PICH and TOP3A cooperate to induce positive DNA supercoiling.
Nat Struct Mol Biol
; 26(4): 267-274, 2019 04.
Article
em En
| MEDLINE
| ID: mdl-30936532
ABSTRACT
All known eukaryotic topoisomerases are only able to relieve torsional stress in DNA. Nevertheless, it has been proposed that the introduction of positive DNA supercoiling is required for efficient sister-chromatid disjunction by Topoisomerase 2a during mitosis. Here we identify a eukaryotic enzymatic activity that introduces torsional stress into DNA. We show that the human Plk1-interacting checkpoint helicase (PICH) and Topoisomerase 3a proteins combine to create an extraordinarily high density of positive DNA supercoiling. This activity, which is analogous to that of a reverse-gyrase, is apparently driven by the ability of PICH to progressively extrude hypernegatively supercoiled DNA loops that are relaxed by Topoisomerase 3a. We propose that this positive supercoiling provides an optimal substrate for the rapid disjunction of sister centromeres by Topoisomerase 2a at the onset of anaphase in eukaryotic cells.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
DNA
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DNA Topoisomerases Tipo I
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DNA Helicases
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article