scholarly journals The Interplay between ESCRT and Viral Factors in the Enveloped Virus Life Cycle

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 324
Author(s):  
Bo Meng ◽  
Andrew M. L. Lever
Keyword(s):  
Life Cycle ◽  
Surface Proteins ◽  
Cellular Functions ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Diverse Families ◽  
Enveloped Virus ◽  
Virus Life Cycle ◽  
Obligate Parasites ◽  
Cellular Factors

Viruses are obligate parasites that rely on host cellular factors to replicate and spread. The endosomal sorting complexes required for transport (ESCRT) system, which is classically associated with sorting and downgrading surface proteins, is one of the host machineries hijacked by viruses across diverse families. Knowledge gained from research into ESCRT and viruses has, in turn, greatly advanced our understanding of many other cellular functions in which the ESCRT pathway is involved, e.g., cytokinesis. This review highlights the interplay between the ESCRT pathway and the viral factors of enveloped viruses with a special emphasis on retroviruses.

scholarly journals The Role of Exosome and the ESCRT Pathway on Enveloped Virus Infection

2021 ◽  
Vol 22 (16) ◽  
pp. 9060 ◽  
Author(s):  
Yichen Ju ◽  
Haocheng Bai ◽  
Linzhu Ren ◽  
Liying Zhang
Keyword(s):  
Virus Infection ◽  
Protein Complexes ◽  
Virus Assembly ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Enveloped Virus ◽  
Peripheral Membrane Protein ◽  
Membrane Protein Complexes ◽  
Membrane Shedding

The endosomal sorting complex required for transport (ESCRT) system consists of peripheral membrane protein complexes ESCRT-0, -I, -II, -III VPS4-VTA1, and ALIX homodimer. This system plays an important role in the degradation of non-essential or dangerous plasma membrane proteins, the biogenesis of lysosomes and yeast vacuoles, the budding of most enveloped viruses, and promoting membrane shedding of cytokinesis. Recent results show that exosomes and the ESCRT pathway play important roles in virus infection. This review mainly focuses on the roles of exosomes and the ESCRT pathway in virus assembly, budding, and infection of enveloped viruses. The elaboration of the mechanism of exosomes and the ESCRT pathway in some enveloped viruses provides important implications for the further study of the infection mechanism of other enveloped viruses.

scholarly journals The Envelope G3L Protein Is Essential for Entry of Vaccinia Virus into Host Cells

2006 ◽  
Vol 80 (17) ◽  
pp. 8402-8410 ◽  
Author(s):  
Ruzan A. Izmailyan ◽  
Cheng-Yen Huang ◽  
Shamim Mohammad ◽  
Stuart N. Isaacs ◽  
Wen Chang
Keyword(s):  
Life Cycle ◽  
Vaccinia Virus ◽  
Transmembrane Domain ◽  
Recombinant Vaccinia Virus ◽  
Host Cells ◽  
Virus Growth ◽  
Enveloped Virus ◽  
Virus Life Cycle ◽  
Infected Cells ◽  
Mature Virus

ABSTRACT The vaccinia virus G3L/WR079 gene encodes a conserved protein with a predicted transmembrane domain. Our proteomic analyses of vaccinia virus revealed that G3L protein is incorporated into intracellular mature virus; however, the function of G3L protein in the vaccinia virus life cycle has not been investigated. In this study, a recombinant vaccinia virus, viG3L, expressing G3L protein under IPTG (isopropyl-β-d-thiogalactopyranoside) regulation was constructed. Under permissive conditions when G3L protein was expressed, the vaccinia virus life cycle proceeded normally, resulting in plaque formation in BSC40 cells. In contrast, under nonpermissive conditions when G3L protein expression was repressed, no plaques were formed, showing that G3L protein is essential for vaccinia virus growth in cell cultures. In infected cells when G3L protein was not expressed, the formation of intracellular mature virus (IMV) and cell-associated enveloped virus occurred normally, showing that G3L protein is not required for virion morphogenesis. IMV particles containing (G3L+) or lacking (G3L−) G3L protein were purified and were found to be indistinguishable on microscopic examination. Both G3L+ and G3L− IMV bound to HeLa cells; however, G3L− IMV failed to enter the cells, showing that G3L protein is required for IMV penetration into cells. Finally, G3L protein was required for fusion of the infected cells under low-pH treatment. Thus, our results provide direct evidence that G3L is an essential component of the vaccinia virus fusion complex, in addition to the previously reported A28, H2, L5, A21, and A16 proteins.

