Akiyoshi Lab - Springer Image KKT4 is a multi-domain kinetochore protein specific to kinetoplastids. In this paper, we reported the 1H, 13C and 15N resonance assignments for the BRCT domain of KKT4 from Trypanosoma brucei. Authors Ludzia, P., Hayashi, H., Robinson, T., Akiyoshi, B., and Redfield, C. Summary of Paper by Eleanor Casey, Marston Lab The kinetochore is a large protein complex which physically links the spindle microtubule to the chromosome during mitosis. Mutations in kinetochore proteins prevent accurate segregation of the chromosomes. This causes growth defects in lower eukaryotes, and diseases in higher organisms. Due to their essentiality in ensuring proper genetic inheritance, kinetochores and kinetochore proteins are highly conserved among most eukaryotes. However, an evolutionarily divergent group of organisms called kinetoplastids have a compositionally and structurally unique kinetochore which bears very little similarity to most eukaryotes. The kinetoplastid group includes the parasite Trypanosoma brucei which causes sleeping sickness in infected individuals. A better understanding of the unique kinetochore structure of T. brucei parasites would provide novel therapeutic targets to treat sleeping sickness. In this paper, Ludzia and colleagues use nuclear magnetic resonance (NMR) spectroscopy to understand the structure the T. brucei kinetochore protein KKT4. The researchers had previously characterized the structure of the KKT4 C terminus by X ray crystallography, although the functional significance of this structure remained unknown. NMR allowed the structure of KKT4 to be observed in solution, and showed that the protein was able to bind phosphate ions through 3 key amino acid residues in a sulphate ion binding site. When these 3 amino acids were mutated in live T. brucei cells to disrupt phosphate ion binding, there was a severe growth defect. This demonstrated the importance of KKT4 binding to phosphorylated proteins in maintaining the T. brucei kinetochore structure, and highlights this binding pocket as a potential target for drug discovery. Related Links Journal URL Akiyoshi Lab Website DOI This article was published on 2024-06-17
