Abstract
Faithful transmission of genetic material is essential for the survival of all organisms. Eukaryotic chromosome segregation is driven by the kinetochore that assembles onto centromeric DNA to capture spindle microtubules and govern the movement of chromosomes. Its molecular mechanism has been actively studied in conventional model eukaryotes, such as yeasts, worms, flies and human. However, these organisms are closely related in the evolutionary time scale and it therefore remains unclear whether all eukaryotes use a similar mechanism. The evolutionary origins of the segregation apparatus also remain enigmatic. To gain insights into these questions, it is critical to perform comparative studies. Here, we review our current understanding of the mitotic mechanism in Trypanosoma brucei, an experimentally tractable kinetoplastid parasite that branched early in eukaryotic history. No canonical kinetochore component has been identified, and the design principle of kinetochores might be fundamentally different in kinetoplastids. Furthermore, these organisms do not appear to possess a functional spindle checkpoint that monitors kinetochore–microtubule attachments. With these unique features and the long evolutionary distance from other eukaryotes, understanding the mechanism of chromosome segregation in T. brucei should reveal fundamental requirements for the eukaryotic segregation machinery, and may also provide hints about the origin and evolution of the segregation apparatus.
Highlights
The numerous organisms living on Earth are divided into three domains of life (Bacteria, Archaea and Eukaryota), and transmission of genetic information from generation to generation is essential for all
The popular model organisms all belong to the supergroup Opisthokonta, which means that these organisms are closely related in the evolutionary time scale
Trypanosoma brucei is the causative agent of African sleeping sickness, which kills more than 10 000 people annually in sub-Saharan Africa [47,48], whereas T. cruzi and Leishmania species are responsible for Chagas disease and leishmaniasis, respectively
Summary
Faithful transmission of genetic material is essential for the survival of all organisms. Its molecular mechanism has been actively studied in conventional model eukaryotes, such as yeasts, worms, flies and human These organisms are closely related in the evolutionary time scale and it remains unclear whether all eukaryotes use a similar mechanism. No canonical kinetochore component has been identified, and the design principle of kinetochores might be fundamentally different in kinetoplastids These organisms do not appear to possess a functional spindle checkpoint that monitors kinetochore–microtubule attachments. With these unique features and the long evolutionary distance from other eukaryotes, understanding the mechanism of chromosome segregation in T. brucei should reveal fundamental requirements for the eukaryotic segregation machinery, and may provide hints about the origin and evolution of the segregation apparatus
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