Lessons From Biodegradation

Dagley, S.

doi:10.1146/annurev.mi.41.100187.000245

Cited by 39 publications

(27 citation statements)

References 44 publications

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“…The formation of the intermediate resembling a C(4a)substituted flavin provides useful insight into the mechanism of this two-component enzyme. Although the intermediate spectrum observed in our experiments did not allow us to distinguish the type of species, it clearly indicated that the mechanism for the hydroxylation reaction proceeded via the formation of the C(4a)-hydroperoxy flavin and the (1). The fully reduced FMN spectrum is shown by a solid line (2).…”

Section: Discussionmentioning

confidence: 59%

“…The oxygenation of phenolic compounds is an important step in the biodegradation of synthethic or natural aromatic compounds. Catabolism of these compounds is often initiated by hydroxylase enzymes that incorporate hydroxyl groups into phenolic substrates resulting in catechol products [1]. Hydroxylations at positions ortho to the phenolic group are usually catalysed by aromatic flavoprotein hydroxylases containing FAD as the prosthetic group.…”

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confidence: 99%

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A novel two-protein component flavoprotein hydroxylase. p-Hydroxyphenylacetate hydroxylase from Acinetobacter baumannii

2001

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p-Hydroxyphenylacetate (HPA) hydroxylase (HPAH) was purified from Acinetobacter baumannii and shown to be a two-protein component enzyme. The small component (C 1 ) is the reductase enzyme with a subunit molecular mass of 32 kDa. C 1 alone catalyses HPA-stimulated NADH oxidation without hydroxylation of HPA. C 1 is a flavoprotein with FMN as a native cofactor but can also bind to FAD. The large component (C 2 ) is the hydroxylase component that hydroxylates HPA in the presence of C 1 . C 2 is a tetrameric enzyme with a subunit molecular mass of 50 kDa and apparently contains no redox centre. FMN, FAD, or riboflavin could be used as coenzymes for hydroxylase activity with FMN showing the highest activity. Our data demonstrated that C 2 alone was capable of utilizing reduced FMN to form the product 3,4-dihydroxyphenylacetate. Mixing reduced flavin with C 2 also resulted in the formation of a flavin intermediate that resembled a C(4a)-substituted flavin species indicating that the reaction mechanism of the enzyme proceeded via C(4a)-substituted flavin intermediates. Based on the available evidence, we conclude that the reaction mechanism of HPAH from A. baumannii is similar to that of bacterial luciferase. The enzyme uses a luciferase-like mechanism and reduced flavin (FMNH 2 , FADH 2 , or reduced riboflavin) to catalyse the hydroxylation of aromatic compounds, which are usually catalysed by FAD-associated aromatic hydroxylases.Keywords: aromatic hydroxylase; flavoprotein; monooxygenase; p-hydroxyphenylacetate; two-component enzyme.The oxygenation of phenolic compounds is an important step in the biodegradation of synthethic or natural aromatic compounds. Catabolism of these compounds is often initiated by hydroxylase enzymes that incorporate hydroxyl groups into phenolic substrates resulting in catechol products [1]. Hydroxylations at positions ortho to the phenolic group are usually catalysed by aromatic flavoprotein hydroxylases containing FAD as the prosthetic group. The hydroxylation reactions are mostly carried out on single polypeptide chains such as the reactions of p-hydroxybenzoate hydroxylase, phenol hydroxylase, salicylate hydroxylase, anthranilate hydroxylase, and 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase [2,3]. However, in the past decade, flavoenzymes catalysing aromatic hydroxylation reactions were found to consist of two proteins, such as the reaction of p-hydroxyphenylacetate (HPA) hydroxylase (HPAH) of Pseudomonas putida [4] and of Escherichia coli W [5], and pyrrole-2-carboxylate monooxygenase [6]. The gene encoding HPAH in Klebsiella pneumoniae also suggests that HPAH exists as a two-component enzyme in this species [7].Studies of P. putida HPAH have shown that FAD is tightly bound to the small component and the large component is a coupling protein that enables hydroxylation to occur [4]. The mechanism of P. putida HPAH is similar to the mechanism of other aromatic flavoprotein hydroxylases except that two proteins are required [8,9]. In contrast, studies of E. coli HPAH have show...

