Journal of Bacteriology, December 1998, p. 6082-6089, Vol. 180, No. 23
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
B Controls the Environmental Stress
Response but Not Starvation Survival or Pathogenicity in a
Mouse Abscess Model
Department of Molecular Biology and
Biotechnology,
Received 13 July 1998/Accepted 18 September 1998
The role of
B, an alternative sigma factor of
Staphylococcus aureus, has been characterized in response
to environmental stress, starvation-survival and recovery, and
pathogenicity.
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,
B was shown to be involved in
recovery from heat shock at 54°C and in acid and hydrogen peroxide
resistance but not in resistance to ethanol or osmotic shock.
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,
B was not vital for the
starvation-survival or recovery mechanisms.
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,
B expression is
linked to the processes controlling virulence determinant production.
The role of
B as a major regulator of the stress
response, but not of starvation-survival, is discussed.
*
Corresponding author. Mailing address: Department of
Molecular Biology and Biotechnology, University of Sheffield, Firth
Court, Western Bank, Sheffield, S10 2TN, United Kingdom. Phone:
44-114-2224411. Fax: 44-114-2728697. E-mail:
s.foster{at}sheffield.ac.uk.
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