Partition complex structure can arise from sliding and bridging of ParB dimers. 2023

Lara Connolley, and Lucas Schnabel, and Martin Thanbichler, and Seán M Murray
Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology, 35043, Marburg, Germany.

In many bacteria, chromosome segregation requires the association of ParB to the parS-containing centromeric region to form the partition complex. However, the structure and formation of this complex have been unclear. Recently, studies have revealed that CTP binding enables ParB dimers to slide along DNA and condense the centromeric region through the formation of DNA bridges. Using semi-flexible polymer simulations, we demonstrate that these properties can explain partition complex formation. Transient ParB bridges organize DNA into globular states or hairpins and helical structures, depending on bridge lifetime, while separate simulations show that ParB sliding reproduces the multi-peaked binding profile observed in Caulobacter crescentus. Combining sliding and bridging into a unified model, we find that short-lived ParB bridges do not impede sliding and can reproduce both the binding profile and condensation of the nucleoprotein complex. Overall, our model elucidates the mechanism of partition complex formation and predicts its fine structure.

UI MeSH Term Description Entries
D011108 Polymers Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS). Polymer
D002503 Centromere The clear constricted portion of the chromosome at which the chromatids are joined and by which the chromosome is attached to the spindle during cell division. Centromeres
D016935 Caulobacter crescentus A species of gram-negative, aerobic bacteria that consist of slender vibroid cells. Caulobacter vibrioides
D054644 Ear Auricle The shell-like structure projects like a little wing (pinna) from the side of the head. Ear auricles collect sound from the environment. Pinna, Ear,Auricles, Ear,Ear Auricles,Ear Pinna,Auricle, Ear,Ear Pinnas,Pinnas, Ear
D020090 Chromosome Segregation The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS. Chromosome Segregations,Segregation, Chromosome,Segregations, Chromosome

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