Table 1. Pseudomonas aeruginosa T6SS toxins and effectors.
| Effector | Cognate toxin immunity | Description | References | |
|---|---|---|---|---|
| H1-T6SS | Tse1 (PA1844) | Tsi1 (PA1845) | Amidase that hydrolyses peptidoglycan crosslinks causing target cell lysis | [55,56] |
| Tse2 (PA2702) | Tsi2 (PA2703) | NAD dependent ADP-ribosyltransferase that causes quiescence, toxic when expressed in eukaryotic cells | [55,57,58] | |
| Tse3 (PA3484) | Tsi3 (PA3485) | Muramidase that hydrolyses peptidoglycan backbone causing target cell lysis | [55,56] | |
| Tse4 (PA2774) | Tsi4 (PA2775) | Forms ion selective membrane pores that disrupt proton motive force | [38,59] | |
| Tse5 /RhsP1 (PA2684) | Tsi5 /RhsP1i (PA2683.1) | Forms ion selective membrane pores resulting in loss of membrane potential, contains RHS and PAAR domains | [59–61] | |
| Tse6 (PA0093) | Tsi6 (PA0094) | NAD(P)+ glycohydrolase that depletes NAD(P)+ resulting in target bacteriostasis, contains PAAR domain | [59,61,62] | |
| Tse6PA14 /Tas1 (PA14_01140)* | Tis1 (PA14_01130)* | (p)ppApp synthetase that rapidly depletes prey ATP/ADP pool, contains RHS and PAAR domains | [63] | |
| Tse7 (PA0099) | Tsi7 (PA0100) | Tox-GHH2 nuclease, contains PAAR domain | [54,61] | |
| Tse8 (PA4163) | Tsi8 (PA4164) | Targets transamidosome complex disrupting protein synthesis | [53,64] | |
| H2-T6SS | Tle1 (PA3290) | Tli1a (PA3291) Tli1b (PA3292) |
Phospholipase A2 activity | [65–67] |
| Tle2 (PAK_03765)* | Tli2a (PAK_03766)* Tli2b (PAK_03767)* |
Phospholipase A1 activity | [67] | |
| Tle3 (PA0260) | Tli3 (PA0259) | Phospholipase | [67,68] | |
| Tle4 /TplE (PA1510) | Tli4 /TplEi (PA1509) | Phospholipase, contains PGAP1-like domain to aid internalisation into host cells and localisation at ER membrane inducing autophagy, both antibacterial and anti-host toxicity | [67,69,70] | |
| PldA /Tle5a (PA3487) | Tli5a (PA3488) | Phospholipase D with preference for PE (phosphatidylethanolamine) as substrate, activate PI3K/Akt pathway that promotes internalisation into host cells, both antibacterial and anti-host toxicity | [67,69,71–74] | |
| PldB /Tle5b (PA5089) | Tli5b1 (PA5088) Tli5b2 (PA5087) Tli5b3 (PA5086) |
Phospholipase D, activates PI3K/Akt Pathway that promotes internalisation into host cells, both antibacterial and anti-host toxicity | [67,69,73,75] | |
| VgrG2b (PA0262) | VgrG2bi (PA0261) | Contains zinc- metallopeptidase domain, hydrolyses peptidoglycan in cell division plane causing target lysis. Interacts with α- and β-tubulins and γTuRC promoting internalisation into nonphagocytic cells, both antibacterial and anti-host toxicity | [68,76,77] | |
| AmpDh3 (PA0807) | AmpDh3i (PA0808) | Cell wall remodelling amidase that contributes to β-lactam resistance, hydrolyses target cell peptidoglycan cross links | [78–80] | |
| TseT (PA3907) | TsiT (PA3908) | TOX-REase domain containing nuclease | [81] | |
| TseV (PA0822) | TseV (PA0821) | Putative VRR-NUC domain containing nuclease | [82] | |
| PA5265 | PA5264 | Contains MIX (marker for type six effectors) motif | [83] | |
| RhsP2 (PA14_43100)* | RhsP2i (PA14_43090)* | ADP-rebosyltransferase that targets cells ncRNA pool causing growth arrest, contains RHS domain | [61,84,85] | |
| PA2066 | Unknown | Putative Hcp2 associated effector | [48] | |
| Azu (PA4922) | - | Common good effector, copper binding and uptake | [86,87] | |
| ModA (PA1863) | - | Common good effector, molybdite binding and uptake | [82,88] | |
| H3-T6SS | PA0256 | Unknown | Putative Hcp3 associated effector | [48] |
| TseF (PA2374) | - | Common good effector, interacts with PQS and the siderophore receptor FptA aiding in iron uptake | [89] | |
| TepB (PA14_33970)* | Common good effector associated with improved abiotic stress tolerance under biofilm condition, translocated to host cells | [90] |
*Not conserved in P. aeruginosa PAO1