One Knight to Rule Them All: The Role of Rho as a Termination Factor

Source: Cardinale et al (2008). Termination Factor Rho and Its Cofactors NusA and NusG Silence Foreign DNA in E. coli. Science 320: 935-938.

In E. coli, the termination of transcription is achieved through either the formation of stem-loops in the nascent mRNA or the activity of an RNA-DNA helicase known as Rho. In this paper, the authors reveal the global role of this protein as a regulator of transcription in a genome-wide scale. The antibiotic Bicyclomycin (BCM), a potent inhibitor of Rho, is employed to knock-down the activity of this protein (rho is an essential gene) followed by gene-expression microarrays to assess the mRNA content of the cell.

The most prominent observation, in the absence of Rho, is the significant up-regulation of horizontally transfered genes along with prophages in the genome. 2D protein gels, however, show a limited deregulation in the protein content where the differences are limited to an upregulation of anaerobic genes and a number of acid response genes (e.g. cadA).

Deleting the dormant prophages in the genome (e.g. rac) drastically increases the resistance to BCM, emphasizing the role of Rho in suppressing these invasive foreign DNA fragments.

Apart from its exciting results, I like this paper for another reason. Have you ever read a paper and said, "damn it, I had this idea...". In this case, apart from the ideas, I even had the necessary strains and a batch of BCM and I was ready to do this experiment. However, a discussion with my adviser suggested that this was too much off the path from my own project.... and a year later... here it is... published in SCIENCE :)