Targetting to the proteasome often requires the phosphorylation of substrates and subsequent ubiquitination by a pathway involving the enzymes E1 activating, E2 conjugating and several types of E3 ligases. The largest class of E3 ligases is the cullin RING ligase (CRL), which the scaffold protein, CulA, is the target of Nedd8/RubA, an Ub like protein. W e have previously shown that the deneddylation is necessary for fungal development (Busch et al., 2003; 2007). For further exploration of the role of RubA during fungal development, we have tagged RubA (TAP and/or S- tag) to identify the association partners of neddylated cullins. Neddylated Cul1/CulA recruits the counterparts of Skp1/SkpA, Rbx1/RbxA and various F-box proteins, which are core parts of CRLs. In addition, proteins required for the RubA linkage pathway were identified. A genetic analysis of the identified interacting proteins showed that the corresponding genes often are essential for A. nidulans growth. We showed this by heterokaryon rescue for the RubA encoding gene. Experiments with higher eukaryotes are difficult, because mutations often result in embryonic death of the organism. A deletion analysis revealed that not even parts of the rubA encoding gene can be deleted. CulA, RbxA, and RubA-E2 conjugating enzyme, UbcL, also seem to be essential. Busch et al., Mol. Microbiol. 49, 717-730, 2003. Busch et al., PNAS USA. 104, 8125-8130, 2007.
Full conference title:
6th International Aspergillus Meeting
- Asperfest 6 (2009)