Acetylation of histone H4K4 is cell cycle regulated and mediated by HAT3 in Trypanosoma brucei

T. Nicolai Siegel, Taemi Kawahara, Jeffrey A. DeGrasse, Christian J. Janzen, David Horn, George A. M. Cross

    Research output: Contribution to journalArticle

    43 Citations (Scopus)

    Abstract

    Post-translational histone modifications have been studied intensively in several eukaryotes. It has been proposed that these modifications constitute a 'histone code' that specifies epigenetic information for transcription regulation. With a limited number of histone-modifying enzymes, implying less redundancy, Trypanosoma brucei represents an excellent system in which to investigate the function of individual histone modifications and histone-modifying enzymes. In this study, we characterized the acetylation of lysine 4 of histone H4 (H4K4), the most abundant acetylation site in T brucei histones. Because of the large sequence divergence of T brucei histones, we generated highly specific antibodies to acetylated and unmodified H4K4. Immunofluorescence microscopy and Western blots with sorted cells revealed a strong enrichment of unmodified H4K4 in S phase and suggested a G1/G0-specific masking of the site, owing to non-covalently binding factors. Finally, we showed that histone acetyltransferase 3 (HAT3) is responsible for H4K4 acetylation and that treatment of cells with the protein synthesis inhibitor cycloheximide led to an almost instantaneous loss of unmodified H4K4 sites. As HAT3 is located inside the nucleus, our findings suggest that newly synthesized histone H4 with an unmodified K4 is imported rapidly into the nucleus, where it is acetylated, possibly irreversibly.

    Original languageEnglish
    Pages (from-to)762-771
    Number of pages10
    JournalMolecular Microbiology
    Volume67
    Issue number4
    DOIs
    Publication statusPublished - Feb 2008

    Keywords

    • GENOME
    • ACETYLTRANSFERASE
    • AFRICAN TRYPANOSOME
    • CHROMATIN
    • TRANSCRIPTION
    • ANTIGENIC VARIATION
    • GENE ACTIVATION
    • SITES
    • DEACETYLASES
    • YEAST

    Cite this

    Siegel, T. Nicolai ; Kawahara, Taemi ; DeGrasse, Jeffrey A. ; Janzen, Christian J. ; Horn, David ; Cross, George A. M. / Acetylation of histone H4K4 is cell cycle regulated and mediated by HAT3 in Trypanosoma brucei. In: Molecular Microbiology. 2008 ; Vol. 67, No. 4. pp. 762-771.
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    Acetylation of histone H4K4 is cell cycle regulated and mediated by HAT3 in Trypanosoma brucei. / Siegel, T. Nicolai; Kawahara, Taemi; DeGrasse, Jeffrey A.; Janzen, Christian J.; Horn, David; Cross, George A. M.

    In: Molecular Microbiology, Vol. 67, No. 4, 02.2008, p. 762-771.

    Research output: Contribution to journalArticle

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    T1 - Acetylation of histone H4K4 is cell cycle regulated and mediated by HAT3 in Trypanosoma brucei

    AU - Siegel, T. Nicolai

    AU - Kawahara, Taemi

    AU - DeGrasse, Jeffrey A.

    AU - Janzen, Christian J.

    AU - Horn, David

    AU - Cross, George A. M.

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    AB - Post-translational histone modifications have been studied intensively in several eukaryotes. It has been proposed that these modifications constitute a 'histone code' that specifies epigenetic information for transcription regulation. With a limited number of histone-modifying enzymes, implying less redundancy, Trypanosoma brucei represents an excellent system in which to investigate the function of individual histone modifications and histone-modifying enzymes. In this study, we characterized the acetylation of lysine 4 of histone H4 (H4K4), the most abundant acetylation site in T brucei histones. Because of the large sequence divergence of T brucei histones, we generated highly specific antibodies to acetylated and unmodified H4K4. Immunofluorescence microscopy and Western blots with sorted cells revealed a strong enrichment of unmodified H4K4 in S phase and suggested a G1/G0-specific masking of the site, owing to non-covalently binding factors. Finally, we showed that histone acetyltransferase 3 (HAT3) is responsible for H4K4 acetylation and that treatment of cells with the protein synthesis inhibitor cycloheximide led to an almost instantaneous loss of unmodified H4K4 sites. As HAT3 is located inside the nucleus, our findings suggest that newly synthesized histone H4 with an unmodified K4 is imported rapidly into the nucleus, where it is acetylated, possibly irreversibly.

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    KW - GENE ACTIVATION

    KW - SITES

    KW - DEACETYLASES

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