MxA GTPase blocks reporter gene expression of reconstituted Thogoto virus ribonucleoprotein complexes.
Human MxA protein accumulates in the cytoplasm of interferon-treated cells and inhibits the multiplication of several RNA viruses, including Thogoto virus (THOV), a tick-borne orthomyxovirus that transcribes and replicates its genome in the cell nucleus. The antiviral mechanism of MxA was investigated by using two alternative minireplicon systems in which recombinant viral ribonucleoprotein complexes (vRNPs) of THOV were reconstituted from cloned cDNAs. A chloramphenicol acetyltransferase reporter minigenome RNA was expressed either by T7 RNA polymerase in the cytoplasm of transfected cells or, alternatively, by RNA polymerase I in the nucleus. The inhibitory effect of MxA was studied in both cellular compartments by coexpressing wild-type MxA or TMxA, an artificial nuclear form of MxA. Our results indicate that both MxA proteins recognize the assembled vRNP rather than the newly synthesized unassembled components. The present findings are consistent with previous data which indicated that cytoplasmic MxA prevents transport of vRNPs into the nucleus, whereas nuclear MxA directly inhibits the viral polymerase activity in the nucleus.
Weber
F
F
Abteilung Virologie, Institut für Medizinische Mikrobiologie und Hygiene, Universität Freiburg, D-79008 Freiburg, Germany.
Haller
O
O
Kochs
G
G
D000818:Animals; D019556:COS Cells; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000502:physiology*; D019204:GTP-Binding Proteins; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D017930:Genes, Reporter; D064547:Myxovirus Resistance Proteins; D011506:Proteins / Q000502:physiology*; D012261:Ribonucleoproteins / Q000235:genetics*; D013347:Subcellular Fractions / Q000378:metabolism; D018117:Thogotovirus / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics
C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D011506:Proteins; D012261:Ribonucleoproteins; D014764:Viral Proteins; D015500:Chloramphenicol O-Acetyltransferase; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins