Bidirectional transport of macromolecules between the nucleus and cytoplasm occurs through nuclear pore complexes (NPCs) by a signal-mediated mechanism that is directed targeting signals (NLSs) residing on transported molecules or "cargoes." Nuclear starts after interaction signal with soluble cellular receptors. After formation cargo-receptor complex in cytosol, this crosses NPC. Herein, we use gold particles various sizes coated to determine precisely how large crossing NPC could be. We...

While studying the import of hepatitis B virus genome into nucleus permeabilized tissue culture cells, we found that viral capsids were imported in intact form through nuclear pore basket. Import depended on phosphorylation capsid protein and was mediated by cellular transport receptors importin alpha beta. Virus-derived contained mature able to release DNA nucleoplasm. The uncoating reaction independent Ran, a GTP-binding enzyme responsible for dissociating other cargo from inner face pore....

Although many viruses replicate in the nucleus, little is known about processes involved nuclear import of viral genomes. We show here that vitro generated core particles human hepatitis B virus bind to pore complexes (NPCs) digitonin-permeabilized mammalian cells. This only occurred if cores contained phosphorylated proteins. Binding was inhibited by wheat germ agglutinin, antinuclear complex antibodies, and peptides corresponding either classical localization signals (NLS) or COOH-terminal...

Virtually all DNA viruses including hepatitis B (HBV) replicate their genome inside the nucleus. In non-dividing cells, has to pass through nuclear pore complexes (NPCs) by aid of transport receptors as e.g. importin β (karyopherin). Most release in cytoplasm or at cytosolic face NPC, diameter capsids exceeds size NPC. The HBV is derived from reverse transcription an RNA pregenome. Genome maturation occurs and progeny can deliver into nucleus causing amplification. karyophilic are small...

A two-step, high-throughput RNAi silencing screen was used to identify host cell factors required during human papillomavirus type 16 (HPV16) infection. Analysis of validated hits implicated a cluster mitotic genes and revealed previously undetermined mechanism for import the viral DNA (vDNA) into nucleus. In interphase cells, viruses were endocytosed, routed perinuclear area, uncoated, but vDNA failed be imported Upon nuclear envelope perforation in cells HPV16 infection occured. During...

Significance Viral RNA may be edited by enzymes of the ADAR family that deaminate adenosine residues with ensuing A→G mutations. We found multiple mutations in minor viral populations SARS-CoV-2 genome. accumulated receptor binding domain spike gene, which cause structural changes altering to ACE2 receptor. Presence was associated reduced load, implying limit replication. Analyses >250,000 European samples from 2020 revealed were inversely correlated mortality as a reflection incidence....

Phosphorylation of core particles derived either from hepatitis B viruses or livers B-infected individuals has been long recognized, but the nature and function phosphorylating enzyme remained unknown. By immunoblotting with a monoclonal antibody, we have now detected protein kinase C within liver-derived particles. To study significance encapsidated for viral life cycle, established an in vitro assembly system consisting Escherichia coli-expressed protein, C, vitro-synthesized virus RNA....

APOBEC3G is a cellular cytidine deaminase displaying broad antiretroviral activity. Recently, it was shown that can also suppress hepatitis B virus (HBV) production in human hepatoma cells. In the present study, we characterized mechanisms of APOBEC-mediated antiviral activity against HBV and related hepadnaviruses. We show blocks mammalian nonmammalian cells active duck as well. Early steps viral morphogenesis, including RNA protein synthesis, binding pregenomic to core protein,...

Assembly and disassembly of viral capsids are essential steps in the life cycle. Studies on their kinetics mostly performed vitro, allowing application biochemical, biophysical visualizing techniques. In vivo poorly understood transferability vitro models to cellular environment remains speculative. We analyzed capsid hepatitis B virus digitonin-permeabilized cells which support nuclear entry subsequent genome release. Using gradient centrifugation, size exclusion chromatography immune...

ABSTRACT Adeno-associated virus type 2 (AAV2) has gained much interest as a gene delivery vector. A hallmark of AAV2-mediated transfer is an intracellular conformational change the capsid, leading to exposure infection-relevant protein domains. These domains, which are located on N-terminal portion structural proteins VP1 and VP2, include catalytic phospholipase domain three clusters basic amino acids. We have identified additional sequence motifs VP1/2 N terminus that also proved be...

Hepatitis B virus (HBV) has been reported to exist in peripheral blood mononuclear cells (PBMC), but it is not clear whether replicates there. A precondition for replication should be the formation of covalently closed viral DNA and transcription all essential mRNAs. The mRNAs HBV form a nested box with common 3' ends. In order detect even low levels potential replication, we developed quantitative reverse transcription-PCR method detection smaller mRNA species presence larger ones. All...

ABSTRACT The hepatitis B virus (HBV) is an enveloped DNA which highly infectious in vivo. In vitro, only primary hepatocytes of humans and Tupaia belangeri or the novel HepaRG cell line are susceptible to HBV, but infection inefficient study early events single cells unsatisfactory. Since hepatoma replicate efficiently after transfection, this limited efficiency must be related initial entry phase. Here, we describe lipid-based delivery HBV capsids into nonsusceptible cells, circumventing...

In this study, we characterized the molecular basis for binding of adenovirus (AdV) to cytoplasmic face nuclear pore complex (NPC), a key step during delivery viral genome into nucleus. We used RNA interference (RNAi) deplete cells either Nup214 or Nup358, two major Phe-Gly (FG) repeat nucleoporins localized on side NPC, and evaluated impact hexon AdV infection. The accumulation purified trimers partially disassembled at envelope (NE) was observed in digitonin-permeabilized absence cytosolic...

Disassembly of the nuclear lamina is essential in mitosis and apoptosis requiring multiple coordinated enzymatic activities nucleus cytoplasm. Activation coordination different poorly understood moreover complicated as some factors translocate between cytoplasm preparatory phases. Here we used ability parvoviruses to induce membrane breakdown understand triggers key mitotic enzymes. Nuclear envelope disintegration was shown upon infection, microinjection but also their application...

Hepatitis B virus (HBV) capsids are found in many forms: immature single-stranded RNA-filled cores, DNA-filled replication intermediates, mature cores with relaxed circular double-stranded DNA, and empty capsids. A capsid, the protein shell of core, is a complex 240 copies core protein. Mature transported to nucleus by that includes both importin α β (Impα Impβ), which bind protein's C-terminal domains (CTDs). Here we have investigated interactions HBV importins vitro. Strikingly, free can...

Hepadnaviruses contain a DNA genome, but they replicate via an RNA intermediate, synthesized by the cellular polymerase II in nucleus of infected cell. Thus, nuclear transport viral is required life cycle. Protein-free only poorly imported into nucleus, so one or more proteins must be involved genome. In order to identify these proteins, we purified woodchuck hepadnavirus (WHV) core particles from liver, isolated WHV DNA, and extracted covalent complex using urea. Intact particles,...

With about 350 million people chronically infected around the world hepatitis B is a major health problem. Template for progeny HBV synthesis viral genome, organized as minichromosome (cccDNA) inside hepatocyte nucleus. How cccDNA gene expression regulated by its chromatin structure; more importantly, how modulation of this structure impacts on remains elusive. Here, we found that enzyme SetDB1 contributes to setting up repressed state. This repressive state activated histone lysine...