Genetic and molecular analysis of a tRNA(Leu) missense suppressor of nudC3, a mutation that blocks nuclear migration in Aspergillus nidulans.

NudC encodes a protein of unknown biochemical function that is required for nuclear migration. In an attempt to define its function by identifying interacting proteins, a screen for extragenic suppressors of the temperature-sensitive nudC3 mutation was undertaken that identified nine snc genes. Here we demonstrate that nudC3 has a missense mutation at amino acid 146 that causes leucine to be replaced by proline and that sncB69 encodes a mutant tRNA(Leu) that corrects the mutation. The sncB69 mutation deletes a single nucleotide in the anticodon of a tRNA(Leu) that changes its normal 5'CAG3' leucine anticodon to the proline anticodon 5'CCG3', which presumably allows incorporation of leucine at the mutant nudC3 proline codon 146 and thereby causes suppression of the nudC3 mutant phenotype.