MUTATIONS IN THE HEAVY-CHAIN OF CYTOPLASMIC DYNEIN SUPPRESS THE NUDF NUCLEAR MIGRATION MUTATION OF ASPERGILLUS-NIDULANS

To identify proteins that interact directly or indirectly with the NUD F protein, which is required for nuclear migration in Aspergillus nidu lans, We initiated a screen for extragenic suppressors of the heat-sen sitive nudF6 mutation. Suppressor mutations in at least five genes, de signated snfA-snf6, caused improved growth and nuclear migration at hi gh temperatures compared to the nudF6 parent. Two snfC mutations mappe d near the nudA gene, which encodes the cytoplasmic dynein heavy chain , and could be repaired by transformation with wild-type nudA DNA, dem onstrating that they are mutations in nudA. The snfC mutations are byp ass suppressors of nudF and genetic evidence indicated that NUDA and N UDF act in the same nuclear migration pathway. Taken together, our dat a suggests that NUDF affects nuclear migration by acting on the dynein motor system.