Membrane rearrangements in plant virus RNA replication
Abstract
Positive-strand RNA viruses constitute a large group of infectious agents causing major plant, animal and human diseases. Genome replication occurs in association with host cell membrane structures derived from the endoplasmic reticulum (ER) (picornaviruses, potyviruses, comoviruses, nepoviruses and bromoviruses) or from the limiting membrane of organelles such as lysosomes or endosomes (alphaviruses), vacuoles (cucumoviruses), mitochondria (nodaviruses, some tombusviruses, carmoviruses, ampeloviruses and maculaviruses), peroxisomes (several tombusviruses) and chloroplasts (tymoviruses and some marafiviruses). Viral proteins are involved in targeting the replication complex to the specific intracellular membranes. Intracellular membranes are normally modified to form vesicular structures with a narrow neck through which the interior of the vesicles communicates with the cytosol. A variety of observations indicates that, indeed, virus replication takes place in the closed environment of the vesicles, including co-localization of virus replicase and virus RNA progeny with cell membranes and strong dependance of viral synthesis on lipid metabolism. Confinement of the virus replication complexes in closed environments represents an advantage for the viral RNA, which is protected from degradation of host ribonucleases and recognition of host defence reactions. Vesiculation of the target cellular membrane in natural hosts and in the yeast Saccharomyces cerevisisae, an alternative model host for studying virus replication, is well documented for nodaviruses (animal viruses) and bromo- and tombusviruses (plant viruses). Flock house virus (FHV, genus Nodavirus, family Nodaviridae) protein A is a transmembrane protein that contains N-terminal signals targeting the outer membrane of mitochondria and elicits the formation of vesicular structures. Brome mosaic virus (BMV, genus Bromovirus, family Bromoviridae) replication occurs on the ER membranes, in spherules containing genomic RNA, the 2a replicase protein and the 1a virus RNA replication factor. The 1a multifunctional protein has RNA capping and helicase functions, and directs targeting and assembly of the replication complex on the ER membranes. The replication of members of the genus Tombusvirus (family Tombusviridae) has been studied in plant and yeast cells. Carnation Italian ringspot virus p36 protein contains the determinants for targeting the replication complex to the outer membrane of mitochondria; the p33 of several other tombusviruses contains sequences necessary to localize virus replication on the limiting membrane of peroxisomes.
Anno di pubblicazione
2015
ISSN
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ISBN
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Numero di citazioni Wos
Nessuna citazione
Ultimo Aggiornamento Citazioni
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Numero di citazioni Scopus
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Settori ERC
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Codici ASJC
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