The functionally conserved nucleoporins Nup124p from fission yeast and the human Nup153 mediate nuclear import and activity of the Tf1 retrotransposon and HIV-1 Vpr.
We report that the fission yeast nucleoporin Nup124p is required for the nuclear import of both, retrotransposon Tf1-Gag as well as the retroviral HIV-1 Vpr. Failure to import Tf1-Gag into the nucleus in a nup124 null mutant resulted in complete loss of Tf1 transposition. Similarly, nuclear import of HIV-1 Vpr was impaired in nup124 null mutant strains and cells became resistant to Vpr's cell-killing activity. On the basis of protein domain similarity, the human nucleoporin Nup153 was identified as a putative homolog of Nup124p. We demonstrate that in vitro-translated Nup124p and Nup153 coimmunoprecipitate Tf1-Gag or HIV-1 Vpr. Though full-length Nup153 was unable to complement the Tf1 transposition defect in a nup124 null mutant, we provide evidence that both nucleoporins share a unique N-terminal domain, Nup124p(AA264-454) and Nup153(AA448-634) that is absolutely essential for Tf1 transposition. Epigenetic overexpression of this domain in a wild-type (nup124(+)) background blocked Tf1 activity implying that sequences from Nup124p and the human Nup153 challenged the same pathway affecting Tf1 transposition. Our results establish a unique relationship between two analogous nucleoporins Nup124p and Nup153 wherein the function of a common domain in retrotransposition is conserved.
Varadarajan
Padmapriya
P
Laboratory of Nucleopore Biology, Institute of Molecular and Cell Biology, Republic of Singapore.
Mahalingam
Sundarasamy
S
Liu
Peiyun
P
Ng
Sarah Boon Hsi
SB
Gandotra
Sheetal
S
Dorairajoo
Desmond Suresh Kumar
DS
Balasundaram
David
D
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D015966:Gene Expression Regulation, Fungal; D016336:Gene Products, vpr / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018626:Retroelements / Q000235:genetics / Q000502:physiology*; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D054325:vpr Gene Products, Human Immunodeficiency Virus
D016336:Gene Products, vpr; C079377:NUP153 protein, human; D028861:Nuclear Pore Complex Proteins; D018626:Retroelements; D029702:Schizosaccharomyces pombe Proteins; C120536:nup124 protein, S pombe; D054325:vpr Gene Products, Human Immunodeficiency Virus