The histone chaperone Asf1 is dispensable for direct de novo histone deposition in Xenopus egg extracts
- 19 June 2007
- journal article
- research article
- Published by Springer Science and Business Media LLC in Chromosoma
- Vol. 116 (5), 487-496
- https://doi.org/10.1007/s00412-007-0112-x
Abstract
Histone chaperones that escort histones during their overall lifetime from synthesis to sites of usage can participate in various tasks. Their requirement culminates in the dynamic processes of nucleosome assembly and disassembly. In this context, it is important to define the exact role of the histone chaperone Asf1. In mammals, Asf1 interacts with two other chaperones, CAF-1 and HIRA, which are critical in DNA synthesis-coupled and synthesis-uncoupled nucleosome assembly pathways, respectively. A key issue is whether Asf1 is able or not to deposit histones onto DNA by itself in both pathways. Here, to delineate the precise role of Asf1 in chromatin assembly, we used Xenopus egg extracts as a powerful system to assay de novo chromatin assembly pathways in vitro. Following characterization of both Xenopus Asf1 and p60 (CAF-1), we used immunodepletion strategies targeting Asf1, HIRA, or CAF-1. Strikingly, the depletion of Asf1 led to the simultaneous depletion of HIRA and consequently impaired the DNA synthesis-independent nucleosome assembly pathway. The rescue of nucleosome assembly capacity in such extracts was effective when adding HIRA along with H3/H4 histones, yet addition of Asf1 along with H3/H4 histones did not work. Moreover, nucleosome assembly coupled to DNA repair was not affected in these Asf1/HIRA-depleted extracts, a pathway impaired by CAF-1 depletion. Thus, these data show that Asf1 is not directly involved in de novo histone deposition during DNA synthesis-independent and synthesis-dependent pathways in egg extracts. Based on our results, it becomes important to consider the implications for Asf1 function during early development in Xenopus.Keywords
This publication has 54 references indexed in Scilit:
- Drosophila GAGA factor directs histone H3.3 replacement that prevents the heterochromatin spreadingJournal of Bone and Joint Surgery, 2007
- Chromatin Challenges during DNA Replication and RepairCell, 2007
- Structural Basis for the Histone Chaperone Activity of Asf1Cell, 2006
- Structure of a human ASF1a–HIRA complex and insights into specificity of histone chaperone complex assemblyNature Structural & Molecular Biology, 2006
- Asymmetry in Histone H3 variants and lysine methylation between paternal and maternal chromatin of the early mouse zygoteMechanisms of Development, 2005
- Histone H3.1 and H3.3 Complexes Mediate Nucleosome Assembly Pathways Dependent or Independent of DNA SynthesisCell, 2004
- Histones Are First Hyperacetylated and Then Lose Contact with the Activated PHO5 PromoterMolecular Cell, 2003
- Chromatin Assembly Coupled to DNA Repair: A New Role for Chromatin Assembly Factor ICell, 1996
- Soluble acidic complexes containing histones H3 and H4 in nuclei of Xenopus laevis oocytesCell, 1982
- Assembly of SV40 chromatin in a cell-free system from Xenopus eggsCell, 1977