Engineering Escherichia coli heat-resistance by synthetic gene amplification

Organisms have evolved to exploit new environments by processes that involve both mutations and gene amplifications. Though in some cases amplified genes mutate to perform a different molecular function, in other cases altering gene copy number alone is sufficient to change organism function. Here we selected a library of genes, provided at high copy number, for their ability to confer survival on Escherichia coli cells at un-physiologically high temperatures. We find that a single gene (evgA), encoding a master transcriptional regulator, is overwhelmingly selected and allows survival upon heating to temperatures in excess of 50 degrees C. While the detailed mechanisms of this resistance remained unclear, our results demonstrate the potential of copy number manipulation for the engineering of organisms.