Aquarius helicase facilitates HIV-1 integration into R-loop enriched genomic regions.

HIV-1 integration into host chromosomes, essential for viral replication, is catalysed by viral integrase (IN). IN recurrently targets intronic regions of transcriptionally active genes, but a detailed understanding of this process is still unclear. Here, using ex vivo activated human primary CD4T cells, we find that genomic RNA:DNA hybrids (R-loops) preferentially map to intronic regions of active genes that are typical HIV-1 integration sites.

Timed chromatin invasion during mitosis governs prototype foamy virus integration site selection and infectivity.

Selection of a suitable chromatin environment during retroviral integration is a tightly regulated process. Most retroviruses, including spumaretroviruses, require mitosis for nuclear entry. However, whether intrinsic chromatin dynamics during mitosis modulates retroviral genome invasion is unknown.

Integrase-LEDGF/p75 complex triggers the formation of biomolecular condensates that modulate HIV-1 integration efficiency in vitro.

The pre-integration steps of the HIV-1 viral cycle are some of the most valuable targets of recent therapeutic innovations. HIV-1 integrase (IN) displays multiple functions, thanks to its considerable conformational flexibility. Recently, such flexible proteins have been characterized by their ability to form biomolecular condensates as a result of Liquid-Liquid-Phase-Separation (LLPS), allowing them to evolve in a restricted microenvironment within cells called membrane-less organelles (MLO).

Cassette recombination dynamics within chromosomal integrons are regulated by toxin-antitoxin systems.

Integrons are adaptive bacterial devices that rearrange promoter-less gene cassettes into variable ordered arrays under stress conditions, thereby sampling combinatorial phenotypic diversity. Chromosomal integrons often carry hundreds of silent gene cassettes, with integrase-mediated recombination leading to rampant DNA excision and integration, posing a potential threat to genome integrity. How this activity is regulated and controlled, particularly through selective pressures, to maintain such large cassette arrays is unknown.

Integron cassettes integrate into bacterial genomes via widespread non-classical attG sites.

Integrons are genetic elements involved in bacterial adaptation which capture, shuffle and express genes encoding adaptive functions embedded in cassettes. These events are governed by the integron integrase through site-specific recombination between attC and attI integron sites. Using computational and molecular genetic approaches, here we demonstrate that the integrase also catalyses cassette integration into bacterial genomes outside of its known att sites.

Selection of Bis-Indolyl Pyridines and Triphenylamines as New Inhibitors of SARS-CoV-2 Cellular Entry by Modulating the Spike Protein/ACE2 Interfaces.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the infectious agent that has caused the current coronavirus disease (COVID) pandemic. Viral infection relies on the viral S (spike) protein/cellular receptor ACE2 interaction. Disrupting this interaction would lead to early blockage of viral replication.

Cassette recruitment in the chromosomal Integron of Vibrio cholerae.

Integrons confer a rapid adaptation capability to bacteria. Integron integrases are able to capture and shuffle novel functions embedded in cassettes. Here, we investigated cassette recruitment in the Vibrio cholerae chromosomal integron during horizontal transfer.

, and Models for Monitoring SARS-CoV-2 Spike/Human ACE2 Complex, Viral Entry and Cell Fusion.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent responsible for the recent coronavirus disease 2019 (COVID-19) pandemic. Productive SARS-CoV-2 infection relies on viral entry into cells expressing angiotensin-converting enzyme 2 (ACE2). Indeed, viral entry into cells is mostly mediated by the early interaction between the viral spike protein S and its ACE2 receptor.

Two-long terminal repeat (LTR) DNA circles are a substrate for HIV-1 integrase.

Integration of the HIV-1 DNA into the host genome is essential for viral replication and is catalyzed by the retroviral integrase. To date, the only substrate described to be involved in this critical reaction is the linear viral DNA produced in reverse transcription. However, during HIV-1 infection, two-long terminal repeat DNA circles (2-LTRcs) are also generated through the ligation of the viral DNA ends by the host cell's nonhomologous DNA end-joining pathway.

Human H4 tail stimulates HIV-1 integration through binding to the carboxy-terminal domain of integrase.

