The beta-lactamase motif in Snm1 is required for repair of DNA double-strand breaks caused by interstrand crosslinks in S. cerevisiae.

The SNM1 gene of Saccharomyces cerevisiae is specific for repair of DNA interstrand crosslinks (ICLs). We report that the SNM1 gene functions in steps needed for the reformation of chromosomal DNA after double-strand breaks (DSBs) made in the process of ICL repair. However, SNM1 function is not needed for repair of HO endonuclease-generated DSBs. Therefore, the function of the SNM1 gene appears to act in the processing of the intermediates of the DSB repair, since the rate and extent of DSB appearance after ICL formation is normal in mutants lacking SNM1 function. The action of the SNM1 gene does not appear to depend on homologous recombination, but it does depend on an intact beta-lactamase domain conserved with Artemis, a protein required for processing of V(D)J recombination intermediates.