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Spotlights on Recent JACS Publications.

The deliberate instillation of mutations across the genome landscape is now a standard approach for investigating evolution, in order to gain insight into human health and development and the causes of diseases. However, current global mutagenesis methods can be limited by the introduction of off-target mutations, which may adversely affect gene library size and characteristics. Tackling this limitation, Matthew D. Shoulders and co-workers report the creation of a targeted mutagenesis agent, called MutaT7, that channels mutations to precise regions of DNA (DOI: 10.1021/jacs.8b04001). MutaT7 is a fusion of cytidine deaminase, a DNA-damaging enzyme, and T7 RNA polymerase, an enzyme that binds with high specificity to T7 promoter regions in DNA and traverses downstream regions with high specificity. The researchers show that insertion of T7 terminator regions confines mutagenesis to regions upstream of the terminator sequence. Use of MutaT7 also results in larger library sizes than those induced by global mutagens, likely due to the ability of MutaT7 to maximize ontarget mutations while minimizing off-target, potentially toxic mutations. The authors suggest that this innovative mutagenesis strategy will be a valuable tool for genomic exploration, and its application could be expanded by incorporating other DNAaltering agents. Eva J. Gordon, Ph.D.