ADP heptose, a novel pathogen-associated molecular pattern identified in Helicobacter pylori.

The gastric pathogen Helicobacter pylori activates the NF-κB pathway in human epithelial cells via the recently discovered α-kinase 1 TRAF-interacting protein with forkhead-associated domain (TIFA) axis. We and others showed that this pathway can be triggered by heptose 1,7-bisphosphate (HBP), an LPS intermediate produced in gram-negative bacteria that represents a new pathogen-associated molecular pattern (PAMP). Here, we report that our attempts to identify HBP in lysates of H. pylori revealed surprisingly low amounts, failing to explain NF-κB activation. Instead, we identified ADP-glycero-ß-D-manno-heptose (ADP heptose), a derivative of HBP, as the predominant PAMP in lysates of H. pylori and other gram-negative bacteria. ADP heptose exhibits significantly higher activity than HBP, and cells specifically sensed the presence of the ß-form, even when the compound was added extracellularly. The data lead us to conclude that ADP heptose not only constitutes the key PAMP responsible for H. pylori-induced NF-κB activation in epithelial cells, but it acts as a general gram-negative bacterial PAMP.-Pfannkuch, L., Hurwitz, R., Traulsen, J., Sigulla, J., Poeschke, M., Matzner, L., Kosma, P., Schmid, M., Meyer, T. F. ADP heptose, a novel pathogen-associated molecular pattern identified in Helicobacter pylori.

Chlamydia trachomatis Prevents Apoptosis Via Activation of PDPK1-MYC and Enhanced Mitochondrial Binding of Hexokinase II.

The intracellular human bacterial pathogen Chlamydia trachomatis pursues effective strategies to protect infected cells against death-inducing stimuli. Here, we show that Chlamydia trachomatis infection evokes 3-phosphoinositide-dependent protein kinase-1 (PDPK1) signaling to ensure the completion of its developmental cycle, further leading to the phosphorylation and stabilization of MYC. Using biochemical approaches and imaging we demonstrate that Chlamydia-induced PDPK1-MYC signaling induces host hexokinase II (HKII), which becomes enriched and translocated to the mitochondria. Strikingly, preventing the HKII interaction with mitochondria using exogenous peptides triggers apoptosis of infected cells as does inhibiting either PDPK1 or MYC, which also disrupts intracellular development of Chlamydia trachomatis. These findings identify a previously unknown pathway activated by Chlamydia infection, which exhibits pro-carcinogenic features. Targeting the PDPK1-MYC-HKII-axis may provide a strategy to overcome therapeutic resistance of infection.