Article
The 6-Phosphogluconate Dehydrogenase of Leishmania (Leishmania) mexicana : Gene Characterization and Protein Structure Prediction
Autor
González, Deyanira
Pérez, José Luis
Serrano, María Luisa
Igoillo-Esteve, Mariana
Cazzulo, Juan José
Barrett, Michael P.
Bubis, José
Mendoza-León, Alexis
Institución
Resumen
6-Phosphogluconate dehydrogenase (6PGDH) is a key enzyme of the oxidative branch involved in the generation of NADPH and ribulose 5-phosphate. In the present work, we describe the cloning, sequencing and characterization of a 6PGDH gene from Leishmania (Leishmania) mexicana. The gene encodes a polypeptide chain of 479 amino acid residues with a predicted molecular mass of 52 kDa and a pI of 5.77. The recombinant protein possesses a dimeric quaternary structure and displays kinetic parameter values intermediate between those reported for Trypanosoma brucei and T . cruzi with apparent Km values of 6.93 and 5.2 uM for 6PG and NADP+, respectively. The three-dimensional structure of the enzymes of Leishmania and T. cruzi were modelled
from their amino acid sequence using the crystal structure of the enzyme of T. brucei as template. The amino acid residues located in the 6PGDH C-terminal region, which are
known to participate in the salt bridges maintaining the protein dimeric structure, differed significantly among the enzymes
of Leishmania , T. cruzi , and T. brucei . Our results strongly suggest that 6PGDH can be selected as a potential target for the development of new therapeutic drugs in order
to improve existing chemotherapeutic treatments against these parasites. This work was funded by the European Commission INCO-DC programme and CDCH-UCV, and partial funds from grants Fonacit 2000001639 and Misión Ciencia 2007000960–2 to J.B. D.G. had Venezuelan fellowships from the CDCH-UCV and FONACIT, and received financial support from UNU-BIOLAC to visit J.J. Cazzulo’s laboratory.