Comparative Transcriptional Analysis of Clinically Relevant Heat Stress Response in Clostridium difficile Strain 630

Abstract

Clostridium difficile is considered to be one of the most important causes of health care-associated infections worldwide. In order to understand more fully the adaptive response of the organism to stressful conditions, we examined transcriptional changes resulting from a clinically relevant heat stress (41°C versus 37°C) in C. difficile strain 630 and identified 341 differentially expressed genes encompassing multiple cellular functional categories. While the transcriptome was relatively resilient to the applied heat stress, we noted upregulation of classical heat shock genes including the groEL and dnaK operons in addition to other stress-responsive genes. Interestingly, the flagellin gene (fliC) was downregulated, yet genes encoding the cell-wall associated flagellar components were upregulated suggesting that while motility may be reduced, adherence – to mucus or epithelial cells – could be enhanced during infection. We also observed that a number of phage associated genes were downregulated, as were genes associated with the conjugative transposon Tn5397 including a group II intron, thus highlighting a potential decrease in retromobility during heat stress. These data suggest that maintenance of lysogeny and genome wide stabilisation of mobile elements could be a global response to heat stress in this pathogen.

Short-Term Exposure of Paddy Soil Microbial Communities to Salt Stress Triggers Different Transcriptional Responses of Key Taxonomic Groups

“…Previous studies have shown that in Clostridium difficile strain 630, the flagellin gene ( fliC ) will be down-regulated in response to heat shock (Ternan et al, 2012). Contrary to this finding, salt stress triggered a significant increase in the clostridial transcript abundance related to flagellar synthesis (3.4 log 2 fold) and motility (4.8 log 2 fold) at 600 mM NaCl ( Table 1 ).…”

Pleiotropic Role of the RNA Chaperone Protein Hfq in the Human Pathogen Clostridium difficile

“…Hfq inactivation is frequently associated with increased sensitivity to various stresses in bacteria (14,17). In C. difficile, the global response to several environmental (temperature, pH, and oxygen) and antibiotic stresses that bacteria could encounter in the gut has been recently studied by a transcriptome approach (63,64,82). Interestingly, several genes encoding cell wall proteins and membrane transporters or having involvement in various metabolic pathways that are differentially expressed in the Hfq-depleted strain are induced by acid, alkali pH, heat shock, and the presence of subinhibitory concentrations of amoxicillin or clindamycin antibiotic (63) (see Table S4 in the supplemental material).…”

“…This included several genes probably in- During host infection, C. difficile is exposed to several stresses and responds to stress stimuli by inducing different mechanisms of defense (62). Among stress-related genes, we observed about 2-fold upregulation of genes encoding heat shock proteins, including groEL (CD0194) and grpE (CD2462) that are induced by clinically relevant heat stress and acid pH conditions in C. difficile (63,64) and by metabolic stresses in Clostridium acetobutylicum (65). Moreover, the expression of several genes that might be involved in the oxygen tolerance response and cell redox balance was altered in the CDIP53 strain compared to the CDIP51 strain.…”

Semiquantitative Analysis of Clinical Heat Stress in Clostridium difficile Strain 630 Using a GeLC/MS Workflow with emPAI Quantitation

“…In support of this, CD3068 was down regulated some 1.9-fold by microarray, as indeed was CD3069, the IId component at 2.2-fold down [42]. In the combined proteome, the EI component (CD2755), common to, and essential for all phosphotransferase systems in the cell, was down regulated by 3.9 fold, although transcripts were reduced by only 1.46 fold [42].…”

“…Interestingly, the CD2532 transcript does not change significantly under heat stress as revealed by both microarray and qRT-PCR analysis [42]. CD2531 and CD2532 are predicted to generate a bicistronic messenger and indeed the transcript for CD2531 was also unchanged [42].…”