Solution X-ray scattering highlights discrepancies in Plasmodium multi-aminoacyl-tRNA synthetase complexes

Area of Science:

• * Molecular parasitology
• * Structural biology
• * Malaria research

Background:

• * Plasmodium, the malaria parasite, possesses a unique tRNA import protein, tRip.
• * tRip interacts with three aminoacyl-tRNA synthetases (aaRSs): glutamyl- (ERS), glutaminyl- (QRS), and methionyl- (MRS) tRNA synthetases.
• * These interactions form multi-aaRSs complexes (MSCs), analogous to eukaryotic complexes regulating aaRS moonlighting activities.

Purpose of the Study:

• * To elucidate the structural architecture of Plasmodium MSCs, specifically the Q-complex (tRip:ERS:QRS) and M-complex (tRip:ERS:MRS).
• * To investigate the role of the N-terminal GST-like domains in complex assembly and stability.
• * To understand the unique homodimerization of tRip within these complexes.

Main Methods:

• * X-ray crystallography to determine the structure of the ERS N-terminal GST-like domain.
• * Small-angle X-ray scattering (SAXS) to analyze the solution architecture of the Q- and M-complexes.
• * Engineering of a tRip-N-ERS-N chimeric protein to study complex assembly.

Main Results:

• * The crystal structure of the ERS N-terminal domain was solved, providing insights into its role in complex formation.
• * SAXS analysis revealed the solution structure of the Q- and M-complexes, confirming a 2:2:2 stoichiometry.
• * The study confirmed the central role of tRip-N:ERS-N association and tRip homodimerization in MSC assembly.

Conclusions:

• * The structural organization of Plasmodium MSCs is critical for their function in the parasite.
• * The N-terminal GST-like domains of tRip and ERS are key structural components for complex assembly.
• * Understanding these structural arrangements offers potential avenues for antimalarial drug development targeting essential parasite pathways.