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Nat Commun 2021 May 18;121:2917. doi: 10.1038/s41467-021-23205-w.
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Guiding functions of the C-terminal domain of topoisomerase IIα advance mitotic chromosome assembly.

Shintomi K , Hirano T .

Topoisomerase II (topo II) is one of the six proteins essential for mitotic chromatid reconstitution in vitro. It is not fully understood, however, mechanistically how this enzyme regulates this process. In an attempt to further refine the reconstitution assay, we have found that chromosomal binding of Xenopus laevis topo IIα is sensitive to buffer conditions and depends on its C-terminal domain (CTD). Enzymological assays using circular DNA substrates supports the idea that topo IIα first resolves inter-chromatid entanglements to drive individualization and then generates intra-chromatid entanglements to promote thickening. Importantly, only the latter process requires the CTD. By using frog egg extracts, we also show that the CTD contributes to proper formation of nucleosome-depleted chromatids by competing with a linker histone for non-nucleosomal DNA. Our results demonstrate that topo IIα utilizes its CTD to deliver the enzymatic core to crowded environments created during mitotic chromatid assembly, thereby fine-tuning this process.

PubMed ID: 34006877
PMC ID: PMC8131626
Article link: Nat Commun
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: asf1a h2ac21 h2bc21 npm2 pnp tab3 top2a
Antibodies: H3f3a Ab33

Article Images: [+] show captions
References [+] :
Adachi, Preferential, cooperative binding of DNA topoisomerase II to scaffold-associated regions. 1989, Pubmed