Table 2.

Different subfamilies of injectisome T3SS. The names of the subfamilies, selected species containing T3SS of this subfamily, the distribution throughout bacteria and particularities of the subfamily are listed. The SPI-1 subfamily is sometimes referred to as Inv-Mxi-Spa, the SPI-2 subfamily is also called Ssa-Esc. Data compiled from [12,17,38].

nameselected speciesdistribution/comments
YscYersinia spp. (Ysc)
Pseudomonas aeruginosa
Vibrio parahaemolyticus
Bordetella pertussis
present in β-, γ- and δ-proteobacteria,
predominantly in animal pathogens
SPI-1Salmonella enterica (SPI-1)
Shigella flexneri
Burkholderia pseudomallei
Yersina enterocolitica (Ysa)
present in β- and γ-proteobacteria,
predominantly in animal pathogens
SPI-2Salmonella enterica (SPI-2)
Escherichia coli EHEC/EPEC
Citrobacter rodentium
Yersinia pestis (chromosome-encoded)
present in β- and γ-proteobacteria,
predominantly in animal pathogens
ChlamydiaChlamydia spp.present in Chlamydiales, obligate intracellular pathogens
Hrp1Pseudomonas syringae
Erwinia amylovora
present in γ-proteobacteria,
predominantly in plant pathogens
Hrp2Xanthomonas campestris
Ralstonia solanacearum
Burkholderia pseudomallei
present in β- and γ-proteobacteria,
predominantly in plant pathogens
RhizobiumRhizobium spp.
Mesorhizobium loti
present in plant symbiotic α-proteobacteria,
involved in nitrogen fixation
MyxococcusMyxococcus xanthuspresent in two different variants in these δ-proteobacteria, incomplete and presumably needle-less T3SS