Compartmentalization of Mammalian Pantothenate Kinases

Alfonso-Pecchio, Adolfo; Garcia, Matthew R.; Leonardi, Roberta; Jackowski, Suzanne

doi:10.1371/journal.pone.0049509

Cited by 63 publications

(75 citation statements)

References 42 publications

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“…Likewise, the PANK3⅐ADP⅐N7-pantothenamide (PDB code 3SMS) and the PANK2⅐ADP⅐pantothenate (PDB code 5E26) complexes are in the closed active conformation. The mammalian pantothenate kinases have different sensitivities to acetyl-CoA inhibition and exhibit tissue-specific expression profiles (6). Minor sequence differences in the flexible loop that covers the pantothenatebinding site are candidate residues that may account for the affinity differences between the isoforms, but additional comparative research is needed to test this idea.…”

Section: Discussionmentioning

confidence: 99%

“…In mammals, there are four distinct kinases that exhibit tissue-specific expression as follows: PANK1␣ and PANK1␤ are splice variants of the PANK1 gene, and PANK2 and PANK3 are encoded by the PANK2 and PANK3 genes, respectively (4,5). The kinase isoforms possess almost identical catalytic cores but differ in their amino termini that direct the enzymes to different subcellular compartments (6). Isoform 1␣ is targeted to the nucleus, whereas isoform 1␤ is associated with endosomes in humans and mice.…”

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confidence: 99%

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Allosteric Regulation of Mammalian Pantothenate Kinase

Subramanian

Yun²,

Yao

et al. 2016

Journal of Biological Chemistry

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Pantothenate kinase catalyzes the key regulatory step in CoA biosynthesis in bacteria and mammals (1-3). In mammals, there are four distinct kinases that exhibit tissue-specific expression as follows: PANK1␣ and PANK1␤ are splice variants of the PANK1 gene, and PANK2 and PANK3 are encoded by the PANK2 and PANK3 genes, respectively (4, 5). The kinase isoforms possess almost identical catalytic cores but differ in their amino termini that direct the enzymes to different subcellular compartments (6). Isoform 1␣ is targeted to the nucleus, whereas isoform 1␤ is associated with endosomes in humans and mice. Isoform 2 of mice is cytosolic, but the PANK2 gene in humans encodes a protein with both nuclear localization and mitochondrial targeting sequences. Isoform 3 is cytosolic in both species. All pantothenate kinases operate by a compulsory ordered mechanism with ATP⅐Mg 2ϩ as the leading substrate followed by pantothenate ( Fig. 1) (7). The principal mechanism for controlling mammalian pantothenate kinase activity is through feedback inhibition by acetyl-CoA, and the isoforms differ in their sensitivity to this regulator ( Fig. 1) (4, 8, 9). The 1␣ and 1␤ isoforms are least sensitive to inhibition, whereas isoforms 2 and 3 are more potently inhibited by acetyl-CoA. Acetyl-CoA inhibition is competitive with ATP⅐Mg 2ϩ , but acetyl-CoA binds far more tightly than ATP (10). Acyl-carnitines antagonize the inhibition of pantothenate kinases by acetyl-CoA (8).The importance of pantothenate kinase to mammalian physiology is highlighted by the phenotypes of knock-out mice and their connection to human disease. Isoform 1 is most highly expressed in the liver, and Pank1 Ϫ/Ϫ mice have lower total hepatic CoA and exhibit fatty acid ␤-oxidation and glucose homeostasis defects in the fasted state (11). In addition, Pank1 Ϫ/Ϫ Lep Ϫ/Ϫ mice have dramatically lower blood glucose and insulin levels compared with their diabetic Lep Ϫ/Ϫ counterparts, which highlights the connection between isoform 1 and glucose homeostasis (12). Consistent with this, an association between polymorphisms in the PANK1 gene and insulin levels was uncovered in a cohort of individuals in Finland (13). It has also been shown that the severe neurodegenerative disease pantothenate kinase-associated neurodegeneration arises from mutations in the human PANK2 gene (14). Unfortunately, Pank2 Ϫ/Ϫ mice do not recapitulate the pantothenate kinaseassociated neurodegeneration disease phenotype (15,16), and this may be due either to differences in the levels of isoform expression in mouse and human brains or to the fact that human PANK2 accumulates in the intra-membrane space in mitochondria, whereas mouse isoform 2 is cytosolic (9). Finally, Pank1 Ϫ/Ϫ Pank2 Ϫ/Ϫ double knock-out mice are unable to metabolize fats and ketones resulting in early postnatal death (16), and Pank1 Ϫ/Ϫ Pank3 Ϫ/Ϫ and Pank2 Ϫ/Ϫ Pank3 Ϫ/Ϫ double knock-out mice are both embryonic lethal. A chemical knockout of all pantothenate kinases in adult mice resulted in an 80% reduction in hepatic CoA levels a...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Allosteric Regulation of Mammalian Pantothenate Kinase

