The Yeast Mitochondrial Carrier Leu5p and Its Human Homologue Graves' Disease Protein Are Required for Accumulation of Coenzyme A in the Matrix

Prohl, Corinna; Pelzer, Winfried; Diekert, Kerstin; Kmita, Hanna; Bedekovics, Tibor; Kispál, Gyula; Lill, Roland

doi:10.1128/mcb.21.4.1089-1097.2001

Cited by 103 publications

(81 citation statements)

References 72 publications

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“…Rather than having the features of a keto acid carrier, the proposed pyruvate carrier (32), YIL006w, has a binding motif typical of an adenine nucleotide carrier. Leu5p also has a contact point II predicting adenine nucleotide binding, which is consistent with it being the coenzyme A carrier (33). Mtm1p, which is proposed to transport a manganese cofactor (34), has a contact point II typical of an amino acid carrier, and the proposed iron transporters Mrs3p and Mrs4p (35) share a novel M-N motif at contact point II, suggesting that they transport neither nucleotides nor keto acids or amino acids and could form a distinct subfamily transporting coordinated iron.…”

Section: Resultssupporting

confidence: 54%

Mitochondrial carriers in the cytoplasmic state have a common substrate binding site

Robinson

Kunji

2006

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

239

289

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Mitochondrial carriers link biochemical pathways in the cytosol and mitochondrial matrix by transporting substrates across the inner mitochondrial membrane. Substrate recognition is specific for each carrier, but sequence similarities suggest the carriers have similar structures and mechanisms of substrate translocation. By considering conservation of amino acids, distance and chemical constraints, and by modeling family members on the known structure of the ADP͞ATP translocase, we have identified a common substrate binding site. It explains substrate selectivity and proton coupling and provides a mechanistic link to carrier opening by substrate-induced perturbation of the salt bridges that seal the pathway to and from the mitochondrial matrix. It enables the substrate specificity of uncharacterized mitochondrial carriers to be predicted.comparative modeling ͉ membrane protein ͉ sequence alignment M embers of the mitochondrial carrier family are located in the inner mitochondrial membrane and allow exchange of substrates between the cytosol and the mitochondrial matrix (1). The family is exclusive to eukaryotes, and its members are unrelated to other transporter families, including the major facilitator superfamily and the ABC transporters. Their substrates include nucleotides, amino acids, cofactors, carboxylic acids, and inorganic anions required by the organelle for oxidative phosphorylation, gluconeogenesis, synthesis and degradation of amino and fatty acids, macromolecular synthesis of proteins and nucleic acids, sterol metabolism, and thermogenesis (1). Mutations of the carriers are associated with diseases, including progressive external opthalmoplegia, adult-and neonatal-onset type II citrullinaemia, Amish-type microcephaly, hyperornithinemia-hyperammonia-homocitrullinuria, carnitineacylcarnitine translocase deficiency, neonatal myoclonic epilepsy, severe obesity, and type II diabetes (1).The mitochondrial carriers have three tandem repeats of Ϸ100 aa, each containing two transmembrane ␣-helices linked by a large loop (2) and a conserved signature motif P-X-[DE]-X-X-[RK] (3). The carriers exist in two distinct conformational states: the cytoplasmic state (c-state) in which the carrier accepts its substrate from the cytoplasm, and the matrix state in which it accepts a substrate from the mitochondrial matrix. For the ADP͞ATP carrier, the inhibitor carboxyatractyloside (CATR) is known to bind to the carrier in the c-state only and prevent the binding of ADP. In the atomic model of the ADP͞ATP carrier 1 from Bos taurus (BtAAC1) in complex with CATR (4), the six-transmembrane ␣-helices form a barrel that has pseudo-3-fold symmetry. CATR is bound in the internal aqueous cavity (see Fig. 4, which is published as supporting information on the PNAS web site), which is open to the cytosol and closed to the mitochondrial matrix, consistent with the structure representing the c-state. The prolines of the signature motif kink the transmembrane helices, bringing their C-terminal ends together at the base of the cavit...

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Section: Resultssupporting

confidence: 54%

Mitochondrial carriers in the cytoplasmic state have a common substrate binding site

Robinson

Kunji

2006

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

239

289

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“…The LEU5 null mutant did not grow on YP supplemented with glycerol, a phenotype explained by its inability to import CoA, or a precursor, into the mitochondrial matrix (29). Thus, expression of a mitochondrial carrier protein that recognizes CoA as a substrate should mitigate or abolish the severe growth defect of the ⌬LEU5 knockout.…”

Section: Resultsmentioning

confidence: 99%

“…SLC25A42 Functions as a CoA Transporter in S. cerevisiaeThe closest relative of SLC25A42 in S. cerevisiae is YPR011c, whose function is not yet known, followed by Leu5p, which has been proposed to transport CoA or a precursor thereof (29). The LEU5 null mutant did not grow on YP supplemented with glycerol, a phenotype explained by its inability to import CoA, or a precursor, into the mitochondrial matrix (29).…”

