The open reading frame 3a protein of severe acute respiratory syndrome-associated coronavirus promotes membrane rearrangement and cell death.
The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains eight open reading frames (ORFs) that encode novel proteins. These accessory proteins are dispensable for in vitro and in vivo replication and thus may be important for other aspects of virus-host interactions. We investigated the functions of the largest of the accessory proteins, the ORF 3a protein, using a 3a-deficient strain of SARS-CoV. Cell death of Vero cells after infection with SARS-CoV was reduced upon deletion of ORF 3a. Electron microscopy of infected cells revealed a role for ORF 3a in SARS-CoV induced vesicle formation, a prominent feature of cells from SARS patients. In addition, we report that ORF 3a is both necessary and sufficient for SARS-CoV-induced Golgi fragmentation and that the 3a protein accumulates and localizes to vesicles containing markers for late endosomes. Finally, overexpression of ADP-ribosylation factor 1 (Arf1), a small GTPase essential for the maintenance of the Golgi apparatus, restored Golgi morphology during infection. These results establish an important role for ORF 3a in SARS-CoV-induced cell death, Golgi fragmentation, and the accumulation of intracellular vesicles.
Freundt
Eric C
EC
Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Yu
Li
L
Goldsmith
Cynthia S
CS
Welsh
Sarah
S
Cheng
Aaron
A
Yount
Boyd
B
Liu
Wei
W
Frieman
Matthew B
MB
Buchholz
Ursula J
UJ
Screaton
Gavin R
GR
Lippincott-Schwartz
Jennifer
J
Zaki
Sherif R
SR
Xu
Xiao-Ning
XN
Baric
Ralph S
RS
Subbarao
Kanta
K
Lenardo
Michael J
MJ
D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016923:Cell Death; D002462:Cell Membrane / Q000473:pathology / Q000821:virology; D002522:Chlorocebus aethiops; D022162:Cytoplasmic Vesicles / Q000378:metabolism / Q000821:virology; D017353:Gene Deletion; D006056:Golgi Apparatus / Q000378:metabolism / Q000473:pathology; D054884:Host-Pathogen Interactions; D006801:Humans; D045473:Severe acute respiratory syndrome-related coronavirus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D014162:Transfection; D014709:Vero Cells / Q000473:pathology; D015678:Viral Structural Proteins / Q000378:metabolism*; D000086082:Viroporin Proteins
D020823:ADP-Ribosylation Factor 1; D015678:Viral Structural Proteins; C515313:ORF3A protein, SARS coronavirus; D000086082:Viroporin Proteins