This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fu, Z. Q. Articles by Alfano, J. R. Search for Related Content PubMed PubMed Citation Articles by Fu, Z. Q. Articles by Alfano, J. R.

 Previous Article  |  Next Article 

Journal of Bacteriology, September 2006, p. 6060-6069, Vol. 188, No. 17
0021-9193/06/$08.00+0     doi:10.1128/JB.00718-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Pseudomonas syringae HrpJ Is a Type III Secreted Protein That Is Required for Plant Pathogenesis, Injection of Effectors, and Secretion of the HrpZ1 Harpin

Zheng Qing Fu, Ming Guo, and James R. Alfano^*

Plant Science Initiative and Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68588-0660

Received 18 May 2006/ Accepted 19 June 2006

The bacterial plant pathogen Pseudomonas syringae requires a type III protein secretion system (TTSS) to cause disease. The P. syringae TTSS is encoded by the hrp-hrc gene cluster. One of the genes within this cluster, hrpJ, encodes a protein with weak similarity to YopN, a type III secreted protein from the animal pathogenic Yersinia species. Here, we show that HrpJ is secreted in culture and translocated into plant cells by the P. syringae pv. tomato DC3000 TTSS. A DC3000 hrpJ mutant, UNL140, was greatly reduced in its ability to cause disease symptoms and multiply in Arabidopsis thaliana. UNL140 exhibited a reduced ability to elicit a hypersensitive response (HR) in nonhost tobacco plants. UNL140 was unable to elicit an AvrRpt2- or AvrB1-dependent HR in A. thaliana but maintained its ability to secrete AvrB1 in culture via the TTSS. Additionally, UNL140 was defective in its ability to translocate the effectors AvrPto1, HopB1, and AvrPtoB. Type III secretion assays showed that UNL140 secreted HrpA1 and AvrPto1 but was unable to secrete HrpZ1, a protein that is normally secreted in culture in relatively large amounts, into culture supernatants. Taken together, our data indicate that HrpJ is a type III secreted protein that is important for pathogenicity and the translocation of effectors into plant cells. Based on the failure of UNL140 to secrete HrpZ1, HrpJ may play a role in controlling type III secretion, and in its absence, specific accessory proteins, like HrpZ1, may not be extracellularly localized, resulting in disabled translocation of effectors into plant cells.

---

* Corresponding author. Mailing address: Plant Science Initiative, The Beadle Center for Genetic Research, University of Nebraska, 1901 Vine St., Lincoln, NE 68588-0660. Phone: (402) 472-0395. Fax: (402) 472-3139. E-mail: jalfano2{at}unl.edu.

---

Journal of Bacteriology, September 2006, p. 6060-6069, Vol. 188, No. 17
0021-9193/06/$08.00+0     doi:10.1128/JB.00718-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Buttner, D., He, S. Y. (2009). Type III Protein Secretion in Plant Pathogenic Bacteria. Plant Physiol. 150: 1656-1664 [Full Text]  
• Ramos, A. R., Morello, J. E., Ravindran, S., Deng, W.-L., Huang, H.-C., Collmer, A. (2007). Identification of Pseudomonas syringae pv. syringae 61 Type III Secretion System Hrp Proteins That Can Travel the Type III Pathway and Contribute to the Translocation of Effector Proteins into Plant Cells. J. Bacteriol. 189: 5773-5778 [Abstract] [Full Text]