X-ray diffraction and in vivo studies reveal the quinary structure of Trypanosoma cruzi nucleoside diphosphate kinase 1: a novel helical oligomer structure

MIRANDA, MARIANA RENEÉ; AGUILAR, CARLOS FERNANDO; GOMEZ BARROSO, JUAN ARTURO; GARRATT, RICHARD CHARLES; PEREIRA, CLAUDIO ALEJANDRO

Acta Crystallographica Section D Structural Biology

Wiley

Año: 2022 vol. 78 p. 30 - 42

2059-7983

Trypanosoma cruzi is a flagellated protozoan parasite that causes Chagasdisease, which represents a serious health problem in the Americas. Nucleosidediphosphate kinases (NDPKs) are key enzymes that are implicated in cellularenergy management. TcNDPK1 is the canonical isoform in the T. cruzi parasite.TcNDPK1 has a cytosolic, perinuclear and nuclear distribution. It is also foundin non-membrane-bound filaments adjacent to the nucleus. In the present work,X-ray diffraction and in vivo studies of TcNDPK1 are described. The structurereveals a novel, multi-hexameric, left-handed helical oligomer structure. Theresults of directed mutagenesis studies led to the conclusion that the microscopicTcNDPK1 granules observed in vivo in T. cruzi parasites are made up by theassociation of TcNDPK1 oligomers. In the absence of experimental data,analysis of the interactions in the X-ray structure of the TcNDPK1 oligomersuggests the probable assembly and disassembly steps: dimerization, assembly ofthe hexamer as a trimer of dimers, hexamer association to generate the lefthandedhelical oligomer structure and finally oligomer association in a parallelmanner to form the microscopic TcNDPK1 filaments that are observed in vivoin T. cruzi parasites. Oligomer disassembly takes place on the binding ofsubstrate in the active site of TcNDPK1, leading to dissociation of the hexamers.This study constitutes the first report of such a protein arrangement, which hasnever previously been seen for any protein or NDPK. Further studies areneeded to determine its physiological role. However, it may suggest a paradigmfor protein storage reflecting the complex mechanism of action of TcNDPK1.