The Aspergillus nidulans uvsB gene encodes an ATM-related kinase required for multiple facets of the DNA damage response

In Aspergillus nidulans, uvsB and uvsD belong to the same epistasis group o f DNA repair mutants. Recent observations suggest that these genes are like ly to control cell cycle checkpoint responses to DNA damage and incomplete replication. Consistent with this notion, we show here that UVSB is a membe r of the conserved family of ATM-related kinases. Phenotypic characterizati on of uvsB mutants shows that they possess defects in additional aspects of the DNA damage response besides checkpoint control, including inhibition o f septum formation, regulation of gene expression, and induced mutagenesis. The musN227 mutation partially suppresses the poor growth and DNA damage s ensitivity of uvsB mutants. Although musN227 partially suppresses several u vsB defects, it does not restore checkpoint function to uvsB mutants. Notab ly, the failure of uvsB mutants to restrain septum formation in the presenc e of DNA damage is suppressed by the musN227 mutation. We propose that UVSB functions as the central regulator of the A. nidulans DNA damage response, whereas MUSN promotes recovery by modulating a subset of the response.