Phenylalanine Ammonia-Lyase

Hanson, Kenneth R.; Havir, Evelyn A.

doi:10.1016/b978-0-12-675407-0.50026-9

Cited by 55 publications

(64 citation statements)

References 180 publications

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“…therein). Enhanced biosynthesis, especially of 3-deoxycatechins after transient inhibition of flavanone 3-hydroxylase, correlated with improved resistance to pathogens, whereas decreased flavonoid levels after competitive inhibition of Phe ammonia-lyase, which initiates phenylpropanoid metabolism (Hanson and Havir, 1981), enhanced the susceptibility to pathogens. Recently, constitutive expression in cv Holsteiner Cox of the maize (Zea mays) regulatory leaf color (Lc) gene, which encodes a transcription factor, resulted in both increased transcript levels of flavonoid biosynthetic enzymes and increased concentrations of specific flavonoid classes, such as anthocyanins, flavan-3-ols, and proanthocyanidins (Li et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Differential Expression of Biphenyl Synthase Gene Family Members in Fire-Blight-Infected Apple ‘Holsteiner Cox’

Chizzali

Gaid²,

Belkheir³

et al. 2011

Plant Physiol.

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Fire blight, caused by the bacterium Erwinia amylovora, is a devastating disease of apple (Malus 3 domestica). The phytoalexins of apple are biphenyls and dibenzofurans, whose carbon skeleton is formed by biphenyl synthase (BIS), a type III polyketide synthase. In the recently published genome sequence of apple 'Golden Delicious', nine BIS genes and four BIS gene fragments were detected. The nine genes fall into four subfamilies, referred to as MdBIS1 to MdBIS4. In a phylogenetic tree, the BIS amino acid sequences from apple and Sorbus aucuparia formed an individual cluster within the clade of the functionally diverse type III polyketide synthases. cDNAs encoding MdBIS1 to MdBIS4 were cloned from fire-blight-infected shoots of apple 'Holsteiner Cox,' heterologously expressed in Escherichia coli, and functionally analyzed. Benzoyl-coenzyme A and salicoylcoenzyme A were the preferred starter substrates. In response to inoculation with E. amylovora, the BIS3 gene was expressed in stems of cv Holsteiner Cox, with highest transcript levels in the transition zone between necrotic and healthy tissues. The transition zone was the accumulation site of biphenyl and dibenzofuran phytoalexins. Leaves contained transcripts for BIS2 but failed to form immunodetectable amounts of BIS protein. In cell cultures of apple 'Cox Orange,' expression of the BIS1 to BIS3 genes was observed after the addition of an autoclaved E. amylovora suspension. Using immunofluorescence localization under a confocal laser-scanning microscope, the BIS3 protein in the transition zone of stems was detected in the parenchyma of the bark. Dot-shaped immunofluorescence was confined to the junctions between neighboring cortical parenchyma cells.

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Section: Discussionmentioning

confidence: 99%

Differential Expression of Biphenyl Synthase Gene Family Members in Fire-Blight-Infected Apple ‘Holsteiner Cox’

Chizzali

Gaid²,

Belkheir³

et al. 2011

Plant Physiol.

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“…Since we determined antioxidant properties and polyphenolics content of cyanobacterial extracts, it was pertinent to assess the activity of PAL enzyme which catalyzes the initial reaction of phenylpropanoid biosynthesis in plants (Hanson and Havir 1981). The activity of PAL is known to undergo dramatic changes in the cells under the conditions of biotic and abiotic stresses (Ronald and Soderhall 1985;Aydas et al 2013).…”

