Project description:Kinetochores are essential macromolecular complexes anchoring chromosomes to the mitotic spindle, ensuring faithful cell division. Despite their critical role, the structural organization of kinetochores over large centromeric regions and across diverse species remains poorly understood. We present the inner kinetochore (CCAN) structure of the silkmoth Bombyx mori, an insect without the canonical centromeric CENP-A gene and with chromosome-wide centromeric activity (holocentric). Our analyses reveal a ring-shaped complex with structural parallels to the known human and yeast kinetochores. Notably, B. mori CCAN incorporates four previously uncharacterized proteins, Centromeric Subunits 1-4, which have unexpected evolutionary relationships to the outer kinetochore Dam1/DASH complex. We demonstrate that CCAN binds DNA as a distinctive head-to-head dimer, folding the DNA into a loop and generating an alternative point-centromere-like architecture poised for chromosome segregation. Our work establishes this self-contained CCAN dimer as a key structural unit that forms the basis of a holocentric organization and suggests that large-scale centromere architectures can emerge from the modular arrangement of such discrete kinetochore units.
Project description:Little is known about plant pathogenic response to parasitic plants, although some parasitic plants affect crop production in certain areas. To study this, we chose Glycine max as the model host plant and investigated changes in expression patterns after parasitization by Cuscuta using microarrays. Transcriptional change of Glycine max stem with and without Cuscuta at 2 different stages were compared
Project description:Genome organization in diverse eukaryotes follows conserved principles including the formation of chromosome territories (CT), chromatin compartments, and TADs. Here, we describe the 3D architecture of holocentric chromosomes in the silkworm Bombyx mori. At the genome-wide scale, B. mori chromosomes are highly territorial lacking any visible trans contact pattern. At the chromosomal scale, B. mori chromosomes segregate into three chromatin compartments: an active A and an inactive B as described in other eukaryotes, and a third type, X, with a unique contact pattern. Compartment X is strongly enriched for short-range interactions and depleted of long-range interactions, hosts a specific combination of genetic and epigenetic features and localizes towards the periphery of CT. Biophysical simulations reveal the necessity of the combined effects of affinity-based compartmentalization and activity-based loop extrusion to lead to the unique interaction patterns observed. Our analyses contribute to our understanding how chromosomes fold highlighting the evolutionary plasticity of 3D genome organization.
Project description:Genome organization in diverse eukaryotes follows conserved principles including the formation of chromosome territories (CT), chromatin compartments, and TADs. Here, we describe the 3D architecture of holocentric chromosomes in the silkworm Bombyx mori. At the genome-wide scale, B. mori chromosomes are highly territorial lacking any visible trans contact pattern. At the chromosomal scale, B. mori chromosomes segregate into three chromatin compartments: an active A and an inactive B as described in other eukaryotes, and a third type, X, with a unique contact pattern. Compartment X is strongly enriched for short-range interactions and depleted of long-range interactions, hosts a specific combination of genetic and epigenetic features and localizes towards the periphery of CT. Biophysical simulations reveal the necessity of the combined effects of affinity-based compartmentalization and activity-based loop extrusion to lead to the unique interaction patterns observed. Our analyses contribute to our understanding how chromosomes fold highlighting the evolutionary plasticity of 3D genome organization.