The transcriptional co-activator LEDGF/p75 displays a dynamic scan-and-lock mechanism for chromatin tethering

Laboratory for Biomolecular Dynamics, University of Leuven, Leuven, Flanders, B-3000, Belgium.
Nucleic Acids Research (Impact Factor: 9.11). 10/2010; 39(4):1310-25. DOI: 10.1093/nar/gkq933
Source: PubMed

ABSTRACT Nearly all cellular and disease related functions of the transcriptional co-activator lens epithelium-derived growth factor (LEDGF/p75) involve tethering of interaction partners to chromatin via its conserved integrase binding domain (IBD), but little is known about the mechanism of in vivo chromatin binding and tethering. In this work we studied LEDGF/p75 in real-time in living HeLa cells combining different quantitative fluorescence techniques: spot fluorescence recovery after photobleaching (sFRAP) and half-nucleus fluorescence recovery after photobleaching (hnFRAP), continuous photobleaching, fluorescence correlation spectroscopy (FCS) and an improved FCS method to study diffusion dependence of chromatin binding, tunable focus FCS. LEDGF/p75 moves about in nuclei of living cells in a chromatin hopping/scanning mode typical for transcription factors. The PWWP domain of LEDGF/p75 is necessary, but not sufficient for in vivo chromatin binding. After interaction with HIV-1 integrase via its IBD, a general protein-protein interaction motif, kinetics of LEDGF/p75 shift to 75-fold larger affinity for chromatin. The PWWP is crucial for locking the complex on chromatin. We propose a scan-and-lock model for LEDGF/p75, unifying paradoxical notions of transcriptional co-activation and lentiviral integration targeting.

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    • "Integration of viral genome into human genome is a crucial step in infection by HIV-1. The protein-protein interaction between IN and LEDGF/p75 is crucial for integration[8]. This interaction is detectable as translocation of IN into the nucleus. "
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    ABSTRACT: Translocation of viral integrase (IN) into the nucleus is a critical precondition of integration during the life cycle of HIV, a causative agent of Acquired Immunodeficiency Syndromes (AIDS). As the first discovered cellular factor to interact with IN, Lens epithelium-derived growth factor (LEDGF/p75) plays an important role in the process of integration. Disruption of the LEDGF/p75-IN interaction has provided a great interest for anti-HIV agent discovery. In this work, we reported that one small molecular compound, 1,4-bis(5-(naphthalen-1-yl)thiophen-2-yl)naphthalene(Compound 15), potently inhibit the IN- LEDGF/p75 interaction and affect the HIV-1 IN nuclear distribution at 1μM. The putative binding mode of Compound 15 was constructed by a molecular docking simulation to provide structural insights into the ligand-binding mechanism. Compound 15 suppressed viral replication by measuring p24 antigen production in HIV-1IIIB acute infected C8166 cells with EC50 value of 11.19μM. Compound 15 might supply useful structural information for further anti-HIV agent discovery.
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