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

Autor(es)

Pascoalino, Bruno ^[1] ; Dindar, Guelcin ^[2] ; Vieira-da-Rocha, Joao P. ^[3] ; Machado, Carlos Renato ^[3] ; Janzen, Christian J. ^[2] ; Schenkman, Sergio ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Paulo, Depto Microbiol Imunol & Parasitol, BR-04039032 Sao Paulo - Brazil

^[2] Univ Wurzburg, Biozentrum, Theodor Boveri Inst, Lehrstuhl Zell & Entwicklungsbiol, D-97074 Wurzburg - Germany

^[3] Univ Fed Minas Gerais, Depto Bioquim & Imunol, Inst Ciencias Biol, BR-30161970 Belo Horizonte, MG - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Nucleic Acids Research; v. 42, n. 5, p. 2906-2918, MAR 2014.
• Citações Web of Science: 9

Resumo

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. (AU)

• Processo FAPESP: 11/51973-3 - Mecanismo de sinalização celular de Trypanosoma em resposta a alterações nutricionais e agentes genotóxicos
• Beneficiário: Sergio Schenkman
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 07/59950-7 - Estudo funcional das acetilações da histona h4 de Trypanosoma
• Beneficiário: Bruno dos Santos Pascoalino
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto