Scrambling E.coli

On a more scientific and interesting note, a new paper in Nature reports on what happens to E.coli if you mess with its regulatory network in a big way. Not only is the paper interesting, but fellow blogger Pedro Beltrao is one of the authors.

The paper takes various promoters and various transcriptional regulators and reassorts which are attached to which. Nearly 600 such combinations were constructed in wild-type E.coli, meaning that the same regulator was also present in its normal regulatory context. The regulators tested also had GFP downstream, so fluorescence could be used to get a rough guide to the level of transcription in the construct.

It is perhaps surprising that most such rewirings are viable; only a few couldn't be built. But, all sorts of perturbations in growth patterns were observed. Some were even more fit than wild type.

Bacteria generally appear to be genetic carpet sweepers, taking in all sorts of genes & trying them out. While most of those genes will be structural, some will be regulators which may bind to existing regulatory motifs (or random motifs in promoters) and activate those genes. Perhaps it is not surprising that E.coli can tolerate many rewirings, as such rewirings must frequently occur naturally -- and activators are often located near the potentially useful genes they activate. If you get the good stuff, you are likely to import an activator, so its useful to be able to adjust to it.