Role of Type I Secretion in Pierce's Disease - Dean Gabriel - Pierce's Disease Conference 2008
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Role of Type I Secretion in Pierce's Disease - Dean Gabriel - Pierce's Disease Conference 2008

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Role of Type I Secretion in Pierce's Disease

Role of Type I Secretion in Pierce's Disease

Presenters: Dean Gabriel

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Role of Type I Secretion in Pierce's Disease - Dean Gabriel - Pierce's Disease Conference 2008 Role of Type I Secretion in Pierce's Disease - Dean Gabriel - Pierce's Disease Conference 2008 Presentation Transcript

  • Role of Type I Secretion in Pierce’s Disease Project Leader: Dean W. Gabriel Plant Pathology Department University of Florida Gainesville, FL 32611 Cooperator: Donald Hopkins Mid Florida Res. Edu. Center University of Florida Apopka, FL Postdoctoral Associate : Shujian Zhang Plant Pathology Department University of Florida Gainesville, FL 32611 Funding: U.C. Davis subaward from USDA Cooperative Agreement SA6477 Research Associate : Stephanie Reddy Plant Pathology Department University of Florida Gainesville, FL 32611
  • Working hypothesis:
    • Leaf scorch (PD) and necrotic leaf lesions (CVC) not typical of vascular blockage alone
    • Two Type I secretion systems (hemolysin & colicin V) available.
    • 10 PFTs: 6 hemolysins, 3 colicinVs, & 1bacteriocin
    • Multiple RTX effectors
    • found in Temecula genome
    • (equivalents in Dixon, Ann1
    • & 9a5c):
    • Hemolysins :
    • PD0143 PD1506
    • PD0282 PD2094
    • PD0305 PD536
    • Colicin V precursors :
    • PD0215
    • PD0216
    • (PD0217)
    • Bacteriocin :
    • PD1427
    Mechanism/s of the disease: Type I secreted RTX Effectors (PFTs)? View slide
  • O.M. Peptidoglycan I.M. Periplasm Secretion of proteins produced by the bacterium Efflux of toxic substances entering the bacterium ATP ADP Type I secretion machine has 2 roles View slide
  • Type I secretion (PD1964) Figure from Koronakis et al. 2004 Ann. Rev. Biochem. 73:467 (PD0783) (PD1404) AcrF AcrD Only one (1) TolC (PD1964) in X. fastidiosa
  • Figure from Koronakis et al. 2004 Ann. Rev. Biochem. 73:467 Type I secretion: PD1964 (TolC) is common component. (PD1964) (PD1413) (PD1412) Two potential toxin secretion systems: HlyD (PD1413)/ HlyB (PD1412) & CvaA (PD0496)/ CvaB (PD0499)
  • Reddy et al. 2007. MPMI 20:403-10. PD1964 ( tolC ) 1019 bp 3033 bp A D C B Marker exchange of tolC in Temecula nptII 4033 bp F E D A B C 2019 bp 2000 bp 1454 bp 1kb wt M1 M2 wt M1 M2 wt M1 M2 wt M1 M2 wt M1 M2 100 bp A & D B & C A & E F & D RST31&33 pJR6.1 nptII PD1964 ( tolC ) 23 9 Wt M1
  • PD-T Wild Type 64 dpi Type I secretion/efflux tolC ¯ tolC :: nptII mutants are completely nonpathogenic... Reddy et al. 2007. MPMI 20:403-10.
    • var. Carignane
    Protein Secretion (hlyBD :: nptII) (cvaA :: nptII) (cvaB :: nptII) Drug efflux ( acrF :: nptII) (acrD :: nptII) ...and knockouts of all other Type I system components exhibit reduced pathogenicity. Xf Temecula ( tolC)
  • PD-T Wild Type 64 dpi Type I MDR efflux acrD ¯
  • PD-T Wild Type 64 dpi Type I hemolysin secretion hlyBD ¯
  • PD-T Wild Type 64 dpi Type I colicin secretion cvaA ¯
  • PD-T Wild Type 64 dpi Type I colicin secretion cvaB ¯
  • # total leaves produced = # asymptomatic (healthy) leaves, # symptomatic (diseased) leaves, # bare petioles, # bare nodes # total symptomatic leaves = # symptomatic leaves, # bare petioles, # bare nodes
  • MDR efflux: acrD, acrF, tolC Type I effector secretion: hlyB, hlyD, cvaA, cvaB, tolC
  • TolC is externally exposed and might be blocked by chemicals or engineered plants. (PD1964)
  • Conclusions
    • X. fastidiosa absolutely requires tolC for in planta survival; MDR efflux is critical.
    • Knockouts of all other Xf Type I machine components exhibit reduced pathogenicity, including those used for PFT (hemolysin & colicin V) secretion.
    • Knockouts of all 3 colicin V effectors exhibit reduced pathogenicity, possibly indicating a direct role in symptom elicitation (apoptotic?).
    • TolC should have an exposed region and present a potential target for drugs/antibody strategy to control this pathogen
    Funding: U.C. Davis subaward from USDA Cooperative Agreement SA6477