Pantothenate Kinase Regulation of the Intracellular Concentration of Coenzyme A

Rock, Charles O.; Calder, R. Brent; Karim, Mohammad A.; Jackowski, Suzanne

doi:10.1074/jbc.275.2.1377

Cited by 180 publications

(178 citation statements)

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“…In E. coli, the activities of PanK and PPAT are controlled by feedback inhibition by CoA and its thioesters (15,22,29). Multiple PanK isozymes are found in mammalian cells, and several have been found to be inhibited by CoA, acetyl-CoA, malonylCoA, and/or palmitoyl-CoA (11,20,21). However, CoA and acetyl-CoA did not have any effect on PoK activity.…”

Section: Discussionmentioning

confidence: 95%

Biochemical Characterization of Pantoate Kinase, a Novel Enzyme Necessary for Coenzyme A Biosynthesis in the Archaea

et al. 2012

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Although bacteria and eukaryotes share a pathway for coenzyme A (CoA) biosynthesis, we previously clarified that most archaea utilize a distinct pathway for the conversion of pantoate to 4=-phosphopantothenate. Whereas bacteria/eukaryotes use pantothenate synthetase and pantothenate kinase (PanK), the hyperthermophilic archaeon Thermococcus kodakarensis utilizes two novel enzymes: pantoate kinase (PoK) and phosphopantothenate synthetase (PPS). Here, we report a detailed biochemical examination of PoK from T. kodakarensis. Kinetic analyses revealed that the PoK reaction displayed Michaelis-Menten kinetics toward ATP, whereas substrate inhibition was observed with pantoate. PoK activity was not affected by the addition of CoA/acetyl-CoA. Interestingly, PoK displayed broad nucleotide specificity and utilized ATP, GTP, UTP, and CTP with comparable k cat /K m values. Sequence alignment of 27 PoK homologs revealed seven conserved residues with reactive side chains, and variant proteins were constructed for each residue. Activity was not detected when mutations were introduced to Ser104, Glu134, and Asp143, suggesting that these residues play vital roles in PoK catalysis. Kinetic analysis of the other variant proteins, with mutations S28A, H131A, R155A, and T186A, indicated that all four residues are involved in pantoate recognition and that Arg155 and Thr186 play important roles in PoK catalysis. Gel filtration analyses of the variant proteins indicated that Thr186 is also involved in dimer assembly. A sequence comparison between PoK and other members of the GHMP kinase family suggests that Ser104 and Glu134 are involved in binding with phosphate and Mg 2؉ , respectively, while Asp143 is the base responsible for proton abstraction from the pantoate hydroxy group.

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Section: Discussionmentioning

confidence: 95%

Biochemical Characterization of Pantoate Kinase, a Novel Enzyme Necessary for Coenzyme A Biosynthesis in the Archaea

et al. 2012

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“…5), suggests that CoA biosynthesis is regulated differently by P. falciparum and erythrocytes, and that the rate of pantothenate phosphorylation does not determine the rate of CoA production by the parasite as it does in other organisms (16,41). PanK activity in P. falciparum lysates is, however, inhibited by CoA (IC 50 ϳ 200 M (42)) and hence is not refractory to feedback inhibition (as shown for Staphyloccoccus aureus PanK (43)).…”

Section: Discussionmentioning

confidence: 99%

The Human Malaria Parasite Plasmodium falciparum Is Not Dependent on Host Coenzyme A Biosynthesis

Spry

Saliba

2009

Journal of Biological Chemistry

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Pantothenate, a precursor of the fundamental enzyme cofactor coenzyme A (CoA), is essential for growth of the intraerythrocytic stage of human and avian malaria parasites. Avian malaria parasites have been reported to be incapable of de novo CoA synthesis and instead salvage CoA from the host erythrocyte; hence, pantothenate is required for CoA biosynthesis within the host cell and not the parasite itself. Whether the same is true of the intraerythrocytic stage of the human malaria parasite, Plasmodium falciparum, remained to be established. In this study we investigated the metabolic fate of [ 14 C]pantothenate within uninfected and P. falciparum-infected human erythrocytes. We provide evidence consistent with normal human erythrocytes, unlike rat erythrocytes (which have been reported to possess an incomplete CoA biosynthesis pathway), being capable of CoA biosynthesis from pantothenate. We also show that CoA biosynthesis is substantially higher in P. falciparum-infected erythrocytes and that P. falciparum, unlike its avian counterpart, generates most of the CoA synthesized in the infected erythrocyte, presumably necessitated by insufficient CoA biosynthesis in the host erythrocyte. Our data raise the possibility that malaria parasites rationalize their biosynthetic activity depending on the capacity of their host cell to synthesize the metabolites they require. Pantothenate (vitamin B 5 ) is an essential nutrient for the virulent human malaria parasite Plasmodium falciparum, required to support the rapid growth and replication of the parasite during the intraerythrocytic stage of its life cycle (1-3). In bacteria, plants, and mammalian tissues, pantothenate serves as a precursor of coenzyme A (CoA), 3 an essential enzyme cofactor involved in numerous metabolic reactions in the cell. Pantothenate is converted to CoA via five universal enzyme-mediated steps (see Fig. 1).Several decades ago, Trager (4) showed that pantothenate supported the survival of the avian malaria parasite Plasmodium lophurae during its development within duck erythrocytes in vitro. Trager (5, 6) later demonstrated, however, that CoA, and not pantothenate, stimulated exoerythrocytic growth of the intraerythrocytic stage of P. lophurae, and proposed that avian malaria parasites are incapable of metabolizing pantothenate to CoA, and instead rely on CoA synthesized by the host erythrocyte. In support of this proposal, CoA biosynthesis enzymes are readily detectable in duck erythrocytes, but appear to be absent from P. lophurae parasites isolated from their host erythrocyte (7,8). Pantothenate is therefore required by the P. lophurae-infected duck erythrocyte for CoA biosynthesis within the host cell and not the parasite itself.By contrast with nucleated avian erythrocytes, mammalian erythrocytes are thought to be incapable of CoA biosynthesis. In the only study on the subject, Annous and Song (9) reported that although pantothenate is phosphorylated within rat erythrocytes (the first step in CoA biosynthesis), there is no evidence for the su...

