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

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

ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022

0907-4449

The Trypanosoma cruzi is a flagellated protozoan parasite causative of Chagas disease which represents a serious health problem in the Americas. Nucleoside diphosphate kinases (NDPKs) are key enzymes implicated in the cell energy management. TcNDPK1 is the canonical isoform in T. cruzi parasite. TcNDPK1 has a cytosolic, perinuclear and nuclear distribution. It is also found in non-membrane bounded filaments adjacent to the nucleus. In the present work, we describe the X-ray diffraction plus in vivo studies of TcNDPK1. The structure reveals a novel, multi-hexameric, left-handed helical oligomer structure. The amino acids responsible for inter-hexameric contacts and helix interactions were established. The results of directed mutagenesis studies allowed concluding that the microscopic TcNDPK1-granules in vivo observed in T. cruzi parasites are made of the association of TcNDPK1-oligomers. In absence of experimental data analysis of the interactions in TcNDPK1 X-ray oligomer structure may suggests the probable assembly-disassembly steps: dimerization, assembly of the hexamer as a trimer of dimers, hexamer association to generate the left-handed helical oligomer structure and the final oligomer association in a parallel wise manner to form the microscopic TcNDPK1-filaments in vivo observed in T. cruzi parasites. Oligomer disassembly is generated by the binding of substrate in the active site of TcNDPK1 producing the dissociation of the hexamers. This study constitutes the first report of such protein arrangement, never seen before for any protein or NDPKs. Further studies are needed to determine its physiological role. However, it may suggests a paradigm for protein storage reflecting the complex mechanism of action of TcNDPK1.