Tyrosinase from &lt;i&gt;Rhizobium etli&lt;/i&gt; Is Involved in Nodulation Efficiency and Symbiosis-Associated Stress Resistance

Piñero, Silvia; Rivera, Javier; Romero, David; Cevallos, Miguel A.; Martı́nez, Alfredo; Bolívar, Francisco; Gosset, Guillermo

doi:10.1159/000103595

Cited by 41 publications

(22 citation statements)

References 65 publications

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“…The intracellular location of Rhizobium tyrosinase suggests that it plays the same role as Streptomyces MelD2 in protecting the cells from damage by phenolics. Consistent with this view, melA mutants of R. etli are more sensitive to H 2 O 2 , and less efficient in forming nodules [44]. Furthermore, E. coli expressing the R. etli melA gene exhibits increased resistance to p -hydroxybenzoic acid, vanillinic acid, and syringic acids, which are phenolics often present in the soil [44].…”

Section: Discussionmentioning

confidence: 87%

Extracellular and Intracellular Polyphenol Oxidases Cause Opposite Effects on Sensitivity of Streptomyces to Phenolics: A Case of Double-Edged Sword

Yang¹,

Chen²

2009

PLoS ONE

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Many but not all species of Streptomyces species harbour a bicistronic melC operon, in which melC2 encodes an extracellular tyrosinase (a polyphenol oxidase) and melC1 encodes a helper protein. On the other hand, a melC-homologous operon (melD) is present in all sequenced Streptomyces chromosomes and could be isolated by PCR from six other species tested. Bioinformatic analysis showed that melC and melD have divergently evolved toward different functions. MelD2, unlike tyrosinase (MelC2), is not secreted, and has a narrower substrate spectrum. Deletion of melD caused an increased sensitivity to several phenolics that are substrates of MelD2. Intracellularly, MelD2 presumably oxidizes the phenolics, thus bypassing spontaneous copper-dependent oxidation that generates DNA-damaging reactive oxygen species. Surprisingly, melC+ strains were more sensitive rather than less sensitive to phenolics than melC − strains. This appeared to be due to conversion of the phenolics by MelC2 to more hydrophobic and membrane-permeable quinones. We propose that the conserved melD operon is involved in defense against phenolics produced by plants, and the sporadically present melC operon probably plays an aggressive role in converting the phenolics to the more permeable quinones, thus fending off less tolerant competing microbes (lacking melD) in the phenolic-rich rhizosphere.

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Section: Discussionmentioning

confidence: 87%

Extracellular and Intracellular Polyphenol Oxidases Cause Opposite Effects on Sensitivity of Streptomyces to Phenolics: A Case of Double-Edged Sword

Yang¹,

Chen²

2009

PLoS ONE

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“…3A) was more beneficial than that of any single element and that the tripartite configuration ensured their cotransfer. Our preliminary bioinformatic analyses indicate that genes on region β encode enzymes (Mesci_2556, Mesci_2561, Mesci_2562) resembling those involved in melanin biosynthesis (36)(37)(38). However, the β region of ICEMlSym 2037 , although similarly sized to that of ICEMcSym 1271 , lacks this cluster, suggesting the specific gene complement on each region is not a conserved feature of tripartite ICEs.…”

