Cardiovirus Leader proteins bind exportins: Implications for virus replication and nucleocytoplasmic trafficking inhibition.
Cardiovirus Leader proteins (LX) inhibit cellular nucleocytoplasmic trafficking by directing host kinases to phosphorylate Phe/Gly-containing nuclear pore proteins (Nups). Resolution of the Mengovirus LM structure bound to Ran GTPase, suggested this complex would further recruit specific exportins (karyopherins), which in turn mediate kinase selection. Pull-down experiments and recombinant complex reconstitution now confirm that Crm1 and CAS exportins form stable dimeric complexes with encephalomyocarditis virus LE, and also larger complexes with LE:Ran. shRNA knockdown studies support this idea. Similar activities could be demonstrated for recombinant LS and LT from Theiloviruses. When mutations were introduced to alter the LE zinc finger domain, acidic domain, or dual phosphorylation sites, there was reduced exportin selection. These regions are not involved in Ran interactions, so the Ran and Crm1 binding sites on LE must be non-overlapping. The involvement of exportins in this mechanism is important to viral replication and the observation of trafficking inhibition by LE.
Institute for Molecular Virology and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States.
Jessica J
JJ
Ciomperlik
Department of Biology, Rocky Mountain College, Billings, MT, United States.
Holly A
HA
Basta
Institute for Molecular Virology and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States. Electronic address: acpalmen@wisc.edu.
Ann C
AC
Palmenberg
D021581:Active Transport, Cell Nucleus / Q000235:genetics*; D001665:Binding Sites / Q000235:genetics; D017943:Cardiovirus / Q000378:metabolism*; D045744:Cell Line, Tumor; D004686:Encephalomyocarditis virus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism*; D008574:Mengovirus / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D034622:RNA Interference; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D017945:Theilovirus / Q000378:metabolism; D014779:Virus Replication / Q000235:genetics; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D000097606:Exportin 1 Protein
D028884:Karyopherins; D028861:Nuclear Pore Complex Proteins; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear; D020931:ran GTP-Binding Protein; D000097606:Exportin 1 Protein; C120587:RAN protein, human
Cardiovirus; Crm1; Leader protein; Nucleocytoplasmic trafficking inhibition