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Title: CHARACTERIZATION OF NUCLEAR IMPORT OF POTATO SPINDLE TUBER VIROID RNA IN PERMEABILIZED PROTOPLASTS

Author
item WOO, YOUNG-MIN - OK STATE UNIV STILLWATER
item ITAYA, ASUKA - OK STATE UNIV STILLWATER
item Owens, Robert
item TANG, LI - OK STATE UNIV STILLWATER
item Hammond, Rosemarie
item CHOU, HUEI-CHI - SCHOOL OF MED LOS ANGELES
item LAI, MICHAEL - SCHOOL OF MED LOS ANGELES
item DING, BIAO - OK STATE UNIV STILLWATER

Submitted to: International Congress of Virology
Publication Type: Abstract Only
Publication Acceptance Date: 1/22/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Potato spindle tuber (PSTVd) and related viroids replicate in the nuclei of infected plant cells. Nuclear import of the incoming viroid RNA thus represents a key control point for establishment of systemic infection, and we are studying the ability of infectious PSTVd RNA labeled with fluorescein (F-PSTVd) to move into the nuclei of detergent-permeabilized tobacco BY2 cells. F-PSTVd but not several control RNAs of similar size were observed to enter the nucleus within 20-40 min. F-PSTVd import was inhibited by addition a ten-fold excess of non-fluorescent PSTVd but not by similar amounts of control RNAs. Preincubation of permeabilized cells with non-hydrolyzable GTP analogs did not inhibit F-PSTVd import; likewise, disruption of the cytoskeleton with oryzalin or cytochalasin D was without effect. Taken together, our results indicate that (i) PSTVd possesses a sequence and/or structural motif specifying nuclear import and (ii) viroid import into the nucleus is a cytoskeleton-independent process that is mediated by a specific and saturable receptor. Insensitivity to GTP analogs suggests that viroid import is not coupled to the Ran GTPase cycle mediating the nuclear transport of many proteins and nucleic acids. Attempts to identify the sequence/structural motif responsible for PSTVd import will be described.