The integration of the retroviral genome into the chromatin of the infected cell is catalysed by the integrase (IN)•viral DNA complex (intasome). This process requires functional association between the integration complex and the nucleosomes. Direct intasome/histone contacts have been reported to modulate the interaction between the integration complex and the target DNA (tDNA).

Modulation of the functional association between the HIV-1 intasome and the nucleosome by histone amino-terminal tails.

Background: Stable insertion of the retroviral DNA genome into host chromatin requires the functional association between the intasome (integrase·viral DNA complex) and the nucleosome. The data from the literature suggest that direct protein-protein contacts between integrase and histones may be involved in anchoring the intasome to the nucleosome. Since histone tails are candidates for interactions with the incoming intasomes we have investigated whether they could participate in modulating the nucleosomal integration process.

Modulation of chromatin structure by the FACT histone chaperone complex regulates HIV-1 integration.

Background: Insertion of retroviral genome DNA occurs in the chromatin of the host cell. This step is modulated by chromatin structure as nucleosomes compaction was shown to prevent HIV-1 integration and chromatin remodeling has been reported to affect integration efficiency. LEDGF/p75-mediated targeting of the integration complex toward RNA polymerase II (polII) transcribed regions ensures optimal access to dynamic regions that are suitable for integration.

Functional characterization of a chimeric soluble Fas ligand polymer with in vivo anti-tumor activity.

Binding of ligand FasL to its receptor Fas triggers apoptosis via the caspase cascade. FasL itself is homotrimeric, and a productive apoptotic signal requires that FasL be oligomerized beyond the homotrimeric state. We generated a series of FasL chimeras by fusing FasL to domains of the Leukemia Inhibitory Factor receptor gp190 which confer homotypic oligomerization, and analyzed the capacity of these soluble chimeras to trigger cell death.

Hunting down fungal secretomes using liquid-phase IEF prior to high resolution 2-DE.

The secreted proteins (secretome) of fungi play a key role in interactions of pathogenic and symbiotic fungi with plants. Using the plant pathogenic fungus Leptosphaeria maculans and symbiont Laccaria bicolor grown in culture, we have established a proteomic protocol for extraction, concentration and resolution of the fungal secretome. As no proteomic data were available on mycelium tissues from both L.

Proteomic analysis of an imatinib-resistant K562 cell line highlights opposing roles of heat shock cognate 70 and heat shock 70 proteins in resistance.

Understanding the molecular basis of resistance to imatinib, a tyrosine kinase inhibitor used as front-line therapy in chronic myeloid leukemia, remains a challenge for successful treatment. In an attempt to identify new mechanisms of resistance, we performed a comparative proteomic analysis of an imatinib-resistant cell line generated from the erythroblastic cell line K562 (K562-r) for which no known mechanism of resistance has been detected. Bidimensional gel electrophoresis was carried out to compare the protein expression pattern of imatinib-sensitive and of imatinib-resistant K562 cells.

Analysis of the Flavobacterium psychrophilum outer-membrane subproteome and identification of new antigenic targets for vaccine by immunomics.

Flavobacterium psychrophilum is an important infectious Gram-negative bacterium causing cold-water disease (CWD) and rainbow trout fry syndrome. Outer-membrane proteins (OMPs) are key molecules with regard to the interface between the cell and its environment. Therefore, we sought to define the outer-membrane (OM) subproteome of F.

Proteome analysis of grape skins during ripening.

The characterization of proteins isolated from skin tissue is apparently an essential parameter for understanding grape ripening as this tissue contains the key compounds for wine quality. It has been particularly difficult to extract proteins from skins for analysis by two-dimensional electrophoresis gels and, therefore, a protocol for this purpose has been adapted. The focus was on the evolution of the proteome profile of grape skin during maturation.

A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis.

Study of the complexome - all the protein complexes of the cell - is essential for a better understanding and more global vision of cell function. Using two-dimensional blue native/SDS-PAGE (2-D BN/SDS-PAGE) technology, the cytosolic and membrane protein complexes of Escherichia coli were separated. Then, the different partners of each protein complex were identified by LC-MS/MS.