Volume 2, Number 4—October 1996
Synopsis
Molecular Mechanisms of Bacterial Virulence: Type III Secretion and Pathogenicity Islands
Table 1
Function and location of components in Type III systemsa
| Yersinia (p)b | S. typhimurium |
S. flexneri (p) | EPEC (c) | Flagellac (c) | Plantd (c) | Possible Functiond | Possible Cellular Locationf | Reference | |
|---|---|---|---|---|---|---|---|---|---|
| SPI I(c) | SPI II(c) | ||||||||
| YscN | SpaL | orf1 | MxiB | SepB | FliI | HrpE | ATPase | cytoplasm, associated with inner membrane (I.M.) | 8, 43, 63 |
| LcrD | InvA | orf9 | MxiA | SepA | FlhA | HrpO | structural/ regulatory | I.M. | 28, 43, 63 |
| YscR | SpaP | orf5 | Spa24 | FliP | HrpT | structural | I.M. | 8, 43 | |
| YscS | SpaQ | orf6 | Spa9 | FliQ | HrpU | “ | “ | 28, 43 | |
| YscT | SpaR | orf7 | Spa40 | FliR | HrpC | “ | “ | 8, 43 | |
| YscU | SpaS | orf8 | Spa40 | FhlB | HrpN | “ | “ | 8, 43, 63 | |
| YscC | InvG | orf11 | MxiD | SepC | HrpA | structural/channel forming | outer membrane (O.M.) | 28, 43, 63 | |
| YscJ | PrgK | orf10 | MxiJ | SepD | FliF | HrpI | lipoprotein/ structural | O.M. | 8, 28, 43, 63 |
| VirG | “ | “ | 52 | ||||||
| YscD | essential, but unknown | I.M. | 48 | ||||||
| YscE | “ | unknown | 51 | ||||||
| YscF | PrgI | MxiH | needed for YopB and D secretion | “ | 28, 51 | ||||
| YscG | essential, butunknown | equally distributed between membrane and soluble fractions | 48 | ||||||
| YscI | “ | unknown | 51 | ||||||
| YscK | “ | “ | 51 | ||||||
| YscL | HrpF | “ | “ | 8 | |||||
| YscO | SpaM | orf2 | Spa13 | unknown | “ | 12, 28, 43 | |||
| YscP | SpaN | orf3 | Spa32 | “ | “ | 12, 28, 43 | |||
| YscQ | SpaO | orf4 | Spa33 | FliN | HrpQ | SpaO needed for secretion of Sips (see below) | Spa O: secreted | 8, 28, 43 | |
| YopB | SipB | IpaB | homology to pore forming toxins/delivery of effector moleculesto host cells | secreted/targeted to host cell | 26, 28, 55 | ||||
| YopD | delivery of effector molecules to host cells | secreted | 55 | ||||||
| SipD | IpaD | “ | secreted | 26 | |||||
| SycD | SicA | IpgC | chaperone for YopB and D/ IpaB and IpaC in Shigella | cytoplasm | 56 | ||||
| SycE | chaperone for YopE | “ | 56 | ||||||
| SycH | chaperone for YopH | “ | 56 | ||||||
| YopN | InvE | MxiC | regulatory: cell-contact sensing pathway | O.M./secreted | 28 | ||||
| LcrG | “ | cytosol/I.M. | 59, S. Straley pers. comm. | ||||||
| LcrQ | regulatory | cytoplasm/secreted | 54 | ||||||
| VirF | InvF | MxiE | HrpB | regulatory:temperature | cytoplasm | 28 | |||
| YopE | effector molecule:depolymerizes actin antiphagocytic | host cell | 27 | ||||||
| YopH | effector molecule: tyrosine phosphatase anti-phagocytic | “ | 36 | ||||||
| SipC | IpaC | effector molecule: induces entry into epithelial cells | secreted | 17, 28 | |||||
| EspB (EaeB) | effector molecule: induces AE lesions | 33, 63 | |||||||
aListed are names of proteins in type III secretion systems
bp-proteins are encoded by genes on a plasmid; c-proteins are encoded by genes on the chromosome.
cProtein names are those from the S. Typhimurium flagella; for list of flagellar protein names from other bacteria, see ref. 23.
dProtein names are those from the plant pathogen Pseudomonas solanacearum; for a list of components of type III secretion systems in other plant pathogens, see ref. 8.
eThese are the possible functions for these factors in Yersinia, unless noted.
fThese are the possible locations for these factors in Yersinia, unless noted.
