Synthesis and degradation of cAMP in Giardia lamblia: possible role and characterization of a nucleotidyl cyclase with a single cyclase homology domain
- 21 November 2017
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 474 (23), 4001-4017
- https://doi.org/10.1042/bcj20170590
Abstract
Despite its importance in the regulation of growth and differentiation processes of a variety of organisms, the mechanism of synthesis and degradation of cAMP (cyclic AMP) has not yet been described in Giardia lamblia. In this work, we measured significant quantities of cAMP in trophozoites of G. lamblia incubated in vitro and later detected how it increases during the first hours of encystation, and how it then returns to basal levels at 24 h. Through an analysis of the genome of G. lamblia, we found sequences of three putative enzymes — one phosphodiesterase (gPDE) and two nucleotidyl cyclases (gNC1 and gNC2) — that should be responsible for the regulation of cAMP in G. lamblia. Later, an RT-PCR assay confirmed that these three genes are expressed in trophozoites. The bioinformatic analysis indicated that gPDE is a transmembrane protein of 154 kDa, with a single catalytic domain in the C-terminal end; gNC1 is predicted to be a transmembrane protein of 74 kDa, with only one class III cyclase homology domain (CHD) at the C-terminal end; and gNC2 should be a transmembrane protein of 246 kDa, with two class III CHDs. Finally, we cloned and enriched the catalytic domain of gNC1 (gNC1cd) from bacteria. After that, we confirmed that gNC1cd has adenylyl cyclase (AC) activity. This enzymatic activity depends on the presence of Mn2+ and Ca2+, but no significant activity was displayed in the presence of Mg2+. Additionally, the AC activity of gNC1cd is competitively inhibited with GTP, so it is highly possible that gNC1 has guanylyl cyclase activity as well.This publication has 54 references indexed in Scilit:
- MAFFT Multiple Sequence Alignment Software Version 7: Improvements in Performance and UsabilityMolecular Biology and Evolution, 2013
- The minimal kinome of Giardia lamblia illuminates early kinase evolution and unique parasite biologyGenome Biology, 2011
- Zoonotic Potential and Molecular Epidemiology ofGiardiaSpecies and GiardiasisClinical Microbiology Reviews, 2011
- Regulation by Ca2+-Signaling Pathways of Adenylyl CyclasesCold Spring Harbor Perspectives in Biology, 2010
- Mechanism for the allosteric regulation of phosphodiesterase 2A deduced from the X-ray structure of a near full-length constructProceedings of the National Academy of Sciences of the United States of America, 2009
- Structural Basis for Inhibition of Mammalian Adenylyl Cyclase by CalciumBiochemistry, 2009
- The crystal structure of the catalytic domain of a eukaryotic guanylate cyclaseBMC Structural Biology, 2008
- GiardiaDB and TrichDB: integrated genomic resources for the eukaryotic protist pathogens Giardia lamblia and Trichomonas vaginalisNucleic Acids Research, 2008
- Molecular Details of cAMP Generation in Mammalian Cells: A Tale of Two SystemsJournal of Molecular Biology, 2006
- A new medium for the axenic cultivation of Entamoeba histolytica and other EntamoebaTransactions of the Royal Society of Tropical Medicine and Hygiene, 1978