An insight into the significance of the DnaK heat shock system in Staphylococcus aureus.

The bacterium Staphylococcus aureus utilizes a variety of different mechanisms to survive unfavorable stress conditions that are critical for its persistence in the environment and for pathogenicity. The staphylococcal DnaK heat shock system functions as a major protein folding machine under stress conditions that cause aggregation and un-folding of proteins. In prior studies, S. aureus cells with a non-functional DnaK system showed reduced tolerance to heat, oxidative and antibiotic stresses, a lowered carotenoid production, and decreased survival in a murine host. This study provides insights that the altered phenotypes of the dnaK mutant cells are not due to decreased SigB activity in the mutant cell. Transcriptomic profiling studies provide evidence that a large number of genes encoding proteins involved in cell wall biogenesis, virulence and general stress tolerance, and genes encoding proteins involved in metabolic processes are differentially regulated in dnaK mutant cells relative to wild-type S. aureus. It was also determined that loss of functional DnaK caused a reduction in the ability of S. aureus to make biofilms and its adherence to eukaryotic cells. This study provides evidence of a global significance of DnaK heat shock system in S. aureus.