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Journal of Virology, November 2009, p. 11914-11925, Vol. 83, No. 22
0022-538X/09/$08.00+0 doi:10.1128/JVI.01192-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Ty3 Nuclear Entry Is Initiated by Viruslike Particle Docking on GLFG Nucleoporins
,
Nadejda Beliakova-Bethell,1,
Laura J. Terry,2
Virginia Bilanchone,1
Rhonda DaSilva,3,
Kunio Nagashima,3
Susan R. Wente,2 and
Suzanne Sandmeyer1*
Department of Biological Chemistry, University of California, Irvine, California 92697,1 Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232,2 Electron Microscope Laboratory, NCI-Frederick, SAIC Frederick, Inc., Frederick, Maryland 21702-12013
Received 10 June 2009/ Accepted 3 September 2009
Yeast retrotransposons form intracellular particles within which replication occurs. Because fungal nuclear membranes do not break down during mitosis, similar to retroviruses infecting nondividing cells, the cDNA produced must be translocated through nuclear pore complexes. The Saccharomyces cerevisiae long terminal repeat retrotransposon Ty3 assembles its Gag3 and Gag3-Pol3 precursor polyproteins into viruslike particles in association with perinuclear P-body foci. These perinuclear clusters of Ty3 viruslike particles localized to sites of clustered nuclear pore complexes (NPCs) in a nup120
mutant, indicating that Ty3 particles and NPCs interact physically. The NPC channels are lined with nucleoporins (Nups) with extended FG (Phe-Gly) motif repeat domains, further classified as FG, FxFG, or GLFG repeat types. These domains mediate partitioning of proteins between the cytoplasm and the nucleus. Here we have systematically examined the requirements for FG repeat domains in Ty3 nuclear transport. The GLFG domains interacted in vitro with virus-like particle Gag3, and this interaction was disrupted by mutations in the amino-terminal domain of Gag3, which is predicted to lie on the external surface of the particles. Accordingly, Ty3 transposition was decreased in strains with the GLFG repeats deleted. The spacer-nucleocapsid domain of Gag3, which is predicted to be internal to the particle, interacted with GLFG repeats and nucleocapsid localized to the nucleus. We conclude that Ty3 particle docking on nuclear pores is facilitated by interactions between Gag3 and GLFG Nups and that nuclear entry of the preintegration complex is further promoted by nuclear localization signals within the nucleocapsid and integrase.
* Corresponding author. Mailing address: Department of Biological Chemistry, University of California, Irvine, CA 92697. Phone: (949) 824-7571. Fax: (949) 824-2688. E-mail: sbsandme{at}uci.edu
Published ahead of print on 16 September 2009.
Supplemental material for this article may be found at http://jvi.asm.org/.
Present address: University of California, San Diego, Stein Clinical Research Building, Rm. 303, 9500 Gilman Dr., La Jolla, CA 92093-0679.
Present address: Clinical Research Management, Office of Regulated Studies, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702.
Journal of Virology, November 2009, p. 11914-11925, Vol. 83, No. 22
0022-538X/09/$08.00+0 doi:10.1128/JVI.01192-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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