Project description:Diet can have a strong impact on development, to test this effect the strains N2, CB4856, three strains from Orsay (JU1581, JU1944, and JU1949), and three strains from Santeuil (JU1921, JU1930, and JU1932) were grown on two different food-sources. These sources were the standard lab food, Escherichia coli OP50, and the Gram-negative plant pathogen Erwinia rhapontici. The effect of these bacteria on development could also be measured by the start of reproduction, which was delayed while feeding on E. coli. To measure the transcriptional effects, age-synchronized strains were grown for 48 hours at 20 degrees Celsius. The impact of food-source on gene expression was determined by a transcriptional ruler based on the strain N2 (E-MTAB-7019).
Project description:ra05-02_erwinia - erwinia - Identification of Arabidopsis genes regulataed by Erwinia amylovora and of a subset of Arabiddopsis genes regulated by the type three secretion system of Erwinia amylovora. Keywords: normal vs disease comparison
Project description:Sucrose isomerase NX-5 from Erwiniarhapontici efficiently catalyzes the isomerization of sucrose to isomaltulose (main product) and trehalulose (by-product). To investigate the molecular mechanism controlling sucrose isomer formation, we determined the crystal structures of native NX-5 and its mutant complexes E295Q/sucrose and D241A/glucose at 1.70 Å, 1.70 Å and 2.00 Å, respectively. The overall structure and active site architecture of NX-5 resemble those of other reported sucrose isomerases. Strikingly, the substrate binding mode of NX-5 is also similar to that of trehalulose synthase from Pseudomonasmesoacidophila MX-45 (MutB). Detailed structural analysis revealed the catalytic RXDRX motif and the adjacent 10-residue loop of NX-5 and isomaltulose synthase PalI from Klebsiella sp. LX3 adopt a distinct orientation from those of trehalulose synthases. Mutations of the loop region of NX-5 resulted in significant changes of the product ratio between isomaltulose and trehalulose. The molecular dynamics simulation data supported the product specificity of NX-5 towards isomaltulose and the role of the loop(330-339) in NX-5 catalysis. This work should prove useful for the engineering of sucrose isomerase for industrial carbohydrate biotransformations.