Role of cAMP Signaling in the Survival and Infectivity of the Protozoan Parasite, Leishmania donovani

Figure 1

Enzymes intimately associated with cAMP metabolism in Leishmania. Cyclic adenosine monophosphate (cAMP) is formed from adenosine triphosphate (ATP) by adenylate cyclases where pyrophosphate (PPi) is also produced as one of reaction products which is hydrolyzed by pyrophosphatases to inorganic phosphate (Pi). Downstream to cAMP, leishmanial phosphodiesterases (PDE) hydrolyzes cAMP to 5′ adenosine monophosphate (5′AMP). There are 5 different PDEs in the parasite (PDEA, PDEB1, PDEB2, PDEC, and PDED). cAMP-dependent protein kinase A (PKA) exists as an inactive tetramer consisting of two catalytic subunits (PKAC) and two regulatory subunits (PKAR). Binding of cAMP to regulatory subunit releases catalytic subunit.