Rhizobium trifolii

Parameter Escherichia coli M41 46 Parameter Rhizobium trifolii 47... 

Table A31 Structure 47 Rhizobium trifolii Capsular Polysaccharide ...

A number of amide- and ester-linked fatty acids and (/ )-3-hydroxy acids are components of the lipid A part in the LPS from Gram-negative bacteria. The acids have been tabulatedand the chemistry of lipid A summarized. The most common acids in lipid A from Enterobacteriaceae are the saturated 12 0,14 0, and 16 0, and the (/ )-3-hydroxy-14 0, The last is linked to N-2 and 0-3 of the 2-amino-2-deoxy-D-glucopyranosyl residues, and the others are ester-linked to the hydroxy acid, as in the lipid A (44) of Salmonella minnesota. Other linear and branched fatty acids, unsaturated acids, S)-2- and (/ )-3-hydroxy acids, and 3-oxotetradecanoic acid are components of lipid A from certain different species. In the lipid A from Rhizobium trifolii, 2,7-dihydroxyoctanoic acid is linked as amide to a 2-amino-2-deoxy-D-gl ucopy ranosy 1 residue. ... 

Chen, YP, AR Glenn, MJ Dilworth (1985) Aromatic metabolism in Rhizobium trifolii—catechol 1,2-dioxy-genase. Arch Microbiol 141 225-228. 

Chen YP, MJ Dilworth, AR Glenn (1984) Aromatic metabolism in Rhizobium trifolii—protocatechnate 3,4-dioxygenase. Arch Microbiol 138 187-190. 

Heavy-metal cations and oxyanions are generally toxic to bacteria although resistance may be induced by various mechanisms after exposure. Attention is drawn to an unusual example in which AF+ may be significant, since the catechol 1,2-dioxygenase and 3,4-dihydroxybenzoate (protocat-echuate) 3,4-dioxygenase that are involved in the metabolism of benzoate by strains of Rhizobium trifolii are highly sensitive to inhibition by AP (Chen et al. 1985). 

W. Zurkowski and Z. Lorkiewick, Plasmid-mediated control of nodulation in Rhizobium trifolii. Arch. Microbiol. 123 195-201 (1979). 

Using computer modeling, jointly with x-ray fiber diffraction data, the molecular architectures of two different gel-forming polysaccharides have been examined. Preliminary results indicate that the neutral and doubly branched capsular polysaccharide from Rhizobium trifolii can form a 2-fold single helix of pitch 1.96 nm or a half-staggered, 4-fold doublehelix of pitch 3.92 nm. The molecules are likely to be stabilized by main chain — side chain interactions. 

RHIZOBIUM TRIFOLII CAFSULAR FOLYSACCHARIDE. This polysaccharide is very unusual in that it has a doubly branched, neutral hexasaccharide repeating unit (25) shown below. 

Figure 1. An x-ray diffraction pattern from an oriented, noncrystalline fiber of the Rhizobium trifolii capsular polysaccharide using CuKa radiation. (Reproduced with permission from Ref. 16. Copyright 1987 Gordon and Breach.)...

Djordjevic, M.A. et al., Clovers secrete compounds which either stimulate or repress nod gene function in Rhizobium trifolii, EMBO J., 6, 1173, 1987. 

Studies on the white clover -Rhizobium trifolii interaction are the most advanced. Trifoliin A, a lectin present in clover-seedling roots, binds hapten reversibly to carbohydrate antigens cross-reactive on the capsular polysaccharide of R. trifolii and clover epidermal-cells.244 A specific hapten that inhibits binding of trifoliin A to both surfaces is 2-deoxy-D-arabino-hexose.245 It has also been shown that levels of trifoliin A on root hairs decline with increasing concentrations of nitrate, in parallel to root-nodule development,246 and that lectin receptors are transient on R. trifolii, in a way coinciding with its capacity to be adsorbed to clover roots.247... 

Hollingsworth, R.I., Lill-Elghanian, D.A. Isolation and characterization of the unusual lipopolysaccharide component, 2-amino-2-deoxy-2-JV-(27-hydroxyoctacosanoyl)-3-0-(3-hydroxy-tetradecanoyl)-gluco-hexuronic acid, and its de-O-acylation product from the free lipid A of Rhizobium trifolii ANU843. J Biol Chem 264 (1989) 14039-14042. 

The structure (20) of the heptasaccharide repeating unit of an extracellular polysaccharide from Rhizobium trifolii has been established by a combination of methylation analysis, sequential oxidation, and elimination of oxidized... 

Figs. 2-4. Thin sections stained with uranium and lead of nodules from Trifolium repens infected with Rhizobium trifolii NZP 566. (Electron micrographs by courtesy of Pamela Lyttle-ton and Doug Hopcroft.)... 

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