TABLE 1.
Secreted pathogen effectors that localize to the ER or modulate its function
| Pathogen(secretion system) | Effector | Activity | Reference(s) |
|---|---|---|---|
| Brucella abortus(VirB T4ASS) | BspB | Impairs ER-to-Golgi secretory trafficking; interacts with the COG complex in the Golgi and redirects membrane vesicles from the Golgi to Brucella vacuole | 91 |
| VceC | Localizes to ER (ectopic expression); induces ER stress; interacts with BiP/GRP70 | 32–34 | |
| BtpA (TcpB/Btp1) | Induces ER stress; binds microtubules; inhibits TLR signaling | 75–78 | |
| BspA | Unknown; localizes to ER on ectopic expression | 35 | |
| BspD | Unknown; localizes to ER on ectopic expression | 35 | |
| BspK | Unknown; localizes to ER on ectopic expression | 35 | |
| Legionella pneumophila(Dot/Icm T4BSS) | Lgt1 | Inhibits the IRE1 pathway of the UPR; inhibits translation elongation by glucosylation of eukaryotic elongation factor 1A | 82–84 |
| Lgt2 | Inhibits the IRE1 pathway of the UPR; inhibits translation elongation by glucosylation of eukaryotic elongation factor 1A | 82, 84, 92 | |
| SidE | Localizes to the cytoplasmic face of the LCV; regulates ER tubule rearrangement and recruitment of ER markers to the LCV via modulating ubiquitination | 64, 93–95 | |
| SidC | Ubiquitin ligase and PI4P binding activity; promotes the association of LCVs with the ER by recruiting ER vesicles | 66, 68, 96 | |
| SdeA, -B, -C | Promote ER reorganization by progressive ADP-ribosylation of ubiquitin and transfer of phosphoribosyl moiety to Rtn4 | 64, 94, 95, 97 | |
| Ceg9 | Tethers the LCV to the ER via association with Rtn4 | 61 | |
| SidM/DrrA | Recruits Rab1 to LCV; acts as a GEF to recruit vacuoles to the LCV and as a GDF for Rab1; AMPylates Rab1 | 39, 41, 42, 47, 50, 98–100 | |
| LidA | Interacts with GTP-Rab1 to maintain it in the active conformation | 43, 45, 101 | |
| SidD | Catalyzes AMP release from Rab1 | 47 | |
| AnkX | Transfers phosphocholine to Rab1 | 50 | |
| RalF | Acts as a GEF to activate ARF | 37 | |
| Lem3 | Reverses activity of AnkX by removing phosphocholine from Rab1 | 52 | |
| SetA | Glycosylates Rab1 | 102, 103 | |
| LepB | Inactivates Rab1 via RabGAP activity; manipulates phosphoinositide composition of the Legionella-containing vacuole via phosphatidylinositide 4-kinase activity | 48, 104, 105 | |
| Lpg1137 | Cleaves syntaxin 17 at the mitochondrion-associated ER membrane and blocks autophagy | 106 | |
| RavZ | Delipidates Atg8 (LC3-II) at the phagophore to inhibit autophagosome formation | 70 | |
| LpSpl | Sphingosine-1-phosphate lyase disrupts host sphingolipid biosynthesis and inhibits autophagy during infection | 71 | |
| Chlamydia trachomatis(T3SS) | CT229 | C. pneumoniae homolog Cpn0585 recruits Rab1 from the ER to the inclusion membrane (effector that recruits Rab1 to C. trachomatis inclusion has yet to be identified) | 107 |
| IncD | Mediates contact with the ER at MCS via binding to ceramide transfer protein CERT | 54, 108 | |
| IncV | Tethers the C. trachomatis inclusion to the ER via interactions with VAPs | 55 | |
| MrcA | Interacts with the Ca2+ channel inositol-1,4,5-trisphosphate receptor, type 3, to promote release of bacteria from infected cells | 109 | |
| Coxiella burnetii(Dot/Icm T4BSS) | ElpA | Localizes to the ER on ectopic expression and blocks secretory traffic | 59 |
| Anaplasma spp.(VirB T4ASS) | Ats-1 | Nucleates autophagosomes by interacting with Beclin and recruitment of DFCP1 and ATG14L to the pathogen-containing vacuole | 5, 72 |
| Orientia tsutsugamushi(T1SS) | Ank4 | Interacts with eukaryotic chaperone Bat3 to transiently impede ER-associated protein degradation | 9 |
| Ank9 | Destabilizes the ER and Golgi by binding COPB2 and induces ATF4-dependent UPR | 27 | |
| Rickettsia rickettsii(Rvh T4ASS) | RARP-2 | Forms membranous structures in association with the ER; contributes to lysis of infected host cells. | 11 |