Role of Type I Secretion in Pierce’s Disease Project Leader:  Dean W. Gabriel Plant Pathology Department University of Flo...
Working hypothesis: <ul><li>Leaf  scorch  (PD) and  necrotic  leaf lesions (CVC) not typical of vascular blockage alone </...
<ul><li>Multiple RTX effectors </li></ul><ul><li>found in Temecula genome </li></ul><ul><li>(equivalents in Dixon, Ann1  <...
O.M. Peptidoglycan I.M. Periplasm Secretion of proteins  produced by the  bacterium Efflux of toxic substances  entering t...
Type I secretion (PD1964) Figure from Koronakis et al. 2004 Ann. Rev. Biochem. 73:467 (PD0783) (PD1404) AcrF AcrD Only one...
Figure from Koronakis et al. 2004 Ann. Rev. Biochem. 73:467 Type I secretion:  PD1964 (TolC) is common component. (PD1964)...
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 403...
PD-T Wild Type  64 dpi Type I secretion/efflux tolC ¯ tolC  :: nptII  mutants are completely nonpathogenic... Reddy et al....
<ul><li>var. Carignane </li></ul>Protein Secretion (hlyBD  :: nptII) (cvaA  :: nptII)   (cvaB  :: nptII)   Drug efflux  ( ...
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...
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  <ul><li>X. fastidiosa  absolutely requires  tolC  for  in planta  survival; MDR efflux is critical.  </li></u...
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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

Presenters: Dean Gabriel

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

  1. 1. 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
  2. 2. Working hypothesis: <ul><li>Leaf scorch (PD) and necrotic leaf lesions (CVC) not typical of vascular blockage alone </li></ul><ul><li>Two Type I secretion systems (hemolysin & colicin V) available. </li></ul><ul><li>10 PFTs: 6 hemolysins, 3 colicinVs, & 1bacteriocin </li></ul>
  3. 3. <ul><li>Multiple RTX effectors </li></ul><ul><li>found in Temecula genome </li></ul><ul><li>(equivalents in Dixon, Ann1 </li></ul><ul><li>& 9a5c): </li></ul><ul><li>Hemolysins : </li></ul><ul><li>PD0143 PD1506 </li></ul><ul><li>PD0282 PD2094 </li></ul><ul><li>PD0305 PD536 </li></ul><ul><li>Colicin V precursors : </li></ul><ul><li>PD0215 </li></ul><ul><li>PD0216 </li></ul><ul><li>(PD0217) </li></ul><ul><li>Bacteriocin : </li></ul><ul><li>PD1427 </li></ul>Mechanism/s of the disease: Type I secreted RTX Effectors (PFTs)?
  4. 4. 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
  5. 5. 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
  6. 6. 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)
  7. 7. 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
  8. 8. 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.
  9. 9. <ul><li>var. Carignane </li></ul>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)
  10. 10. PD-T Wild Type 64 dpi Type I MDR efflux acrD ¯
  11. 11. PD-T Wild Type 64 dpi Type I hemolysin secretion hlyBD ¯
  12. 12. PD-T Wild Type 64 dpi Type I colicin secretion cvaA ¯
  13. 13. PD-T Wild Type 64 dpi Type I colicin secretion cvaB ¯
  14. 14. # total leaves produced = # asymptomatic (healthy) leaves, # symptomatic (diseased) leaves, # bare petioles, # bare nodes # total symptomatic leaves = # symptomatic leaves, # bare petioles, # bare nodes
  15. 15. MDR efflux: acrD, acrF, tolC Type I effector secretion: hlyB, hlyD, cvaA, cvaB, tolC
  16. 16. TolC is externally exposed and might be blocked by chemicals or engineered plants. (PD1964)
  17. 17. Conclusions <ul><li>X. fastidiosa absolutely requires tolC for in planta survival; MDR efflux is critical. </li></ul><ul><li>Knockouts of all other Xf Type I machine components exhibit reduced pathogenicity, including those used for PFT (hemolysin & colicin V) secretion. </li></ul><ul><li>Knockouts of all 3 colicin V effectors exhibit reduced pathogenicity, possibly indicating a direct role in symptom elicitation (apoptotic?). </li></ul><ul><li>TolC should have an exposed region and present a potential target for drugs/antibody strategy to control this pathogen </li></ul>Funding: U.C. Davis subaward from USDA Cooperative Agreement SA6477

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