6eq1

Structure of the periplasmic binding protein (PBP) MelB (Atu4661) in complex with stachyose from agrobacterium fabrum C58

spinqualitylabelsall models 6eq1, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6eq1 is a 2 chain structure with sequence from Agrobacterium tumefaciens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: CA, EDO, FRU, GAL, GLC, PEG, PG4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed The bacterial plant pathogen Agrobacterium fabrum uses periplasmic binding proteins (PBPs) along with ABC transporters to import a wide variety of plant molecules as nutrients. Nonetheless, how A. fabrum acquires plant metabolites is incompletely understood. Using genetic approaches and affinity measurements, we identified here the PBP MelB and its transporter as being responsible for the uptake of the raffinose family of oligosaccharides (RFOs), which are the most widespread Dgalactose containing oligosaccharides in higher plants. We also found that the RFO precursor galactinol, recently described as a plant defense molecule, is imported into Agrobacterium via MelB with nanomolar range affinity. Structural analyses and binding mode comparisons of the X-ray structures of MelB in complex with raffinose, stachyose, galactinol, galactose and melibiose (a raffinose degradation product) revealed how MelB recognizes the nonreducing end galactose common to all these ligands and that MelB has a strong preference for a two-unit sugar ligand. Of note, MelB conferred a competitive advantage to A. fabrum in colonizing the rhizosphere of tomato plants. Our integrative work highlights the structural and functional characteristics of melibiose and galactinol assimilation by A. fabrum, leading to a competitive advantage for these bacteria in the rhizosphere. We propose that the PBP MelB, which is highly conserved among both symbionts and pathogens from Rhizobiace family, is a major trait in these bacteria required for early steps of plant colonization. The plant defense signal galactinol is specifically used as a nutrient by the bacterial pathogen Agrobacterium fabrum.,Meyer T, Vigouroux A, Aumont-Nicaise M, Comte G, Vial L, Lavire C, Morera S J Biol Chem. 2018 Mar 30. pii: RA118.001856. doi: 10.1074/jbc.RA118.001856. PMID:29602905 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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