Intellectual Merit: DNA mismatch repair recognizes and repairs DNA polymerase errors that are incorporated during genome replication. The vast majority of research efforts on bacterial mismatch repair have been devoted to the study of the pathway in the Gram-negative bacterium Escherichia coli. E. coli uses a DNA methylation-dependent repair pathway to detect the newly synthesized DNA strand, which is rare and mostly restricted to E. coli and its close relatives. Recent evidence suggests that a more universal mechanism of mismatch repair operates in most bacteria and all eukaryotic systems. The mismatch repair pathway in the Gram-positive bacterium Bacillus subtilis is methylation-independent and shows a high level of conservation with the mismatch repair pathway present in most other systems, including the hallmark requirement of methylation-independent repair, an endonuclease-containing protein, MutL. The similarity of its mismatch repair system to those of eukaryotes and most other bacteria, together with its numerous genetic, cell biological, and biochemical tools, makes B. subtilis an ideal platform for understanding universal mechanisms of mismatch repair that are conserved throughout biology. This research investigates the mechanisms that couple mismatch repair to the DNA replication machinery in B. subtilis. Recently, the PI's laboratory found that mismatch repair proteins MutS and MutL directly bind the DNA replication machinery, suggesting that specific contacts between mismatch repair proteins and the DNA replication machinery are critical for several steps in repair. This project will characterize the mechanisms that coordinate mismatch repair with the DNA replication complex, leading to an understanding of conserved steps required for the identification and repair of mismatches in organisms that lack a methylation-directed repair system. Furthermore, this research project will impact and advance information in the fields of DNA repair, DNA replication and mutagenesis. Broader Impacts: This project will impact education at the university and in the community. First, an upper level course for undergraduates evaluating the primary literature will be taught along with an opportunity to learn how hands-on state-of-the-art research is conducted in the PI's laboratory. This experience will foster a unique and effective learning environment that will advance science and fully engage students in learning. Second, in modern science there is a critical need for graduate and undergraduate students to study an intact system as opposed to components in isolation. An integral part of this project is to train graduate and undergraduate students in a scientific approach that takes into account how multiple cellular components function together. Furthermore, graduate and undergraduate students will be involved in all aspects of the interdisciplinary research program. Third, the PI and members of the PI's laboratory will participate in community outreach, which will include visiting local high schools and middle schools, and hosting students in the lab to teach them cutting-edge microbial sciences including live cell imaging techniques.
