Search results for "Structure and Assembly"
showing 10 items of 10 documents
Curvature increases permeability of the plasma membrane for ions, water and the anti-cancer drugs cisplatin and gemcitabine
2019
ABSTRACTIn this work the permeability of a model asymmetric plasma membrane, for ions, water and the anti-cancer drugs cisplatin and gemcitabine is studied by means of all-atom molecular dynamics simulations. It is shown that permeability of the membranes increases from one to three orders of magnitude upon membrane bending depending on the compound and the sign of curvature. Our results show that the membrane curvature is an important factor which should be considered during evaluation of drug translocation.TOC GRAPHICS
Efficient DNA Packaging of Bacteriophage PRD1 Requires the Unique Vertex Protein P6
2007
ABSTRACT The assembly of bacteriophage PRD1 proceeds via formation of empty procapsids containing an internal lipid membrane, into which the linear double-stranded DNA genome is subsequently packaged. The packaging ATPase P9 and other putative packaging proteins have been shown to be located at a unique vertex of the PRD1 capsid. Here, we describe the isolation and characterization of a suppressor-sensitive PRD1 mutant deficient in the unique vertex protein P6. Protein P6 was found to be an essential part of the PRD1 packaging machinery; its absence leads to greatly reduced packaging efficiency. Lack of P6 was not found to affect particle assembly, because in the P6-deficient mutant infecti…
The Tegument Protein pp65 of Human Cytomegalovirus Acts as an Optional Scaffold Protein That Optimizes Protein Uploading into Viral Particles
2014
ABSTRACT The mechanisms that lead to the tegumentation of herpesviral particles are only poorly defined. The phosphoprotein 65 (pp65) is the most abundant constituent of the virion tegument of human cytomegalovirus (HCMV). It is, however, nonessential for virion formation. This seeming discrepancy has not met with a satisfactory explanation regarding the role of pp65 in HCMV particle morphogenesis. Here, we addressed the question of how the overall tegument composition of the HCMV virion depended on pp65 and how the lack of pp65 influenced the packaging of particular tegument proteins. To investigate this, we analyzed the proteomes of pp65-positive (pp65pos) and pp65-negative (pp65neg) viri…
A membrane-destabilizing peptide in capsid protein L2 is required for egress of papillomavirus genomes from endosomes
2005
ABSTRACT Papillomaviruses are internalized via clathrin-dependent endocytosis. However, the mechanism by which viral genomes pass endosomal membranes has not been elucidated. In this report we show that the minor capsid protein L2 is required for egress of viral genomes from endosomes but not for initial uptake and uncoating and that a 23-amino-acid peptide at the C terminus of L2 is necessary for this function. Pseudogenomes encapsidated by L1 and L2 lacking this peptide accumulated in vesicular compartments similar to that observed with L1-only viral particles, and these mutant pseudoviruses were noninfectious. This L2 peptide displayed strong membrane-disrupting activity, induced cytolys…
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…
Assembly and Translocation of Papillomavirus Capsid Proteins
2002
ABSTRACT The major and minor capsid proteins of polyomavirus are preassembled in the cytoplasm and translocated to the nucleus only as a VP1-VP2/VP3 complex. In this study, we describe independent nuclear translocation of the L1 major protein and the L2 minor capsid protein of human papillomavirus type 33 by several approaches. First, we observed that expression and nuclear translocation of L2 in natural lesions precede expression of L1. Second, using a cell culture system for coexpression, we found that accumulation of L2 in nuclear domain 10 (ND10) subnuclear structures precedes L1 by several hours. In contrast, complexes of L2 and mutants of L1 forced to assemble in the cytoplasm are tra…
The Tobacco mosaic virus movement protein associates with but does not integrate into biological membranes
2014
Plant positive-strand RNA viruses require association with plant cell endomembranes for viral translation and replication, as well as for intra- and intercellular movement of the viral progeny. The membrane association and RNA binding of the Tobacco mosaic virus (TMV) movement protein (MP) are vital for orchestrating the macromolecular network required for virus movement. A previously proposed topological model suggests that TMV MP is an integral membrane protein with two putative -helical transmembrane (TM) segments. Here we tested this model using an experimental system that measured the efficiency with which natural polypeptide segments were inserted into the ER membrane under conditions…
Raman Spectroscopic Signatures of Echovirus 1 Uncoating
2014
ABSTRACT In recent decades, Raman spectroscopy has entered the biological and medical fields. It enables nondestructive analysis of structural details at the molecular level and has been used to study viruses and their constituents. Here, we used Raman spectroscopy to study echovirus 1 (EV1), a small, nonenveloped human pathogen, in two different uncoating states induced by heat treatments. Raman signals of capsid proteins and RNA genome were observed from the intact virus, the uncoating intermediate, and disrupted virions. Transmission electron microscopy data revealed general structural changes between the studied particles. Compared to spectral characteristics of proteins in the intact v…
The Minor Capsid Protein VP11 of Thermophilic Bacteriophage P23-77 Facilitates Virus Assembly by Using Lipid-Protein Interactions
2015
ABSTRACT Thermus thermophilus bacteriophage P23-77 is the type member of a new virus family of icosahedral, tailless, inner-membrane-containing double-stranded DNA (dsDNA) viruses infecting thermophilic bacteria and halophilic archaea. The viruses have a unique capsid architecture consisting of two major capsid proteins assembled in various building blocks. We analyzed the function of the minor capsid protein VP11, which is the third known capsid component in bacteriophage P23-77. Our findings show that VP11 is a dynamically elongated dimer with a predominantly α-helical secondary structure and high thermal stability. The high proportion of basic amino acids in the protein enables electrost…
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.