Quantitative Genetic Screens for Mapping Bacterial Pathways and Functional Networks.

Escherichia coli synthetic genetic array (eSGA) screening procedure enables high-throughput systematic mapping of pairwise genetic interactions in E. coli. The eSGA method exploits E. coli's rapid growth, its ease of genetic manipulation, and efficient genetic exchange via conjugation. Replica pinning is used to grow and mate arrayed sets of single gene mutant strains as well as to select double mutants en masse. Strain fitness, which is the eSGA readout, is determined by the digital imaging of the plates and subsequent colony size measurements. Comparing single and double mutant colony sizes then allows for identifying interacting genes. Using eSGA on a global or a smaller process-centric scale can help reveal gene functions and reconstruct genetic interaction networks with known and novel connections between genes and pathways.