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Published on: July 30, 2020
Structural basis of reversine selectivity in inhibiting Mps1 more potently than aurora B kinase
Yoshitaka Hiruma1, Andre Koch2, Shreya Dharadhar1
1Division of Biochemistry, Netherlands Cancer Institute, 1066CX, Amsterdam, The Netherlands.
Abstract:
Monopolar spindle 1 (Mps1, also known as TTK) is a protein kinase crucial for ensuring that cell division progresses to anaphase only after all chromosomes are connected to spindle microtubules. Incomplete chromosomal attachment leads to abnormal chromosome counts in the daughter cells (aneuploidy), a condition common in many solid cancers. Therefore Mps1 is an established target in cancer therapy. Mps1 kinase inhibitors include reversine (2-(4-morpholinoanilino)-6-cyclohexylaminopurine), a promiscuous compound first recognized as an inhibitor of the Aurora B mitotic kinase. Here, we present the 3.0-Å resolution crystal structure of the Mps1 kinase domain bound to reversine. Structural comparison of reversine bound to Mps1 and Aurora B, indicates a similar binding pose for the purine moiety of reversine making three conserved hydrogen bonds to the protein main chain, explaining the observed promiscuity of this inhibitor. The cyclohexyl and morpholinoaniline moieties of reversine however, have more extensive contacts with the protein in Mps1 than in Aurora B. This is reflected both in structure-based docking energy calculations, and in new experimental data we present here, that both confirm that the affinity of reversine towards Mps1 is about two orders of magnitude higher than towards Aurora B. Thus, our data provides detailed structural understanding of the existing literature that argues reversine inhibits Mps1 more efficiently than Aurora B based on biochemical and in-cell assays. Proteins 2016; 84:1761-1766. © 2016 Wiley Periodicals, Inc.
Insights
Monopolar spindle 1 (Mps1) is vital for accurate cell division and is a cancer therapy target. Reversine, an Mps1 inhibitor, binds Mps1 with higher affinity than Aurora B, as revealed by its crystal structure.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Monopolar spindle 1 (Mps1) kinase is essential for accurate chromosome segregation during cell division.
- Mps1 dysfunction leads to aneuploidy, a hallmark of many solid cancers, making it a key therapeutic target.
- Reversine is a known inhibitor of Mps1 and Aurora B mitotic kinases, but its differential binding affinities were not fully understood.
Purpose of the Study:
- To elucidate the structural basis for reversine's differential inhibition of Mps1 and Aurora B kinases.
- To provide a detailed structural understanding of Mps1-reversine interactions.
- To explain the higher affinity of reversine for Mps1 compared to Aurora B.
Main Methods:
- X-ray crystallography to determine the 3.0-Å resolution structure of the Mps1 kinase domain bound to reversine.
- Structural comparison of reversine bound to Mps1 and Aurora B.
- Structure-based docking energy calculations.
- Biochemical and in-cell assays to confirm binding affinities.
Main Results:
- The crystal structure reveals the binding mode of reversine within the Mps1 kinase domain.
- Reversine's purine moiety forms conserved hydrogen bonds with both Mps1 and Aurora B, explaining its promiscuity.
- The cyclohexyl and morpholinoaniline groups of reversine exhibit more extensive interactions with Mps1 than with Aurora B.
- Binding energy calculations and experimental data confirm reversine has approximately 100-fold higher affinity for Mps1 than for Aurora B.
Conclusions:
- The structural and experimental data provide a clear explanation for reversine's higher inhibitory potency against Mps1.
- This study enhances the understanding of Mps1 as a cancer target and the mechanism of its inhibitors.
- The findings support the development of more selective Mps1 inhibitors for cancer therapy.
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