Inactivation of the dnaK gene in Clostridium difficile 630 Delta erm yields a temperature-sensitive phenotype and increases biofilm-forming ability

Shailesh Jain, Deborah Smyth, Barry O'Hagan, John Heap, Geoff McMullan, Nigel Minton, Nigel Ternan

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Clostridium difficile infection is a growing problem in healthcare settings worldwide and resultsin a considerable socioeconomic impact. New hypervirulent strains and acquisition of antibioticresistance exacerbates pathogenesis; however, the survival strategy of C. difficile in the challenginggut environment still remains incompletely understood. We previously reported that clinically relevant heat-stress (37–41 °C) resulted in a classical heat-stress response with up-regulation of cellular chaperones. We used ClosTron to construct an insertional mutation in the dnaK gene of C. difficile 630 Δerm. The dnaK mutant exhibited temperature sensitivity, grew more slowly than C. difficile 630 Δerm and was less thermotolerant. Furthermore, the mutant was non-motile, had 4-fold lower expression of the fliC gene and lacked flagella on the cell surface. Mutant cells were some 50% longer than parental strain cells, and at optimal growth temperatures, they exhibited a 4-fold increase in the expression of class I chaperone genes including GroEL and GroES. Increased chaperone expression, in addition to the non-flagellated phenotype of the mutant, may account for the increased biofilm formation observed. Overall, the phenotype resulting from dnaK disruption is more akin to that observed in Escherichia coli dnaK mutants, rather than those in the Gram-positive model organism Bacillus subtilis.Clostridium difficile is recognised as the most common cause of infectious antibiotic-associated
Original languageEnglish
Article number17522
JournalScientific Reports
Early online date13 Dec 2017
Publication statusE-pub ahead of print - 13 Dec 2017



  • Clostridium difficile gut pathogen ClosTron
  • chaperone gene dnaK

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