Abstract
Pseudomonas syringae is a gram-negative bacterial plant pathogen that is dependent on a type III protein secretion system (TTSS) and the effector proteins it translocates into plant cells for pathogenicity. The P. syringae TTSS is encoded by hrp-hrc genes that reside in a central region of a pathogenicity island (Pai). Flanking one side of this Pai is the exchangeable effector locus (EEL). We characterized the transcriptional expression of the open reading frames (ORFs) within the EEL of P. syringae pv. tomato DC3000. One of these ORFs, PSPTO1406 (hopB1) is expressed in the same transcriptional unit as hrpK. Both HopB1 and HrpK were secreted in culture and translocated into plant cells via the TTSS. However, the translocation of HrpK required its C-terminal half. HrpK shares low similarity with a putative translocator, HrpF, from Xanthomonas campestris pv. vesicatoria. DC3000 mutants lacking HrpK were significantly reduced in disease symptoms and multiplication in planta, whereas DC3000 hopB1 mutants produced phenotypes similar to the wild type. Additionally, hrpK mutants were reduced in their ability to elicit the hypersensitive response (HR), a programmed cell death associated with plant defense. The reduced HR phenotype exhibited by hrpK mutants was complemented by hrpK expressed in bacteria but not by HrpK transgenically expressed in tobacco, suggesting that HrpK does not function inside plant cells. Further experiments identified a C-terminal transmembrane domain within HrpK that is required for HrpK translocation. Taken together, HopB1 is a type III effector and HrpK plays an important role in the TTSS and is a putative type III translocator.
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Claims 9
Claim · model-written summary
HopB1 and HrpK were secreted in culture and translocated into plant cells.
- Taxon
- plante0
- Interactor
- Pseudomonas syringae
Pseudomonas syringaee1pathogen - Gene
- HopB1 and HrpKe0
- Outcome
- translocated into plant cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both HopB1 and HrpK were secreted in culture and translocated into plant cells via the TTSS”
e1“Pseudomonas syringae is a gram-negative bacterial plant pathogen”
Claim · model-written summary
HrpK translocation required its C-terminal half.
Verbatim
e0“the translocation of HrpK required its C-terminal half”
e1“translocated into plant cells”
Claim · model-written summary
HrpK-deficient DC3000 mutants produced significantly fewer disease symptoms in plants.
- Taxon
- plante1
- Treatment
- DC3000 mutants lacking HrpKe0
- Gene
- HrpKe0
- Outcome
- disease symptomse0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“DC3000 mutants lacking HrpK were significantly reduced in disease symptoms and multiplication in planta”
e1“plant pathogen”
Claim · model-written summary
HrpK-deficient DC3000 mutants multiplied significantly less in plants.
- Taxon
- plante1
- Treatment
- DC3000 mutants lacking HrpKe0
- Gene
- HrpKe0
- Outcome
- multiplication in plantae0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“DC3000 mutants lacking HrpK were significantly reduced in disease symptoms and multiplication in planta”
e1“plant pathogen”
Claim · model-written summary
DC3000 hopB1 mutants had phenotypes similar to wild type.
Verbatim
e0“DC3000 hopB1 mutants produced phenotypes similar to the wild type”
e1“plant pathogen”
Claim · model-written summary
HrpK mutants had reduced ability to elicit the plant hypersensitive response.
- Taxon
- plante0
- Treatment
- hrpK mutantse0
- Gene
- hrpKe0
- Outcome
- ability to elicit the hypersensitive responsee0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“hrpK mutants were reduced in their ability to elicit the hypersensitive response (HR), a programmed cell death associated with plant defense”
Claim · model-written summary
Bacterial hrpK complemented the reduced HR phenotype.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- hrpK expressed in bacteriae0
- Gene
- hrpKe0
- Outcome
- reduced HR phenotypee0
- Direction
- complementede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The reduced HR phenotype exhibited by hrpK mutants was complemented by hrpK expressed in bacteria but not by HrpK transgenically expressed in tobacco”
Claim · model-written summary
HrpK expressed in tobacco did not complement the reduced HR phenotype.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- HrpK transgenically expressed in tobaccoe0
- Gene
- HrpKe0
- Outcome
- reduced HR phenotypee0
- Direction
- note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The reduced HR phenotype exhibited by hrpK mutants was complemented by hrpK expressed in bacteria but not by HrpK transgenically expressed in tobacco”
Claim · model-written summary
A C-terminal transmembrane domain was required for HrpK translocation.
Verbatim
e0“a C-terminal transmembrane domain within HrpK that is required for HrpK translocation”
e1“inside plant cells”
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