Proteolytic processing of polyphenol oxidase from plants and fungi

Flurkey, William H.; Inlow, Jennifer K.

doi:10.1016/j.jinorgbio.2008.08.007

Cited by 84 publications

(91 citation statements)

References 73 publications

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“…Flurkey and Inlow (2008) identified an N-terminal and a C-terminal processing site in the PPO protein. They suggested that cleavage at these sites exposed an N-terminal tyrosine residue and a C-terminal arginine residue which interact to stabilize the protein secondary structure.…”

Section: Biochemistry Of Oxidative Discolourationmentioning

confidence: 99%

Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life

et al. 2017

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Lettuce discolouration is a key post-harvest trait. The major enzyme controlling oxidative discolouration has long been considered to be polyphenol oxidase (PPO) however, levels of PPO and subsequent development of discolouration symptoms have not always correlated. The predominance of a latent state of the enzyme in plant tissues combined with substrate activation and contemporaneous suicide inactivation mechanisms are considered as potential explanations for this phenomenon. Leaf tissue physical properties have been associated with subsequent discolouration and these may be influenced by variation in nutrient availability, especially excess nitrogen and head maturity at harvest. Mild calcium and irrigation stress has also been associated with a reduction in subsequent discolouration, although excess irrigation has been linked to increased discolouration potentially through leaf physical properties. These environmental factors, including high temperature and UV light intensities, often have impacts on levels of phenolic compounds linking the environmental responses to the biochemistry of the PPO pathway. Breeding strategies targeting the PAL and PPO pathway biochemistry and environmental response genes are discussed as a more cost-effective method of mitigating oxidative discolouration then either modified atmosphere packaging or post-harvest treatments, although current understanding of the biochemistry means that such programs are likely to be limited in nature and it is likely that they will need to be deployed alongside other methods for the foreseeable future.Keywords Lettuce Á Discolouration Á Biochemistry Á Environment Á Polyphenols Á Phenylpropanoid pathway Á Review The value of lettuceThe UK processed salad sector was valued at approximately £848 million in

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Section: Biochemistry Of Oxidative Discolourationmentioning

confidence: 99%

Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life

et al. 2017

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“…10,5052 This suggests that the pro-form of plant catechol oxidases are subject to an analogous processing during maturation. 51 …”

Section: Activation Of Pro-tyrosinase By Proteolytic Treatmentmentioning

confidence: 99%

Controlling Dicopper Protein Functions

Fujieda¹,

Itoh²

2016

Bulletin of the Chemical Society of Japan

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Maturation processes of dinuclear copper proteins such as tyrosinase, catechol oxidase, and hemocyanin have been a long-standing mystery in copper protein chemistry. Until now, several crystal structures have revealed that these copper proteins share a similar dinuclear copper active site, where each copper ion is ligated by three histidine imidazoles, and binds molecular oxygen in a side-on fashion to form a (¯-η 2 :η 2 -peroxido)dicopper(II) species not only as the dioxygen-adduct in oxy-hemocyanins but also as the key reactive intermediate for the hydroxylation of phenols to catechols (phenolase reaction) and the oxidation of catechols to o-quinones (catecholase reaction) in tyrosinases and catechol oxidases. Recently, we have succeeded in determining the high-resolution crystal structures of the recombinant pro-form of yellow koji mold tyrosinase to find the existence of a distinct C-terminal domain containing a CXXC unit, that is the common sequence motif of the copper chaperons. Thus, the C-terminal domain apparently acts as a copper chaperon, helping construction of the dinuclear copper active site of tyrosinase. Furthermore, we have found that the proteolytic cleavage of the C-terminal domain from the pro-form (inactive-form) of tyrosinase greatly enhances the tyrosinase activity, thus suggesting that the Cterminal domain also acts as a shielding domain to regulate the enzymatic activity. In fact, overall structure of the pro-form resembles the structure of one of the functional units of octopus hemocyanin (oxygen carrier protein), which also has a similar C-terminal domain prohibiting the monooxygenase activity. On the basis of these results together with the detailed kinetic and spectroscopic analyses, the maturation process of the dinuclear copper proteins is discussed to provide new insights into the regulation mechanism of the dicopper protein functions; dioxygen binding and activation. We have also succeeded in evolving phenolase activity from molluscan and arthropod hemocyanins by treating them with a hydrolytic enzyme or an acid, and demonstrated that the reaction mechanism of their phenolase activity is the same to that of tyrosinase itself, that is the electrophilic aromatic substitution mechanism. Furthermore, we have developed an artificial dicopper protein exhibiting catecholase activity using metallo-β-lactamase, a dinuclear zinc enzyme, as a metal binding platform.

