Methyl-directed DNA mismatch repair in Escherichia coli.

Some of the molecular aspects of methyl-directed mismatch repair in E. coli have been characterized. These include: mismatch recognition by mutS protein in which different mispairs are bound with different affinities; the direct involvement of d(GATC) sites; and strand scission by mutH protein at d(GATC) sequences with strand selection based on methylation of the DNA at those sites. In addition, communication over a distance between a mismatch and d(GATC) sites has been implicated. Analysis of mismatch correction in a defined system (Lahue et al., unpublished) should provide a direct means to further molecular aspects of this process.