Table 1.
Metal transport systems involved in overcoming nutritional immunity.
| Name in Ngoa (alternative name) | Metal/ligand or function | Locus tag in NGO FA1090 | Homolog in Nmeb MC58 (alternative name) | Neisseria locus tag | MWc | Expression in vitro | Expression in vivo (women) | Virulence impacts | Distribution |
|---|---|---|---|---|---|---|---|---|---|
| TbpA/TbpB | Fe/Transferrin | NGO1495/NGO1496 | NMB0461/NMB0460 | NEIS1690/NEIS1691 | 100 kDa | Fe repressed | High 4/4 | Required for human infection | Most Neisseriae |
| LbpA/LbpB | Fe/Lactoferrin | NGO0260 (truncated) | NMB1540/NMB1541 | NEIS1468/NEIS1469 | 102 kDa | Fe repressed | Low 3/4 | Can substitute for Tf-Fe uptake system in human infection | Gene deletion in many Ngo; locus present in most Neisseriae |
| HpuA/HpuB | Heme/Hemoglobin | NGO2110/NGO2109 | None | NEIS1946/NEIS1947 | 90 kDa | Fe repressed | Low 2/4 | Phase ‘on’ during first half of menstrual cycle in infected women | Most Neisseriae; phase variable |
| FetA | Fe/catecholate Siderophores | NGO2093 | NMB1988 | NEIS1963 | 79 kDa | Fe repressed | 2/4 | None known | All Neisseriae; phase variable |
| TdfF | Fe? | NGO0021 | NMB1882 | NEIS0338 | 80 kDa | Fe repressedd | No | Contributes to intracellular survival | Only in pathogenic Neisseriae |
| TdfG | Unknown | NGO0553 | None | NEIS2646 | 136 kDa | Fe repressed | Low 2/4 | None known | Only in Ngo and N. elongata |
| TdfH | Zn/Calprotectin | NGO0952 | NMB1497 (CbpA) | NEIS1428 | 104 kDa | Zn repressed | 4/4 | Important for NET survival | Most Neisseriae |
| TdfJ | Zn/? | NGO1205 | NMB0964 (ZnuD) | NEIS0944 | 86 kDa | Fe induced; Zn repressed | 4/4 | Facilitates systemic Nme infection in mice | All Neisseriae |
| FbpA | Fe | NGO0217 | NMB0634 | NEIS0578 | 35 kDa | Fe repressed | High 4/4 | Decreased Fe uptake from Tf/Lf | Most Neisseriae |
| FbpB | Fe | NGO0216 | NMB0633 | NEIS0577 | 56 kDa | Fe repressed | High 4/4 | Decreased Fe uptake from Tf/Lf | Most Neisseriae |
| FbpC | Fe | NGO0215 | NMB0632 | NEIS0576 | 38 kDa | Fe repressed | High 4/4 | Decreased Fe uptake from Tf/Lf | Most Neisseriae |
| ZnuC (MntA) | Zn | NGO0170 | NMB0588 | NEIS530 | 28 kDa | Zn repressed | High 2/4 | Contributes to intracellular survival and resistance to oxidative stress | Most Neisseriae |
| ZnuB (MntB) | Zn | NGO0169 | NMB0587 | NEIS0529 | 29 kDa | Zn repressed | 3/4 | Contributes to intracellular survival and resistance to oxidative stress | Most Neisseriae |
| ZnuA (MntC) | Zn | NGO0168 | NMB0586 | NEIS528 | 34 kDa | Zn repressed | High 4/4 | Contributes to intracellular survival and resistance to oxidative stress | Most Neisseriae |
| TonB | Energization system | NGO1379 | NMB1730 | NEIS1650 | 29 kDa | Iron repressed | High 4/4 | Impaired metal uptake | All Neisseriae |
| ExbB | Energization system | NGO1378 | NMB1729 | NEIS1649 | 26 kDa | Iron repressed | High 4/4 | Impaired metal uptake | All Neisseriae |
| ExbD | Energization system | NGO1377 | NMB1728 | NEIS1648 | 15 kDa | Iron repressed | High 4/4 | Impaired metal uptake | All Neisseriae |
a
N. gonorrhoeae
b
N. meningitidis
c
Molecular weight
d
Not expressed in bacteriological medium.