Recruitment of the Nuclear Form of Uracil DNA Glycosylase into Virus Particles Participates in the Full Infectivity of HIV-1

INSERM, U1016, Institut Cochin, Paris, France.
Journal of Virology (Impact Factor: 4.44). 12/2011; 86(5):2533-44. DOI: 10.1128/JVI.05163-11
Source: PubMed


The HIV-1 Vpr protein participates in the early steps of the virus life cycle by influencing the accuracy of reverse transcription. This role of Vpr was related to the recruitment of the nuclear form of the uracil DNA glycosylase (UNG2) enzyme into virus particles, but several conflicting findings have been reported regarding the role of UNG2 encapsidation on viral infectivity. Here, we report that the catalytic activity of UNG2 was not required for influencing HIV-1 mutation, and this function of UNG2 was mapped within a 60-amino-acid domain located in the N-terminal region of the protein required for direct interaction with the p32 subunit of the replication protein A (RPA) complex. Importantly, enforced recruitment of overexpressed UNG2 into virions resulted in a net increase of virus infectivity, and this positive effect on infectivity was also independent of the UNG2 enzymatic activity. In contrast, virus infectivity and replication, as well as the efficiency of the viral DNA synthesis, were significantly reduced when viruses were produced from cells depleted of either endogenous UNG2 or RPA p32. Taken together, these results demonstrate that incorporation of UNG2 into virions has a positive impact on HIV-1 infectivity and replication and positively influences the reverse transcription process through a nonenzymatic mechanism involving the p32 subunit of the RPA complex.

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Available from: Louis M Mansky, Aug 25, 2014
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    • "In addition, Vpr is reported to be a component of the reverse transcription complex (RTC) and co-localizes with the viral nucleic acid and integrase within purified HIV-1 RTCs [20], [21]. Human uracil DNA glycosylase 2 (UNG2), which is an enzyme that is part of the DNA repair machinery [22], is the only protein that has been identified to date that may be involved along with Vpr in influencing HIV-1 reverse transcription [23]. However, the function of UNG2 remains controversial because various studies have reported that its impact on HIV-1 reverse transcription is negative, positive or even nil [24]–[26]. "
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    ABSTRACT: TRIM11 has been reported to be able to restrict HIV-1 replication, but the detailed aspects of the interfering mechanisms remain unclear. In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts. Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB. Deletion mutant experiments showed that the RING domain of TRIM11 was indispensable in inhibiting the early steps of HIV-1 transduction but was dispensable in decreasing NF-κB and LTR activities. Moreover, we found that low levels of Vpr decreased TRIM11 protein levels, while high levels increased them, and these regulations were independent of the VprBP-associated proteasome machinery. These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes. Thus, our work confirms TRIM11 as a host cellular factor that interferes with the early steps of HIV-1 replication and provides a connection between viral protein and host antiviral factors.
    PLoS ONE 08/2014; 9(8):e104269. DOI:10.1371/journal.pone.0104269 · 3.23 Impact Factor
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    • "Due to its specific incorporation into the viral particle by interaction with the Pr55Gag-derived p6 protein, Vpr is readily present upon entry of the virus into the cell, which speaks in favor for enrollment during early steps of viral replication (see Figure 1). In this regard, Vpr has been shown to influence the reverse transcription of HIV-1 via the interaction and recruitment of the human uracil DNA glycosylase 2, an enzyme of the DNA repair machinery (Guenzel et al., 2012). A relationship that is not without controversy since different research reports argue whether UNG2 might rather have a negative impact or even no impact on HIV-1 replication (Schrofelbauer et al., 2005; Kaiser and Emerman, 2006; Yang et al., 2007). "
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    ABSTRACT: Like other HIV-1 auxiliary proteins, Vpr is conserved within all the human (HIV-1, HIV-2) and simian (SIV) immunodeficiency viruses. However, Vpr and homologous HIV-2, and SIV Vpx are the only viral auxiliary proteins specifically incorporated into virus particles through direct interaction with the Gag precursor, indicating that this presence in the core of the mature virions is mainly required for optimal establishment of the early steps of the virus life cycle in the newly infected cell. In spite of its small size, a plethora of effects and functions have been attributed to Vpr, including induction of cell cycle arrest and apoptosis, modulation of the fidelity of reverse transcription, nuclear import of viral DNA in macrophages and other non-dividing cells, and transcriptional modulation of viral and host cell genes. Even if some more recent studies identified a few cellular targets that HIV-1 Vpr may utilize in order to perform its different tasks, the real role and functions of Vpr during the course of natural infection are still enigmatic. In this review, we will summarize the main reported functions of HIV-1 Vpr and their significance in the context of the viral life cycle.
    Frontiers in Microbiology 03/2014; 5:127. DOI:10.3389/fmicb.2014.00127 · 3.99 Impact Factor
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    • "Accumulating evidence indicates that UNG has a function other than U removal: (a) host UNG is required for HIV viral genome integration, in which UNG interacts with an integrase and DNA preintegration complex, and UNG's catalytic activity has recently been shown to be indispensable for this interaction (Guenzel et al., 2011); (b) although UNG is essential for vaccinia virus genome replication, its catalytic activity is not required (De Silva and Moss, 2003, 2008); and (c) the histone H3 variant CENP-A is required for chromosome segregation during mitosis. CENP-A assembly on DNA depends on UNG, but not on UNG's catalytic activity (Zeitlin et al., 2011). "
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    ABSTRACT: Activation-induced cytidine deaminase (AID), which is both essential and sufficient for forming antibody memory, is also linked to tumorigenesis. AID is found in many B lymphomas, in myeloid leukemia, and in pathogen-induced tumors such as adult T cell leukemia. Although there is no solid evidence that AID causes human tumors, AID-transgenic and AID-deficient mouse models indicate that AID is both sufficient and required for tumorigenesis. Recently, AID's ability to cleave DNA has been shown to depend on topoisomerase 1 (Top1) and a histone H3K4 epigenetic mark. When the level of Top1 protein is decreased by AID activation, it induces irreversible cleavage in highly transcribed targets. This finding and others led to the idea that there is an evolutionary link between meiotic recombination and class switch recombination, which share H3K4 trimethyl, topoisomerase, the MRN complex, mismatch repair family proteins, and exonuclease 3. As Top1 has recently been shown to be involved in many transcription-associated genome instabilities, it is likely that AID took advantage of basic genome instability or diversification to evolve its mechanism for immune diversity. AID targets are therefore not highly specific to immunoglobulin genes and are relatively abundant, although they have strict requirements for transcription-induced H3K4 trimethyl modification and repetitive sequences prone to forming non-B structures. Inevitably, AID-dependent cleavage takes place in nonimmunoglobulin targets and eventually causes tumors. However, battles against infection are waged in the context of acute emergencies, while tumorigenesis is rather a chronic, long-term process. In the interest of survival, vertebrates must have evolved AID to prevent infection despite its long-term risk of causing tumorigenesis.
    Advances in Cancer Research 01/2012; 113:1-44. DOI:10.1016/B978-0-12-394280-7.00001-4 · 5.32 Impact Factor
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