White arrows indicate colocalization of cluster proteins to vesicular structures positive for PdtIns(3), pink arrows indicate cluster proteins on vesicular structures showing no colocalization. respiratory tract, such as pneumonia, asthma, and bronchitis (Hahn NVP-BGJ398 phosphate et al., 1991). All are obligate intracellular parasites with a unique biphasic life cycle consisting of the alternation of two morphological forms: the infectious elementary body (EB), and the metabolically active, non-infectious reticulate body (RB) which replicates in the host cell (Chi et al., 1987; Miyashita et al., 1993; Wolf et al., 2000). Adhesion of EBs to their target cells is the first essential step in the infection process. This is followed by internalization of EBs into a membrane-bound compartment, termed the inclusion, in which EBs develop into replicative RBs. Initial contact between the EB and the host cell is usually mediated by binding of NVP-BGJ398 phosphate conserved adhesins to numerous host cell structures. Of these, OmcB binds to heparan-sulfate-like proteoglycans (GAG), while LipP (CPn0473) binds to phospholipids in the host membrane, and Pmp21 interacts with the epidermal growth factor receptor (EGFR), providing as both an adhesin and an invasin (Moelleken and Hegemann, 2008; M?lleken et al., 2013; Fechtner et al., 2016). This last conversation promotes internalization of the EB by activating the EGFR, and the developing inclusion at first remains associated with the activated receptor (M?lleken et al., 2013). Supported is the adhesin-receptor mediated internalization by type III (T3) secreted effector proteins. CPn0572 (TarP ortholog) binds actin and enhances actin polymerization at the access site (Clifton et al., 2004; Jewett et al., 2010; Zrieq et al., 2017) while the most recently discovered SemC (CPn0678), binds and deforms the host plasma membrane (PM). SemC recruits the endocytic scaffold protein SNX9 to facilitate uptake of the EB into the cell (Hansch et al., 2020). During endocytosis of EGFR the internalized receptor is generally delivered to the early or sorting endosomal compartment, so that it is usually either recycled back to the PM or delivered to the lysosome for degradation, respectively (Madshus and Stang, 2009). However, disrupts these pathways to avoid both EGFR-triggered degradation and immediate recycling to the PM. Recently, we have shown that within an hour of initial EGFR-mediated adhesion, the nascent inclusion specifically acquires an early endosomal identity with a PtdIns(3)P-positive membrane (Molleken and Hegemann, 2017). Furthermore, several TRKA endosomal Rab GTPases are recruited to the early inclusion immediately after internalization. These include Rab4 and Rab11, both of which regulate fast and slow recycling (Lindsay et al., 2002; Campa et al., 2018), the late endosomal Rab7 (Stroupe, 2018), and Rab14, which is usually involved in the biosynthetic/recycling pathway between the Golgi and endosomal compartments (Junutula et al., 2004). While Rab11 and Rab14 remain associated with the inclusion membrane, Rab4 and Rab7 disappear 30 minutes after internalization (Molleken and Hegemann, 2017). Taken together, these findings suggest that actively regulates the membrane identity of the nascent inclusion by acquiring a specific lipid composition, and by avoiding degradation through the lysosomal pathway. This requires conversation of secreted bacterial virulence factors, so-called effector proteins, which either alter membrane lipid composition or recruit or displace Rab proteins or their modulating effectors. This is a conserved trait of intracellular pathogens that subvert host defense mechanisms and engage host organelles to establish their unique intracellular niches (Stein et al., 2012; Spano and Galan, NVP-BGJ398 phosphate 2018). Thus far many of those bacterial effectors share the common ability to interact with membrane structures of the host, by transporting membrane-binding domains (Weigele et al., 2017). Other effectors directly target host Rab GTPases in order to manipulate vesicular trafficking (Stein et al., 2012). In this statement, we analyzed the function of the newly recognized gene cluster Gene Cluster Is usually Specific for GiD isolate (Jantos et al., 1997; Weinmaier et al., 2015) against the human genome, and sequences of effector proteins from numerous obligate intracellular bacterial pathogens. In this screen, the hypothetical protein GiD_A_04840 was recognized, based on its 27.9% overall identity to the human GTPase Rab36, which is known.