title: A soluble phosphodiesterase in Leishmania donovani negatively regulates cAMP signaling by inhibiting protein kinase A through a two way process involving catalytic as well as non-catalytic sites.
abstract: Intracellular cAMP level and cAMP mediated responses are elevated when Leishmania are exposed to macrophage phagolysosome conditions (37 °C and pH 5.5). Phosphodiesterases play major role in cAMP regulation and in the present study we have cloned and characterized a 2.1 kb cytosolic isoform of phosphodiesterase from Leishmania donovani (LdPDED) which plays important role in cAMP homeostasis when the promastigotes are exposed to macrophage phagolysome conditions for converting to axenic amastigotes. Domain characterization suggested the presence of two pseudo-substrate sites similar to the ones present in the regulatory subunit of cAMP-dependent protein kinase A (PKA) and a putative PKA phosphorylation site at T(708) of C-terminus of LdPDED. Deletion constructs and site directed mutagenesis revealed the ability of LdPDED to interact with L. donovani PKA catalytic subunits (LdPKAC1 and LdPKAC2) resulting in inhibition of kinase activity in one hand and increase of phosphodiesterase activity through PKA mediated phosphorylation at putative phosphorylation site on the other hand. This study therefore identifies a unique phosphodiesterase in L. donovani which appears to regulate cAMP-dependent PKA signaling through a two way process.
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Vij
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Arunima
authors.initials: A
authors.lastname: Biswas
authors.affiliation: Department of Microbiology, Tripura University, India.
authors.forename: Arijit
authors.initials: A
authors.lastname: Bhattacharya
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India. Electronic address: pijushdas@iicb.res.in.
authors.forename: Pijush K
authors.initials: PK
authors.lastname: Das
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D007893:Leishmania donovani / Q000201:enzymology / Q000378:metabolism*; D008969:Molecular Sequence Data; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction
chemical_list: D017868:Cyclic AMP-Dependent Protein Kinases; D010727:Phosphoric Diester Hydrolases
keywords: L. donovani; Phosphodiesterase; Phosphorylation; Protein kinase A; Psudosubstrate residues