Summary The canonical function of kinases is to transfer a phosphoryl group to substrates, initiating a signaling cascade; while their non-canonical role is to bind other kinases or substrates, acting as scaffolds, competitors, and signal integrators. Here, we show how to uncouple kinases' dual function by tuning the binding cooperativity between nucleotide (or inhibitors) and substrate allosterically. We demonstrate this new concept for the C subunit of protein kinase A (PKA-C). Using thermocalorimetry and nuclear magnetic resonance, we found a linear correlation between the degree of cooperativity and the population of the closed state of PKA-C. The non-hydrolyzable ATP analog (ATPγC) does not follow this correlation, suggesting that changing the chemical groups around the phosphoester bond can uncouple kinases' dual function. Remarkably, this uncoupling was also found for two ATP-competitive inhibitors, H89 and balanol. Since the mechanism for allosteric cooperativity is not conserved in different kinases, these results may suggest new approaches for designing selective kinase inhibitors.
Bibliographical noteFunding Information:
This work is supported by the NIH ( GM100310 and GM72701 to G.V. and T32AR007612 to J.K.). We thank Prof. Alessandro Cembran (University of Minnesota-Duluth) and Prof. Larry Masterson (Hamline University) for helpful discussions, and Prof. Robert Geraghty (University of Minnesota) for access to the VP-ITC instrument. NMR experiments were carried out at the Minnesota NMR Center.
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- canonical and non-canonical function
- protein kinase A