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X-ray structure of the self-defense and signaling protein DIR1 from Arabidopsis talianaX-ray structure of the self-defense and signaling protein DIR1 from Arabidopsis taliana
Structural highlights
FunctionDIRL1_ARATH Putative lipid transfer protein required for systemic acquired resistance (SAR) long distance signaling. May interact with a lipid-derived molecule to promote long distance signaling associated with SAR. Together with AZI1, required for glycerol-3-phosphate- (G3P) and azelaic acid- (AA) induced systemic acquired resistance (SAR). Component of plant systemic immunity involved in priming defenses in a AA-dependent manner, by modulating production and/or translocation of a mobile signal(s) during SAR.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedScreening of transfer DNA (tDNA) tagged lines of Arabidopsis thaliana for mutants defective in systemic acquired resistance led to the characterization of dir1-1 (defective in induced resistance [systemic acquired resistance, SAR]) mutant. It has been suggested that the protein encoded by the dir1 gene, i.e., DIR1, is involved in the long distance signaling associated with SAR. DIR1 displays the cysteine signature of lipid transfer proteins, suggesting that the systemic signal could be lipid molecules. However, previous studies have shown that this signature is not sufficient to define a lipid transfer protein, i.e., a protein capable of binding lipids. In this context, the lipid binding properties and the structure of a DIR1-lipid complex were both determined by fluorescence and X-ray diffraction. DIR1 is able to bind with high affinity two monoacylated phospholipids (dissociation constant in the nanomolar range), mainly lysophosphatidyl cholines, side-by-side in a large internal tunnel. Although DIR1 shares some structural and lipid binding properties with plant LTP2, it displays some specific features that define DIR1 as a new type of plant lipid transfer protein. The signaling function associated with DIR1 may be related to a specific lipid transport that needs to be characterized and to an additional mechanism of recognition by a putative receptor, as the structure displays on the surface the characteristic PxxP structural motif reminiscent of SH3 domain signaling pathways. The structure of "defective in induced resistance" protein of Arabidopsis thaliana, DIR1, reveals a new type of lipid transfer protein.,Lascombe MB, Bakan B, Buhot N, Marion D, Blein JP, Larue V, Lamb C, Prange T Protein Sci. 2008 Sep;17(9):1522-30. Epub 2008 Jun 13. PMID:18552128[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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