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Unphosphorylated Mengovirus Leader Protein: NMR Studies of the Phosphorylation of the Mengovirus Leader Protein Reveal Stabilization of Intermolecular Domain InteractionsUnphosphorylated Mengovirus Leader Protein: NMR Studies of the Phosphorylation of the Mengovirus Leader Protein Reveal Stabilization of Intermolecular Domain Interactions
Structural highlights
Publication Abstract from PubMedCardiovirus Leader (L) proteins induce potent antihost inhibition of active cellular nucleocytoplasmic trafficking by triggering aberrant hyperphosphorylation of nuclear pore proteins (Nup). To achieve this, L binds protein RanGTPase (Ran), a key trafficking regulator, and diverts it into tertiary or quaternary complexes with required kinases. The activity of L is regulated by two phosphorylation events not required for Ran binding. Matched NMR studies on the unphosphorylated, singly, and doubly phosphorylated variants of Mengovirus L (LM) show both modifications act together to partially stabilize a short internal alpha-helix comprising LM residues 43-46. This motif implies that ionic and Van der Waals forces contributed by phosphorylation help organize downstream residues 48-67 into a new interface. The full structure of LM as bound to Ran (unlabeled) and Ran (216 aa) as bound by LM (unlabeled) places LM into the BP1 binding site of Ran, wrapped by the conformational flexible COOH tail. The arrangement explains the tight KD for this complex and places the LM zinc finger and phosphorylation interface as surface exposed and available for subsequent reactions. The core structure of Ran, outside the COOH tail, is not altered by LM binding and remains accessible for canonical RanGTP partner interactions. Pull-down assays identify at least one putative Ran:LM partner as an exportin, Crm1, or CAS. A model of Ran:LM:Crm1, based on the new structures suggests LM phosphorylation status may mediate Ran's selection of exportin(s) and cargo(s), perverting these native trafficking elements into the lethal antihost Nup phosphorylation pathways. Solution structures of Mengovirus Leader protein, its phosphorylated derivatives, and in complex with nuclear transport regulatory protein, RanGTPase.,Bacot-Davis VR, Ciomperlik JJ, Basta HA, Cornilescu CC, Palmenberg AC Proc Natl Acad Sci U S A. 2014 Oct 20. pii: 201411098. PMID:25331866[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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