Section: Resultsmentioning

confidence: 99%

Antioxidant properties and polyphenolic content in terrestrial cyanobacteria

et al. 2017

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Cell-free extracts of twenty terrestrial cyanobacteria were evaluated for their antioxidant properties in terms of free-radical scavenging (DPPH and ABTS) and metal chelating activity and deoxyribose protection. Extract of Anabaena constricta was the most prominent antioxidant agent (IC 50 for DPPH activity 0.91 mg ml -1 , ABTS 0.23 mg ml -1 , deoxyribose protection 0.63 mg ml -1 and Fe ?2 -ion chelating 0.9 mg ml -1 ). The extracts of cyanobacterial species contained high quantity of total phenol and total flavonoid that were supposed to impart prominent antioxidant properties. Cyanobacterial species also showed fairly high PAL activity. We reported varied quantities of polyphenolics gallic, chlorogenic, caffeic, vanillic and ferulic acids and flavonoids rutin, quercetin and kaempferol in cyanobacterial extracts. The presence of these polyphenolics was linked with the free radical scavenging, metal chelating and antioxidative damage protecting properties of the organisms. Cyanobacteria are the most feasible, promising and alternative candidates for searching out new chemical leads for industrial applications in pharmaceuticals, neutraceuticals and biomolecules of importance. Presence of biomolecules such as polyphenolics and their connection with the prominent biological functions (e.g., antioxidant properties) make these organisms a potential source of secondary metabolites with predominant biological activities. Additionally, dominant presence of polyphenols as antioxidant agents in cyanobacterial species may reflect their adaptation strategies against abiotic stresses for their ecological success in different habitats.

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“…located downstream of the enzyme with the highest apparent K m for Phe was most sensitive to reduction in Phe level. The highest reduction was observed for phenylacetaldehyde, which is synthesized by PAAS, whose K m value (1.2 mM) is 17-to 80-fold higher than those of plant PALs (15 to 70 mM) (Hanson and Havir, 1981;Jorrin and Dixon, 1990;Appert et al, 1994;Cochrane et al, 2004;Kaminaga et al, 2006). By contrast, the least affected isoeugenol branch is located downstream of cinnamate 4-hydroxylase, which generally has a very low K m value toward cinnamic acid, ranging in plants from 2.5 to 9 mM (Gabriac et al, 1991;Koopmann et al, 1999;Hü bnera et al, 2003).…”

Section: Role Of Phe Levels In the Formation Of Phenylpropanoid/benzementioning

confidence: 99%

RNAi Suppression of Arogenate Dehydratase1 Reveals That Phenylalanine Is Synthesized Predominantly via the Arogenate Pathway in Petunia Petals

et al. 2010

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L-Phe, a protein building block and precursor of numerous phenolic compounds, is synthesized from prephenate via an arogenate and/or phenylpyruvate route in which arogenate dehydratase (ADT) or prephenate dehydratase, respectively, plays a key role. Here, we used Petunia hybrida flowers, which are rich in Phe-derived volatiles, to determine the biosynthetic routes involved in Phe formation in planta. Of the three identified petunia ADTs, expression of ADT1 was the highest in petunia petals and positively correlated with endogenous Phe levels throughout flower development. ADT1 showed strict substrate specificity toward arogenate, although with the lowest catalytic efficiency among the three ADTs. ADT1 suppression via RNA interference in petunia petals significantly reduced ADT activity, levels of Phe, and downstream phenylpropanoid/benzenoid volatiles. Unexpectedly, arogenate levels were unaltered, while shikimate and Trp levels were decreased in transgenic petals. Stable isotope labeling experiments showed that ADT1 suppression led to downregulation of carbon flux toward shikimic acid. However, an exogenous supply of shikimate bypassed this negative regulation and resulted in elevated arogenate accumulation. Feeding with shikimate also led to prephenate and phenylpyruvate accumulation and a partial recovery of the reduced Phe level in transgenic petals, suggesting that the phenylpyruvate route can also operate in planta. These results provide genetic evidence that Phe is synthesized predominantly via arogenate in petunia petals and uncover a novel posttranscriptional regulation of the shikimate pathway.

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Phenylalanine Ammonia-Lyase

Cited by 55 publications

References 180 publications

Differential Expression of Biphenyl Synthase Gene Family Members in Fire-Blight-Infected Apple ‘Holsteiner Cox’

Differential Expression of Biphenyl Synthase Gene Family Members in Fire-Blight-Infected Apple ‘Holsteiner Cox’

Antioxidant properties and polyphenolic content in terrestrial cyanobacteria

RNAi Suppression of Arogenate Dehydratase1 Reveals That Phenylalanine Is Synthesized Predominantly via the Arogenate Pathway in Petunia Petals

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