Section: Resultsmentioning

confidence: 99%

“…Nothing is known about YPR011c. On the other hand, a role was assigned to Leu5p in the cellular distribution of CoA (29). More precisely, it was proposed that either CoA, or a precursor of CoA, is the substrate of Leu5p based on the decreased CoA level in mitochondria and decreased activity of mitochondrial CoA-dependent enzymes in ⌬LEU5 cells (29).…”

Section: Discussionmentioning

confidence: 99%

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A Novel Member of Solute Carrier Family 25 (SLC25A42) Is a Transporter of Coenzyme A and Adenosine 3′,5′-Diphosphate in Human Mitochondria

Fiermonte

Paradies

Todisco

et al. 2009

Journal of Biological Chemistry

139

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Mitochondrial carriers are a family of proteins that transport metabolites, nucleotides, and cofactors across the inner mitochondrial membrane thereby connecting cytosolic and matrix functions. The essential cofactor coenzyme A (CoA) is synthesized outside the mitochondrial matrix and therefore must be transported into mitochondria where it is required for a number of fundamental processes. In this work we have functionally identified and characterized SLC25A42, a novel human member of the mitochondrial carrier family. The SLC25A42 gene (Haitina, T., Lindblom, J., Renström, T., and Fredriksson, R., 2006, Genomics 88, 779 -790) was overexpressed in Escherichia coli, purified, and reconstituted into phospholipid vesicles. Its transport properties, kinetic parameters, and targeting to mitochondria demonstrate that SLC25A42 protein is a mitochondrial transporter for CoA and adenosine 3,5-diphosphate. SLC25A42 catalyzed only a counter-exchange transport, exhibited a high transport affinity for CoA, dephospho-CoA, ADP, and adenosine 3,5-diphosphate, was saturable and inhibited by bongkrekic acid and other inhibitors of mitochondrial carriers to various degrees. The main physiological role of SLC25A42 is to import CoA into mitochondria in exchange for intramitochondrial (deoxy)adenine nucleotides and adenosine 3,5-diphosphate. This is the first time that a mitochondrial carrier for CoA and adenosine 3,5-diphosphate has been characterized biochemically.The mitochondrial carrier family, or the solute carrier family 25 (SLC25), 3 comprises a large group of proteins that transport a variety of substrates across the inner mitochondrial membrane and, in a few cases, across other membranes (1, 2). Common structural features of the mitochondrial carrier family members consist in a tripartite structure (three repeats of ϳ100 amino acids), the presence of two transmembrane ␣-helices separated by hydrophilic loops in each repeat, and the presence of a signature motif at the C terminus of the first helix in each repeat (Ref. 3 and references therein). The SLC25 family is by far the largest of the currently known 43 SLC families. The Saccharomyces cerevisiae genome contains 35 members, that of Arabidopsis thaliana 58, and the human genome at least 48 SLC25 members. Until now, nearly 30 members and isoforms of this family have been identified in humans. These include the uncoupling protein and the carriers for ADP/ATP, phosphate, 2-oxoglutarate/malate, citrate, carnitine/acylcarnitine, dicarboxylates, ornithine and other basic amino acids, oxodicarboxylates, deoxynucleotides and thiamine pyrophosphate, aspartate-glutamate, glutamate, S-adenosylmethionine, ATPMg/Pi, pyrimidine nucleotides, and adenine nucleotides in peroxisomes (see Ref. 1 for a review and Refs. 4 -8). The present investigation was undertaken to identify the function of SLC25A42, a novel member of the SLC25 family recently found in the human genome (9). SLC25A42 is 318 amino acids long and is highly expressed in virtually all tissues, in most at higher levels than ma...

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“…The potent inhibition of PanK2 by acyl-CoAs maintains the enzyme in a normally off position by preventing the binding of ATP:Mg 2ϩ ; however, the presence of long-chain acylcarnitine antagonizes the inhibitory action of acyl-CoA and activates PanK2. This regulatory effect on the rate-controlling enzyme in CoA biosynthesis boosts the cytosolic concentration of CoASH, which is actively transported into the mitochondrial matrix by the Leu5p protein, an inner membrane carrier (25). The mitochondrial localization of PanK2 places it in an ideal subcellular location to sense the levels of long-chain acylcarnitine and the status of mitochondrial ␤-oxidation.…”

Section: Discussionmentioning

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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The Yeast Mitochondrial Carrier Leu5p and Its Human Homologue Graves' Disease Protein Are Required for Accumulation of Coenzyme A in the Matrix

Cited by 103 publications

References 72 publications

Mitochondrial carriers in the cytoplasmic state have a common substrate binding site

Mitochondrial carriers in the cytoplasmic state have a common substrate binding site

A Novel Member of Solute Carrier Family 25 (SLC25A42) Is a Transporter of Coenzyme A and Adenosine 3′,5′-Diphosphate in Human Mitochondria

Activation of human mitochondrial pantothenate kinase 2 by palmitoylcarnitine

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