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Hooper, Alan B.; Vannelli, Todd; Bergmann, David; Arciero, David M.

doi:10.1023/a:1000133919203

Cited by 311 publications

(83 citation statements)

References 77 publications

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“…There are often multiple copies of these pmo genes in methanotrophs (78,79). Recent studies have shown that native pMMO forms a complex with methanol dehydrogenase (MeDH), which may supply electrons to the pMMO (80,81), similar to what has been found for the hydroxylamine oxidoreductase and ammonia monooxygenase redox couples (82)(83)(84)(85).…”

Section: Physiology and Biochemistry Of Methanotrophsmentioning

confidence: 84%

Methanobactin and the Link between Copper and Bacterial Methane Oxidation

DiSpirito

Semrau

Murrell

et al. 2016

Microbiol Mol Biol Rev

127

157

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SUMMARYMethanobactins (mbs) are low-molecular-mass (<1,200 Da) copper-binding peptides, or chalkophores, produced by many methane-oxidizing bacteria (methanotrophs). These molecules exhibit similarities to certain iron-binding siderophores but are expressed and secreted in response to copper limitation. Structurally, mbs are characterized by a pair of heterocyclic rings with associated thioamide groups that form the copper coordination site. One of the rings is always an oxazolone and the second ring an oxazolone, an imidazolone, or a pyrazinedione moiety. The mb molecule originates from a peptide precursor that undergoes a series of posttranslational modifications, including (i) ring formation, (ii) cleavage of a leader peptide sequence, and (iii) in some cases, addition of a sulfate group. Functionally, mbs represent the extracellular component of a copper acquisition system. Consistent with this role in copper acquisition, mbs have a high affinity for copper ions. Following binding, mbs rapidly reduce Cu2+to Cu1+. In addition to binding copper, mbs will bind most transition metals and near-transition metals and protect the host methanotroph as well as other bacteria from toxic metals. Several other physiological functions have been assigned to mbs, based primarily on their redox and metal-binding properties. In this review, we examine the current state of knowledge of this novel type of metal-binding peptide. We also explore its potential applications, how mbs may alter the bioavailability of multiple metals, and the many roles mbs may play in the physiology of methanotrophs.

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Section: Physiology and Biochemistry Of Methanotrophsmentioning

confidence: 84%

Methanobactin and the Link between Copper and Bacterial Methane Oxidation

DiSpirito

Semrau

Murrell

et al. 2016

Microbiol Mol Biol Rev

127

157

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“…Ammonia oxidizing bacteria (AOB) in the nitrifying activated sludge are able to degrade a range of aromatic compounds due to its nonspecific enzyme ammonium monooxygenase (AMO) [10,11], following cometabolism in the obligatory presence of a growth substrate such as ammonium [12]. AMO was capable of oxidizing a broad range of aromatic substrates [10,13], probably due to the mechanism of reaction with oxygenated form of AMO [14]. On the other hand, heterotrophs also showed the ability to degrade some pharmaceuticals (ketoprofen, acetaminophen) following metabolic biodegradation pathways [15,16].…”

Section: Introductionmentioning

confidence: 99%

Biodegradation of atenolol by an enriched nitrifying sludge: Products and pathways

Radjenović

Yuan

et al. 2017

Chemical Engineering Journal

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Biodegradation of β-blocker atenolol was investigated using an enriched nitrifying culture at controlled ammonium concentration and without ammonium addition. Analysis of the kinetics and structural elucidation of biodegradation products showed that atenolol biodegradation was found to be linked to the activity of nitrifying bacteria in the presence of ammonium. Atenolol was degraded cometabolically by ammonia-oxidizing bacteria (AOB), likely due to a broad substrate range of ammonia monooxyenase (AMO). Four products were formed during atenolol biodegradation with ammonia oxidation, including P267 (atenolol acid) and three new products P117 (1-isopropylamino-2-propanol), P167 (1-amino-3-phenoxy-2-propanol), and an unknown product P227 with a nominal molecular mass of 227. In comparison, only P267 and P227 were identified during atenolol biodegradation without ammonia oxidation. Follow-up experiments using atenolol acid as the parent compound indicated the formation of products P117, P167 and P227 in the presence of ammonium. Based on the products identified, a tentative biodegradation pathway of atenolol is suggested, which involves two steps independent of the presence of ammonium: i) microbial amide-bond hydrolysis to carboxyl group and formation of P267 (atenolol acid) and ii) a possible formation of P227 with its unidentified structure and other two cometabolically induced reactions: iii) breakage of ether bond in the alkyl side chain and formation of P117 and iv) a minor pathway through N-dealkylation and loss of acetamide moiety from the aromatic ring, yielding P167. This study provided an important insight regarding the biotransformation pathways under different metabolic conditions.

