Hrp pilus: an hrp-dependent bacterial surface appendage produced by Pseudomonas syringae pv. tomato DC3000

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-04, Vol.94 (7), p.3459-3464
• Main Authors: Roine, E. (University of Helsinki, Helsinki, Finland.), Wei, W, Yuan, J, Nurmiaho-Lassila, E.L, Kalkkinen, N, Romantschuk, M, He, S.Y
• Format: Article
• Language: English
• Subjects: Agrobacterium tumefaciens; Appendages; ARABIDOPSIS THALIANA; BACTERIA; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Biological Sciences; Botany; Culture Media; ESTRUCTURA CELULAR; EXPERIMENTACION IN VIVO; EXPERIMENTATION IN VIVO; Fimbriae, Bacterial; Flagella; Flowers & plants; Gels; GENE; GENES; INFECCION EXPERIMENTAL; INFECTION EXPERIMENTALE; LYCOPERSICON ESCULENTUM; Mutagenesis; MUTANT; MUTANTES; Mutation; NICOTIANA TABACUM; Open reading frames; PATHOGENESE; Pathogenesis; PATOGENESIS; Plant cells; Plants; PROTEINAS; PROTEINE; Proteins; Pseudomonas - metabolism; PSEUDOMONAS SYRINGAE; Pseudomonas syringae tomato; Salmonella typhimurium; Secretion; SINTESIS DE PROTEINAS; STRUCTURE CELLULAIRE; SYNTHESE PROTEIQUE
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.7.3459

Hypersensitive response and pathogenicity (hrp) genes control the ability of major groups of plant pathogenic bacteria to elicit the hypersensitive response (HR) in resistant plants and to cause disease in susceptible plants. A number of Hrp proteins share significant similarities with components of the type III secretion apparatus and flagellar assembly apparatus in animal pathogenic bacteria. Here we report that Pseudomonas syringae pv. tomato strain DC3000 (race 0) produces a filamentous surface appendage (Hrp pilus) of 6-8 nm in diameter in a solid minimal medium that induces hrp genes. Formation of the Hrp pilus is dependent on at least two hrp genes, hrpS and hrpH (recently renamed hrcC), which are involved in gene regulation and protein secretion, respectively. Our finding of the Hrp pilus, together with recent reports of Salmonella typhimurium surface appendages that are involved in bacterial invasion into the animal cell and of the Agrobacterium tumefaciens virB-dependent pilus that is involved in the transfer of T-DNA into plant cells, suggests that surface appendage formation is a common feature of animal and plant pathogenic bacteria in the infection of eukaryotic cells. Furthermore, we have identified HrpA as a major structural protein of the Hrp pilus. Finally, we show that a nonpolar hrpA mutant of P. syringae pv. tomato DC3000 is unable to form the Hrp pilus or to cause either an HR or disease in plants