Bacteria Fighting Back: How Pathogens Target and Subvert the Host Innate Immune System  L. Evan Reddick, Neal M. Alto  Molecular Cell  Volume 54, Issue 2, Pages 321-328 (April 2014) DOI: 10.1016/j.molcel.2014.03.010 Copyright © 2014 Elsevier Inc. Terms and Conditions

Figure 1 Bacterial Effectors that Target and Manipulate the Innate Immune and Inflammatory Pathways Upon LPS stimulation, the TLR4 dimer associates with MD2 and forms a complex with CD14 to signal through the cytoplasmic tails of TLR4. Stimulated TLR4 binds MyD88 and Mal (also TIRAP), which recruits IRAK1 and IRAK4, TRAF6, and TRICA1 to stimulate inflammatory cell-survival pathways (MAPK and NF-κB). Bacterial effector proteins inhibit this process in many different ways. MprF, from Staphylococcus aureus, repels cationic defensin peptides electrostatically. ClpX proteolytically degrades defensin molecules. The M1 protein binds and sequesters the AMP LL-37. YopK shields the type III translocon from being recognized by host intracellular sensors. Tir, while functioning to maintain intimate contact between A/E pathogens and host, also utilizes ITIM-like motifs to downregulate TLR signaling. OspF possesses phosphothreonine lyase activity, which potently downregulates the MAPK cascade through covalent modification. OspI prevents TRAF6 autopolyubiquitinylation in order to reduce NF-κB signaling. YopJ is an acetyl transferase that targets the MAPK pathway and also has activity against TAK1. LF cleaves the amino terminus of MAPKK1 and MAPKK2. AvrA inhibits the JNK pathway through acetyltransferase activity toward MAPKKs. IpaH9.8 targets the NEMO complex for proteasomal degradation. OspG binds to ubiquitylated E2 enzymes in order to prevent the eventual ubiquitinylation of IκBα. NleC is a protease that degrades the p65 subunit of NF-κB. NleE modifies TAB2 and TAB3 to regulate NF-κB signaling. Molecular Cell 2014 54, 321-328DOI: (10.1016/j.molcel.2014.03.010) Copyright © 2014 Elsevier Inc. Terms and Conditions

Figure 2 Bacterial Effectors that Inhibit the GSP to Suppress Innate Immune Secretory Mechanisms NleF binds to the transmembrane protein Tmp21 in order to prevent COPI docking and thereby disrupt retrograde traffic. IpaJ cleaves the N-terminal myristoyl tail from Arf1, thus removing it from the membrane and promoting Golgi destruction. NleA (EspI) prevent the uncoating of CopII vesicles, thus inhibiting their fusion during anterograde traffic. EspG disrupts the GSP through its Arf binding and Rab1GAP activities. VirA possesses Rab1GAP activity that acts to disrupt Golgi architecture. Molecular Cell 2014 54, 321-328DOI: (10.1016/j.molcel.2014.03.010) Copyright © 2014 Elsevier Inc. Terms and Conditions