Search results for "Bol"
showing 10 items of 18211 documents
Nuclear localization but not PML protein is required for incorporation of the papillomavirus minor capsid protein L2 into virus-like particles.
2004
ABSTRACT Recent reports suggest that nuclear domain(s) 10 (ND10) is the site of papillomavirus morphogenesis. The viral genome replicates in or close to ND10. In addition, the minor capsid protein, L2, accumulates in these subnuclear structures and recruits the major capsid protein, L1. We have now used cell lines deficient for promyelocytic leukemia (PML) protein, the main structural component of ND10, to study the role of this nuclear protein for L2 incorporation into virus-like particles (VLPs). L2 expressed in PML protein knockout (PML −/− ) cells accumulated in nuclear dots, which resemble L2 aggregates forming at ND10 in PML protein-containing cells. These L2 assemblies also attracted…
DNA-induced structural changes in the papillomavirus capsid.
2001
ABSTRACT Human papillomavirus capsid assembly requires intercapsomeric disulfide bonds between molecules of the major capsid protein L1. Virions isolated from naturally occurring lesions have a higher degree of cross-linking than virus-like particles (VLPs), which have been generated in eukaryotic expression systems. Here we show that DNA encapsidation into VLPs leads to increased cross-linking between L1 molecules comparable to that seen in virions. A higher trypsin resistance, indicating a tighter association of capsomeres through DNA interaction, accompanies this structural change.
Papillomavirus assembly requires trimerization of the major capsid protein by disulfides between two highly conserved cysteines.
1998
ABSTRACT We have used viruslike particles (VLPs) of human papillomaviruses to study the structure and assembly of the viral capsid. We demonstrate that mutation of either of two highly conserved cysteines of the major capsid protein L1 to serine completely prevents the assembly of VLPs but not of capsomers, whereas mutation of all other cysteines leaves VLP assembly unaffected. These two cysteines form intercapsomeric disulfides yielding an L1 trimer. Trimerization comprises about half of the L1 molecules in VLPs but all L1 molecules in complete virions. We suggest that trimerization of L1 is indispensable for the stabilization of intercapsomeric contacts in papillomavirus capsids.
Lipid Binding Controls Dimerization of the Coat Protein p24 Transmembrane Helix
2019
Abstract Coat protein (COP) I and COP II complexes are involved in the transport of proteins between the endoplasmic reticulum and the Golgi apparatus in eukaryotic cells. The formation of COP I/II complexes at membrane surfaces is an early step in vesicle formation and is mastered by p24, a type I transmembrane protein. Oligomerization of p24 monomers was suggested to be mediated and/or stabilized via interactions within the transmembrane domain, and the p24 transmembrane helix appears to selectively bind a single sphingomyelin C18:0 molecule. Furthermore, a potential cholesterol-binding sequence has also been predicted in the p24 transmembrane domain. Thus, sphingomyelin and/or cholestero…
The Extracellular δ-Domain is Essential for the Formation of CD81 Tetraspanin Webs
2014
AbstractCD81 is a ubiquitously expressed member of the tetraspanin family. It forms large molecular platforms, so-called tetraspanin webs that play physiological roles in a variety of cellular functions and are involved in viral and parasite infections. We have investigated which part of the CD81 molecule is required for the formation of domains in the cell membranes of T-cells and hepatocytes. Surprisingly, we find that large CD81 platforms assemble via the short extracellular δ-domain, independent from a strong primary partner binding and from weak interactions mediated by palmitoylation. The δ-domain is also essential for the platforms to function during viral entry. We propose that, ins…
In vitro studies on the activation of the hepatitis C virus NS3 proteinase by the NS4A cofactor.
1996
AbstractProteolytic processing of the nonstructural proteins of the hepatitis C virus (HCV) is mediated by two viral proteinases: the NS2-3 proteinase cleaving at the NS2/3 junction and the NS3 serine-type proteinase responsible for processing at the NS3/4A, NS4A/B, NS4B/5A, and NS5A/B sites. Activity of the NS3 proteinase is modulated by NS4A. In the absence of this cofactor processing at the NS3-dependent sites does not occur or, in the case of the NS5A/B junction, is poor but increased when NS4A is present. Although recent studies demonstrated that proteinase activation requires direct interaction between NS3 and NS4A, the mechanism by which NS4A exerts the activation function is not kno…
Immune responses during COVID-19 infection
2020
International audience; Over the past 16 years, three coronaviruses (CoVs), severe acute respiratory syndrome CoV (SARS-CoV) in 2002, Middle East respiratory syndrome CoV (MERS-CoV) in 2012 and 2015, and SARS-CoV-2 in 2020, have been causing severe and fatal human epidemics. The unpredictability of coronavirus disease-19 (COVID-19) poses a major burden on health care and economic systems across the world. This is caused by the paucity of in-depth knowledge of the risk factors for severe COVID-19, insufficient diagnostic tools for the detection of SARS-CoV-2, as well as the absence of specific and effective drug treatments. While protective humoral and cellular immune responses are usually m…
A short introduction to papillomavirus biology.
2003
In this report, the tropism of papillomaviruses, the structure of virions, the function of viral proteins and the use of pseudovirions for the analysis of the immune response against papillomaviruses and the search for the viral receptor are briefly described.
Autophagy interferes with human cytomegalovirus genome replication, morphogenesis, and progeny release
2020
Viral infections are often accompanied by the induction of autophagy as an intrinsic cellular defense mechanism. Herpesviruses have developed strategies to evade autophagic degradation and to manipulate autophagy of the host cells to their benefit. Here we addressed the role of macroautophagy/autophagy in human cytomegalovirus replication and for particle morphogenesis. We found that proteins of the autophagy machinery localize to cytoplasmic viral assembly compartments and enveloped virions in the cytoplasm. Surprisingly, the autophagy receptor SQSTM1/p62 was also found to colocalize with HCMV capsids in the nucleus of infected cells. This finding indicates that the autophagy machinery int…
Truncated forms of viral VP2 proteins fused to EGFP assemble into fluorescent parvovirus-like particles
2006
Fluorescence correlation spectroscopy (FCS) monitors random movements of fluorescent molecules in solution, giving information about the number and the size of for example nano-particles. The canine parvovirus VP2 structural protein as well as N-terminal deletion mutants of VP2 (-14, -23, and -40 amino acids) were fused to the C-terminus of the enhanced green fluorescent protein (EGFP). The proteins were produced in insect cells, purified, and analyzed by western blotting, confocal and electron microscopy as well as FCS. The non-truncated form, EGFP-VP2, diffused with a hydrodynamic radius of 17 nm, whereas the fluorescent mutants truncated by 14, 23 and 40 amino acids showed hydrodynamic r…