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JOURNAL OF BACTERIOLOGY, Sept. 2006, p. 60606069 Vol. 188, No. 17 0021-9193/06/$08.00 0 doi:10.1128/JB.00718-06
 

Summary: JOURNAL OF BACTERIOLOGY, Sept. 2006, p. 60606069 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 hyper-
sensitive 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

  

Source: Alfan, James R. - Department of Plant Pathology, University of Nebraska-Lincoln

 

Collections: Biology and Medicine