Aurora kinases are a family of serine/threonine protein kinases that play essential roles in mitosis and cytokinesis. AurB (Aurora B kinase) has shown a clear link to cancer and is being pursued as an attractive cancer target. Multiple small molecules targeting AurB have entered the clinic for the treatment of cancer. A protein cofactor, INCENP (inner centromere protein), regulates the cellular localization and activation of AurB. In the present study, we examined the effect of INCENP on the activation kinetics of AurB and also elucidated the kinetic mechanism of AurB-catalysed substrate phosphorylation. We have concluded that: (i) substoichoimetric concentrations of INCENP are sufficient for AurB autophosphorylation at the activation loop residue Thr(232), and hence INCENP plays a catalytic role in AurB autophosphorylation; (ii) AurB/INCENP-catalysed phosphorylation of a peptide substrate proceeds through a rapid equilibrium random Bi Bi kinetic mechanism; and (iii) INCENP has relatively minor effects on the specific activity of AurB using a peptide substrate when compared with its role in AurB autoactivation. These results indicate that the effects of INCENP, and probably accessory proteins in general, may differ when enzymes are acting on different downstream targets.
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http://dx.doi.org/10.1042/BJ20081365 | DOI Listing |
Chem Sci
January 2025
Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University Suzhou Jiangsu 215123 China
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Department of Chemical and Biological Physics, Weizmann Institute of Science Rehovot 761001 Israel
Proteins often harness extensive motions of domains and subunits to promote their function. Deciphering how these movements impact activity is key for understanding life's molecular machinery. The enzyme adenylate kinase is an intriguing example for this relationship; it ensures efficient catalysis by large-scale domain motions that lead to the enclosure of the bound substrates ATP and AMP.
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Department of Chemistry, Debre Tabor University Ethiopia.
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January 2025
Department of Soil Science, Faculty of Agriculture, University of Jiroft, Jiroft, 7867161167, Iran.
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January 2025
Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IET-2), Forschungszentrum Jülich, 91058 Erlangen, Germany.
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