Towards the specification of consecutive steps in macrolecular lignin assembly

Nose, M.; Bernards, Mark A.; Furlan, Maysa; Zajíček, Jaroslav; Eberhardt, Thomas L.; Lewis, Norman

doi:10.1016/0031-9422(95)95268-y

Cited by 113 publications

(93 citation statements)

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“…Careful evaluation of the reported data revealed that only about 17% of this 'lignin' had been extracted from the tissues for analysis, and that the total contribution to the overall plant lignin from the dihydroconiferyl alcohol unit was < 5-6%. These data are much more in accord with the consequences of the infusion process resulting in the deployment of insoluble lignan oligomers, in which are incorporated the reduction products of dehydrodiconiferyl alcohol, as previously reported (80,137,and Chapter 25). Therefore, there appears to be no biochemical justification for identifying these substances as 'abnormal' lignins.…”

Section: Relationship Between Lignan and Lignin Biosynthetic Pathwayssupporting

confidence: 76%

“…Using lignin formation as an example, peroxidases (32,80,85,86), peroxidases and laccases (32,87,88), laccases (31,(89)(90)(91), (poly)phenol oxidases (92), coniferyl alcohol oxidase (93), and even cytochrome oxidases (94) have all been implicated. This has occurred primarily because of the large variety of oxidative enzymes with broad substrate specificity that exists in plants, to which the assignment of physiological function has unfortunately all too often been arbitrary.…”

Section: Oxidases and Peroxidases Involved In Lignificationmentioning

confidence: 99%

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Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lewis

Davin

Sarkanen

1998

ACS Symposium Series

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Before 1996, the framework within which lignin biosynthesis was understood at the molecular level had not fundamentally changed for 4 decades. During the same period nothing at all had been explicitly proposed about the mechanistic basis for lignan formation in vivo. The associated deficit in plant biochemistry was not minor: lignins and lignans together account for roughly 30% of the organic carbon in vascular plants. On the other hand, the biochemical transformations in phenylpropanoid metabolism leading, via the shikimate-chorismate pathway through phenylalanine or tyrosine, to the so-called monolignols (namely, the monomeric lignin/lignan precursors) came to be reasonably well documented. Indeed, attention has more recently been drawn to the identification of de facto rate-limiting steps in the various metabolic segments of the pathway as potential control-points for biotechnological manipulation. The most curious characteristic usually attributed to the lignin/lignan biosynthetic pathway is that the monolignol-derived radical coupling processes leading to lignans are regio-and stereospecific, whereas those resulting in lignin macromolecules ostensibly are not. Now that the molecular basis for the dehydrogenative dimerization of monolignols to lignans has been unraveled, however, it appears likely that an analogous mechanism may be operative in the dehydrogenative polymerization of monolignols to lignins. The investigation of this possibility has indeed become a central concern in the field of lignin biosynthesis.It has been almost three decades (7) since a comprehensive attempt had been made to summarize and evaluate contending views about lignin biosynthesis. Accordingly, the present volume draws together the current, yet conceptually vastly differing, ideas about how lignin composition and structure are established in living plants. It differs from all prior contributions, not only in introducing fresh evidence to support a compelling new paradigm that seeks to understand how lignin structure is established in vivo, but also in including lignan biosynthesis for comparative purposes. Indeed it appears that the first committed step in lignan biosynthesis bears an important relationship to the manner in which the configurations of lignins are specified in vivo.

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Section: Relationship Between Lignan and Lignin Biosynthetic Pathwayssupporting

confidence: 76%

Section: Oxidases and Peroxidases Involved In Lignificationmentioning

confidence: 99%

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lewis

Davin

Sarkanen

1998

ACS Symposium Series

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“…During culturing in liquid medium, micromolar levels of H 2 O 2 are detectable in the culture medium (Kärkönen and Fry, 2006;Kärkönen et al, 2009). The substantial scavenging of H 2 O 2 from the medium by KI (Huwiler et al, 1985;Nose et al, 1995; Fig. 2C) at a concentration of 5 mM prevented extracellular lignin formation ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…S1). Spruce callus cells maintained on a solid culture medium were transferred into liquid cultures with a concomitant decrease in 2,4-dichlorophenoxyacetic acid concentration (by 20-fold), and the nutrient medium was supplemented with potassium iodide (KI; 5 mM), an H 2 O 2 scavenger (Nose et al, 1995). Control cells treated with KCl (5 mM) or an equivalent volume of water (to ascertain that KI effects were due to iodide and not potassium) produced extracellular lignin after 5 d in liquid culture, visible as a fine, white precipitate in the culture medium (Figs.…”

