Activation of Aurora-A Kinase by Protein Partner Binding and Phosphorylation Are Independent and Synergistic

Charlotte Dodson, Richard Bayliss

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

Protein kinases are activated by phosphorylation and by the binding of activator proteins. The interplay of these two factors is incompletely understood. We applied energetic analysis to this question and characterized the activation process of the serine/threonine kinase Aurora-A by phosphorylation and by its protein partner, targeting protein for Xenopus kinesin-like protein 2 (TPX2). We discovered that these two activators act synergistically and without a predefined order: each can individually increase the activity of Aurora-A, and the effect of both bound together is the exact sum of their individual contributions to catalysis. Unexpectedly, the unphosphorylated enzyme has catalytic activity that is increased 15-fold by the binding of TPX2 alone. The energetic contribution of phosphorylation to catalysis is 2-fold greater than that of TPX2 binding, which is independent of the phosphorylation state of the enzyme. Based on this analysis, we propose a revised, fluid model of Aurora-A activation in which the first step is a reduction in the mobility of the activation loop by either TPX2 binding or phosphorylation. Furthermore, our results suggest that unphosphorylated Aurora-A bound to the mitotic spindle by TPX2 is catalytically active and that the phosphorylation state of Aurora-A is an inaccurate surrogate for its activity. Extending this form of analysis will allow us to compare quantitatively the effects of the whole network of kinase-activating partners. Comparison with other kinases showed that kinetic characterization detects those kinases whose activation loops undergo a rearrangement upon phosphorylation and thus whose unphosphorylated state offers a distinct target for the development of Type II inhibitors.
Original languageEnglish
Pages (from-to)1150-1157
Number of pages8
JournalJournal of Biological Chemistry
Volume287
Early online date16 Nov 2011
DOIs
Publication statusPublished - 6 Jan 2012

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Aurora Kinase A
Phosphorylation
Protein Binding
Chemical activation
Phosphotransferases
Catalysis
Xenopus Proteins
Kinesin
Spindle Apparatus
Proteins
Protein-Serine-Threonine Kinases
Protein Transport
Enzymes
Protein Kinases
Catalyst activity
Carrier Proteins
Kinetics
Fluids

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Activation of Aurora-A Kinase by Protein Partner Binding and Phosphorylation Are Independent and Synergistic. / Dodson, Charlotte; Bayliss, Richard.

In: Journal of Biological Chemistry, Vol. 287, 06.01.2012, p. 1150-1157.

Research output: Contribution to journalArticle

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