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“…In humans, there are three genes that express four isoforms of PanK. PanK1␣ and 1␤ arise from the use of alternate initiation exons of the PANK1 gene (2,3), and the PANK3 gene produces a single polypeptide (4). The PANK2 gene differs from the others in that it encodes a protein that is targeted to the mitochondria (5-7).…”

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confidence: 99%

“…Two shorter PanK2 isoforms have been described, one of which also localizes to mitochondria (7), whereas the second does not because of the lack of targeting sequences (6). A common feature of all PanK proteins is that they are feedback inhibited by CoA thioesters (1); however, the isoforms are distinguished by their unique sensitivities to the CoA thioester pool (2)(3)(4)8). A fourth gene, PANK4, lacks the essential catalytic glutamate residue present in all other enzymes (9) and may not be a functional PanK.…”

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confidence: 99%

Activation of human mitochondrial pantothenate kinase 2 by palmitoylcarnitine

Leonardi

Rock

Jackowski

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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The human isoform 2 of pantothenate kinase (PanK2) is localized to the mitochondria, and mutations in this protein are associated with a progressive neurodegenerative disorder. PanK2 inhibition by acetyl-CoA is so stringent (IC50 < 1 M) that it is unclear how the enzyme functions in the presence of intracellular CoA concentrations. Palmitoylcarnitine was discovered to be a potent activator of PanK2 that functions to competitively antagonize acetyl-CoA inhibition. Acetyl-CoA was a competitive inhibitor of purified PanK2 with respect to ATP. The interaction between PanK2 and acetylCoA was stable enough that a significant proportion of the purified protein was isolated as the PanK2⅐acetyl-CoA complex. The longchain acylcarnitine activation of PanK2 explains how PanK2 functions in vivo, by providing a positive regulatory mechanism to counteract the negative regulation of PanK2 activity by acetyl-CoA. Our results suggest that PanK2 is located in the mitochondria to sense the levels of palmitoylcarnitine and up-regulate CoA biosynthesis in response to an increased mitochondrial demand for the cofactor to support ␤-oxidation.carnitine ͉ coenzyme A ͉ ␤-oxidation ͉ pantothenate kinase-associated neurodegeneration P antothenate kinase (PanK) catalyzes the first and ratecontrolling step in the biosynthesis of CoA (for review, see ref. 1). In humans, there are three genes that express four isoforms of PanK. PanK1␣ and 1␤ arise from the use of alternate initiation exons of the PANK1 gene (2, 3), and the PANK3 gene produces a single polypeptide (4). The PANK2 gene differs from the others in that it encodes a protein that is targeted to the mitochondria (5-7). The PanK2 protein translated from the most 5Ј start site is sequentially cleaved at two sites by mitochondrial processing peptidases, generating a long-lived 48-kDa mature protein (5). Two shorter PanK2 isoforms have been described, one of which also localizes to mitochondria (7), whereas the second does not because of the lack of targeting sequences (6). A common feature of all PanK proteins is that they are feedback inhibited by CoA thioesters (1); however, the isoforms are distinguished by their unique sensitivities to the CoA thioester pool (2-4, 8). A fourth gene, PANK4, lacks the essential catalytic glutamate residue present in all other enzymes (9) and may not be a functional PanK.The PanK2 isoform is the focus of much current research because mutations in the human PANK2 gene give rise to PanK-associated neurodegeneration (PKAN), an inherited autosomal recessive disease (10). PKAN patients constitute a subset of those diagnosed with neurodegeneration with brain iron accumulation, formerly known as Hallervorden-Spatz syndrome (11). PKAN patients have a pathological accumulation of iron in the basal ganglia and a combination of motor symptoms in the forms of dystonia, dysarthria, intellectual impairment, and gait disturbance (11). Early-onset patients have a rapidly progressive disease, and late-onset patients have a slowly progressive, atypical disease, where park...

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Pantothenate Kinase Regulation of the Intracellular Concentration of Coenzyme A

Cited by 180 publications

References 46 publications

Biochemical Characterization of Pantoate Kinase, a Novel Enzyme Necessary for Coenzyme A Biosynthesis in the Archaea

Biochemical Characterization of Pantoate Kinase, a Novel Enzyme Necessary for Coenzyme A Biosynthesis in the Archaea

The Human Malaria Parasite Plasmodium falciparum Is Not Dependent on Host Coenzyme A Biosynthesis

Activation of human mitochondrial pantothenate kinase 2 by palmitoylcarnitine

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