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Characterization of Three Druggable Hot-Spots in the Aurora-A/TPX2 Interaction Using Biochemical, Biophysical, and Fragment-Based Approaches
journal contribution
posted on 2017-10-18, 00:00 authored by Patrick
J. McIntyre, Patrick M. Collins, Lukáš Vrzal, Kristian Birchall, Laurence H. Arnold, Chido Mpamhanga, Peter J. Coombs, Selena G. Burgess, Mark W. Richards, Anja Winter, Václav Veverka, Frank von Delft, Andy Merritt, Richard BaylissThe
mitotic kinase Aurora-A and its partner protein TPX2 (Targeting Protein for Xenopus kinesin-like protein 2) are overexpressed in cancers,
and it has been proposed that they work together as an oncogenic holoenzyme.
TPX2 is responsible for activating Aurora-A during mitosis, ensuring
proper cell division. Disruption of the interface with TPX2 is therefore
a potential target for novel anticancer drugs that exploit the increased
sensitivity of cancer cells to mitotic stress. Here, we investigate
the interface using coprecipitation assays and isothermal titration
calorimetry to quantify the energetic contribution of individual residues
of TPX2. Residues Tyr8, Tyr10, Phe16, and Trp34 of TPX2 are shown
to be crucial for robust complex formation, suggesting that the interaction
could be abrogated through blocking any of the three pockets on Aurora-A
that complement these residues. Phosphorylation of Aurora-A on Thr288
is also necessary for high-affinity binding, and here we identify
arginine residues that communicate the phosphorylation of Thr288 to
the TPX2 binding site. With these findings in mind, we conducted a
high-throughput X-ray crystallography-based screen of 1255 fragments
against Aurora-A and identified 59 hits. Over three-quarters of these
hits bound to the pockets described above, both validating our identification
of hotspots and demonstrating the druggability of this protein–protein
interaction. Our study exemplifies the potential of high-throughput
crystallography facilities such as XChem to aid drug discovery. These
results will accelerate the development of chemical inhibitors of
the Aurora-A/TPX2 interaction.