scholarly journals Current Understanding of the Role of Cholesterol in the Life Cycle of Alphaviruses

Viruses ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 35
Author(s):  
Ivanildo P. Sousa ◽  
Carlos A. M. Carvalho ◽  
Andre M. O. Gomes
Keyword(s):  
Life Cycle ◽  
Host Cell ◽  
Cell Lines ◽  
New World ◽  
Cholesterol Metabolism ◽  
Enveloped Viruses ◽  
Important Group ◽  
Virus Life Cycle ◽  
Alphavirus Infection

Enveloped viruses rely on different lipid classes present in cell membranes to accomplish several steps of their life cycle in the host. Particularly for alphaviruses, a medically important group of arboviruses, which are part of the Togaviridae family, cholesterol seems to be a critical lipid exploited during infection, although its relevance may vary depending on which stage of the virus life cycle is under consideration and whether infection takes place in vertebrate or invertebrate hosts. In this review, the role of cholesterol in both early and late events of alphavirus infection and how viral replication may affect cholesterol metabolism are summarized, taking into account studies on Old World and New World alphaviruses in different cell lines. Moreover, the importance of cholesterol for the structural stability of alphavirus particles is also discussed, shedding light on the role played by this lipid when they leave the host cell.

scholarly journals A Duplicated ESCRT-III Factor Blocks Enveloped Virus Budding Without Inhibiting Cellular ESCRT Functions

2020 ◽  
Author(s):  
Lara Rheinemann ◽  
Diane Miller Downhour ◽  
Kate Bredbenner ◽  
Gaelle Mercenne ◽  
Kristen A. Davenport ◽  
...  
Keyword(s):  
Cellular Membrane ◽  
New World Monkeys ◽  
Virus Budding ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Adaptive Mutations ◽  
Enveloped Virus ◽  
Viral Budding ◽  
Membrane Fission ◽  
Infected Cells

SummaryMany enveloped viruses require the endosomal sorting complexes required for transport (ESCRT) pathway to exit infected cells. This highly conserved pathway mediates essential cellular membrane fission events and therefore has limited potential to acquire adaptive mutations to counteract this co-option by viruses. Here, we describe duplicated and truncated copies of the ESCRT-III factor CHMP3 that arose independently in New World monkeys and mice and that block ESCRT-dependent virus budding. When expressed in human cells, these retroCHMP3 proteins potently inhibit the release of retroviruses, paramyxoviruses and filoviruses. RetroCHMP3 proteins have evolved to reduce interactions with other ESCRT-III factors, and to have little effect on cellular ESCRT processes, revealing routes for decoupling cellular ESCRT functions from exploitation by viruses. The repurposing of duplicated ESCRT-III proteins thus provides a mechanism to generate broad-spectrum viral budding inhibitors without disrupting highly conserved essential cellular ESCRT functions.

scholarly journals Cellular factors involved in the hepatitis C virus life cycle

2021 ◽  
Vol 27 (28) ◽  
pp. 4555-4581
Author(s):  
Hui-Chun Li ◽  
Chee-Hing Yang ◽  
Shih-Yen Lo
Keyword(s):  
Life Cycle ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Life Cycle ◽  
Cellular Factors

scholarly journals Role of Virally-Encoded Deubiquitinating Enzymes in Regulation of the Virus Life Cycle

2021 ◽  
Vol 22 (9) ◽  
pp. 4438
Author(s):  
Jessica Proulx ◽  
Kathleen Borgmann ◽  
In-Woo Park
Keyword(s):  
Immune Response ◽  
Life Cycle ◽  
Deubiquitinating Enzyme ◽  
Deubiquitinating Enzymes ◽  
Antiviral Immune Response ◽  
Cellular Processes ◽  
Virus Life Cycle ◽  
Infected Cells ◽  
Dependent Processes

