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Direct Interaction between Nucleosome Assembly Protein 1 and the Papillomavirus E2 Proteins Involved in Activation of Transcription

Institute of Virology, University of Cologne, 50935 Cologne, Germany.
Molecular and Cellular Biology (Impact Factor: 5.04). 04/2004; 24(5):2153-68. DOI: 10.1128/MCB.24.5.2153-2168.2004
Source: PubMed

ABSTRACT Using a yeast two-hybrid screen, we identified human nucleosome assembly protein 1 (hNAP-1) as a protein interacting with the activation domain of the transcriptional activator encoded by papillomaviruses (PVs), the E2 protein. We show that the interaction between E2 and hNAP-1 is direct and not merely mediated by the transcriptional coactivator p300, which is bound by both proteins. Coexpression of hNAP-1 strongly enhances activation by E2, indicating a functional interaction as well. E2 binds to at least two separate domains within hNAP-1, one within the C terminus and an internal domain. The binding of E2 to hNAP-1 is necessary for cooperativity between the factors. Moreover, the N-terminal 91 amino acids are crucial for the transcriptional activity of hNAP-1, since deletion mutants lacking this N-terminal portion fail to cooperate with E2. We provide evidence that hNAP-1, E2, and p300 can form a ternary complex efficient in the activation of transcription. We also show that p53 directly interacts with hNAP-1, indicating that transcriptional activators in addition to PV E2 interact with hNAP-1. These results suggest that the binding of sequence-specific DNA binding proteins to hNAP-1 may be an important step contributing to the activation of transcription.

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    • "This association is driving the E2-mediated tethering of viral genomes to host chromatin, and at the same time is retaining the viral genomes in transcriptionally active regions of the nucleus to escape silencing (Jang et al., 2009; Kurg et al., 2005). The transactivation domain mediates functional interactions with cellular transcription factors Sp1 and AP1, histone acetylase complexes containing CBP/p300 and pCAF, and with nucleosome assembly protein hNAP1 (Lee et al., 2002a; Lee et al., 2000; Li et al., 1991; Müller et al., 2002; Rehtanz et al., 2004; Thierry et al., 1992). E2-dependent activities are also modulated by interactions with Brm, a chromatin remodeling protein associated with SWI/SNF ATP-dependent chromatin remodeling complex, and with EP400, a component of the NuA4/TIP60 histone acetylase complex, and SMCX, also known as histone demethylase JARID1C , and Tax1BP1 (Kumar et al., 2007; Smith et al., 2010; Wang et al., 2009b). "
    DNA Replication-Current Advances, 08/2011; , ISBN: 978-953-307-593-8
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    • "Interactions of E2 with other components of the transcriptional machinery or of the chromatin have been less well characterized although they are usually participating to its transcriptional activation (Table 1). Among the published interaction of the E2 protein are components of the basal transcriptional machinery such as TFIIB and TFIID [46] [47] [48], coactivators such as AMF-1 [49] [50], BRCA1 [51] [129], PARP1 [52], TAF1 [53] topoisomerase 1 [54], TopBP1 [55] [56] [57], and chromatin remodeling components p/CAF [58], p300/CBP [59], BRM [60], hSNF5 [61] and NAP-1 [62]. It has been proposed that E2 represses the HPV LCR by steric hindrance of the recruitment of TFIID and Sp1 [43] [44] [63] [64] as well as of coactivators such as SMCX , BRD4 and EP400 [31]. "
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    ABSTRACT: The papillomavirus (PV) E2 proteins have been shown to exert many functions in the viral cycle including pivotal roles in transcriptional regulation and in viral DNA replication. Besides these historical roles, which rely on their aptitude to bind to specific DNA sequences, E2 has also been shown to modulate the host cells through direct protein interactions mainly through its amino terminal transactivation domain. We will describe here some of these new functions of E2 and their potential implication in the HPV-induced carcinogenesis. More particularly we will focus on E2-mediated modulation of the host cell cycle and consequences to cell transformation. In all, the HPV E2 proteins exhibit complex functions independent of transcription that can modulate the host cells in concert with the viral vegetative cycle and which could be involved in early carcinogenesis.
    American Journal of Cancer Research 01/2011; 1(3):373-389. · 3.97 Impact Factor
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    • "Increasing evidence indicates that viruses usurp Nap1 for various purposes. For example the E2 protein of papillomavirus forms a ternary complex with Nap1 and p300 that is important for transcriptional activation (Rehtanz et al., 2004). Similarly, the interaction of Nap1 with HIV-1 Tat was shown to be important for Tat-mediated activation of the LTR (Vardabasso et al., 2008) and Nap1 binding to the EBNA1 protein of Epstein–Barr virus was shown to contribute to EBNA1-mediated transcriptional activation from the EBV FR enhancer element (Holowaty et al., 2003) (Wang and Frappier, in preparation). "
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    ABSTRACT: The Rev protein of HIV-1 is essential for HIV-1 proliferation due to its role in exporting viral RNA from the nucleus. We used a modified version of tandem affinity purification (TAP) tagging to identify proteins interacting with HIV-1 Rev in human cells and discovered a prominent interaction between Rev and nucleosome assembly protein 1 (Nap1). This interaction was also observed by specific retention of Nap1 from human cell lysates on a Rev affinity column. Nap1 was found to bind Rev through the Rev arginine-rich domain and altered the oligomerization state of Rev in vitro. Overexpression of Nap1 stimulated the ability of Rev to export RNA, reduced the nucleolar localization of Rev, and affected Rev nuclear import rates. The results suggest that Nap-1 may influence Rev function by increasing the availability of Rev.
    Virology 04/2009; 388(1):103-11. DOI:10.1016/j.virol.2009.03.005 · 3.28 Impact Factor
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Gertrud Steger