Secretion and translocation signals and DspB/F-binding domains in the type III effector DspA/E of Erwinia amylovora.
DspA/E is a type III effector of Erwinia amylovora, the bacterial pathogen that causes fire blight disease in roseaceous plants. This effector is indispensable for disease development, and it is translocated into plant cells. A DspA/E-specific chaperone, DspB/F, is necessary for DspA/E secretion and possibly for its translocation. In this work, DspB/F-binding sites and secretion and translocation signals in the DspA/E protein were determined. Based on yeast two-hybrid assays, DspB/F was found to bind DspA/E within the first 210 amino acids of the protein. Surprisingly, both DspB/F and OrfA, the putative chaperone of Eop1, also interacted with the C-terminal 1059 amino acids of DspA/E; this suggests another chaperone-binding site. Secretion and translocation assays using serial N-terminal lengths of DspA/E fused with the active form of AvrRpt2 revealed that at least the first 109 amino acids, including the first N-terminal chaperone-binding motif and DspB/F, were required for efficient translocation of DspA/E, although the first 35 amino acids were sufficient for its secretion and the presence of DspB/F was not required. These results indicate that secretion and translocation signals are present in the N terminus of DspA/E, and that at least one DspB/F-binding motif is required for efficient translocation into plant cells.
Oh
Chang-Sik
CS
Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA.
Carpenter
Sara C D
SCD
Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA.
Hayes
Marshall L
ML
Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA.
Beer
Steven V
SV
Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA.
D017360:Arabidopsis / Q000382:microbiology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044084:Erwinia amylovora / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D011485:Protein Binding; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D014026:Nicotiana / Q000382:microbiology; D020798:Two-Hybrid System Techniques
D001426:Bacterial Proteins; D021382:Protein Sorting Signals