Different respiratory-defective phenotypes of Neurospora crassa and Saccharomyces cerevisiae after inactivation of the gene encoding the mitochondrial acyl carrier protein

Schneider, Ralf; Massow, Michael; Lisowsky, Thomas; Weiss, Hanns

doi:10.1007/bf00313188

Cited by 108 publications

(113 citation statements)

References 58 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…Although the cytosolic ACP and fatty acid synthetase complex have been characterized as the major proteins involved in fatty acid synthesis, a mitochondrial ACP protein distinct from cytosolic ACP has also been identified and shown to contain a phosphopantetheine prosthetic group (Sackmann et al, 1991;Zhang et al, 2003). The precise role of a separate mitochondrial pathway for fatty acid synthesis is not yet clear, but there is evidence in fungal systems that it may be essential for maintenance of phospholipids of the mitochondrial membranes (Schneider et al, 1995(Schneider et al, , 1997. Alternatively, other fatty acyl CoA derivatives may be important products of this pathway.…”

Section: Discussionmentioning

confidence: 99%

Altered Neuronal Mitochondrial Coenzyme A Synthesis in Neurodegeneration with Brain Iron Accumulation Caused by Abnormal Processing, Stability, and Catalytic Activity of Mutant Pantothenate Kinase 2

Kotzbauer¹,

Truax²,

Trojanowski³

et al. 2005

J. Neurosci.

133

126

View full text Add to dashboard Cite

Mutations in the pantothenate kinase 2 (PANK2) gene have been identified in patients with neurodegeneration with brain iron accumulation (NBIA; formerly Hallervorden-Spatz disease). However, the mechanisms by which these mutations cause neurodegeneration are unclear, especially given the existence of multiple pantothenate kinase genes in humans and multiple PanK2 transcripts with potentially different subcellular localizations. We demonstrate that PanK2 protein is localized to mitochondria of neurons in human brain, distinguishing it from other pantothenate kinases that do not possess mitochondrial-targeting sequences. PanK2 protein translated from the most 5Ј start site is sequentially cleaved at two sites by the mitochondrial processing peptidase, generating a long-lived 48 kDa mature protein identical to that found in human brain extracts. The mature protein catalyzes the initial step in coenzyme A (CoA) synthesis but displays feedback inhibition in response to species of acyl CoA rather than CoA itself. Some, but not all disease-associated point mutations result in significantly reduced catalytic activity. The most common mutation, G521R, results in marked instability of the intermediate PanK2 isoform and reduced production of the mature isoform. These results suggest that NBIA is caused by altered neuronal mitochondrial lipid metabolism caused by mutations disrupting PanK2 protein levels and catalytic activity.

show abstract

Section: Discussionmentioning

confidence: 99%

Altered Neuronal Mitochondrial Coenzyme A Synthesis in Neurodegeneration with Brain Iron Accumulation Caused by Abnormal Processing, Stability, and Catalytic Activity of Mutant Pantothenate Kinase 2

Kotzbauer¹,

Truax²,

Trojanowski³

et al. 2005

J. Neurosci.

133

126

View full text Add to dashboard Cite

show abstract

“…For example, disruption of the nuclear-encoded gene for mitochondrial ACP in Neurospora crassa results in an accumulation of lysophospholipids in mitochondrial membranes and an accompanying respiratory-deficient phenotype. Disruption of the nuclear-encoded gene for either the mitochondrial ␤-ketoacyl synthase or ACP in S. cerevisiae also produces a respiratory-deficient phenotype and, in the case of the ACP-defective strain, it has been established that cellular lipoic acid concentration is reduced to Ͻ10% of that of the wild-type strain (4,33). Furthermore, addition of lipoic acid to the growth medium could not compensate for the block in endogenous lipoic acid synthesis, suggesting that in this species lipoic acid may not readily be taken up into mitochondria (4).…”

Section: Inhibition Of the Human Mitochondrial ␤-Ketoacylmentioning

confidence: 99%

Cloning, Expression, and Characterization of the Human Mitochondrial β-Ketoacyl Synthase

Zhang¹,

Joshi²,

Hofmann

et al. 2005

Journal of Biological Chemistry

View full text Add to dashboard Cite

A human ␤-ketoacyl synthase implicated in a mitochondrial pathway for fatty acid synthesis has been identified, cloned, expressed, and characterized. Sequence analysis indicates that the protein is more closely related to freestanding counterparts found in prokaryotes and chloroplasts than it is to the ␤-ketoacyl synthase domain of the human cytosolic fatty acid synthase. The full-length nuclear-encoded 459-residue protein includes an N-terminal sequence element of ϳ38 residues that functions as a mitochondrial targeting sequence. The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial ␤-ketoacyl synthase and exhibits lowered lipoic acid levels. To date, four components of a putative type II mitochondrial fatty acid synthase pathway have been identified in humans: acyl carrier protein, malonyl transferase, ␤-ketoacyl synthase, and enoyl reductase. The substrate specificity and complementation data for the ␤-ketoacyl synthase suggest that, as in plants and fungi, in humans this pathway may play an important role in the generation of octanoyl-acyl carrier protein, the lipoic acid precursor, as well as longer chain fatty acids that are required for optimal mitochondrial function.Over the last decade, it has become clear that fungal and plant mitochondria are capable of synthesizing fatty acids de novo (1-6). The enzymes involved in the pathway are freestanding, monofunctional proteins of the type II variety and are distinct from the multifunctional polypeptide type I FASs 1 present in the cytosol of fungi and animals. Thus far, the preponderance of evidence suggests that these mitochondrial FAS pathways function to produce octanoyl-ACP, the precursor of lipoic acid (4) and longer chain-length fatty acids that may be utilized for the remodeling of mitochondrial membrane phospholipids (7). The presence of a similar mitochondrial FAS system in animals has been suspected for some time, based initially on the discovery of an ACP-like protein in animal mitochondria (8, 9). However, only recently have other components of a putative mitochondrial FAS been identified, cloned, and characterized; they include the human ACP and malonyl transferase (10) and enoyl reductase (11). In continuation of the search for other components, we have now identified and characterized a single candidate for a type II human mitochondrial ␤-ketoacyl synthase, the critical enzyme required for catalysis of the chain-elongating condensation reaction. EXPERIMENTAL PROCEDURESCloning of the Human Mitochondrial ␤-Ketoacyl Synthase-Using the sequences of several authentic type I and type II ␤-ketoacyl synthases as probes to BLAST search the human genome sequence data base, we identified a sequence (accession NP_060367) that also was represented in a human EST clone (IMAGE clone 3446492, ATCC MGC-4956) and appeared likely to encode...

