Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a
<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas syringae </it>pv. phaseolicola 1448a (<it>P. syringae </it>1448a), the causative agent of bean halo blight, is a bacterium capable of occupying diverse biological niches. Under conditions of ir...
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| Format: | Article |
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BMC
2011-10-01
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| Series: | BMC Microbiology |
| Online Access: | http://www.biomedcentral.com/1471-2180/11/218 |
| _version_ | 1819140380684189696 |
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| author | Owen Jeremy G Ackerley David F |
| author_facet | Owen Jeremy G Ackerley David F |
| author_sort | Owen Jeremy G |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p><it>Pseudomonas syringae </it>pv. phaseolicola 1448a (<it>P. syringae </it>1448a), the causative agent of bean halo blight, is a bacterium capable of occupying diverse biological niches. Under conditions of iron starvation <it>P. syringae </it>1448a secretes siderophores for active uptake of iron. The primary siderophore of <it>P. syringae </it>1448a is pyoverdine, a fluorescent molecule that is assembled from amino acid precursors by non-ribosomal peptide synthetase (NRPS) enzymes. Whereas other species of <it>Pseudomonas </it>often exhibit structural variations in the pyoverdine produced by different strains, all <it>P. syringae </it>pathovars previously tested have been found to make an identical pyoverdine molecule. <it>P. syringae </it>1448a also appears to have the genetic potential to make two secondary siderophores, achromobactin and yersiniabactin, each of which has previously been detected in different <it>P. syringae </it>pathovars.</p> <p>Results</p> <p>Five putative pyoverdine NRPS genes in <it>P. syringae </it>1448a were characterized <it>in-silico </it>and their role in pyoverdine biosynthesis was confirmed by gene knockout. Pyoverdine was purified from <it>P. syringae </it>1448a and analyzed by MALDI-TOF and MS/MS spectroscopy. Peaks were detected corresponding to the expected sizes for the pyoverdine structure previously found in other <it>P. syringae </it>pathovars, but surprisingly <it>P. syringae </it>1448a appears to also produce a variant pyoverdine species that has an additional 71 Da monomer incorporated into the peptide side chain. Creation of pyoverdine null mutants of <it>P. syringae </it>1448a revealed that this strain also produces achromobactin as a temperature-regulated secondary siderophore, but does not appear to make yersiniabactin. Pyoverdine and achromobactin null mutants were characterized in regard to siderophore production, iron uptake, virulence and growth in iron limited conditions.</p> <p>Conclusions</p> <p>This study provides the first evidence of a <it>P. syringae </it>pathovar producing a side chain variant form of pyoverdine. We also describe novel IC<sub>50 </sub>and liquid CAS assays to quantify the contribution of different siderophores across a range of iron starvation conditions, and show that although achromobactin has potential to contribute to fitness its contribution is masked by the presence of pyoverdine, which is a significantly more effective siderophore. Neither pyoverdine nor achromobactin appear to be required for <it>P. syringae </it>1448a to cause bean halo blight, indicating that these siderophores are not promising targets for crop protection strategies.</p> |
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| language | English |
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| spelling | doaj.art-fde5728c62a64b93b5b14df5c5c2f59c2022-12-21T18:27:23ZengBMCBMC Microbiology1471-21802011-10-0111121810.1186/1471-2180-11-218Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448aOwen Jeremy GAckerley David F<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas syringae </it>pv. phaseolicola 1448a (<it>P. syringae </it>1448a), the causative agent of bean halo blight, is a bacterium capable of occupying diverse biological niches. Under conditions of iron starvation <it>P. syringae </it>1448a secretes siderophores for active uptake of iron. The primary siderophore of <it>P. syringae </it>1448a is pyoverdine, a fluorescent molecule that is assembled from amino acid precursors by non-ribosomal peptide synthetase (NRPS) enzymes. Whereas other species of <it>Pseudomonas </it>often exhibit structural variations in the pyoverdine produced by different strains, all <it>P. syringae </it>pathovars previously tested have been found to make an identical pyoverdine molecule. <it>P. syringae </it>1448a also appears to have the genetic potential to make two secondary siderophores, achromobactin and yersiniabactin, each of which has previously been detected in different <it>P. syringae </it>pathovars.</p> <p>Results</p> <p>Five putative pyoverdine NRPS genes in <it>P. syringae </it>1448a were characterized <it>in-silico </it>and their role in pyoverdine biosynthesis was confirmed by gene knockout. Pyoverdine was purified from <it>P. syringae </it>1448a and analyzed by MALDI-TOF and MS/MS spectroscopy. Peaks were detected corresponding to the expected sizes for the pyoverdine structure previously found in other <it>P. syringae </it>pathovars, but surprisingly <it>P. syringae </it>1448a appears to also produce a variant pyoverdine species that has an additional 71 Da monomer incorporated into the peptide side chain. Creation of pyoverdine null mutants of <it>P. syringae </it>1448a revealed that this strain also produces achromobactin as a temperature-regulated secondary siderophore, but does not appear to make yersiniabactin. Pyoverdine and achromobactin null mutants were characterized in regard to siderophore production, iron uptake, virulence and growth in iron limited conditions.</p> <p>Conclusions</p> <p>This study provides the first evidence of a <it>P. syringae </it>pathovar producing a side chain variant form of pyoverdine. We also describe novel IC<sub>50 </sub>and liquid CAS assays to quantify the contribution of different siderophores across a range of iron starvation conditions, and show that although achromobactin has potential to contribute to fitness its contribution is masked by the presence of pyoverdine, which is a significantly more effective siderophore. Neither pyoverdine nor achromobactin appear to be required for <it>P. syringae </it>1448a to cause bean halo blight, indicating that these siderophores are not promising targets for crop protection strategies.</p>http://www.biomedcentral.com/1471-2180/11/218 |
| spellingShingle | Owen Jeremy G Ackerley David F Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a BMC Microbiology |
| title | Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a |
| title_full | Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a |
| title_fullStr | Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a |
| title_full_unstemmed | Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a |
| title_short | Characterization of pyoverdine and achromobactin in <it>Pseudomonas syringae </it>pv. phaseolicola 1448a |
| title_sort | characterization of pyoverdine and achromobactin in it pseudomonas syringae it pv phaseolicola 1448a |
| url | http://www.biomedcentral.com/1471-2180/11/218 |
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