Alladi Ramakrishnan Hall

The Centromere Code Hypothesis

Kaustuv Sanyal

JNCASR Bengaluru

The fungal kingdom has been estimated to have more than 3 million species and one of the most well-studied groups to understand the evolutionary trajectory of fundamental cellular processes. One such process is chromosome segregation mediated by dynamic interactions between spindle microtubules and chromosomes. The centromere/kinetochore complex serves as the chromosomal attachment site of the mitotic spindle. Centromeres can be localized to a defined region to form monocentric chromosomes or may diffuse across the chromosomal length to form holocentric chromosomes. Holocentric chromosomes are found in animals and plants but not yet in fungi. Centromeres of varying lengths in monocentric chromosomes were identified and mapped in more than 60 fungal species making it possible to find both conserved and diverged centromere features ( Guin et al., 2020, Ann Rev Microbiol ). Paradoxically, there is no magic common DNA sequence that determines the centromere identity across all fungal species. While centromeres are recognized genetically by exclusive centromere DNA sequence-specific binding of certain proteins in a few budding yeast species, centromeres are non-genetically/epigenetically defined in most other species. During the presentation, I intend to propose the centromere code hypothesis by providing evidence that a set of factors together may determine centromere identity across fungal species.