Present address: University of Utrecht, Department of Molecular and Cellular Biology, PO Box 80 056, 3508 TB Utrecht, The Netherlands.
Eukaryotic features of the Xanthomonas type III effector AvrBs3: protein domains involved in transcriptional activation and the interaction with nuclear import receptors from pepper
Article first published online: 23 DEC 2001
The Plant Journal
Volume 26, Issue 5, pages 523–534, June 2001
How to Cite
Szurek, B., Marois, E., Bonas, U. and Van den Ackerveken, G. (2001), Eukaryotic features of the Xanthomonas type III effector AvrBs3: protein domains involved in transcriptional activation and the interaction with nuclear import receptors from pepper. The Plant Journal, 26: 523–534. doi: 10.1046/j.0960-7412.2001.01046.x
- Issue published online: 23 DEC 2001
- Article first published online: 23 DEC 2001
- Received 22 February 2001; accepted 16 March 2001.
- transcription activation;
- importin α;
- yeast two-hybrid
The AvrBs3 protein of the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria is targeted to host-plant cells by the bacterial Hrp type III secretion system. In pepper plants containing the Bs3 resistance gene, AvrBs3 induces the hypersensitive response (HR). AvrBs3 recognition is thought to occur in the plant cell nucleus as HR induction is dependent on nuclear localization signals (NLSs) and an acidic transcription activation domain (AAD). In a search for AvrBs3-interacting pepper proteins using the yeast two-hybrid system, we have isolated eight different classes of cDNA inserts including two genes for importin α proteins. Importin α is part of the nuclear import machinery and interacts with AvrBs3 through an NLS in the carboxy-terminus of the protein, both in yeast and in vitro. The mechanism of AvrBs3 recognition was further studied by analysis of the C-terminal AAD. This putative transcription-activation domain was shown to be required for AvrBs3 HR-inducing activity, and could be functionally replaced with the VP16 AAD from the Herpes simplex virus. Our data support the model in which the AvrBs3 effector localizes to the nucleus, where the Bs3-mediated surveillance system of resistant plants detects AvrBs3 through its interference with host gene transcription.