Section: Discussionmentioning

confidence: 89%

Assembly and transfer of tripartite integrative and conjugative genetic elements

Haskett

Terpolilli

Bekuma

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Integrative and conjugative elements (ICEs) are ubiquitous mobile genetic elements present as "genomic islands" within bacterial chromosomes. Symbiosis islands are ICEs that convert nonsymbiotic mesorhizobia into symbionts of legumes. Here we report the discovery of symbiosis ICEs that exist as three separate chromosomal regions when integrated in their hosts, but through recombination assemble as a single circular ICE for conjugative transfer. Whole-genome comparisons revealed exconjugants derived from nonsymbiotic mesorhizobia received three separate chromosomal regions from the donor Mesorhizobium ciceri WSM1271. The three regions were each bordered by two nonhomologous integrase attachment (att) sites, which together comprised three homologous pairs of attL and attR sites. Sequential recombination between each attL and attR pair produced corresponding attP and attB sites and joined the three fragments to produce a single circular ICE, ICEMcSym 1271 . A plasmid carrying the three attP sites was used to recreate the process of tripartite ICE integration and to confirm the role of integrase genes intS, intM, and intG in this process. Nine additional tripartite ICEs were identified in diverse mesorhizobia and transfer was demonstrated for three of them. The transfer of tripartite ICEs to nonsymbiotic mesorhizobia explains the evolution of competitive but suboptimal N 2 -fixing strains found in Western Australian soils. The unheralded existence of tripartite ICEs raises the possibility that multipartite elements reside in other organisms, but have been overlooked because of their unusual biology. These discoveries reveal mechanisms by which integrases dramatically manipulate bacterial genomes to allow cotransfer of disparate chromosomal regions.integrative and conjugative elements | integrase | recombination | conjugation | symbiosis H orizontal gene transfer plays an instrumental role in prokaryotic evolution because it facilitates the rapid acquisition of complex phenotypic traits required for pathogenicity, symbiosis, metabolism, fitness, and antimicrobial resistance (1-8). Integrative and conjugative elements (ICEs) are an abundant class of conjugative elements in bacteria, but they are also the most recently recognized and least characterized (8,9). An ICE integrates site-specifically within the chromosome of its host and is flanked by a direct repeat sequence that demarcates the insertion site. Before transfer, site-specific recombination between the flanking sequences results in excision and circularization of the ICE and restoration of the host chromosome. A single-stranded DNA copy of the circularized ICE is then formed via rollingcircle replication and transferred to recipient cells via an ICEencoded conjugative type IV secretion system. Following delivery of the ICE to the recipient cell, the second DNA strand of the ICE is synthesized and the circularized ICE integrates sitespecifically into the recipient genome (10).Symbiosis islands are the largest documented ICEs and their transfer converts nonsymb...

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“…Bacteria usually produce either DOPA-or HGA-based melanins such as eumelanin or pyomelanin. Bacteria that produce DOPA-based melanin include Bacillus, Rhizobium, Streptomyces, and Marinomonas [12][13][14], whereas those that produce HGA-based pyomelanin include Pseudomonas aeurginosa, Vibrio, Shewanella, Xanthomonas, and Burkholderia [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Identification of a Gene Involved in the Negative Regulation of Pyomelanin Production in Ralstonia solanacearum

Ahmad

Lee

Khan

et al. 2017

Journal of Microbiology and Biotechnology

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Ralstonia solanacearum causes bacterial wilt in a wide variety of host plant species and produces a melanin-like blackish-brown pigment in stationary phase when grown in minimal medium supplemented with tyrosine. To study melanin production regulation in R. solanacearum, five mutants exhibiting overproduction of melanin-like pigments were selected from a transposon (Tn) insertion mutant library of R. solanacearum SL341. Most of the mutants, except one (SL341T), were not complemented by the original gene or overproduced melanins. SL341T showed Tn insertion in a gene containing a conserved domain of eukaryotic transcription factor. The gene was annotated as a hypothetical protein, given its weak similarity to any known proteins. Upon complementation with its original gene, the mutant strains reverted to their wild-type phenotype. SL341T produced 3-folds more melanin at 72 h post-incubation compared with wild-type SL341 when grown in minimal medium supplemented with tyrosine. The chemical analysis of SL341T cultural filtrate revealed the accumulation of a higher amount of homogentisate, a major precursor of pyomelanin, and a lower amount of dihydroxyphenylalanine, an intermediate of eumelanin, compared with SL341. The expression study showed a relatively higher expression of hppD (encoding hydroxyphenylpyruvate dioxygenase) and lower expression of hmgA (encoding homogentisate dioxygenase) and nagL (encoding maleylacetoacetate isomerase) in SL341T than in SL341. SL341 showed a significantly higher expression of tyrosinase gene compared with SL341T at 48 h post-incubation. These results indicated that R. solanacearum produced both pyomelanin and eumelanin, and the novel hypothetical protein is involved in the negative regulation of melanin production.

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Tyrosinase from <i>Rhizobium etli</i> Is Involved in Nodulation Efficiency and Symbiosis-Associated Stress Resistance

Cited by 41 publications

References 65 publications

Extracellular and Intracellular Polyphenol Oxidases Cause Opposite Effects on Sensitivity of Streptomyces to Phenolics: A Case of Double-Edged Sword

Extracellular and Intracellular Polyphenol Oxidases Cause Opposite Effects on Sensitivity of Streptomyces to Phenolics: A Case of Double-Edged Sword

Assembly and transfer of tripartite integrative and conjugative genetic elements

Identification of a Gene Involved in the Negative Regulation of Pyomelanin Production in Ralstonia solanacearum

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