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Solution Structure of the C65A/C167A Mutant of Human Lipocalin-type Prostaglandin D SynthaseSolution Structure of the C65A/C167A Mutant of Human Lipocalin-type Prostaglandin D Synthase
Structural highlights
FunctionPTGDS_HUMAN Catalyzes the conversion of PGH2 to PGD2, a prostaglandin involved in smooth muscle contraction/relaxation and a potent inhibitor of platelet aggregation. Involved in a variety of CNS functions, such as sedation, NREM sleep and PGE2-induced allodynia, and may have an anti-apoptotic role in oligodendrocytes. Binds small non-substrate lipophilic molecules, including biliverdin, bilirubin, retinal, retinoic acid and thyroid hormone, and may act as a scavenger for harmful hydrophopic molecules and as a secretory retinoid and thyroid hormone transporter. Possibly involved in development and maintenance of the blood-brain, blood-retina, blood-aqueous humor and blood-testis barrier. It is likely to play important roles in both maturation and maintenance of the central nervous system and male reproductive system.[1] [2] Publication Abstract from PubMedLipocalin-type prostaglandin D synthase (L-PGDS) is a secretory lipid-transporter protein that was shown to bind a wide variety of hydrophobic ligands in vitro. Exploiting this function, we previously examined the feasibility of using L-PGDS as a novel delivery vehicle for poorly water-soluble drugs. However, the mechanism by which human L-PGDS binds to poorly water-soluble drugs is unclear. In this study, we determined the solution structure of human L-PGDS and investigated the mechanism of L-PGDS binding to 6-nitro-7-sulfamoyl-benzo[f]quinoxalin-2,3-dione (NBQX), an alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor antagonist. NMR experiments showed that human L-PGDS has an eight-stranded antiparallel beta-barrel structure that forms a central cavity, a short 3(10) -helix and two alpha-helices. Titration with NBQX was monitored using (1) H-(15) N HSQC spectroscopy. At higher NBQX concentrations, some cross-peaks of the protein exhibited fast-exchanging shifts with a curvature, indicating at least two binding sites. These residues were located in the upper portion of the cavity. Singular value decomposition analysis revealed that human L-PGDS has two NBQX binding sites. Large chemical shift changes were observed in the H2-helix and A-, B-, C-, D-, H- and I-strands and H2-helix upon NBQX binding. Calorimetric experiments revealed that human L-PGDS binds two NBQX molecules with dissociation constants of 46.7 mum for primary binding and 185.0 mum for secondary binding. Molecular docking simulations indicated that these NBQX binding sites are located within the beta-barrel. These results provide new insights into the interaction between poorly water-soluble drugs and human L-PGDS as a drug carrier. Structural and interaction analysis of human lipocalin-type prostaglandin D synthase with the poorly water-soluble drug NBQX.,Miyamoto Y, Nakatsuji M, Yoshida T, Ohkubo T, Inui T FEBS J. 2023 Apr 6. doi: 10.1111/febs.16791. PMID:37021622[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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