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“…AMO, a membrane-bound enzyme, catalyzes the oxidation of ammonia in the reaction NH 3 + O 2 + 2e -+ 2H + f NH 2 OH + H 2 O. HAO, a soluble enzyme found in the periplasm, catalyzes the reaction NH 2 OH + H 2 O f NO 2 -+ 4e -+ 5H + , as well as the oxidation of hydrazine to dinitrogen (2,3). The reducing equivalents generated in the oxidation of hydroxylamine are the starting point for essential electron transfer to the tetraheme cytochrome c 554 , ubiquinone, a bc 1 complex, and cytochrome oxidase processes leading to ATP synthesis, reverse electron flow to NADP + , and return of electrons to the primary monooxygenase reaction (1). An HAO with very similar molecular and catalytic properties is found in the organism responsible for anaerobic ammonium oxidation where the growthsupporting reaction is NH 4 + + NO 2 -f N 2 + 2H 2 O with hydrazine as intermediate (4).…”

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confidence: 99%

Spectroscopic Characterization of the NO Adduct of Hydroxylamine Oxidoreductase

et al. 2002

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Hydroxylamine oxidoreductase (HAO) from the autotrophic nitrifying bacterium Nitrosomonas europaea catalyzes the oxidation of NH 2 OH to NO 2 -. The enzyme contains eight hemes per subunit which participate in catalysis and electron transport. NO is found to bind to the enzyme and inhibit electron flow to the acceptor protein, cytochrome c 554 . NO is found to oxidize either partially or fully reduced HAO, but NO will not reduce ferric HAO. Since NO can be reduced but not oxidized to product by HAO, NO is not considered to be a long-lived intermediate in the catalytic mechanism. Substrate oxidation occurs in the presence of bound NO or cyanide, suggesting a second interaction site for substrate with HAO and providing a means for recovery of the NO-inhibited form of the enzyme. Upon addition of NO to oxidized HAO, the integer-spin EPR signal from the active site vanishes, an IR band from NO appears at 1920 cm -1 , and a diamagnetic quadrupole iron doublet appears in Mössbauer spectroscopy with δ ) 0.06 mm/s and ∆Eq ) 2.1 mm/s. The NO stretching frequency and Mössbauer parameters are characteristic of an {FeNO} 6 heme complex. New Mössbauer data on ferric myoglobin-NO are also presented for comparison. The results indicate that NO binds to heme P460 and that the loss of the integer-spin EPR signal is due to the conversion of heme P460 to a diamagnetic S ) 0 state and concomitant loss of magnetic interaction with neighboring heme 6. In previous studies where the heme P460-heme 6 interaction was affected by substrate or cyanide binding, a signal attributable to heme 6 was not observable. In contrast, in this work, the NO-induced loss of the signal is accompanied by the appearance of a previously unobserved large g max (or HALS) low-spin EPR signal from heme 6.

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Abstract: The enzymes which catalyze the oxidation of ammonia to nitrite by autotrophic bacteria are reviewed. A comparison is made with enzymes which catalyze the same reactions in methylotrophs and organotrophic heterotrophic bacteria.

Cited by 311 publications

References 77 publications

Methanobactin and the Link between Copper and Bacterial Methane Oxidation

Methanobactin and the Link between Copper and Bacterial Methane Oxidation

Biodegradation of atenolol by an enriched nitrifying sludge: Products and pathways

Spectroscopic Characterization of the NO Adduct of Hydroxylamine Oxidoreductase

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