Functional genomics reveals that Clostridium difficile Spo0A coordinates sporulation, virulence and metabolism

Background

Clostridium difficile is an anaerobic, Gram-positive bacterium that can reside as a commensal within the intestinal microbiota of healthy individuals or cause life-threatening antibiotic-associated diarrhea in immunocompromised hosts. C. difficile can also form highly resistant spores that are excreted facilitating host-to-host transmission. The C. difficile spo0A gene encodes a highly conserved transcriptional regulator of sporulation that is required for relapsing disease and transmission in mice.

Results

Here we describe a genome-wide approach using a combined transcriptomic and proteomic analysis to identify Spo0A regulated genes. Our results validate Spo0A as a positive regulator of putative and novel sporulation genes as well as components of the mature spore proteome. We also show that Spo0A regulates a number of virulence-associated factors such as flagella and metabolic pathways including glucose fermentation leading to butyrate production.

Conclusions

The C. difficile spo0A gene is a global transcriptional regulator that controls diverse sporulation, virulence and metabolic phenotypes coordinating pathogen adaptation to a wide range of host interactions. Additionally, the rich breadth of functional data allowed us to significantly update the annotation of the C. difficile 630 reference genome which will facilitate basic and applied research on this emerging pathogen.

Supplemental Material

Identification of differentially expressed genes in C. difficile 630∆erm spo0A mutant by transcriptional profiling. Scatter plot of the log2 fold changes against the normalised mean read abundance per gene (calculated at the base level). Red dots represent genes considered to be significantly differentially expressed (P = ≤ 0.01). Black dots signify genes not deemed to be significantly differentially expressed according to these criteria.

Table summarizing genes differentially expressed in a C. difficile spo0A mutant relative to the parental strain based on transcriptomics and proteomics. Datasets are presented in the context of the entire updated reference genome annotation for C. difficile 630.

Table summarizing gene regulation genes that are controlled by C. difficile Spo0A.