Project description:The three-dimensional organization of chromosomes can have a profound impact on their replication and expression. The chromosomes of higher eukaryotes possess discrete compartments that are characterized by differing transcriptional activities. Contrastingly, most bacterial chromosomes have simpler organization with local domains, the boundaries of which are influenced by gene expression. Numerous studies have revealed that the higher-order architectures of bacterial and eukaryotic chromosomes are dependent on the actions of Structural Maintenance of Chromosomes (SMC) superfamily protein complexes, in particular the near-universal condensin complex. Intriguingly, however, many archaea, including members of the genus Sulfolobus do not encode canonical condensin. We describe chromosome conformation capture experiments on Sulfolobus species. These reveal the presence of distinct domains along Sulfolobus chromosomes that undergo discrete and specific higher-order interactions, thus defining two compartment types. We observe causal linkages between compartment identity, gene expression and binding of a hitherto uncharacterized SMC superfamily protein that we term “coalescin”.
Project description:Chromosome conformation capture (3C) technologies have identified topologically associating domains (TADs) and larger A/B compartments as two salient structural features of eukaryotic chromosomes. These structures are sculpted by the combined actions of transcription and structural maintenance of chromosomes (SMC) superfamily proteins. Bacterial chromosomes fold into TAD-like chromosomal interaction domains (CIDs) but do not display A/B compartment-type organization. Here, we reveal that chromosomes of Sulfolobus archaea are organized into CID-like topological domains in addition to the larger A/B compartment-type structures that we described recently. We uncover local rules governing the identity of the topological domains. We also identify long-range loop structures which provide evidence of a hub-like structure that colocalizes genes involved in ribosome biogenesis. In addition to providing high resolution description of archaeal chromosome architectures, our data provide evidence for multiple modes of organization in prokaryotic chromosomes and yield novel insight into the evolution of eukaryotic chromosome conformation.
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.