Structure-based, in silico approaches for the development of novel cAMP FRET reporters

A significant contribution to the research in cAMP signaling has been made by the development of genetically encoded FRET sensors that allow detection of local concentrations of second messengers in living cells. Nowadays, the availability of a number of 3D structures of cyclic nucleotide-binding domains (CNBD) undergoing conformational transitions upon cAMP binding, along with computational tools, can be exploited for the design of novel or improved sensors. In this chapter we will overview some coarse-grained geometrical considerations on fluorescent proteins, CNBD, and linker peptides to draw simple qualitative rules that may aid the design of novel sensors. Finally, we will illustrate how the application of these simple rules can be used to describe the mechanistic basis of cAMP sensors reported in the literature.