Subramanian

Yun²,

Yao

et al. 2016

Journal of Biological Chemistry

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“…The following outline is a step-by-step protocol (modified from 37,88 ) to assess mitochondrial integrity by Western blotting after exposure to permeabilizing agent.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive measurement of respiratory activity in permeabilized cells using extracellular flux analysis

2014

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Extracellular flux (XF) analysis has become a mainstream method to measure bioenergetic function in cells and tissues. While this technique is commonly used to measure energetics in intact cells, we outline here a detailed XF protocol for measuring respiration in permeabilized cells. Cells are permeabilized using saponin, digitonin, or recombinant perfringolysin O (XF PMP reagent) and provided with specific substrates to measure complex I- or II-mediated respiratory activity, Complex III+IV respiratory activity, or Complex IV activity. Medium- and long-chain acylcarnitines or glutamine may also be provided for measuring fatty acid oxidation or glutamine oxidation, respectively. This protocol allows for such measurements using a minimal number of cells compared with other protocols, without the need for mitochondrial isolation. The results are highly reproducible, and mitochondria remain well coupled. Collectively, this protocol provides comprehensive and detailed information regarding mitochondrial activity and efficiency, and, following preparative steps, takes approximately 6 hours to complete.

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“…Most bacteria, fungi and lower metazoans have one gene encoding PanK, whereas mammals have three genes that express four catalytically active isoforms: PanK1α, PanK1β, PanK2 and PanK3 [3]. The four human and mouse PanK isoforms share a homologous carboxy-terminal catalytic domain, but differ in their amino-termini which direct the isoforms to different cellular compartments [8]. All cell types studied to date express several PanK isoforms [9] providing some degree of functional redundancy.…”

Section: Introductionmentioning

confidence: 99%

Correction of a genetic deficiency in pantothenate kinase 1 using phosphopantothenate replacement therapy

Zano

Pate

Frank

et al. 2015

Molecular Genetics and Metabolism

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Coenzyme A (CoA) is a ubiquitous cofactor involved in numerous essential biochemical transformations, and along with its thioesters is a key regulator of intermediary metabolism. Pantothenate (vitamin B5) phosphorylation by pantothenate kinase (PanK) is thought to control the rate of CoA production. Pantothenate kinase associated neurodegeneration is a hereditary disease that arises from mutations that inactivate the human PANK2 gene. Aryl phosphoramidate phosphopantothenate derivatives were prepared to test the feasibility of using phosphopantothenate replacement therapy to bypass the genetic deficiency in the Pank1−/− mouse model. The efficacies of candidate compounds were first compared by measuring the ability to increase CoA levels in Pank1−/− mouse embryo fibroblasts. Administration of selected candidate compounds to Pank1−/− mice corrected their deficiency in hepatic CoA. The PanK bypass was confirmed by the incorporation of intact phosphopantothenate into CoA using tripleisotopically labeled compound. These results provide strong support for PanK as a master regulator of intracellular CoA and illustrate the feasibility of employing PanK bypass therapy to restore CoA levels in genetically deficient mice.

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Compartmentalization of Mammalian Pantothenate Kinases

Cited by 63 publications

References 42 publications

Allosteric Regulation of Mammalian Pantothenate Kinase

Allosteric Regulation of Mammalian Pantothenate Kinase

Comprehensive measurement of respiratory activity in permeabilized cells using extracellular flux analysis

Correction of a genetic deficiency in pantothenate kinase 1 using phosphopantothenate replacement therapy

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