title: Structure of human Eg5 in complex with a new monastrol-based inhibitor bound in the R configuration.
abstract: Drugs that target mitotic spindle proteins have been proven useful for tackling tumor growth. Eg5, a kinesin-5 family member, represents a potential target, since its inhibition leads to prolonged mitotic arrest through the activation of the mitotic checkpoint and apoptotic cell death. Monastrol, a specific dihydropyrimidine inhibitor of Eg5, shows stereo-specificity, since predominantly the (S)-, but not the (R)-, enantiomer has been shown to be the biologically active compound in vitro and in cell-based assays. Here, we solved the crystal structure (2.7A) of the complex between human Eg5 and a new keto derivative of monastrol (named mon-97), a potent antimitotic inhibitor. Surprisingly, we identified the (R)-enantiomer bound in the active site, and not, as for monastrol, the (S)-enantiomer. The absolute configuration of this more active (R)-enantiomer has been unambiguously determined via chemical correlation and x-ray analysis. Unexpectedly, both the R- and the S-forms inhibit Eg5 ATPase activity with IC(50) values of 110 and 520 nM (basal assays) and 150 nm and 650 nm (microtubule-stimulated assays), respectively. However, the difference was large enough for the protein to select the (R)- over the (S)-enantiomer. Taken together, these results show that in this new monastrol family, both (R)- and (S)-enantiomers can be active as Eg5 inhibitors. This considerably broadens the alternatives for rational drug design.
authors.affiliation: Laboratoire des Moteurs Moléculaires, IBS, Institut de Biologie Structurale Jean-Pierre Ebel, CNRS-Commissariat à l'Energie Atomique (CEA)-Université Joseph Fourier, 41 rue Jules Horowitz, F-38027 Grenoble.
authors.forename: Isabel
authors.initials: I
authors.lastname: Garcia-Saez
authors.affiliation: Laboratoire des Moteurs Moléculaires, IBS, Institut de Biologie Structurale Jean-Pierre Ebel, CNRS-Commissariat à l'Energie Atomique (CEA)-Université Joseph Fourier, 41 rue Jules Horowitz, F-38027 Grenoble.
authors.forename: Salvatore
authors.initials: S
authors.lastname: DeBonis
authors.affiliation: Groupe de Chimie Combinatoire et Criblage à haut débit, CEA-Saclay, Service de Marquage Moléculaire et de Chimie Bioorganique, Bat 547, 91191 Gif-sur-Yvette.
authors.forename: Roman
authors.initials: R
authors.lastname: Lopez
authors.affiliation: Groupe de Chimie Combinatoire et Criblage à haut débit, CEA-Saclay, Service de Marquage Moléculaire et de Chimie Bioorganique, Bat 547, 91191 Gif-sur-Yvette.
authors.forename: Fernando
authors.initials: F
authors.lastname: Trucco
authors.affiliation: Groupe de Chimie Combinatoire et Criblage à haut débit, CEA-Saclay, Service de Marquage Moléculaire et de Chimie Bioorganique, Bat 547, 91191 Gif-sur-Yvette.
authors.forename: Bernard
authors.initials: B
authors.lastname: Rousseau
authors.affiliation: Service de Chimie Moléculaire DSM/DRECAM, CEA/Saclay 91191 Gif-sur-Yvette, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Thuéry
authors.affiliation: Laboratoire des Moteurs Moléculaires, IBS, Institut de Biologie Structurale Jean-Pierre Ebel, CNRS-Commissariat à l'Energie Atomique (CEA)-Université Joseph Fourier, 41 rue Jules Horowitz, F-38027 Grenoble. Electronic address: frank.kozielski@ibs.fr.
authors.forename: Frank
authors.initials: F
authors.lastname: Kozielski
mesh_terms: D050256:Antimitotic Agents / Q000737:chemistry / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D006801:Humans; D016547:Kinesins / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D011487:Protein Conformation; D011743:Pyrimidines / Q000737:chemistry* / Q000494:pharmacology*; D013237:Stereoisomerism; D013871:Thiones / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D050256:Antimitotic Agents; C470243:KIF11 protein, human; D011743:Pyrimidines; D013871:Thiones; C400223:monastrol; D016547:Kinesins