TY  - JOUR
A1  - Pascoalino, Bruno
A1  - Dindar, Gülcin
A1  - Vieira-da-Rocha, João P.
A1  - Machado, Carlos Renato
A1  - Janzen, Christian J.
A1  - Schenkman, Sergio
T1  - Characterization of two different Asf1 histone chaperones with distinct cellular localizations and functions in Trypanosoma brucei
JF  - Nucleic Acids Research
N2  - 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 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.
KW  - chromatin assembly factors
KW  - DNA-damage checkpoint
KW  - tousled-like kinases
KW  - saccharomyes cerevisiae
KW  - gene expression
KW  - acetyltransferase RTT109
KW  - african trypanosomes
KW  - antigenetic variation
KW  - cycle regulation
KW  - nuclear import
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-117220
SN  - 1362-4962
VL  - 42
IS  - 5
ER  -