MxA GTPase: oligomerization and GTP-dependent interaction with viral RNP target structures.
MxA protein is an interferon-induced GTPase of human cells that inhibits the multiplication of several RNA viruses, including influenza viruses and bunyaviruses. Studies on MxA transgenic mice have shown that MxA is a powerful antiviral agent in vivo. It has been suggested that this cellular protein also protects humans from viral disease, but the mechanism(s) by which MxA exerts its antiviral action is still poorly understood. Using an in vitro cosedimentation assay, we now demonstrate that MxA tightly interacts with components of the ribonucleoprotein complex of Thogoto virus, an influenza-like virus transmitted by ticks. This assay demonstrates for the first time a physical interaction between MxA GTPase and a viral target structure. It is based on three elements, namely, highly active MxA GTPases as effector molecules, viral ribonucleoprotein particles as viral targets, and GTPgammaS as a stabilizing factor. Furthermore, using a simple nuclear translocation assay, we show that human MxA protein forms oligomers in vivo. This assay provides a stringent test for tight association of partner molecules in intact mammalian cells. It not only will be useful for studying physical interactions of MxA with partner molecules, but may also be applicable to other studies on protein-protein interactions in living cells.
Kochs
G
G
Institut für Medizinische Mikrobiologie und Hygiene, Universität Freiburg, Hermann-Herder-Strasse 11, Freiburg, D-79008, Germany.
Trost
M
M
Janzen
C
C
Haller
O
O
D000818:Animals; D001692:Biological Transport; D001704:Biopolymers; D002467:Cell Nucleus / Q000378:metabolism; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019204:GTP-Binding Proteins; D005982:Glutathione Transferase / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D051379:Mice; D064547:Myxovirus Resistance Proteins; D011233:Precipitin Tests; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012328:RNA Viruses / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*
D001704:Biopolymers; C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D006160:Guanosine Triphosphate; D005982:Glutathione Transferase; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins