An evolutionary perspective on the relationship between kinetochore size and CENP-E dependence for chromosome...

Area of Science:

• Cell Biology
• Evolutionary Biology
• Genetics

Background:

• Mitotic chromosome alignment is crucial for accurate cell division.
• The CENP-E (kinesin-7) motor protein assists chromosome alignment at kinetochores.
• Previous work suggested a negative correlation between kinetochore size and CENP-E dependence for alignment.

Purpose of the Study:

• To investigate the evolutionary relationship between kinetochore structure and CENP-E dependence for chromosome alignment.
• To test the hypothesis that larger kinetochores correlate with reduced reliance on CENP-E.

Main Methods:

• Phylogenetic profiling of CENP-E across monocentric and holocentric clades.
• Functional experiments in nematodes (Caenorhabditis elegans and Pristionchus pacificus) with varying CENP-E presence.
• Assessing chromosome alignment defects and mitotic viability upon CENP-E manipulation.

Main Results:

• CENP-E was frequently lost in taxa with holocentric chromosomes, indicating evolutionary dispensability.
• Human CENP-E partially rescued alignment defects in C. elegans lacking endogenous CENP-E.
• CENP-E inactivation in P. pacificus did not impair mitosis or viability.

Conclusions:

• Mitotic chromosome alignment can proceed efficiently without CENP-E, particularly in species with larger kinetochores.
• The data support the dispensability of CENP-E for mitotic chromosome alignment in certain evolutionary lineages.