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Section: Discussionmentioning

confidence: 59%

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confidence: 99%

A novel two-protein component flavoprotein hydroxylase. p-Hydroxyphenylacetate hydroxylase from Acinetobacter baumannii

2001

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“…There may be several tens of millions of organic and inorganic compounds that could be bioremediated (Dagley 1987), but natural degradation pathways are known for only a few thousand. Understanding the complete metabolic pathways is necessary for at least two reasons.…”

Section: Metal Biodegradation Pathway Mapmentioning

confidence: 99%

Microbial Growth and Action: Implications for Passive Bioremediation of Acid Mine Drainage

2006

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Due to the variable environmental nature of mine water, several species of bacteria are important in the generation of acid mine drainage (AMD) and in bioremediation treatment technology. Enzymatic metal transport and transformation allow bacteria to survive in high-metal environments and to oxidize, reduce, and exude metals. For example, the enzymes Cr (VI) reductase and cytochrome-c3 hydrogenase allow Pseudomonas sp. to reduce Cr (VI) to less toxic Cr (III). Much more toxic organomercuric compounds are transformed by Pseudomonas fluorescens and Escherichia coli, using the enzymes organomercurial lyase and mercuric reductase. The role of bacteria in the AMD environment is not yet fully understood and consequently researchers should pay attention in this field.

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“…However, this is only a small fraction of the total metabolic capability likely to exist in the soils and waters of earth. Many of the more than 10 million organic compounds known are thought to be biodegradable (Dagley, 1987). As the number of chemical substances subjected to microbial catabolism is large (>10 6 ), a comparably large number of distinct enzymes and pathways must occur in nature.…”

Section: Narrowing the Biodegradation Knowledge Gapmentioning

confidence: 99%

“…Collectively, microorganisms possess the greatest enzymatic diversity found on earth and metabolize millions of organic compounds to capture chemical energy for growth. This metabolism, called catabolism or biodegradation, is the principal driving force in the degradative half of the earth's carbon cycle (Dagley, 1987). Microorganisms are increasingly used in engineered systems to biodegrade hazardous, xenobiotic compounds, an application commonly known as bioremediation (Alexander, 1994).…”

Section: Introductionmentioning

confidence: 99%

Predicting biodegradation

Wackett¹,

Ellis

1999

Environmental Microbiology

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SummaryBiodegradation is important for natural and industrial cycling of environmental chemicals. Industries and government regulators increasingly seek to know the fate of chemicals in the environment and thus prevent potential negative impacts on human or ecosystem health. However, millions of organic compounds are known, and most will remain unstudied with respect to biodegradation. This necessitates the development of organized biodegradation information coupled with predictive methods. Biodegradation prediction methods are being developed using the information contained in the University of Minnesota Biocatalysis/ Biodegradation database. Heuristic rules are derived from compiled biodegradation information. Additional rules are generated by deconstructing compounds into a set of the 40 most common organic functional groups. The rules consist of deriving biochemically plausible catabolic reactions for each of the functional groups. More complex compounds, containing multiple functional groups, are analysed using higher order rules requiring prioritizing enzymatic attack and reactions cleaving functional groups. While biodegradation prediction, like weather prediction, will never be perfect, it can be an important tool for guiding industry, regulators and experimentalists.

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Lessons From Biodegradation

Cited by 39 publications

References 44 publications

A novel two-protein component flavoprotein hydroxylase. p-Hydroxyphenylacetate hydroxylase from Acinetobacter baumannii

A novel two-protein component flavoprotein hydroxylase. p-Hydroxyphenylacetate hydroxylase from Acinetobacter baumannii

Microbial Growth and Action: Implications for Passive Bioremediation of Acid Mine Drainage

Predicting biodegradation

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