TY - JOUR
T1 - An Incomplete TCA Cycle Increases Survival of Salmonella Typhimurium during Infection of Resting and Activated Murine Macrophages
AU - Bowden, Steven D.
AU - Ramachandran, Vinoy K.
AU - Knudsen, Gitte Maegaard
AU - Hinton, Jay C. D.
AU - Thompson, Arthur
PY - 2010
Y1 - 2010
N2 - Background: In comparison to the comprehensive analyses performed on virulence gene expression, regulation and action,
the intracellular metabolism of Salmonella during infection is a relatively under-studied area. We investigated the role of the
tricarboxylic acid (TCA) cycle in the intracellular replication of Salmonella Typhimurium in resting and activated
macrophages, epithelial cells, and during infection of mice.
Methodology/Principal Findings: We constructed deletion mutations of 5 TCA cycle genes in S. Typhimurium including
gltA, mdh, sdhCDAB, sucAB, and sucCD. We found that the mutants exhibited increased net intracellular replication in resting
and activated murine macrophages compared to the wild-type. In contrast, an epithelial cell infection model showed that
the S. Typhimurium DsucCD and DgltA strains had reduced net intracellular replication compared to the wild-type. The
glyoxylate shunt was not responsible for the net increased replication of the TCA cycle mutants within resting macrophages.
We also confirmed that, in a murine infection model, the S. Typhimurium DsucAB and DsucCD strains are attenuated for
virulence.
Conclusions/Significance: Our results suggest that disruption of the TCA cycle increases the ability of S. Typhimurium to
survive within resting and activated murine macrophages. In contrast, epithelial cells are non-phagocytic cells and unlike
macrophages cannot mount an oxidative and nitrosative defence response against pathogens; our results show that in
HeLa cells the S. Typhimurium TCA cycle mutant strains show reduced or no change in intracellular levels compared to the
wild-type [1]. The attenuation of the S. Typhimurium DsucAB and DsucCD mutants in mice, compared to their increased net
intracellular replication in resting and activated macrophages suggest that Salmonella may encounter environments within
the host where a complete TCA cycle is advantageous.
AB - Background: In comparison to the comprehensive analyses performed on virulence gene expression, regulation and action,
the intracellular metabolism of Salmonella during infection is a relatively under-studied area. We investigated the role of the
tricarboxylic acid (TCA) cycle in the intracellular replication of Salmonella Typhimurium in resting and activated
macrophages, epithelial cells, and during infection of mice.
Methodology/Principal Findings: We constructed deletion mutations of 5 TCA cycle genes in S. Typhimurium including
gltA, mdh, sdhCDAB, sucAB, and sucCD. We found that the mutants exhibited increased net intracellular replication in resting
and activated murine macrophages compared to the wild-type. In contrast, an epithelial cell infection model showed that
the S. Typhimurium DsucCD and DgltA strains had reduced net intracellular replication compared to the wild-type. The
glyoxylate shunt was not responsible for the net increased replication of the TCA cycle mutants within resting macrophages.
We also confirmed that, in a murine infection model, the S. Typhimurium DsucAB and DsucCD strains are attenuated for
virulence.
Conclusions/Significance: Our results suggest that disruption of the TCA cycle increases the ability of S. Typhimurium to
survive within resting and activated murine macrophages. In contrast, epithelial cells are non-phagocytic cells and unlike
macrophages cannot mount an oxidative and nitrosative defence response against pathogens; our results show that in
HeLa cells the S. Typhimurium TCA cycle mutant strains show reduced or no change in intracellular levels compared to the
wild-type [1]. The attenuation of the S. Typhimurium DsucAB and DsucCD mutants in mice, compared to their increased net
intracellular replication in resting and activated macrophages suggest that Salmonella may encounter environments within
the host where a complete TCA cycle is advantageous.
U2 - 10.1371/journal.pone.0013871
DO - 10.1371/journal.pone.0013871
M3 - Journal article
SN - 1932-6203
VL - 5
SP - e13871
JO - P L o S One
JF - P L o S One
IS - 11
ER -