent conversion of carboxyaminoimidazole ribonucleotide (CAIR) and l-aspartate to N-succinylcarboxamide-5-aminoimidazole ribonucleotide (SAICAR). Of note, we present the first structures of human octameric PAICS in complexes with native ligands. In particular, we report the structure of PAICS with CAIR bound in the active sites of both domains and SAICAR bound in one of the SAICAR synthetase domains. Moreover, we report the PAICS structure with SAICAR and an ATP analog occupying the SAICAR synthetase active site. These structures provide insight into substrate and product binding and the architecture of the active sites, disclosing important structural information for rational design of PAICS inhibitors as potential anticancer drugs.
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| 2. |
- Škerlová, Jana, et al.
(författare)
-
Structure and steroid isomerase activity of Drosophila glutathione transferase E14 essential for ecdysteroid biosynthesis
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:7, s. 1187-1195
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Tidskriftsartikel (refereegranskat)abstract
- Ecdysteroids are critically important for the formation of the insect exoskeleton. Cholesterol is a precursor of ecdysone and its active form 20-hydroxyecdysone, but some steps in the ecdysteroid biosynthesis pathway remain unknown. An essential requirement of glutathione (GSH) transferase GSTE14 in ecdysteroid biosynthesis has been established in Drosophila melanogaster, but its function is entirely unknown. Here, we have determined the crystal structure of GSTE14 in complex with GSH and investigated the kinetic properties of GSTE14 with alternative substrates. GSTE14 has high-ranking steroid double-bond isomerase activity, albeit 50-fold lower than the most efficient mammalian GSTs. Corresponding steroid isomerizations are unknown in insects, and their exact physiological role remains to be shown. Nonetheless, the essential enzyme GSTE14 is here demonstrated to be catalytically competent and have a steroid-binding site.
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