The nuclear pore complex component SONB is involved in mitotic regulation and a DNA damage response pathway in Aspergillus nidulans.

Osmani, Colin De Souza and Stephen


The NIMA kinase is essential for mitotic entry in Aspergillus nidulans and is required for nuclear localization of mitotic regulators. We have isolated two nuclear pore complex (NPC) proteins as suppressors of the nimA1 temperature sensitive allele which normally arrests with uncondensed DNA, interphase microtubules and cytoplasmic NIMA. These proteins, SONA and SONB, physically interact and are apparent at the nuclear periphery during interphase but remarkably disperse upon mitotic entry before localizing once again at the nuclear periphery during mitotic exit. We also find that NIMA itself localizes to the nuclear periphery during mitotic entry and that expression of dominant negative NIMA constructs enhances this localization. We propose NIMA regulates mitotic entry by promoting SONA and SONB dissociation from the NPC (see also De Souza and Osmani Wed Mar 19). SONB is a member of the human NUP98/NUP96 family of nucleoporins. Interestingly, at 42oC, the sonB1 allele also displays a remarkably high sensitivity to agents which induce double strand DNA breaks, but less sensitivity to DNA damage induced by UV irradiation which does not cause double strand breaks. We provide evidence that this DNA damage sensitivity is not due to loss of checkpoint regulation over mitotic entry. We will also describe an extra copy suppressor screen aimed at identifying genes genetically interacting with SONB in response to DNA damage

abstract No: 

Fungal Genet. Newsl. 50 (Supl):abstract

Full conference title: 

22nd Fungal Genetics Conference
    • Fungal Genetics Conference 22nd (2001)