Table I.

Contribution of secreted and cytoplasmic control proteins from plant pathogenic bacteria to virulence

Bacterial Species/Predicted Protein FunctionProteinaLocalizationbContribution to T3S and VirulenceReference
E. amylovora:
    Pilus proteinHrpASEssential for disease and T3SJin et al. (2001)
    Translocon proteinsHrpKSHomologous to HrpK1 from P. syringae, dispensable for virulenceNissinen et al. (2007)
    Control proteinHrpNS+THarpin, contributes to translocation of the effector DspA/EBocsanczy et al. (2008)
HrpJSRequired for virulence, contributes to secretion of harpins and translocation of the effector DspA/ENissinen et al. (2007); Bocsanczy et al. (2008)
P. syringae pv tomato:
    Pilus proteinHrpASEssential for disease and T3SRoine et al. (1997)
    Translocon proteinHrpK1S+TContributes to disease and effector protein translocationPetnicki-Ocwieja et al. (2005)
    Control proteinsHrpZ1S+THarpin, forms ion channelsLee et al. (2001); Kvitko et al. (2007); Engelhardt et al. (2009)
HrpW1S+THarpin, C-terminal pectate lyase domain
HopAK1S+THarpin, C-terminal pectate lyase domain
HrpZ1, HrpW, and HopAK1 contribute to effector protein translocation and disease
HrpHTHrpH, HopP1, and HopAJ1 are predicted lytic transglycosylases and contribute to effector protein translocation and diseaseOh et al. (2007)
HopP1T
HopAJ1NT
HrpJS+TRequired for disease, contributes to T3SFu et al. (2006)
HrpPTPredicted T3S4 protein, essential for diseaseMorello and Collmer (2009)
R. solanacearum:
    Pilus proteinHrpYSEssential for disease and T3SVan Gijsegem et al. (2000)
    Translocon proteinPopF1SEssential for diseaseMeyer et al. (2006)
PopF2SDispensable for diseaseMeyer et al. (2006)
    Control proteinsHpaBn.a.Required for diseaseMukaihara et al. (2004)
Xanthomonas spp.:
    Pilus proteinHrpEXcvSEssential for disease and T3SWeber et al. (2005)
    Translocon proteinHrpFXcvSEssential for disease and effector protein translocationBüttner et al. (2002)
HrpFXooSContributes to diseaseSugio et al. (2005)
    Control proteinsHpaAXcvS+TContributes to disease, secreted regulator of HpaBLorenz et al. (2008a)
HpaBXcvCGlobal T3S chaperone, essential for diseaseBüttner et al. (2004)
HpaCXcvCT3S4 protein, contributes to diseaseLorenz et al. (2008a)
HpaHXcvn.a.Predicted lytic transglycosylase, contributes to effector protein translocation and diseaseBüttner et al. (2007)
  • a Xcv, X. campestris pv vesicatoria; Xoo, X. oryzae pv oryzae.

  • b Localization: C, cytoplasmic; n.a., not analyzed; NT, not translocated; S, secreted; T, translocated.