The ubiquitin (Ub) proteasome system (UPS) plays a pivotal role in regulation of numerous cellular processes, including innate and adaptive immune responses that are essential for restriction of the virus life cycle in the infected cells. Deubiquitination by the deubiquitinating enzyme, deubiquitinase (DUB), is a reversible molecular process to remove Ub or Ub chains from the target proteins. Deubiquitination is an integral strategy within the UPS in regulating survival and proliferation of the infecting virus and the virus-invaded cells. Many viruses in the infected cells are reported to encode viral DUB, and these vial DUBs actively disrupt cellular Ub-dependent processes to suppress host antiviral immune response, enhancing virus replication and thus proliferation. This review surveys the types of DUBs encoded by different viruses and their molecular processes for how the infecting viruses take advantage of the DUB system to evade the host immune response and expedite their replication.

scholarly journals Conformational Plasticity of Hepatitis B Core Protein Spikes Promotes Peptide Binding Independent of the Secretion Phenotype

2021 ◽  
Vol 9 (5) ◽  
pp. 956
Author(s):  
Cihan Makbul ◽  
Vladimir Khayenko ◽  
Hans Michael Maric ◽  
Bettina Böttcher
Keyword(s):  
Hepatitis B ◽  
Core Protein ◽  
Peptide Binding ◽  
Surface Proteins ◽  
Binding Motif ◽  
Virus Particles ◽  
Enveloped Virus ◽  
Conformational Plasticity ◽  
Viral Maturation ◽  
Hepatitis B Core Protein

Hepatitis B virus is a major human pathogen, which forms enveloped virus particles. During viral maturation, membrane-bound hepatitis B surface proteins package hepatitis B core protein capsids. This process is intercepted by certain peptides with an “LLGRMKG” motif that binds to the capsids at the tips of dimeric spikes. With microcalorimetry, electron cryo microscopy and peptide microarray-based screens, we have characterized the structural and thermodynamic properties of peptide binding to hepatitis B core protein capsids with different secretion phenotypes. The peptide “GSLLGRMKGA” binds weakly to hepatitis B core protein capsids and mutant capsids with a premature (F97L) or low-secretion phenotype (L60V and P5T). With electron cryo microscopy, we provide novel structures for L60V and P5T and demonstrate that binding occurs at the tips of the spikes at the dimer interface, splaying the helices apart independent of the secretion phenotype. Peptide array screening identifies “SLLGRM” as the core binding motif. This shortened motif binds only to one of the two spikes in the asymmetric unit of the capsid and induces a much smaller conformational change. Altogether, these comprehensive studies suggest that the tips of the spikes act as an autonomous binding platform that is unaffected by mutations that affect secretion phenotypes.

scholarly journals The role of VPS4 in ESCRT-III polymer remodeling

2019 ◽  
Vol 47 (1) ◽  
pp. 441-448 ◽  
Author(s):  
Christophe Caillat ◽  
Sourav Maity ◽  
Nolwenn Miguet ◽  
Wouter H. Roos ◽  
Winfried Weissenhorn
Keyword(s):  
Active Role ◽  
Mechanistic Models ◽  
Membrane Remodeling ◽  
Filament Formation ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Membrane Fission ◽  
Dynamic Assembly ◽  
Inside Out

Abstract The endosomal sorting complex required for transport-III (ESCRT-III) and VPS4 catalyze a variety of membrane-remodeling processes in eukaryotes and archaea. Common to these processes is the dynamic recruitment of ESCRT-III proteins from the cytosol to the inner face of a membrane neck structure, their activation and filament formation inside or at the membrane neck and the subsequent or concomitant recruitment of the AAA-type ATPase VPS4. The dynamic assembly of ESCRT-III filaments and VPS4 on cellular membranes induces constriction of membrane necks with large diameters such as the cytokinetic midbody and necks with small diameters such as those of intraluminal vesicles or enveloped viruses. The two processes seem to use different sets of ESCRT-III filaments. Constriction is then thought to set the stage for membrane fission. Here, we review recent progress in understanding the structural transitions of ESCRT-III proteins required for filament formation, the functional role of VPS4 in dynamic ESCRT-III assembly and its active role in filament constriction. The recent data will be discussed in the context of different mechanistic models for inside-out membrane fission.

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