Correction: Y-box-binding protein 1 supports the early and late steps of HIV replication.

[This corrects the article DOI: 10.1371/journal.pone.

Y-box-binding protein 1 supports the early and late steps of HIV replication.

The human immunodeficiency virus (HIV) depends on cellular proteins, so-called cofactors, to complete its replication cycle. In search for new therapeutic targets we identified the DNA and RNA binding protein Y-box-binding Protein 1 (YB-1) as a cofactor supporting early and late steps of HIV replication. YB-1 depletion resulted in a 10-fold decrease in HIV-1 replication in different cell lines.

Bidirectional Allosteric Communication between the ATP-Binding Site and the Regulatory PIF Pocket in PDK1 Protein Kinase.

Allostery is a phenomenon observed in many proteins where binding of a macromolecular partner or a small-molecule ligand at one location leads to specific perturbations at a site not in direct contact with the region where the binding occurs. The list of proteins under allosteric regulation includes AGC protein kinases. AGC kinases have a conserved allosteric site, the phosphoinositide-dependent protein kinase 1 (PDK1)-interacting fragment (PIF) pocket, which regulates protein ATP-binding, activity, and interaction with substrates.

Molecular mechanism of regulation of the atypical protein kinase C by N-terminal domains and an allosteric small compound.

Protein kinases play important regulatory roles in cells and organisms. Therefore, they are subject to specific and tight mechanisms of regulation that ultimately converge on the catalytic domain and allow the kinases to be activated or inhibited only upon the appropriate stimuli. AGC protein kinases have a pocket in the catalytic domain, the PDK1-interacting fragment (PIF)-pocket, which is a key mediator of the activation.

The BET family of proteins targets moloney murine leukemia virus integration near transcription start sites.

A hallmark of retroviral replication is integration of the viral genome into host cell DNA. This characteristic makes retrovirus-based vectors attractive delivery vehicles for gene therapy. However, adverse events in gene therapeutic trials, caused by activation of proto-oncogenes due to murine leukemia virus (MLV)-derived vector integration, hamper their application.

2-(3-Oxo-1,3-diphenylpropyl)malonic acids as potent allosteric ligands of the PIF pocket of phosphoinositide-dependent kinase-1: development and prodrug concept.

The protein kinase C-related kinase 2 (PRK2)-interacting fragment (PIF) pocket of phosphoinositide-dependent kinase-1 (PDK1) was proposed as a novel target site for allosteric modulators. In the present work, we describe the design, synthesis, and structure-activity relationship of a series of 2-(3-oxo-1,3-diphenylpropyl)malonic acids as potent allosteric activators binding to the PIF pocket. Some congeners displayed AC(50) values for PDK1 activation in the submicromolar range.

Substrate-selective inhibition of protein kinase PDK1 by small compounds that bind to the PIF-pocket allosteric docking site.

The PIF-pocket of AGC protein kinases participates in the physiologic mechanism of regulation by acting as a docking site for substrates and as a switch for the transduction of the conformational changes needed for activation or inhibition. We describe the effects of compounds that bind to the PIF-pocket of PDK1. In vitro, PS210 is a potent activator of PDK1, and the crystal structure of the PDK1-ATP-PS210 complex shows that PS210 stimulates the closure of the kinase domain.

In vitro DNA tethering of HIV-1 integrase by the transcriptional coactivator LEDGF/p75.

Although LEDGF/p75 is believed to act as a cellular cofactor of lentiviral integration by tethering integrase (IN) to chromatin, there is no good in vitro model to analyze this functionality. We designed an AlphaScreen assay to study how LEDGF/p75 modulates the interaction of human immunodeficiency virus type 1 IN with DNA. IN bound with similar affinity to DNA mimicking the long terminal repeat or to random DNA.

In search of small molecules blocking interactions between HIV proteins and intracellular cofactors.

One of the major obstacles to pursue the discovery of small molecule inhibitors targeting protein-protein interactions is the flat nature of their interface. X-Ray structures have indeed shown that a large part of the interaction area is buried with atoms closely packed together, implying a lack of available cavities for small molecule binding. Yet, it has become clear that some protein-protein interfaces have a well-defined compact area, commonly referred to as a hot spot, that plays a major role in the affinity of the interaction.

Differential interaction of HIV-1 integrase and JPO2 with the C terminus of LEDGF/p75.

The transcriptional co-activator lens epithelium-derived growth factor (LEDGF) has been shown to protect cells against environmental stress. The protein has been implicated in auto-immunity and cancer, and is present in cells as the p52 or p75 splice variant. Recently, LEDGF/p75, but not p52, was identified as the prominent interaction partner of human immunodeficiency virus type 1 (HIV-1) integrase.

Identification of the LEDGF/p75 binding site in HIV-1 integrase.

Lens epithelium-derived growth factor (LEDGF)/p75 is an important cellular co-factor for human immunodeficiency virus (HIV) replication. We originally identified LEDGF/p75 as a binding partner of integrase (IN) in human cells. The interaction has been mapped to the integrase-binding domain (IBD) of LEDGF/p75 located in the C-terminal part.

Cellular co-factors of HIV-1 integration.

To achieve productive infection, the reverse transcribed cDNA of human immunodeficiency virus type 1 (HIV-1) is inserted in the host cell genome. The main protein responsible for this reaction is the viral integrase. However, studies indicate that the virus is assisted by cellular proteins, or co-factors, to achieve integration into the infected cell.

Integrase mutants defective for interaction with LEDGF/p75 are impaired in chromosome tethering and HIV-1 replication.

The insertion of a DNA copy of its RNA genome into a chromosome of the host cell is mediated by the viral integrase with the help of mostly uncharacterized cellular cofactors. We have recently described that the transcriptional co-activator LEDGF/p75 strongly interacts with HIV-1 integrase. Here we show that interaction of HIV-1 integrase with LEDGF/p75 is important for viral replication.

The interaction of LEDGF/p75 with integrase is lentivirus-specific and promotes DNA binding.

We have previously shown that the p75 isoform of the transcriptional co-activator lens epithelium-derived growth factor (LEDGF) interacts tightly with human immunodeficiency virus (HIV)-1 integrase (IN) and is essential for nuclear targeting of this protein in human cells (Cherepanov, P., Maertens, G., Proost, P.

LEDGF/p75 is essential for nuclear and chromosomal targeting of HIV-1 integrase in human cells.

We have reported that human immunodeficiency virus type 1 (HIV-1) integrase (IN) forms a specific nuclear complex with human lens epithelium-derived growth factor/transcription co-activator p75 (LEDGF/p75) protein. We now studied the IN-LEDGF/p75 interaction and nuclear import of IN in living cells using fusions of IN and LEDGF/p75 with enhanced green fluorescent protein and far-red fluorescent protein HcRed1. We show that both the N-terminal zinc binding domain and the central core domains of IN are involved in the interaction with LEDGF/p75.