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Characterization of two different Asf1 histone chaperones with distinct cellular localizations and functions in Trypanosoma brucei

Please always quote using this URN: urn:nbn:de:bvb:20-opus-117220
  • The anti-silencing function protein 1 (Asf1) is a chaperone that forms a complex with histones H3 and H4 facilitating dimer deposition and removal from chromatin. Most eukaryotes possess two different Asf1 chaperones but their specific functions are still unknown. Trypanosomes, a group of early-diverged eukaryotes, also have two, but more divergent Asf1 paralogs than Asf1 of higher eukaryotes. To unravel possible different functions, we characterized the two Asf1 proteins in Trypanosoma brucei. Asf1A is mainly localized in the cytosol butThe anti-silencing function protein 1 (Asf1) is a chaperone that forms a complex with histones H3 and H4 facilitating dimer deposition and removal from chromatin. Most eukaryotes possess two different Asf1 chaperones but their specific functions are still unknown. Trypanosomes, a group of early-diverged eukaryotes, also have two, but more divergent Asf1 paralogs than Asf1 of higher eukaryotes. To unravel possible different functions, we characterized the two Asf1 proteins in Trypanosoma brucei. Asf1A is mainly localized in the cytosol but translocates to the nucleus in S phase. In contrast, Asf1B is predominantly localized in the nucleus, as described for other organisms. Cytosolic Asf1 knockdown results in accumulation of cells in early S phase of the cell cycle, whereas nuclear Asf1 knockdown arrests cells in S/G2 phase. Overexpression of cytosolic Asf1 increases the levels of histone H3 and H4 acetylation. In contrast to cytosolic Asf1, overexpression of nuclear Asf1 causes less pronounced growth defects in parasites exposed to genotoxic agents, prompting a function in chromatin remodeling in response to DNA damage. Only the cytosolic Asf1 interacts with recombinant H3/H4 dimers in vitro. These findings denote the early appearance in evolution of distinguishable functions for the two Asf1 chaperons in trypanosomes.show moreshow less

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Metadaten
Author: Bruno Pascoalino, Gülcin Dindar, João P. Vieira-da-Rocha, Carlos Renato Machado, Christian J. Janzen, Sergio Schenkman
URN:urn:nbn:de:bvb:20-opus-117220
Document Type:Journal article
Faculties:Fakultät für Biologie / Theodor-Boveri-Institut für Biowissenschaften
Language:English
Parent Title (English):Nucleic Acids Research
ISSN:1362-4962
Year of Completion:2014
Volume:42
Issue:5
Pagenumber:2906-2918
Source:Nucleic Acids Research, 2014, Vol. 42, No. 5, 2906–2918. doi:10.1093/nar/gkt1267
DOI:https://doi.org/10.1093/nar/gkt1267
Pubmed Id:https://pubmed.ncbi.nlm.nih.gov/24322299
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Tag:DNA-damage checkpoint; acetyltransferase RTT109; african trypanosomes; antigenetic variation; chromatin assembly factors; cycle regulation; gene expression; nuclear import; saccharomyes cerevisiae; tousled-like kinases
Release Date:2015/08/17
Licence (German):License LogoCC BY-NC: Creative-Commons-Lizenz: Namensnennung, Nicht kommerziell