Detailed map of the Pseudomonas aeruginosa Crc regulon using a new parameter for tracking post-transcriptional regulation

Bacterial physiology in general and the bacterial response to the presence of nutrients and to external signals in particular is regulated at different levels, from mRNA synthesis to translational regulation and protein modification. However, there are not standardized parameters for defining post-transcriptional regulation. Herein, we propose a simple parameter, dubbed post-transcriptional variation (PTV), that allow extracting information on translational regulation from the combined analysis of transcriptomic and proteomic data. We have applied this parameter for precisely defining the regulon of the Pseudomonas aeruginosa post-transcriptional regulator Crc. P. aeruginosa is a free-living microorganism that, besides colonizing a diversity of environmental habitats, is able to infect a large number of patients at hospitals. Part of the ability of P. aeruginosa for colonizing such a variety of habitats relies on its capability of using a large number of carbon sources. This hierarchical assimilation is regulated by Crc, which together with Hfq, binds its target RNA impeding their translation when catabolite repression is triggered. Most studies cannot provide information on post-transcriptional regulation when analysed independently. Using the defined PTV parameter, we present a comprehensive map of the Crc post-transcriptional regulon.