Analysis of the binding of p53 to DNAs containing mismatched and bulged bases

The tumor suppressor protein p53 modulates cellular response to DNA damage by a variety of mechanisms that may include direct recognition of some form s of primacy DNA damage. Linear 49-base pair duplex DNAs were constructed c ontaining all possible single-base mismatches as well as a S-cytosine bulge . Filter binding and gel retardation assays revealed that the affinity of p 53 for a number of these lesions was equal to or greater than that of the h uman mismatch repair complex, hMSH2-hMSH6, under the same binding condition s. However, other mismatches including G/T, which is bound strongly by hMSH 2-hMSH6, were poorly recognized by p53. The general order of affinity of p5 3 was greatest for a 3-cytosine bulge followed by A/G and C/C mismatches, t hen C/T and G/T mismatches, and finally all the other mismatches.