IncV, a FFAT motif-containing Chlamydia protein, tethers the endoplasmic reticulum to the pathogen-containing vacuole

Abstract

Membrane contact sites (MCS) are zones of contact between the membranes of two organelles. At MCS, specific proteins tether the organelles in close proximity and mediate the nonvesicular trafficking of lipids and ions between the two organelles. The endoplasmic reticulum (ER) integral membrane protein VAP is a common component of MCS involved in both tethering and lipid transfer by binding directly to proteins containing a FFAT [two phenylalanines (FF) in an acidic tract (AT)] motif. In addition to maintaining cell homeostasis, MCS formation recently emerged as a mechanism by which intracellular pathogens hijack cellular resources and establish their replication niche. Here, we investigated the mechanism by which the Chlamydia-containing vacuole, termed the inclusion, establishes direct contact with the ER. We show that the Chlamydia protein IncV, which is inserted into the inclusion membrane, displays one canonical and one noncanonical FFAT motif that cooperatively mediated the interaction of IncV with VAP. IncV overexpression was sufficient to bring the ER in close proximity of IncV-containing membranes. Although IncV deletion partially decreased VAP association with the inclusion, it did not suppress the formation of ER-inclusion MCS, suggesting the existence of redundant mechanisms in MCS formation. We propose a model in which IncV acts as one of the primary tethers that contribute to the formation of ER-inclusion MCS. Our results highlight a previously unidentified mechanism of bacterial pathogenesis and support the notion that cooperation of two FFAT motifs may be a common feature of VAP-mediated MCS formation. Chlamydiahost cell interaction therefore constitutes a unique system to decipher the molecular mechanisms underlying MCS formation.endoplasmic reticulum-Chlamydia inclusion membrane contact sites | IncV | FFAT motif | VAP proteins | tether

Infection of HeLa cells with Chlamydia trachomatis inhibits protein synthesis and causes multiple changes to host cell pathways

“…The ER is targeted by chlamydial infection, causing close apposition of the ER‐membrane to the inclusion membrane as well as the recruitment of ER‐proteins to the contact sites with the inclusion (Derre, ). Chlamydial proteins are further known that target the ER and appear to connect it to the chlamydial inclusion (Stanhope, Flora, Bayne, & Derre, ). The actin cytoskeleton is also known to respond to chlamydial infection (Wesolowski & Paumet, ).…”

“…Chlamydial proteins are further ATP5A1 AHCY ARPC2 G6PD PSMA6 RCC2 DDX21 PLS3 FLNA DDB1 SRP72 DHX15 PSMB2 TARS RPS6 FABP5 PSME2 RPL8 PABPC1 USP14 Infected and non-infected cells cluster into two according groups. The colour code indicates log 2 H/L ratios of protein intensities known that target the ER and appear to connect it to the chlamydial inclusion (Stanhope, Flora, Bayne, & Derre, 2017). The actin cytoskeleton is also known to respond to chlamydial infection (Wesolowski & Paumet, 2017).…”

Safe haven under constant attack-TheChlamydia-containing vacuole

“…Early Cca inclusion recognition is opposed by secretion of the bacterial deubiquitinase ChlaOTU membrane by their bilobed hydrophobic region (Bannantine et al, 2000). Until today, 62 putative Inc proteins have been predicted, but only for some the molecular role during Chlamydia infection has been revealed (Moore & Ouellette, 2014;Mirrashidi et al, 2015;Nguyen, Lutter, & Hackstadt, 2018;Stanhope, Flora, Bayne, & Derre, 2017;Zhao et al, 2017). Overall, Incs play a role in host-pathogen interaction, structural integrity of the inclusion, and inhibition of chlamydial recognition by host surveillance systems (Sixt et al, 2017;Weber et al, 2017).…”

“…CERT mediates the transfer of ceramide from the endoplasmic reticulum (ER) to the Golgi at ER-Golgi membrane contact sites (MCS), which is subsequently converted into SM by SM-synthases (Hanada, 2017;Hanada, Kumagai, Tomishige, & Yamaji, 2009). ER-inclusion MCS are formed (Derre, Swiss, & Agaisse, 2011), in part through IncV-VAP interaction (Stanhope et al, 2017). At ERinclusion MCS, IncD recruits CERT and CERT interact with VAP (Agaisse & Derre, 2014;Derre et al, 2011;Elwell et al, 2011).…”

Proximity-dependent proteomics of theChlamydia trachomatisinclusion membrane reveals functional interactions with endoplasmic reticulum exit sites

“…Inclusion maturation was marked by a significant expansion of protein networks related to the MTOC and centrosome, innate immune signaling, proteasome regulation, and clathrin assembly ( Fig 3B). Network analysis also allowed identification of host factors that may potentially interact with known host-Inc interactions, for example VAPA association with IncV [34] and the potential expanded interaction with S10AG and S10AE.…”