Atomic view of the energy landscape in the allosteric regulation of Abl kinase.

The activity of protein kinases is often regulated in an intramolecular fashion by signaling domains, which feature several phosphorylation or protein-docking sites. How kinases integrate such distinct binding and signaling events to regulate their activities is unclear, especially in quantitative terms. We used NMR spectroscopy to show how structural elements within the Abl regulatory module (RM) synergistically generate a multilayered allosteric mechanism that enables Abl kinase to function as a finely tuned switch. We dissected the structure and energetics of the regulatory mechanism to precisely measure the effects of various activating or inhibiting stimuli on Abl kinase activity. The data provide a mechanistic basis explaining genetic observations and reveal a previously unknown activator region within Abl. Our findings show that drug-resistance mutations in the Abl RM exert their allosteric effect by promoting the activated state of Abl and not by decreasing the drug affinity for the kinase.