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  • 1
    Electronic Resource
    Electronic Resource
    NodS is an S-adenosyl-l-methionine-dependent methyltransferase that methylates chitooligosaccharides deacetylated at the non-reducing end (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Scientific Publications
    Molecular microbiology 17 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In response to phenolic compounds exuded by the host plant, symbiotic Rhizobium bacteria produce signal molecules (Nod factors), consisting of lipochitooligosaccharides with strain-specific substitutions. In Azorhizobium caulinodans strain ORS571 these modifications are an O-arabinosyl group, an O-carbamoyl group, and an N-methyl group. Several lines of evidence indicate that the nodS gene located in the nodABCSUIJ operon is implicated in the methylation of Nod factors. Previously we have shown that NodS is an S-adenosyl-l-methionine (SAM)-binding protein, essential for the l-[3H-methyl]-methionine labelling of ORS571 Nod factors in vivo. Here, we present an in vitro assay showing that NodS from either A. caulinodans or Rhizobium species NGR234 methylates end-deacetylated chitooligosaccharides, using [3H-methyl]-SAM as a methyl donor. The enzymatic and SAM-binding activity were correlated with the nodS gene and localized within the soluble protein fraction. The A. caulinodans nodS gene was expressed in Escherichia coli and a glutathione-S-transferase—NodS fusion protein purified. This protein bound SAM and could methylate end-deacetylated chitooligosaccharides, but could not fully methylate acetylated chitooligosaccharides or unmethylated lipo-chitooligosaccharides. These data implicate that the methylation step in the biosynthesis pathway of ORS571 Nod factors occurs after deacetylation and prior to acylation of the chitooligosaccharides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_17020387.x
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  • 2
    Electronic Resource
    Electronic Resource
    Identification of nodSUIJ genes in Nod locus 1 of Azorhizobium caulinodans: evidence that nodS encodes a methyltransferase involved in Nod factor modification (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Azorhizobium caulinodans strain ORS571 nodu-lation genes nodSUIJ were located downstream from nodABC. Complementation data and transcriptional analysis suggest that nodABCSUIJ form a single operon. Mutants with Tn5 insertions in the genes nodS, nodU, and nodJ were delayed in nodulation of Sesbania rostrata roots and stems. The NodS amino acid sequences of ORS571, Bradyrhizobium japonicum, and Rhizobium sp. strain NGR234, contain a consensus with similarity to 5-adenosylmethionine (SAM)-utilizing methyltransferases. A naringenin-inducible nodS-dependent protein of approximately 25kDa could be cross-linked to radiolabelled SAM. By applying L-[methyl-3H]-methionine in vivo. Nod factors of ORS571, known to be N-methylated, could be labelled in wild type and nodU mutants but not in nodS mutants. Therefore, we propose that NodS is a SAM-utilizing methyltransferase involved in Nod factor synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01676.x
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  • 3
    Electronic Resource
    Electronic Resource
    Fucosylation and arabinosylation of Nod factors in Azorhizobium caulinodans: involvement of nolKnodZ as well as noeC and/or downstream genes (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The DNA region downstream of the nodABCSUIJ operon of Azorhizobium caulinodans was further characterized and two new genes, nodZ and noeC were identified in the same operon. The A. caulinodans wild-type strain produces a population of Nod factors that, at the reducing end, are either unmodified or carry a D-arabinosyl and/or an L-fucosyl branch. Nod factors produced by Tn5-insertion mutants in nodZnoeC, and the separate nolK locus, were analysed by thin-layer chromatography and mass spectrometry. Fucosylation of Nod factors depended on both nodZ and nolK. Arabinosylation depended on noeC and/or downstream genes. Protein extracts of A. caulinodans contained an enzymatic activity for fucose transfer from GDP-fucose to chitooligosaccharides and to Nod factors. By mutant analysis and expression of nodZ in Escherichia coli, the fucosyltransferase activity was ascribed to the protein encoded by nodZ. In addition, a Nod factor fucosyltransferase activity, independent of nodZ or other known nod genes, was detected in A. caulinodans. Finally, on the basis of sequence similarity of the nolK gene product, and mass spectrometric analysis of Nod factors produced by a nolK mutant, we propose that this gene is involved in the synthesis of GDP-fucose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.6451366.x
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    Paper (German National Licenses)
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