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“…This showed existence of 4 isoenzymes constituent rated PPO 1 , PPO 2 , PPO 3 and PPO 4 in studied cultivars. When plants were stressed (elicitation and / or inoculation with pathogen), 7 new forms were induced: PPO 5 , PPO 6 , PPO 7 , PPO 8 , PPO 9 , PPO 10 and PPO 11 . Indeed, in yacé, 4 distinct bands representing different forms of PPO were revealed (Figure 1).…”

Section: Native-page Of Polyphenol Oxidasesmentioning

confidence: 99%

“…These results show that increase of PPO isoenzymes was responsible for amplitude of their activity. In many plant tissues, increasing PPO genes in response to hormones related to defense such as salicylic acid and jasmonic acid is implicitly linked to the resistance of these pathogens [2] [11]. In cassava, induced isoenzymes identified were specific to cultivars.…”

Section: Polyphenol Oxidases Activitiesmentioning

confidence: 99%

“…Thus, in cassava processing plants by salicylic acid and phosphorous acid, similar responses were evoked [9] [10]. Therefore, Flurkey and Inlow [11] show that induction of PPO genes in response to plant hormones clearly suggests that these enzymes are released during plant resistance. Based on these results, PPO can be mentioned as marker for plant defenses.…”

Section: Introductionmentioning

confidence: 99%

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Salicylic Acid, Phosphorous Acid and Fungicide Sumi 8 Effects on Polyphenol Oxidases Activities and Cassava Resistance to Anthracnose

Gogbeu¹

2015

AJAF

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Abstract:In Côte d'Ivoire, cassava contributes enormously to improve food security of population by increasing national production and financial resources of vulnerable households. But, plant is attacked by several diseases including anthracnose. This study was done to improve its resistance to anthracnose by stimulating its natural defense following treatment plants with salicylic acid, phosphorous acid and fungicide Sumi 8 as elicitors. Polyphenol oxidases were chosen as resistance marker. Results showed that in the three cultivars (yacé, TMS30572 and I88/00158), yacé was more susceptible to anthracnose (p<0.05; F = 6.83). After treatments, cassava resistance against anthracnose has been improved. Polyphenol oxidases activities were more stimulated in presence of elicitor's phosphorous acid and salicylic acid. Native-PAGE of polyphenol oxidases revealed 11 isoenzymes including 7 new isoenzymes detected in elicited plants, treated plants contaminated or uncontaminated by Colletotrichum gloeosporioïdes, pathogen of anthracnose. Recent isoenzymes were specific for each cultivar. Their appearance was correlated with plant resistance to C. gloeosporioïdes. In these plants, in particular those germinated directly in elicitation medium, anthracnose symptoms were lessened. These elicitors were thus induced and/or stimulated cassava defense especially polyphenol oxidases activities.

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Proteolytic processing of polyphenol oxidase from plants and fungi

Cited by 84 publications

References 73 publications

Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life

Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life

Controlling Dicopper Protein Functions

Salicylic Acid, Phosphorous Acid and Fungicide Sumi 8 Effects on Polyphenol Oxidases Activities and Cassava Resistance to Anthracnose

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