Transgenic expression of the von Willebrand A domain of the BONZAI 1/COPINE 1 protein triggers a lesion-mimic phenotype in Arabidopsis.
The copines are a newly identified, widely distributed class of Ca(2+)-dependent, phospholipid-binding proteins that may be involved in cellular signaling. The copines have a characteristic domain structure: two C2 domains in the N-terminal region and a von Willebrand A (VWA) domain in the C-terminal region. Studies suggest that copines interact with target protein(s) via their VWA domain and recruit the proteins to a membrane location through the activity of the C2 domains. Arabidopsis thaliana (L.) Heynh. plants with loss-of-function mutations in the BONZAI 1/COPINE 1 (BON1/CPN1) gene display aberrant regulation of defense responses, including development of a lesion-mimic phenotype, an accelerated hypersensitive response, and increased resistance to a bacterial and an oomycetous pathogen. The phenotype of mutants in BON1/CPN1 is both humidity- and temperature-sensitive. In this study, we generated transgenic plants expressing either the VWA or the C2 portions of BON1/CPN1 in the wild-type Columbia-0 (Col-0) genetic background. Transgenic plants expressing the BON1/CPN1 C2 domain portion appeared like wild-type plants. However, transgenic plants expressing the BON1/CPN1 VWA domain exhibited a lesion-mimic phenotype that partially phenocopied bon1/cpn1 mutant plants. Our data suggest that BON1/CPN1 VWA domain fragments may interfere with the function of the full-length endogenous BON1/CPN1 protein, possibly by competing with the full-length BON1/CPN1 protein for association with target proteins normally bound to the full-length BON1/CPN1 protein.
Liu
Jianxin
J
Plant Pathology Department, 211 Buckhout Laboratory, Pennsylvania State University, University Park, PA 16802, USA.
Jambunathan
Niranjani
N
McNellis
Timothy W
TW
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics*; D017931:DNA Primers; D005784:Gene Amplification; D006813:Humidity; D008565:Membrane Proteins / Q000235:genetics*; D010935:Plant Diseases; D030821:Plants, Genetically Modified / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014841:von Willebrand Factor / Q000235:genetics*
D029681:Arabidopsis Proteins; C436490:BON1 protein, Arabidopsis; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D011994:Recombinant Proteins; D014841:von Willebrand Factor