PanG, a New Ketopantoate Reductase Involved in Pantothenate Synthesis

Miller, Cheryl N.; LoVullo, Eric D.; Kijek, Todd M.; Fuller, James R.; Brunton, Jason; Steele, Shaun; Taft-Benz, Sharon; Richardson, Anthony R.; Kawula, Thomas H.

doi:10.1128/jb.01740-12

Cited by 20 publications

(25 citation statements)

References 47 publications

(50 reference statements)

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“…An ilvC homologue is not present on the T. kodakarensis genome. In addition, a very recent study demonstrated that some pathogenic bacteria such as Francisella tularensis use a novel type KPR encoded by panG (Miller et al, 2012). However, its homologues are not conserved in any of the archaeal genomes.…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of an archaeal ketopantoate reductase and its involvement in regulation of coenzyme A biosynthesis

Tomita

Imanaka

Atomi

2013

Molecular Microbiology

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SummaryCoenzyme A (CoA) biosynthesis in bacteria and eukaryotes is regulated primarily by feedback inhibition towards pantothenate kinase (PanK). As most archaea utilize a modified route for CoA biosynthesis and do not harbour PanK, the mechanisms governing regulation of CoA biosynthesis are unknown. Here we performed genetic and biochemical studies on the ketopantoate reductase (KPR) from the hyperthermophilic archaeon Thermococcus kodakarensis. KPR catalyses the second step in CoA biosynthesis, the reduction of 2-oxopantoate to pantoate. Gene disruption of TK1968, whose product was 20-29% identical to previously characterized KPRs from bacteria/ eukaryotes, resulted in a strain with growth defects that were complemented by addition of pantoate. The TK1968 protein (Tk-KPR) displayed reductase activity specific for 2-oxopantoate and preferred NADH as the electron donor, distinct to the bacterial/eukaryotic NADPH-dependent enzymes. Tk-KPR activity decreased dramatically in the presence of CoA and KPR activity in cell-free extracts was also inhibited by CoA. Kinetic studies indicated that CoA inhibits KPR by competing with NADH. Inhibition of ketopantoate hydroxymethyltransferase, the first enzyme of the pathway, by CoA was not observed. Our results suggest that CoA biosynthesis in T. kodakarensis is regulated by feedback inhibition of KPR, providing a feasible regulation mechanism of CoA biosynthesis in archaea.

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Section: Discussionmentioning

confidence: 99%

Identification and characterization of an archaeal ketopantoate reductase and its involvement in regulation of coenzyme A biosynthesis

Tomita

Imanaka

Atomi

2013

Molecular Microbiology

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“…This suggests that pantothenate limitation is a common feature of intracellular pathogens. Pantothenate auxotrophs of Francisella tularensis do not have decreased virulence (70), and Listeria, which is incapable of synthesizing some essential vitamins, also is not impaired in intracellular proliferation (71). However, these intracellular pathogens escape into the host cell cytosol, where nutrients are plentiful, eliminating the need for biosynthesis of pantothenate and other vitamins.…”

Section: Discussionmentioning

confidence: 99%

Histoplasma capsulatum Depends on De Novo Vitamin Biosynthesis for Intraphagosomal Proliferation

2014

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During infection of the mammalian host, Histoplasma capsulatum yeasts survive and reside within macrophages of the immune system. Whereas some intracellular pathogens escape into the host cytosol, Histoplasma yeasts remain within the macrophage phagosome. This intracellular Histoplasma-containing compartment imposes nutritional challenges for yeast growth and replication. We identified and annotated vitamin synthesis pathways encoded in the Histoplasma genome and confirmed by growth in minimal medium that Histoplasma yeasts can synthesize all essential vitamins with the exception of thiamine. Riboflavin, pantothenate, and biotin auxotrophs of Histoplasma were generated to probe whether these vitamins are available to intracellular yeasts. Disruption of the RIB2 gene (riboflavin biosynthesis) prevented growth and proliferation of yeasts in macrophages and severely attenuated Histoplasma virulence in a murine model of respiratory histoplasmosis. Rib2-deficient yeasts were not cleared from lung tissue but persisted, consistent with functional survival mechanisms but inability to replicate in vivo. In addition, depletion of Pan6 (pantothenate biosynthesis) but not Bio2 function (biotin synthesis) also impaired Histoplasma virulence. These results indicate that the Histoplasma-containing phagosome is limiting for riboflavin and pantothenate and that Histoplasma virulence requires de novo synthesis of these cofactor precursors. Since mammalian hosts do not rely on vitamin synthesis but instead acquire essential vitamins through diet, vitamin synthesis pathways represent druggable targets for therapeutics.

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“…Panthothenate (which is important in lipid metabolism) was in the past determined to be essential for a number of C. difficile strains tested (Karasawa et al , 1995). More recently, a new ketopantoate reductase (KPR) gene panG was discovered in a number of pathogenic bacteria and found to have a homolog in C. difficile strain 630 (Miller et al , 2013). Therefore, whereas panthothenate is commonly thought to be essential, this essentiality is strain specific and absent in C. difficile strain 630.…”

Section: Resultsmentioning

confidence: 99%

A curated C. difficile strain 630 metabolic network: prediction of essential targets and inhibitors

Larocque

Chénard

Najmanovich

2014

Preprint

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Background: Clostridium difficile is the leading cause of hospital-borne infections occurring when the natural intestinal flora is depleted following antibiotic treatment. Current treatments for Clostridium difficile infections present high relapse rates and new hyper-virulent and multi-resistant strains are emerging, making the study of this nosocomial pathogen necessary to find novel therapeutic targets. Results: We present iMLTC806cdf, an extensively curated reconstructed metabolic network for the C. difficile pathogenic strain 630. iMLTC806cdf contains 806 genes, 703 metabolites and 769 metabolic, 117 exchange and 145 transport reactions. iMLTC806cdf is the most complete and accurate metabolic reconstruction of a gram-positive anaerobic bacteria to date. We validate the model with simulated growth assays in different media and carbon sources and use it to predict essential genes. We obtain 89.2% accuracy in the prediction of gene essentiality when compared to experimental data for B. subtilis homologs (the closest organism for which such data exists). We predict the existence of 76 essential genes and 39 essential gene pairs, a number of which are unique to C. difficile and have non-existing or predicted non-essential human homologs. For 29 of these potential therapeutic targets, we find 125 inhibitors of homologous proteins including approved drugs with the potential for drug repositioning, that when validated experimentally could serve as starting points in the development of new antibiotics.

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PanG, a New Ketopantoate Reductase Involved in Pantothenate Synthesis

Cited by 20 publications

References 47 publications

Identification and characterization of an archaeal ketopantoate reductase and its involvement in regulation of coenzyme A biosynthesis

Identification and characterization of an archaeal ketopantoate reductase and its involvement in regulation of coenzyme A biosynthesis

Histoplasma capsulatum Depends on De Novo Vitamin Biosynthesis for Intraphagosomal Proliferation

A curated C. difficile strain 630 metabolic network: prediction of essential targets and inhibitors

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