Molecular biology of microbial ureases.

Mobley, Harry L. T.; Island, Michael D.; Hausinger, Robert P.

doi:10.1128/mmbr.59.3.451-480.1995

Cited by 875 publications

(596 citation statements)

References 225 publications

(434 reference statements)

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“…For example, copper limitation decreases the activity of the copper-containing enzyme nitrous oxide reductase (NosZ) in denitrifiers (Granger and Ward, 2003). Likewise, nickel (Ni) incorporation is required for microbial synthesis of active urease enzymes (Mobley et al, 1995). Many AOB, including various Nitrosomonas, Nitrosospira and Nitrosococcus species, have Ni-containing urease enzymes and are capable of using urea for growth (Koper et al, 2004).…”

Section: Relationship Between Environmental Variables and Ammonia-oximentioning

confidence: 99%

Relative abundance and diversity of ammonia‐oxidizing archaea and bacteria in the San Francisco Bay estuary

Mosier¹,

Francis²

2008

Environmental Microbiology

351

356

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Ammonia oxidation in marine and estuarine sediments plays a pivotal role in the cycling and removal of nitrogen. Recent reports have shown that the newly discovered ammonia-oxidizing archaea can be both abundant and diverse in aquatic and terrestrial ecosystems. In this study, we examined the abundance and diversity of ammonia-oxidizing archaea (AOA) and betaproteobacteria (beta-AOB) across physicochemical gradients in San Francisco Bay--the largest estuary on the west coast of the USA. In contrast to reports that AOA are far more abundant than beta-AOB in both terrestrial and marine systems, our quantitative PCR estimates indicated that beta-AOB amoA (encoding ammonia monooxygenase subunit A) copy numbers were greater than AOA amoA in most of the estuary. Ammonia-oxidizing archaea were only more pervasive than beta-AOB in the low-salinity region of the estuary. Both AOA and beta-AOB communities exhibited distinct spatial structure within the estuary. AOA amoA sequences from the north part of the estuary formed a large and distinct low-salinity phylogenetic group. The majority of the beta-AOB sequences were closely related to other marine/estuarine Nitrosomonas-like and Nitrosospira-like sequences. Both ammonia-oxidizer community composition and abundance were strongly correlated with salinity. Ammonia-oxidizing enrichment cultures contained AOA and beta-AOB amoA sequences with high similarity to environmental sequences. Overall, this study significantly enhances our understanding of estuarine ammonia-oxidizing microbial communities and highlights the environmental conditions and niches under which different AOA and beta-AOB phylotypes may thrive.

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Section: Relationship Between Environmental Variables and Ammonia-oximentioning

confidence: 99%

Relative abundance and diversity of ammonia‐oxidizing archaea and bacteria in the San Francisco Bay estuary

Mosier¹,

Francis²

2008

Environmental Microbiology

351

356

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“…E. coli containing the cloned rocF gene from H. pylori exhibited arginase activity and this activity was markedly higher when heat-activated with cobalt rather than manganese Arginase and urease are both multisubunit, metal cofactor-containing enzymes [11,32]. E. coli can express urease activity when transformed with eight H. pylori genes: the ureABIEFGH genes in the H. pylori urease locus and the nixA nickel transporter [33,34].…”

Section: Characterization Of H Pylori Arginasementioning

confidence: 99%

Purification and characterization of Helicobacter pylori arginase, RocF: unique features among the arginase superfamily

McGee

Zabaleta

Viator

et al. 2004

European Journal of Biochemistry

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The urea cycle enzyme arginase (EC 3.5.3.1) hydrolyzes l‐arginine to l‐ornithine and urea. Mammalian arginases require manganese, have a highly alkaline pH optimum and are resistant to reducing agents. The gastric human pathogen, Helicobacter pylori, also has a complete urea cycle and contains the rocF gene encoding arginase (RocF), which is involved in the pathogenesis of H. pylori infection. Its arginase is specifically involved in acid resistance and inhibits host nitric oxide production. The rocF gene was found to confer arginase activity to Escherichia coli; disruption of plasmid‐borne rocF abolished arginase activity. A translationally fused His6–RocF was purified from E. coli under nondenaturing conditions and had catalytic activity. Remarkably, the purified enzyme had an acidic pH optimum of 6.1. Both purified arginase and arginase‐containing H. pylori extracts exhibited optimal catalytic activity with cobalt as a metal cofactor; manganese and nickel were significantly less efficient in catalyzing the hydrolysis of arginine. Viable H. pylori or E. coli containing rocF had significantly more arginase activity when grown with cobalt in the culture medium than when grown with manganese or no divalent metal. His6–RocF arginase activity was inhibited by low concentrations of reducing agents. Antibodies raised to purified His6–RocF reacted with both H. pylori and E. coli extracts containing arginase, but not with extracts from rocF mutants of H. pylori or E. coli lacking the rocF gene. The results indicate that H. pylori RocF is necessary and sufficient for arginase activity and has unparalleled features among the arginase superfamily, which may reflect the unique gastric ecological niche of this organism.

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“…Further, since the work that led to this hypothesis was performed with samples from polar waters, we wanted to determine if this generalization applied equally to nitrification in temperate waters. Because many organisms hydrolyze urea and release ammonium to the environment (Mobley et al, 1995;Burton and Prosser, 2001;Solomon et al, 2010), we performed experiments to determine whether N supplied as urea was released into the extracellular ammonium pool where it would be available to other organism, and we conducted competition experiments to determine whether ammonium affected oxidation of urea N and vice versa. Finally, we extracted DNA and RNA from these samples to investigate relationships between amoA and ureC gene abundance and transcription and oxidation rates of ammonia and urea-derived N.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of urea‐derived nitrogen by thaumarchaeota‐dominated marine nitrifying communities

Tolar

Wallsgrove

Popp

et al. 2016

Environmental Microbiology

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SummaryUrea nitrogen has been proposed to contribute significantly to nitrification by marine thaumarchaeotes. These inferences are based on distributions of thaumarchaeote urease genes rather than activity measurements. We found that ammonia oxidation rates were always higher than oxidation rates of urea-derived N in samples from coastal Georgia, USA (means 6 SEM: 382 6 35 versus 73 6 24 nmol L 21 d 21

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Molecular biology of microbial ureases.

Cited by 875 publications

References 225 publications

Relative abundance and diversity of ammonia‐oxidizing archaea and bacteria in the San Francisco Bay estuary

Relative abundance and diversity of ammonia‐oxidizing archaea and bacteria in the San Francisco Bay estuary

Purification and characterization of Helicobacter pylori arginase, RocF: unique features among the arginase superfamily

Oxidation of urea‐derived nitrogen by thaumarchaeota‐dominated marine nitrifying communities

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