Identification of alysA-Like Gene Required for Tabtoxin Biosynthesis and Pathogenicity inPseudomonas syringaepv.tabaciStrain PTBR2.024

Engst, K; Shaw, Paul D.

doi:10.1094/mpmi-5-322

Cited by 24 publications

(26 citation statements)

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“…In addition, the tabA gene of Pseudomonas syringae pv. tabaci involved in tabtoxin production [41] encodes a protein that ' utilises a substrate analogue of a compound in the lysine biosynthesis pathway ' [41] and also exhibits sequence similarity with ODC, ADC and DapDC. Unlike the mammalian ODC sequences, the Datura ODC does not possess the 3h terminal extension thought to be involved in rapid turnover of the ODC protein.…”

Section: Discussionmentioning

confidence: 99%

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Molecular cloning and functional identification of a plant ornithine decarboxylase cDNA

Michael

Furze

Rhodes

et al. 1996

Biochemical Journal

125

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A cDNA for a plant ornithine decarboxylase (ODC), a key enzyme in putrescine and polyamine biosynthesis, has been isolated from root cultures of the solanaceous plant Datura stramonium. Reverse transcription–PCR employing degenerate oligonucleotide primers representing conserved motifs from other eukaryotic ODCs was used to isolate the cDNA. The longest open reading frame potentially encodes a peptide of 431 amino acids and exhibits similarity to other eukaryotic ODCs, prokaryotic and eukaryotic arginine decarboxylases (ADCs), prokaryotic meso-diaminopimelate decarboxylases and the product of the tabA gene of Pseudomonas syringae cv. tabaci. Residues involved at the active site of the mouse ODC are conserved in the plant enzyme. The plant ODC does not possess the C-terminal extension found in the mammalian enzyme, implicated in rapid turnover of the protein, suggesting that the plant ODC may have a longer half-life. Expression of the plant ODC in Escherichia coli and demonstration of ODC activity confirmed that the cDNA encodes an active ODC enzyme. This is the first description of the primary structure of a eukaryotic ODC isolated from an organism where the alternative ADC route to putrescine is present.

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Section: Discussionmentioning

confidence: 99%

“…tabaci [41]. The first N-terminal 200 amino acids of the leishmanial ODC and the last 22 of the oat and last 19 amino acids of the E. coli ADCs have been removed to facilitate the comparison.…”

Section: Tabacimentioning

confidence: 99%

Molecular cloning and functional identification of a plant ornithine decarboxylase cDNA

Michael

Furze

Rhodes

et al. 1996

Biochemical Journal

125

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“…To confirm deletion of the tabtoxin production and resistance region, the NsiI fragment ( Fig. 2A), present in the contiguous 5.3-and 2.8-kb PvuII fragments conserved in all tabtoxin-producing strains (9,19), was cloned into pGEM-11zf(ϩ) to produce the plasmid designated pGN810. This construct failed to hybridize to DNA fragments obtained by EcoRI or HindIII digestion of genomic DNA from the mutant and separated by agarose gel electrophoresis (see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…A mutant lacking the region responsible for T␤L biosynthesis and T␤L resistance was examined initially because of evidence (9,26,34,40) suggesting a possible redundancy in genes encoding products that function in either T␤L or lysine biosynthesis. A region of more than 25 kb starting from about 10 kb upstream from the left EcoRI site and extending 15 kb downstream of that EcoRI site ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Approximately 3 kb of that region has been sequenced, and two genes (tabA and tblA), essential for T␤L production but with unknown functions, have been identified. The deduced tabA product has an amino acid sequence homologous to meso-DAP decarboxylase (the lysA gene product) characterized in other bacteria (9,32); however, tabA is unable to complement an Escherichia coli lysA mutant (9). The second gene, tblA, encodes a product with an amino acid sequence unrelated to those of known polypeptides (2).…”

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Characterization of dapB, a gene required by Pseudomonas syringae pv. tabaci BR2.024 for lysine and tabtoxinine-beta-lactam biosynthesis

