Host ESCRT proteins are required for bromovirus RNA replication compartment assembly and function.
Positive-strand RNA viruses genome replication invariably is associated with vesicles or other rearranged cellular membranes. Brome mosaic virus (BMV) RNA replication occurs on perinuclear endoplasmic reticulum (ER) membranes in ~70 nm vesicular invaginations (spherules). BMV RNA replication vesicles show multiple parallels with membrane-enveloped, budding retrovirus virions, whose envelopment and release depend on the host ESCRT (endosomal sorting complexes required for transport) membrane-remodeling machinery. We now find that deleting components of the ESCRT pathway results in at least two distinct BMV phenotypes. One group of genes regulate RNA replication and the frequency of viral replication complex formation, but had no effect on spherule size, while a second group of genes regulate RNA replication in a way or ways independent of spherule formation. In particular, deleting SNF7 inhibits BMV RNA replication > 25-fold and abolishes detectable BMV spherule formation, even though the BMV RNA replication proteins accumulate and localize normally on perinuclear ER membranes. Moreover, BMV ESCRT recruitment and spherule assembly depend on different sets of protein-protein interactions from those used by multivesicular body vesicles, HIV-1 virion budding, or tomato bushy stunt virus (TBSV) spherule formation. These and other data demonstrate that BMV requires cellular ESCRT components for proper formation and function of its vesicular RNA replication compartments. The results highlight growing but diverse interactions of ESCRT factors with many viruses and viral processes, and potential value of the ESCRT pathway as a target for broad-spectrum antiviral resistance.
Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
Arturo
A
Diaz
Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech University, Blacksburg, Virginia, United States of America.
Jiantao
J
Zhang
Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
Abigail
A
Ollwerther
Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech University, Blacksburg, Virginia, United States of America.
Xiaofeng
X
Wang
Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America; Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin, United States of America; Morgridge Institute for Research, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
Paul
P
Ahlquist
D015152:Blotting, Northern; D015153:Blotting, Western; D017795:Bromovirus / Q000502:physiology*; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006790:Host-Parasite Interactions / Q000502:physiology*; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D012367:RNA, Viral / Q000502:physiology*; D014779:Virus Replication / Q000502:physiology*
D056827:Endosomal Sorting Complexes Required for Transport; D012367:RNA, Viral