Comparison of the expression profiles of 630E strain and a hfQ mutant after 7.5h of growth in Tyt

Clostridium difficile is an emergent human pathogen and the most common cause of nosocomial diarrhea. Our recent deep-sequencing data strongly suggest the importance of RNA-based mechanisms for the control of gene expression in C. difficile. The RNA chaperon protein Hfq is a key component of post-transcriptional regulatory network in various bacterial systems. In an effort to understand the function of Hfq in C. difficile, we have constructed and characterized an Hfq-depleted strain in this bacterium. We present evidence that Hfq is necessary for the normal cell growth, for the establishment of bacillary form and might be involved in metabolic adaptations, stress response and sporulation, important during C. difficile infection cycle. In accordance to these phenotypic changes, our transcriptome analysis revealed pleiotropic effects of Hfq on gene expression in C. difficile. This microarray analysis showed altered expression of genes encoding cell wall and membrane transport components, sporulation proteins, as well as stress response, transcriptional regulator genes and genes of unknown function. Remarkably, a great number of genes belonging to the regulon dependent on sporulation-specific sigma K factor were generally up-regulated in the strain depleted for Hfq. Many important metabolic pathways were also affected by Hfq depletion. Finally, the altered accumulation of several previously identified sRNAs suggests potential involvement of Hfq in these regulatory RNA function. Altogether, these results provide evidence for the pleiotropic role of Hfq protein in C. difficile physiology expanding our knowledge of Hfq-dependent regulation in Gram-positive bacteria. Two-conditions experiments, 630E strain vs. hfQ mutant grown in TYt, 4 biological replicates for each condition.