Liu

Shaw

1997

J Bacteriol

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The dapB gene, which encodes L-2,3-dihydrodipicolinate reductase, the second enzyme of the lysine branch of the aspartic amino acid family, was cloned and sequenced from a tabtoxin-producing bacterium, Pseudomonas syringae pv. tabaci BR2.024. The deduced amino acid sequence shared 60 to 90% identity to known dapB gene products from gram-negative bacteria and 19 to 21% identity to the dapB products from gram-positive bacteria. The consensus sequence for the NAD(P)H binding site [(V/I)(A/G)(V/I)XGXXGXXG)] and the proposed substrate binding site (HHRHK) were conserved in the polypeptide. A BR2.024 dapB mutant is a diaminopimelate auxotroph and tabtoxin negative. The addition of a mixture of L-,L-, D,D-, and meso-diaminopimelate to defined media restored growth but not tabtoxin production. Cloned DNA fragments containing the parental dapB gene restored the ability to grow in defined media and tabtoxin production to the dapB mutant. These results indicate that the dapB gene is required for both lysine and tabtoxin biosynthesis, thus providing the first genetic evidence that the biosynthesis of tabtoxin proceeds in part along the lysine biosynthetic pathway. These data also suggest that L-2,3,4,5-tetrahydrodipicolinate is a common intermediate for both lysine and tabtoxin biosynthesis.Pseudomonas syringae pv. tabaci BR2.024, a plasmid-free derivative of strain BR2, is a tabtoxin-producing bacterium that causes wildfire disease on green beans (27, 31). Tabtoxin, a dipeptide, is not biologically active, but hydrolysis by peptidases produces tabtoxinine-␤-lactam (T␤L), the active toxin (22). Feeding studies with labeled precursors (26,34,40) indicated that carbons 1 to 6 of T␤L ( Fig. 1) are derived from aspartate and pyruvate, and labelling patterns led to speculation that the T␤L and lysine biosynthetic pathways may have common initial steps. Although lysine and diaminopimelic acid (DAP) are structurally related to T␤L (Fig. 1), label from these amino acids is not effectively incorporated into T␤L. The methyl group of methionine can provide the ␤-lactam carbonyl carbon. Unkefer et al. (40) suggested that the two pathways might diverge after L-dihydrodipicolinate (DHDPA). Reduction to L-2,3,4,5-tetrahydrodipicolinate (THDPA) by DapB (5) would lead to DAP, while hydration would place a hydroxyl group on the carbon that becomes carbon 5 of T␤L.All of the genes required for T␤L biosynthesis and resistance are located in a region of about 32 kb of the BR2 chromosome (19). Approximately 3 kb of that region has been sequenced, and two genes (tabA and tblA), essential for T␤L production but with unknown functions, have been identified. The deduced tabA product has an amino acid sequence homologous to meso-DAP decarboxylase (the lysA gene product) characterized in other bacteria (9, 32); however, tabA is unable to complement an Escherichia coli lysA mutant (9). The second gene, tblA, encodes a product with an amino acid sequence unrelated to those of known polypeptides (2). The transcription of tblA is positively regulated by ...

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Four‐Membered Heterocyclic Rings and Their Fused Derivatives

2015

Biosynthesis of Heterocycles

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Identification of alysA-Like Gene Required for Tabtoxin Biosynthesis and Pathogenicity inPseudomonas syringaepv.tabaciStrain PTBR2.024

Cited by 24 publications

References 0 publications

Molecular cloning and functional identification of a plant ornithine decarboxylase cDNA

Molecular cloning and functional identification of a plant ornithine decarboxylase cDNA

Characterization of dapB, a gene required by Pseudomonas syringae pv. tabaci BR2.024 for lysine and tabtoxinine-beta-lactam biosynthesis

Four‐Membered Heterocyclic Rings and Their Fused Derivatives

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