title: The cystathionine-β-synthase domains on the guanosine 5''-monophosphate reductase and inosine 5'-monophosphate dehydrogenase enzymes from Leishmania regulate enzymatic activity in response to guanylate and adenylate nucleotide levels.
abstract: The Leishmania guanosine 5'-monophosphate reductase (GMPR) and inosine 5'-monophosphate dehydrogenase (IMPDH) are purine metabolic enzymes that function maintaining the cellular adenylate and guanylate nucleotide. Interestingly, both enzymes contain a cystathionine-β-synthase domain (CBS). To investigate this metabolic regulation, the Leishmania GMPR was cloned and shown to be sufficient to complement the guaC (GMPR), but not the guaB (IMPDH), mutation in Escherichia coli. Kinetic studies confirmed that the Leishmania GMPR catalyzed a strict NADPH-dependent reductive deamination of GMP to produce IMP. Addition of GTP or high levels of GMP induced a marked increase in activity without altering the Km values for the substrates. In contrast, the binding of ATP decreased the GMPR activity and increased the GMP Km value 10-fold. These kinetic changes were correlated with changes in the GMPR quaternary structure, induced by the binding of GMP, GTP, or ATP to the GMPR CBS domain. The capacity of these CBS domains to mediate the catalytic activity of the IMPDH and GMPR provides a regulatory mechanism for balancing the intracellular adenylate and guanylate pools.
authors: Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors: Sabrina
authors: S
authors: Smith
authors: Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR, 97239, USA.
authors: Jan
authors: J
authors: Boitz
authors: Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors: Ehzilan Subramanian
authors: ES
authors: Chidambaram
authors: Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors: Abhishek
authors: A
authors: Chatterjee
authors: Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors: Maria
authors: M
authors: Ait-Tihyaty
authors: Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR, 97239, USA.
authors: Buddy
authors: B
authors: Ullman
authors: Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors: Armando
authors: A
authors: Jardim
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D002384:Catalysis; D003541:Cystathionine beta-Synthase / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D050899:GMP Reductase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005786:Gene Expression Regulation; D005816:Genetic Complementation Test; D006157:Guanosine Monophosphate / Q000378:metabolism; D007168:IMP Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D007893:Leishmania donovani / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D018320:Leishmania major / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D009249:NADP / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism
chemical_list: D009711:Nucleotides; D009249:NADP; D006157:Guanosine Monophosphate; D000255:Adenosine Triphosphate; D007168:IMP Dehydrogenase; D050899:GMP Reductase; D003541:Cystathionine beta-Synthase