dna Archives - Gen9 Genetics

Horizontally transferred genetic elements, such as viruses and conjugative plasmids, move DNA between organisms, increasing genetic diversity but destabilizing engineered biological systems. Here, we use a genomically recoded Escherichia coli strain lacking UAG stop codons and recognition protein release factor 1 to study how an alternative genetic code influences the spread of horizontally transferred genetic elements. The alternative genetic code conferred resistance to multiple viruses (λ, M13, P1, MS2) at titers up to 1011 PFU / ml and altered conjugative plasmids (F and RK2) up to 105-fold. By recoding UAG codons to UAA in viruses and plasmids, we restore viral infectivity and conjugative function. The spread of viruses in a mixed community of cells with standard and alternative genetic codes reduced the viral titer, and over time, the viruses adapted to the alternative genetic code. This work demonstrates that the alteration of the genetic code greatly obstructs the propagation of horizontally transferred genetic elements and supports the use of genomic recoding as a strategy to stabilize engineered biological systems.