BERLIN – Researchers at Germany’s Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) have discovered that a protein modification process known as SUMOylation is critical for proper cell division in plants, shedding light on how genetic information is faithfully transmitted.

The study focused on KINETOCHORE NULL2 (αKNL2), a protein essential for loading the centromeric histone H3 (CENH3) and forming the kinetochore, the structure that ensures chromosomes are correctly segregated during cell division.

“We identified that αKNL2 is modified by SUMO proteins and demonstrated how this SUMOylation affects its function,” said Manikandan Kalidass, first author of the study. Using biochemical and computational methods, the team mapped SUMO attachment sites in the protein’s C-terminal region.

When these sites were altered, preventing SUMOylation, the model plant Arabidopsis thaliana showed growth and fertility defects. At the cellular level, the disruption weakened αKNL2’s interaction with CENH3, destabilised the kinetochore and led to chromosome segregation errors.

“The SUMO sites on αKNL2 are crucial for its normal activity,” said Dr. Inna Lermontova, who heads IPK’s “Kinetochore Biology” group. “Our results provide a better understanding of how SUMOylation regulates protein function during chromosome segregation. And this could have implications for similar mechanisms in other eukaryotic systems.”