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confidence: 99%

A Key Role for Apoplastic H₂O₂ in Norway Spruce Phenolic Metabolism

et al. 2017

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Apoplastic events such as monolignol oxidation and lignin polymerization are difficult to study in intact trees. To investigate the role of apoplastic hydrogen peroxide (H 2 O 2 ) in gymnosperm phenolic metabolism, an extracellular lignin-forming cell culture of Norway spruce (Picea abies) was used as a research model. Scavenging of apoplastic H 2 O 2 by potassium iodide repressed lignin formation, in line with peroxidases activating monolignols for lignin polymerization. Time-course analyses coupled to candidate substrate-product pair network propagation revealed differential accumulation of low-molecular-weight phenolics, including (glycosylated) oligolignols, (glycosylated) flavonoids, and proanthocyanidins, in lignin-forming and H 2 O 2 -scavenging cultures and supported that monolignols are oxidatively coupled not only in the cell wall but also in the cytoplasm, where they are coupled to other monolignols and proanthocyanidins. Dilignol glycoconjugates with reduced structures were found in the culture medium, suggesting that cells are able to transport glycosylated dilignols to the apoplast. Transcriptomic analyses revealed that scavenging of apoplastic H 2 O 2 resulted in remodulation of the transcriptome, with reduced carbon flux into the shikimate pathway propagating down to monolignol biosynthesis. Aggregated coexpression network analysis identified candidate enzymes and transcription factors for monolignol oxidation and apoplastic H 2 O 2 production in addition to potential H 2 O 2 receptors. The results presented indicate that the redox state of the apoplast has a profound influence on cellular metabolism.

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“…Since one of the most accepted functions for peroxidase is its role in the lignification of xylem vessels (Nose et al 1995;Otter & Polle 1997;Ros Barceló 1995, 1997, and since a NO synthase-like activity has been putatively localized in the vascular bundles of the root of Lupinus albus (Cueto et al 1996), we have studied the effect of some NO-releasing compounds, and of NO itself, on xylem peroxidase from Zinnia elegans. In addition, the effect of NO-releasing compounds on H 2 O 2 production by the lignifying xylem was also studied.…”

Section: Introductionmentioning

confidence: 99%

Differential effects of nitric oxide on peroxidase and H₂O₂ production by the xylem of Zinnia elegans

Ferrer

Barceló

1999

Plant Cell & Environment

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Sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) are two nitric oxide (NO)-releasing compounds that, when used at 5·0 mol m -3 concentrations, are capable of releasing NO in the aqueous phase at a rate of 35 ± 4 and 47 ± 5 µmol m -3 s -1 , respectively. For this reason, the effect of SNP and SNAP on coniferyl alcohol peroxidase and on H 2 O 2 production by the lignifying xylem of Zinnia elegans (L.) has been studied in order to ascertain whether NO, which is a synchronizing chemical messenger in animals and an air pollutant, has any effect on these plant-specific metabolic aspects. The results showed that both SNP and SNAP provoke an inhibition in the mol m -3 concentration range of the coniferyl alcohol peroxidase activity of a basic peroxidase isoenzyme present in the intercellular washing fluid of Z. elegans. The effect of these NO-releasing compounds on peroxidase was confirmed through histochemical studies, which showed that xylem peroxidase was totally inhibited by treatment with these NO donors at 5·0 mol m -3 , and by NO at a concentration change rate of 55 ± 5 and 110 ± 9 µmol m -3 s -1 . However, SNP, at 5·0 mol m -3 , does not have any effect on H 2 O 2 production by the xylem of Z. elegans. The fact that SNP and SNAP are two structurally dissimilar compounds which only share the common ability to release NO in aqueous buffer, and that similar results were obtained when using NO itself, suggest that NO could be considered as an inhibitor of coniferyl alcohol peroxidase which does not affect H 2 O 2 production in the xylem of Z. elegans.Key-words: Zinnia elegans; coniferyl alcohol oxidation; H 2 O 2 production; inhibition; nitric oxide; peroxidase; xylem.Abbreviations: IWF, intercellular washing fluid; pCMB, pchloromercuribenzoic acid; SNAP, S-nitroso-N-acetyl-penicillamine; SNP, sodium nitroprusside; TMB, 3,3',5,5'-tetramethylbenzidine. INTRODUCTIONNitric oxide (NO) is a paramagnetic relatively stable freeradical molecule involved in many physiological processes in animals, where it serves as a synchronizing chemical messenger involved in vasorelaxation, platelet inhibition, neurotransmission, cytotoxicity and immunoregulation (Anbar 1995). In animal cells, NO is synthesized by the enzyme NO synthase (Knowles 1997), and most of its biological regulatory properties have been explained on the basis of its capacity to act as an iron ligand in haemoproteins (Stamler, Singel & Loscalzo 1992). Dual (activating or inhibitory) effects of NO on haemoproteins have been described (Tsai 1994), and the nature of the effect has been suggested to depend to a great extent on the resting state (oxidation state) of the haemoprotein, which conditions the ligand properties and the electronic configuration of the haem iron (Tsai 1994). In the case of catalase, it has been shown that NO reversibly binds to the haem of catalase and inhibits H 2 O 2 breakdown with a K i of about 0·2 mmol m -3 (Brown et al. 1997).Evidence is emerging to support the possibility that NO may also act as chemical mess...

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Towards the specification of consecutive steps in macrolecular lignin assembly

Cited by 113 publications

References 29 publications

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

A Key Role for Apoplastic H₂O₂ in Norway Spruce Phenolic Metabolism

Differential effects of nitric oxide on peroxidase and H₂O₂ production by the xylem of Zinnia elegans

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Towards the specification of consecutive steps in macrolecular lignin assembly

Cited by 113 publications

References 29 publications

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

A Key Role for Apoplastic H2O2 in Norway Spruce Phenolic Metabolism

Differential effects of nitric oxide on peroxidase and H2O2 production by the xylem of Zinnia elegans

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Product

Resources

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A Key Role for Apoplastic H₂O₂ in Norway Spruce Phenolic Metabolism

Differential effects of nitric oxide on peroxidase and H₂O₂ production by the xylem of Zinnia elegans