Tetracycline-mediated inhibition of de novo bacterial protein synthesis promotes the loss of ubiquitinated proteins from the AVM. This effect is reversible, as removal of tetracycline restores AVM ubiquitination to pretreatment levels. These results demonstrate a novel mechanism

by which A. phagocytophilum remodels the composition of its host cell-derived vacuolar membrane and present the first example of a Rickettsiales pathogen co-opting ubiquitin during intracellular residence. Anaplasma JNK inhibitor concentration phagocytophilum is a tick-transmitted obligate intracellular bacterium that infects neutrophils to cause the emerging and acute febrile infection, human granulocytic anaplasmosis (HGA) (Chen et al., 1994; Rikihisa, 2011). In nature, A. phagocytophilum is maintained in an enzootic cycle between its tick vector and mammalian hosts. Humans are accidental hosts. HGA clinical manifestations range in severity from asymptomatic to severe disease and death. Although often self-limiting, severe complications such as prolonged fever, shock, leucopenia, thrombocytopenia, high levels of C-reactive protein

and hepatic transaminases, pneumonitis, acute renal failure, and hemorrhages can result. Doxycycline is the drug of choice for treating HGA (Thomas et al., 2009). Following entry, A. phagocytophilum facilitates survival by replicating exclusively within a host cell-derived vacuole that exhibits altered Talazoparib fusogenicity. The A. phagocytophilum-occupied selleck screening library vacuole (ApV) does not mature along the endosomal pathway, does not acidify, avoids lysosomal fusion, and prevents bacterial exposure to reactive oxygen species by avoiding fusion with secretory vesicles and specific granules harboring

NADPH oxidase (Webster et al., 1998; Gokce et al., 1999; Mott et al., 1999; Carlyon et al., 2004; IJdo & Mueller, 2004; Huang et al., 2010a). The ApV is not an inert compartment that is completely sequestered from interfacing with its host cell. Rather, it co-opts membrane traffic, host cell molecules, and cellular processes to camouflage itself and obtain requisite nutrients. For example, the ApV selectively recruits recycling endosome-associated Rab GTPases while excluding Rabs that would otherwise direct A. phagocytophilum to the lysosome (Huang et al., 2010a, b, c). Also, the ApV membrane (AVM) has been shown to accumulate early autophagosomal markers, caveolae markers, and cholesterol, each of which is important for bacterial survival, as well as multiple signaling molecules (Lin & Rikihisa, 2003a, b; Niu et al., 2008). These phenomena serve as harbingers that the A. phagocytophilum likely hijacks additional host cell molecules as part of its intracellular survival strategy. Post-translational modification by ubiquitin is a highly conserved eukaryotic cell-specific process. Ubiquitin is a 76 amino acid protein that is covalently attached to lysine residues of target proteins.