Gαi1 inhibition mechanism of ATP-bound adenylyl cyclase type 5

Conversion of adenosine triphosphate (ATP) to the second messenger cyclic adenosine monophosphate (cAMP) is an essential reaction mechanism that takes place in eukaryotes, triggering a variety of signal transduction pathways. ATP conversion is catalyzed by the enzyme adenylyl cyclase (AC), which can be regulated by binding inhibitory, G α i , and stimulatory, G α s subunits. In the past twenty years, several crystal structures of AC in isolated form and complexed to G α s subunits have been resolved. Nevertheless, the molecular basis of the inhibition mechanism of AC, induced by G α i , is still far from being fully understood. Here, classical molecular dynamics simulations of the isolated holo AC protein type 5 and the holo binary complex AC5:G α i have been analyzed to investigate the conformational impact of G α i association on ATP-bound AC5. The results show that G α i appears to inhibit the activity of AC5 by preventing the formation of a reactive ATP conformation.