Identification of Hot and Cold Regions for Mutagenesis in the Escherichia coli tdk Gene: A Catalog of Mutational Sites.

We constructed a catalog of mutational sites in the tdk gene of Escherichia coli that consists of 378 different base pair substitutions at 245 different sites (base pairs). This allows us to examine the tendency of different sub-regions of the gene to be more or less prone to mutations when compared with other sub-regions. We do this by recording the number of occurrences of close to 1100 mutations resulting from 9 different mutagens or mutators at each site within a rolling 20-site interval. We can define 5 mutationally prone regions (MPRs). Aligning the profile of MPRs in tdk next to those we previously described in the thyA gene results in a linear map with 8 MPR regions, reinforcing the concept that certain sub-regions of genes are more mutable than others, even when other variables are accounted for. The catalog should prove useful for future studies.