Abstract
Background: The phagocytic oxidative burst is a primary effector of innate immunity that protects against bacterial infection. However, the mechanism by which reactive oxygen species (ROS) kill or inhibit bacteria is not known. It is often assumed that DNA is a primary target of oxidative damage, consistent with known effects of endogenously produced ROS in the bacterial cytoplasm. But most studies fail to distinguish between effects of host derived ROS versus damage caused by endogenous bacterial sources. We took advantage of both the ability of Salmonella enterica serovar Typhimurium to survive in macrophages and the genetic tractability of the system to test the hypothesis that phagocytic superoxide damages cytoplasmic targets including DNA. Methodology/Principal Findings: SodCI is a periplasmic Cu-Zn superoxide dismutase (SOD) that contributes to the survival of Salmonella Typhimurium in macrophages. Through competitive virulence assays, we asked if sodCI has a genetic interaction with various cytoplasmic systems. We found that SodCI acts independently of cytoplasmic SODs, SodA and SodB. In addition, SodCI acts independently of the base excision repair system and RuvAB, involved in DNA repair. Although sodCI did show genetic interaction with recA, this was apparently independent of recombination and is presumably due to the pleiotropic effects of a recA mutation. Conclusions/Significance: Taken together, these results suggest that bacterial inhibition by phagocytic superoxide is primarily the result of damage to an extracytoplasmic target.
| Original language | English (US) |
|---|---|
| Article number | e4975 |
| Journal | PloS one |
| Volume | 4 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 23 2009 |
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ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)
- General
Cite this
Phagocytic superoxide specifically damages an extracytoplasmic target to inhibit or kill Salmonella. / Craig, Maureen; Slauch, James M.
In: PloS one, Vol. 4, No. 3, e4975, 23.03.2009.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Phagocytic superoxide specifically damages an extracytoplasmic target to inhibit or kill Salmonella
AU - Craig, Maureen
AU - Slauch, James M.
PY - 2009/3/23
Y1 - 2009/3/23
N2 - Background: The phagocytic oxidative burst is a primary effector of innate immunity that protects against bacterial infection. However, the mechanism by which reactive oxygen species (ROS) kill or inhibit bacteria is not known. It is often assumed that DNA is a primary target of oxidative damage, consistent with known effects of endogenously produced ROS in the bacterial cytoplasm. But most studies fail to distinguish between effects of host derived ROS versus damage caused by endogenous bacterial sources. We took advantage of both the ability of Salmonella enterica serovar Typhimurium to survive in macrophages and the genetic tractability of the system to test the hypothesis that phagocytic superoxide damages cytoplasmic targets including DNA. Methodology/Principal Findings: SodCI is a periplasmic Cu-Zn superoxide dismutase (SOD) that contributes to the survival of Salmonella Typhimurium in macrophages. Through competitive virulence assays, we asked if sodCI has a genetic interaction with various cytoplasmic systems. We found that SodCI acts independently of cytoplasmic SODs, SodA and SodB. In addition, SodCI acts independently of the base excision repair system and RuvAB, involved in DNA repair. Although sodCI did show genetic interaction with recA, this was apparently independent of recombination and is presumably due to the pleiotropic effects of a recA mutation. Conclusions/Significance: Taken together, these results suggest that bacterial inhibition by phagocytic superoxide is primarily the result of damage to an extracytoplasmic target.
AB - Background: The phagocytic oxidative burst is a primary effector of innate immunity that protects against bacterial infection. However, the mechanism by which reactive oxygen species (ROS) kill or inhibit bacteria is not known. It is often assumed that DNA is a primary target of oxidative damage, consistent with known effects of endogenously produced ROS in the bacterial cytoplasm. But most studies fail to distinguish between effects of host derived ROS versus damage caused by endogenous bacterial sources. We took advantage of both the ability of Salmonella enterica serovar Typhimurium to survive in macrophages and the genetic tractability of the system to test the hypothesis that phagocytic superoxide damages cytoplasmic targets including DNA. Methodology/Principal Findings: SodCI is a periplasmic Cu-Zn superoxide dismutase (SOD) that contributes to the survival of Salmonella Typhimurium in macrophages. Through competitive virulence assays, we asked if sodCI has a genetic interaction with various cytoplasmic systems. We found that SodCI acts independently of cytoplasmic SODs, SodA and SodB. In addition, SodCI acts independently of the base excision repair system and RuvAB, involved in DNA repair. Although sodCI did show genetic interaction with recA, this was apparently independent of recombination and is presumably due to the pleiotropic effects of a recA mutation. Conclusions/Significance: Taken together, these results suggest that bacterial inhibition by phagocytic superoxide is primarily the result of damage to an extracytoplasmic target.
UR - http://www.scopus.com/inward/record.url?scp=63349084165&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=63349084165&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0004975
DO - 10.1371/journal.pone.0004975
M3 - Article
C2 - 19305502
AN - SCOPUS:63349084165
VL - 4
JO - PLoS One
JF - PLoS One
SN - 1932-6203
IS - 3
M1 - e4975
ER -