Allosteric regulation of cyclic nucleotide-dependent protein kinases

Kinases include a wide variety of valuable drug targets, but full therapeutic exploitation requires a high degree of selectivity. A promising avenue to engineer the desired kinase selectivity relies on allosteric sites. Here, we provide a focused minireview of recent progress in allosteric modulation of cyclic nucleotide-dependent kinases, including protein kinases A and G. We show how apparently diverse emerging concepts, such as allosteric pluripotency, allosteric nonadditive binding, and uncompetitive allosteric inhibition, are all manifestations of complex conformational ensembles. Such ensembles include not only the typical apo-inactive and effector-bound-active states, but also mixed intermediates that feature attributes of the former states within a single molecule. We also discuss how allosteric responses are amplified by aggregation processes, thus establishing a novel interface between the signaling and amyloid fields. Finally, we critically evaluate the challenges and opportunities for clinical translation opened by these emerging allosteric concepts.