Nucleoside diphosphate kinase oligomerization: crystallographic and biological analyses

BARROSO, ARTURO GOMEZ; MIRANDA, MARIANA; PEREIRA, CA; GARRATT, RICHARD CHARLES; AGUILAR, CARLOS

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2012

SAIB

Nucleoside diphosphate kinases (NDPK) are enzymes involved incell nucleotide homeostasis by the interconversion of nucleoside diandtri-phosphates. TcNDPK1 is the canonical isoform of, the causative agent of Chagas?Disease, and likeeukaryotic NDPKs forms active hexamers. In this work we studyTcNDPK1 oligomerization through molecular biology and X-raycrystallography techniques. The three dimensional structure at 3Åresolution showed that the 24 hexamers in the asymmetric unit arearranged into a helix-like oligomeric formation. Theoligomerization observed in the crystalline structure was alsodetected in the parasite by over-expressing the NDPK gene fused toGFP, in order to reduce the intermolecular distance by the formationof weak dimers. Transgenic parasites showed a granularorganization localized mainly in the anterior part of the cell thatcould be destabilized by changes in the intracellular saltconcentration. Electron microscopy analysis indicated that thesegranules were filled structures without membranes. This workrepresents the first report of a NDPK assembled into an organizedarrangement with a physiological relevance.