Legionella pneumophilaIs Directly Sensitive to 2-Deoxyglucose-Phosphate via Its UhpC Transporter but Is Indifferent to Shifts in Host Cell Glycolytic Metabolism
ABSTRACTToll-like receptor (TLR) stimulation induces a pronounced shift to increased glycolytic metabolism in mammalian macrophages. We observed that bone marrow-derived macrophages (BMMs) increase glycolysis in response to infection withLegionella pneumophila, but the role of host macrophage glycolysis in terms of intracellularL. pneumophilareplication is not currently understood. Treatment with 2-deoxyglucose (2DG) blocksL. pneumophilareplication in mammalian macrophages but has no effect on bacteria grown in broth. In addition, we found that 2DG had no effect on bacteria grown in amoebae. We used a serial enrichment strategy to reveal that the effect of 2DG onL. pneumophilain macrophages requires theL. pneumophilahexose-phosphate transporter UhpC. Experiments with UhpC-deficientL. pneumophilarevealed that mutant bacteria are also resistant to growth inhibition following treatment with phosphorylated 2DG in broth, suggesting that the inhibitory effect of 2DG onL. pneumophilain mammalian cells requires 2DG phosphorylation. UhpC-deficientL. pneumophilareplicates without a growth defect in BMMs and protozoan host cells and also replicates without a growth defect in BMMs treated with 2DG. Our data indicate that neither TLR signaling-dependent increased macrophage glycolysis nor inhibition of macrophage glycolysis has a substantial effect on intracellularL. pneumophilareplication. These results are consistent with the view thatL. pneumophilacan employ diverse metabolic strategies to exploit its host cells.IMPORTANCEWe explored the relationship between macrophage glycolysis and replication of an intracellular bacterial pathogen,Legionella pneumophila. Previous studies demonstrated that a glycolysis inhibitor, 2-deoxyglucose (2DG), blocks replication ofL. pneumophiladuring infection of macrophages, leading to speculation thatL. pneumophilamay exploit macrophage glycolysis. We isolatedL. pneumophilamutants resistant to the inhibitory effect of 2DG in macrophages, identifying aL. pneumophilahexose-phosphate transporter, UhpC, that is required for bacterial sensitivity to 2DG during infection. Our results reveal how a bacterial transporter mediates the direct antimicrobial effect of a toxic metabolite. Moreover, our results indicate that neither induction nor impairment of host glycolysis inhibits intracellular replication ofL. pneumophila, which is consistent with a view ofL. pneumophilaas a metabolic generalist.