show abstract

“…Fungi (6,7), animal, and plant cells also contain a type II FAS system in their mitochondria. The role of the mitochondrial FASs is not well established, but it has been suggested that, at least in fungi and plants, they may serve to provide octanoate, the precursor of lipoic acid and/or long-chain fatty acids that are used in the remodeling of mitochondrial phospholipids (7)(8)(9)(10).…”

mentioning

confidence: 99%

“…The role of the mitochondrial FASs is not well established, but it has been suggested that, at least in fungi and plants, they may serve to provide octanoate, the precursor of lipoic acid and/or long-chain fatty acids that are used in the remodeling of mitochondrial phospholipids (7)(8)(9)(10). The ACP component of the mitochondrial FAS appears to be associated with the respiratory complex I in animals and in Neurospora crassa (11,12).…”

mentioning

confidence: 99%

Cloning, Expression, and Characterization of a Human 4′-Phosphopantetheinyl Transferase with Broad Substrate Specificity

Joshi¹,

Zhang²,

Rangan³

et al. 2003

Journal of Biological Chemistry

100

View full text Add to dashboard Cite

The fatty acid synthases (FASs) 1 associated with the soluble cytoplasm of yeast and animal cells comprise large multifunctional polypeptides that contain all of the catalytic components required for the synthesis of long-chain fatty acids from malonyl-CoA de novo. These multifunctional polypeptides are commonly referred to as type I FASs. The animal FASs consist of two identical polypeptides of approximately 2500 residues (␣ 2 ), whereas the yeast FAS comprises six copies each of two nonidentical polypeptides (␣ 6 ␤ 6 ; ␣ ϭ 1845, ␤ ϭ 1887 residues) (1, 2). In most bacteria and in plant plastids, the various catalytic components of the FAS are present on separate discrete polypeptides and are commonly referred to as type II FASs (3). An essential component of both type I and type II systems is a small molecular mass domain/polypeptide known as an acyl carrier protein (ACP) that is posttranslationally modified, by insertion of a 20-Å-long phosphopantetheinyl moiety, derived from CoA, to a positionally conserved serine residue (4). The terminal sulfhydryl of the phosphopantetheinyl moiety provides the site of covalent attachment of the substrates and the growing fatty acyl chain, so that the phosphopantetheine plays an essential role as a "swinging arm" in the translocation of intermediates between different catalytic sites of the FASs (5). ACPs fulfill a similar role in the type I and type II polyketide synthases (PKSs) found mainly in bacteria and fungi that are capable of elaborating a broad range of secondary metabolites.Fungi (6, 7), animal, and plant cells also contain a type II FAS system in their mitochondria. The role of the mitochondrial FASs is not well established, but it has been suggested that, at least in fungi and plants, they may serve to provide octanoate, the precursor of lipoic acid and/or long-chain fatty acids that are used in the remodeling of mitochondrial phospholipids (7-10). The ACP component of the mitochondrial FAS appears to be associated with the respiratory complex I in animals and in Neurospora crassa (11,12). Phosphopantetheinylated carrier proteins also play an essential role as components of the non-ribosomal peptide synthases found in microorganisms that are responsible for producing a variety of short peptides containing both proteogenic and unusual amino acids (13). The nonribosomal peptide synthases also comprise multifunctional polypeptides in which the role of the carrier protein domain is to translocate amino acyl moieties from an adenylation domain to a condensation domain, where formation of a new peptide bond takes place (14).Enzymes capable of phosphopantetheinylating carrier proteins involved in the biosynthesis of fatty acids, polyketides, and peptides have been identified and characterized from a variety of sources. Many organisms have more than one phosphopantetheine transferase (PPTase), and different PPTases commonly are utilized to service carrier proteins associated with FASs and non-ribosomal peptide synthases within the same species (4, 15). Yeast utilizes...

show abstract

Different respiratory-defective phenotypes of Neurospora crassa and Saccharomyces cerevisiae after inactivation of the gene encoding the mitochondrial acyl carrier protein

Cited by 108 publications

References 58 publications

Altered Neuronal Mitochondrial Coenzyme A Synthesis in Neurodegeneration with Brain Iron Accumulation Caused by Abnormal Processing, Stability, and Catalytic Activity of Mutant Pantothenate Kinase 2

Altered Neuronal Mitochondrial Coenzyme A Synthesis in Neurodegeneration with Brain Iron Accumulation Caused by Abnormal Processing, Stability, and Catalytic Activity of Mutant Pantothenate Kinase 2

Cloning, Expression, and Characterization of the Human Mitochondrial β-Ketoacyl Synthase

Cloning, Expression, and Characterization of a Human 4′-Phosphopantetheinyl Transferase with Broad Substrate Specificity

Contact Info

Product

Resources

About