Yeast RNC1 encodes a chimeric protein, RhoNUC, with a human rho motif and deoxyribonuclease activity

The yeast Saccharomyces cerevisiae contains an endoexonuclease yNucR that has been implicated in both recombination and repair. We describe the isolation and characterization of the corresponding gene. Within the predicted N-terminal half of the protein there is extensive homology (approximately 50%) with human rho genes, which are related to the ras oncogene, particularly in the proposed GTP-binding region. The C-terminal region, which is related to the Escherichia coli recC protein, presumably encodes the endoexonuclease activity. The yNucR may thus represent a new class of GTP-binding proteins. Because of the chimeric nature of the polypeptide, this protein is renamed RhoNUC (rather than the original yNucR) and the gene is RNC1 for Rho-associated-NuClease. Over expression of the gene leads to altered cell growth and nuclear morphology. We propose that the gene plays an important role in cell development as well as DNA repair/recombination.