Mimosine, a toxin produced by the tree-legume leucaena provides a nodulation competition advantage to mimosine-degrading rhizobium strains

Soedarjo, Muchdar; Borthakur, Dulal

doi:10.1016/s0038-0717(97)00180-6

Cited by 59 publications

(42 citation statements)

References 25 publications

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“…It was previously shown that mutations in genes responsible for the catabolism of carbon sources, such as rhamnose and myoinositol, and other used nutrients, such as mimosine, are correlated with a decreased ability to compete for nodule occupancy (47)(48)(49)(50). Therefore, we investigated if the presence of the oxalate catabolic pathway could represent a competitive advantage for nodulation occupancy on all host plants.…”

Section: Resultsmentioning

confidence: 99%

A Link between Arabinose Utilization and Oxalotrophy in Bradyrhizobium japonicum

Koch

Delmotte

Ahrens

et al. 2014

Appl Environ Microbiol

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cRhizobia have a versatile catabolism that allows them to compete successfully with other microorganisms for nutrients in the soil and in the rhizosphere of their respective host plants. In this study, Bradyrhizobium japonicum USDA 110 was found to be able to utilize oxalate as the sole carbon source. A proteome analysis of cells grown in minimal medium containing arabinose suggested that oxalate oxidation extends the arabinose degradation branch via glycolaldehyde. A mutant of the key pathway genes oxc (for oxalyl-coenzyme A decarboxylase) and frc (for formyl-coenzyme A transferase) was constructed and shown to be (i) impaired in growth on arabinose and (ii) unable to grow on oxalate. Oxalate was detected in roots and, at elevated levels, in root nodules of four different B. japonicum host plants. Mixed-inoculation experiments with wild-type and oxc-frc mutant cells revealed that oxalotrophy might be a beneficial trait of B. japonicum at some stage during legume root nodule colonization.

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Section: Resultsmentioning

confidence: 99%

A Link between Arabinose Utilization and Oxalotrophy in Bradyrhizobium japonicum

Koch

Delmotte

Ahrens

et al. 2014

Appl Environ Microbiol

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“…A number of mutations that affect competition for nodule occupancy have been reported in the literature (Aneja et al, 2005;Fry et al, 2001;Jiménez-Zurdo et al, 1995;Oresnik et al, 1998;Phillips et al, 1998;Rosenblueth et al, 1998;Soedarjo & Borthakur, 1998;Streit et al, 1996). The magnitude of these phenotypes appears to vary from severe to statistically significant but subtle.…”

Section: Discussionmentioning

confidence: 99%

Sinorhizobium meliloti pSymB carries genes necessary for arabinose transport and catabolism

et al. 2007

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Arabinose is a known component of plant cell walls and is found in the rhizosphere. In this work, a previously undeleted region of the megaplasmid pSymB was identified as encoding genes necessary for arabinose catabolism, by Tn5-B20 random mutagenesis and subsequent complementation. Transcription of this region was measured by b-galactosidase assays of Tn5-B20 fusions, and shown to be strongly inducible by arabinose, and moderately so by galactose and seed exudate. Accumulation of [ 3 H]arabinose in mutants and wild-type was measured, and the results suggested that this operon is necessary for arabinose transport. Although catabolite repression of the arabinose genes by succinate or glucose was not detected at the level of transcription, both glucose and galactose were found to inhibit accumulation of arabinose when present in excess. To determine if glucose was also taken up by the arabinose transport proteins, [ 14 C]glucose uptake rates were measured in wild-type and arabinose mutant strains. No differences in glucose uptake rates were detected between wild-type and arabinose catabolism mutant strains, indicating that excess glucose did not compete with arabinose for transport by the same system. Arabinose mutants were tested for the ability to form nitrogen-fixing nodules on alfalfa, and to compete with the wild-type for nodule occupancy. Strains unable to utilize arabinose did not display any symbiotic defects, and were not found to be less competitive than wild-type for nodule occupancy in co-inoculation experiments. Moreover, the results suggest that other loci are required for arabinose catabolism, including a gene encoding arabinose dehydrogenase.

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“…Our results show that the decrease in mimosine content and the increase in its major degradation product 3H4P at 70°C were not associated with the overexpression of mimosinase; therefore, it is possible that exposure of intact leaf to 70°C might have caused damage to the chloroplast membrane, resulting in the release of mimosinase to the cytoplasm, where it degraded mimosine into 3H4P. L. leucocephala leaves contain ample amounts of mimosine, comprising 3% to 5% of plant dry weight (Soedarjo and Borthakur, 1998).…”

Section: Discussionmentioning

confidence: 68%

“…Leucaena leucocephala is an important agroforestry tree legume of the tropics, and its foliage can be used as a protein-rich fodder (Garcia et al, 1996;Soedarjo and Borthakur, 1998). L. leucocephala is highly tolerant to drought (Shelton and Brewbaker, 1994) and resistant to many pests and diseases.…”

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confidence: 99%

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A Carbon-Nitrogen Lyase from Leucaena leucocephala Catalyzes the First Step of Mimosine Degradation

Negi

Bingham

et al. 2013

Plant Physiology

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The tree legume Leucaena leucocephala contains a large amount of a toxic nonprotein aromatic amino acid, mimosine, and also an enzyme, mimosinase, for mimosine degradation. In this study, we isolated a 1,520-bp complementary DNA (cDNA) for mimosinase from L. leucocephala and characterized the encoded enzyme for mimosine-degrading activity. The deduced amino acid sequence of the coding region of the cDNA was predicted to have a chloroplast transit peptide. The nucleotide sequence, excluding the sequence for the chloroplast transit peptide, was codon optimized and expressed in Escherichia coli. The purified recombinant enzyme was used in mimosine degradation assays, and the chromatogram of the major product was found to be identical to that of 3-hydroxy-4-pyridone (3H4P), which was further verified by electrospray ionization-tandem mass spectrometry. The enzyme activity requires pyridoxal 59-phosphate but not a-keto acid; therefore, the enzyme is not an aminotransferase. In addition to 3H4P, we also identified pyruvate and ammonia as other degradation products. The dependence of the enzyme on pyridoxal 59-phosphate and the production of 3H4P with the release of ammonia indicate that it is a carbon-nitrogen lyase. It was found to be highly efficient and specific in catalyzing mimosine degradation, with apparent K m and V max values of 1.16 3 10 24 M and 5.05 3 10 25 mol s 21 mg 21 , respectively. The presence of other aromatic amino acids, including L-tyrosine, L-phenylalanine, and L-tryptophan, in the reaction did not show any competitive inhibition. The isolation of the mimosinase cDNA and the biochemical characterization of the recombinant enzyme will be useful in developing transgenic L. leucocephala with reduced mimosine content in the future.

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Mimosine, a toxin produced by the tree-legume leucaena provides a nodulation competition advantage to mimosine-degrading rhizobium strains

Cited by 59 publications

References 25 publications

A Link between Arabinose Utilization and Oxalotrophy in Bradyrhizobium japonicum

A Link between Arabinose Utilization and Oxalotrophy in Bradyrhizobium japonicum

Sinorhizobium meliloti pSymB carries genes necessary for arabinose transport and catabolism

A Carbon-Nitrogen Lyase from Leucaena leucocephala Catalyzes the First Step of Mimosine Degradation

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