Asymmetrical localization of components of the Nup107-160 subcomplex within the nuclear pore complex in fission yeast

The nuclear pore complex (NPC) forms a gateway for nucleocytoplasmic transport. The NPC consists of several protein subcomplexes. Nup107-160 is a key subcomplex responsible for building the basal NPC structure by symmetrical localization on the nuclear and cytoplasmic sides of the nuclear pore. Here we found an unusual asymmetrical localization of the Nup107-160 subcomplex in fission yeast. Two disconnected/split pieces of the Nup107-160 subcomplex were differentially distributed to either side of the NPC, as revealed by immunoelectron microscopy and affinity-capture/mass spectrometry for nucleoporins. Nup131 and Nup132 (paralogs of human Nup133) were differentially localized on the cytoplasmic and nuclear sides, respectively. The expression of a fusion protein connecting the disrupted components of the Nup107-160 subcomplex caused symmetrical localization of Nup132, leading to defects in mitosis and meiosis. These observations suggest that the asymmetrical NPC structure is necessary for normal cell cycle progression in fission yeast.