Nup124p is a nuclear pore factor of Schizosaccharomyces pombe that is important for nuclear import and activity of retrotransposon Tf1

The long terminal repeat (LTR)-containing retrotransposon Tf1 propagates wi thin the fission yeast Schizosaccharomyces pombe as the result of several m echanisms that are typical of both retrotransposons and retroviruses. To id entify host factors that contribute to the transposition process, we mutage nized cultures of S. pombe and screened them for strains that were unable t o support Tf1 transposition. One such strain contained a mutation in a gene we named nup124. The product of this gene contains 11 FXFG repeats and is a component of the nuclear pore complex. In addition to the reduced levels of Tf1 transposition, the nup124-1 allele. caused a significant reduction i n the nuclear localization of Tf1 Gag. Surprisingly, the mutation in nup124 -1 did not cause any reduction in the growth rate, the nuclear localization of specific nuclear localization signal-containing proteins, or the cytopl asmic localization of poly(A) mRNA. A two-hybrid analysis and an in vitro p recipitation assay both identified an interaction between Tf1 Gag and the N terminus of Nup124p. These results provide evidence for an unusual mechani sm of nuclear import that relies on a direct interaction between a nuclear pore factor and Tf1 Gag.