Molecular Plant-Microbe Interactions (1998) 11, 1048-1056

E. Roine, D.M. Raineri, M. Romantschuk, M. Wilson and D.N. Nunn (1998)
Characterization of type IV pilus genes in Pseudomonas syringae pv. tomato DC3000
Molecular Plant-Microbe Interactions 11 (11), 1048-1056
Abstract: Many strains of Pseudomonas syringae produce retractile pili that act as receptors for lytic bacteriophage phi6. As these are also characteristics of type IV pili, it was postulated that P. syringae may possess genes for type IV pilus biogenesis. A cosmid clone bank of P. syringae pv. tomato DC3000 genomic DNA was used to complement a mutant of Pseudomonas aeruginosa defective in the PilD (XcpA) prepilin peptidase gene by selection for restoration of extracellular protein secretion, a function also known to require PilD. A cosmid able to complement this mutant was also able to complement mutations in the pilB and pilC genes, suggesting that, if the organization of these genes is similar to that of P. aeruginosa, the cosmid may contain the P. syringae pilA. This was confirmed by sequencing a region from this plasmid that was shown to hybridize at low stringency to the P. aeruginosa pilA gene. The deduced P. syringae PilA polypeptide possesses the characteristic properties of the type IV pilins. Heterologous expression of the P. syringae pilA in P. aeruginosa was also shown, conferring not only phi6 phage sensitivity to P. aeruginosa pilA mutants but also sensitivity to PO4, a lytic bacteriophage specific for the pilus of P. aeruginosa. This suggests that additional components might be present in the mature pilus of P. aeruginosa that are the true receptors for this phage. Chromosomal mutations in P. syringae pv. tomato DC3000 pilA and pilD genes were shown to abolish its sensitivity to bacteriophage phi6. To determine the importance of P. syringae pilus in plant leaf interactions, these mutations were tested under laboratory and field conditions. Although little effect was seen on pathogenicity, culturable leaf-associated population sizes of the pilA mutant were significantly different from those of the wild-type parent. In addition, the expression of the DC3000 pilA gene appears to contribute to the UV tolerance of P. syringae and may play a role in survival on the plant leaf surface.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): E. Roine

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
molecular biology - genes

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pseudomonas syringae pv. tomato	Tomato (Solanum lycopersicum)
	Pseudomonas syringae