FACT plays a major role in histone dynamics affecting VSG expression site control in Trypanosoma brucei.
Mol Microbiol
; 94(4): 945-62, 2014 Nov.
Article
em En
| MEDLINE
| ID: mdl-25266856
ABSTRACT
Chromatin remodelling is involved in the transcriptional regulation of the RNA polymerase I transcribed variant surface glycoprotein (VSG) expression sites (ESs) of Trypanosoma brucei. We show that the T. bruceiâ
FACT complex contains the Pob3 and Spt16 subunits, and plays a key role in ES silencing. We see an inverse correlation between transcription and condensed chromatin, whereby FACT knockdown results in ES derepression and more open chromatin around silent ES promoters. Derepressed ESs show increased sensitivity to micrococcal nuclease (MNase) digestion, and a decrease in histones at silent ES promoters but not telomeres. In contrast, FACT knockdown results in more histones at the active ES, correlated with transcription shut-down. ES promoters are derepressed in cells stalled at the G2/M cell cycle stage after knockdown of FACT, but not in G2/M cells stalled after knockdown of cyclin 6. This argues that the observed ES derepression is a direct consequence of histone chaperone activity by FACT at the G2/M cell cycle stage which could affect transcription elongation, rather than an indirect consequence of a cell cycle checkpoint. These experiments highlight the role of the FACT complex in cell cycle-specific chromatin remodelling within VSG ESs.
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Base de dados:
MEDLINE
Assunto principal:
Fatores de Transcrição
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Trypanosoma brucei brucei
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Histonas
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Glicoproteínas Variantes de Superfície de Trypanosoma
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Regulação da Expressão Gênica
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article