The Staphylococcus aureus alternative sigma factor σB controls the environmental stress response but not starvation survival or pathogenicity in a mouse abscess model

  • 1 December 1998
    • journal article
    • research article
    • Vol. 180  (23) , 6082-6089
Abstract
The role of sigma(B), an alternative sigma factor of Staphylococcus aureus, has been characterized in response to environmental stress, starvation-survival and recovery, and pathogenicity. sigma(B) was mainly expressed during the stationary phase of growth and was repressed by 1 M sodium chloride. A sigB insertionally inactivated mutant was created, In stress resistance studies, sigma(B) was shown to he involved in recovery from heat shock at 54 degrees C and in acid and hydrogen peroxide resistance but not in resistance to ethanol or osmotic shuck. Interestingly, S. aureus acquired increased acid resistance when preincubated at a sublethal pH 4 prior to exposure to a lethal pH 2. This acid-adaptive response resulting in tolerance was mediated via sigB. However, sigma(B) was not vital for the starvation-survival or recovery mechanisms, sigma(B) does not have a major role in the expression of the global regulator of virulence determinant biosynthesis, staphylococcal accessory regulator (sarA), the production of a number of representative virulence factors, and pathogenicity in a mouse subcutaneous abscess model. However, SarA upregulates sigB expression in a growth-phase-dependent manner. Thus, sigma(B) expression is linked to the processes controlling virulence determinant production. The role of sigma(B) as a major regulator of the stress response, but not of starvation-survival, is discussed.