Heterologous expression of NodZ and NoIL proteins in Rhizobium leguminosarum by. viciae led to the production of acetyl fucosylated lipo-chitin oligosaccharides (LCOs), indicating that the NoIL... Show moreHeterologous expression of NodZ and NoIL proteins in Rhizobium leguminosarum by. viciae led to the production of acetyl fucosylated lipo-chitin oligosaccharides (LCOs), indicating that the NoIL protein obtained from Mesorhizobium loti functions as an acetyl transferase. We show that the NoIL-dependent acetylation is specific for the fucosyl penta-N-acetylglucosamine species. In addition, the NoIL protein caused elevated production of LCOs, Efficient nodulation of Lotus japonicus by the NodZ/NoIL-producing strain was demonstrated. Nodulation efficiency was further improved by the addition of the ethylene inhibitor L-alpha-(2-aminoethoxyvinyl) glycine (AVG). Show less
Bloemberg, G.V.; Kamst, E.; Harteveld, M.; Drift, K.M.G.M. van der; Haverkamp, J.; Thomas-Oates, J.E.; ... ; Spaink, H.P. 1995
Previously, we have shown that the nodE gene is a major determinant of the difference in host range between Rhizobium leguminosarum biovars viciae and trifolii. A new genetic test system for... Show morePreviously, we have shown that the nodE gene is a major determinant of the difference in host range between Rhizobium leguminosarum biovars viciae and trifolii. A new genetic test system for stringent functional analysis of nodE genes was constructed. By testing chimeric nodE genes constructed by the exchange of poiymerase chain reaction (PCR)-generated restriction cassettes, we show that a central domain, containing only 44 non-conserved amino acid residues, determines the host specificity of the NodE protein (401 amino acid residues). Mass spectrometric analysis of the lipo-chitin oligosaccharides (LCOs) produced by the new test strain containing the biovar viciae nodE gene shows that molecules containing a polyunsaturated C18:4 (trans-2. trans-4. trans-6. cis-11-octadecatetraenoic) fatty acyl moiety are produced, as is the case for wild-type R. leguminosarum bv. viciae. The LCOs determined by the biovar trifolii nodE gene, which was overproduced in our test strain, carry C1 8:2 and C18:3 fatty acyl chains containing two or three conjugated trans double bonds, respectively. Therefore, the main difference between the nodE-determined LCOs of biovar viviae and trifolii in this system is the presence or absence of one cis double bond, resulting in the very different hydrophobicity of the LCOs. Using a newly developed spot application assay, we show that the 18:2- and C18:3-containing LCOs are able to induce the formation of nodule primordia on roots of Trifolium pratense. On the basis of these and other recent results, we propose that the host range of nodulation of the R. leguminosarum biovars viciae and trifolii is determined by the degree of hydrophobicity of the poly-unsaturated fatty acyl moieties of their LCOs, which is mediated by the host-specific central domain of the NodE protein. Show less
