Microsomal prostaglandin E synthase-1 exhibits one-third-of-the-sites reactivity

Abstract

mPGES-1 (microsomal prostaglandin E synthase-1) is a newly recognized target for the treatment of inflammatory diseases. As the terminal enzyme of the prostaglandin production pathway, mPGES-1 inhibition may have a low risk of side effects. Inhibitors of mPGES-1 have attracted considerable attention as next-generation anti-inflammatory drugs. However, as mPGES-1 is a membrane protein, its enzymatic mechanism remains to be disclosed fully. We used MD (molecular dynamics) simulations, mutation analysis, hybrid experiments and co-IP (co-immunoprecipitation) to investigate the conformation transitions of mPGES-1 during catalysis. mPGES-1 forms a homotrimer with three substrate-binding sites (pockets). In the MD simulation, only one substrate molecule could bind to one of the pockets and form the active complex, suggesting that the mPGES-1 trimer has only one pocket active at any given time. This one-third-of-the-sites reactivity enzyme mechanism was verified further by hybridization experiments and MD simulations. The results of the present study revealed for the first time a novel one-third-of-the-sites reactivity enzyme mechanism for mPGES-1, and the unique substrate-binding pocket in our model constituted an active conformation that was suitable for further enzymatic mechanism study and structural-based drug design against mPGES-1.

Crystal structure of microsomal prostaglandin E2synthase provides insight into diversity in the MAPEG superfamily

“…Given the geometric arrangement of the three active sites and the GSH coordination via Arg73, an element of cooperativity could also be anticipated. Interestingly, such a mechanism has been suggested based on biochemical data both for MGST1 (17) and, more recently, for mPGES-1 (16). However, Arg73 is only conserved in mPGES-1 from higher vertebrates, implicating that any mechanism relating to Arg73 conformation might not translate to other MAPEG family members.…”

“…Based on the atomic detail as well as mutagenesis data available in the literature, we propose a mechanism for mPGES-1-catalyzed isomerization of PGH 2 to PGE 2 . The structure also offers some insight into a possible mechanism for monomer cross-talk, implicated by recent data indicating that mPGES-1 displays 1:3-site reactivity (16). Finally, the structure provides an excellent starting point for rational design of mPGES-1 inhibitors.…”

Perspective of microsomal prostaglandin E2 synthase-1 as drug target in inflammation-related disorders

“…Conformational change might create a large continuous pocket with unknown function. Sjörgen et al speculate about i) an entry channel for GSH to the active site in the membrane bilayer, ii) a solvent exchange function and iii) a mechanism for cooperativity, which would explain the 1:3-site reactivity recently shown for mPGES-1 [34].…”

Combining Structure‐Based Pharmacophore andIn SilicoApproaches to Discover Novel Selective Serotonin Reuptake Inhibitors

“…After molecular docking, the hSERT‐hit 1 , hSERT‐hit 2, and hSERT‐paroxetine complexes were subjected to 20‐ns MD simulations, and the binding affinity of each compound was measured by monitoring the compound RMSD values relative to the compound's initial position throughout the simulation. A stable binding was defined as a binding in which the compound remained within 3 Å of the RMSD at the end of the simulation . The results of the MD simulations are plotted in Figure , which shows that hit 1 and hit 2 reached equilibrium after 10 and 16 ns and their RMSD values around 1.75 and 2 Å, respectively; whereas, the paroxetine has reached equilibrium after 14 ns, and the RMSD value fluctuated at approximately 2.5 Å.…”