A single amino acid change in SNM1-encoded protein leads to thermoconditional deficiency for DNA cross-link repair in Saccharomyces cerevisiae.

Molecular characterization of a thermoconditional mutant snm1-2ts shows that the coding sequence contains three mutations, two of which are silent. The third changes amino acid glycine to arginine at position 256 thereby altering a hydrophilic domain of the protein. While sensitivity to nitrogen mustard of the mutant at 36 degrees C is very similar to that of the non-leaky allele snm1-1, multi-copy vector-mediated overexpression of snm1-2ts leads to a significantly reduced sensitivity to nitrogen mustard.