Cytoplasmic accumulation of a normally mitochondrial malonyl-CoA decarboxylase by the use of an alternate transcription start site

Courchesne-Smith, Cheryl; Jang, Sei‐Heon; Shi, Qiong; DeWille, James W.; Sasaki, Glenn C.; Kolattukudy, Pappachan E.

doi:10.1016/0003-9861(92)90452-3

Cited by 31 publications

(22 citation statements)

References 39 publications

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“…This is similar to the reported goose MCD sequence, where the two separate start codons are able to code for two proteins [11]. These proteins are then targeted to either the cytoplasm or the mitochondria, depending on which translational start site is used [11]. Also, the deduced amino acid sequences of rat and human MCD are highly conserved, demonstrating approx.…”

Section: Discussionsupporting

confidence: 81%

“…The cDNA sequence for rat liver and β-cell MCD shows that two methionines are present within the first 120 bp of the coding region, with each having a fairly well conserved Kozak consensus sequence (Figure 2). This is similar to the reported goose MCD sequence, where the two separate start codons are able to code for two proteins [11]. These proteins are then targeted to either the cytoplasm or the mitochondria, depending on which translational start site is used [11].…”

Section: Discussionsupporting

confidence: 80%

“…Recently we have cloned and expressed the pancreatic β-cell form of rat MCD, which is 68 % identical to MCD from the goose uropygial gland, and predicts a protein of 54.7 kDa [10,11]. Whether the liver MCD cDNA is similar to the pancreatic β-cell cDNA is not known.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of rat liver malonyl-CoA decarboxylase and the study of its role in regulating fatty acid metabolism

Dyck

Berthiaume

Thomas

et al. 2000

Biochemical Journal

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In the liver, malonyl-CoA is central to many cellular processes, including both fatty acid biosynthesis and oxidation. MalonylCoA decarboxylase (MCD) is involved in the control of cellular malonyl-CoA levels, and functions to decarboxylate malonylCoA to acetyl-CoA. MCD may play an essential role in regulating energy utilization in the liver by regulating malonyl-CoA levels in response to various nutritional or pathological states. The purpose of the present study was to investigate the role of liver MCD in the regulation of fatty acid oxidation in situations where lipid metabolism is altered. A single MCD enzyme of molecular mass 50.7 kDa was purified from rat liver using a sequential column chromatography procedure and the cDNA was subsequently cloned and sequenced. The liver MCD cDNA was identical to rat pancreatic β-cell MCD cDNA, and contained two potential translational start sites, producing proteins of 50.7 kDa and 54.7 kDa. Western blot analysis using polyclonal antibodies generated against rat liver MCD showed that the 50.7 kDa isoform of MCD is most abundant in heart and liver, and of relatively low abundance in skeletal muscle (despite elevated MCD transcript levels in skeletal muscle). Tissue distribution experiments demonstrated that the pancreas is the only rat tissue so far identified that contains both the 50.7 kDa and 54.7 kDa isoforms of MCD. In addition, transfection of the full-length rat liver MCD cDNA into COS cells produced two isoforms of MCD. This indicated either that both initiating methionines are functionally active, generating two proteins, or that the 54.7 kDa isoform is the only MCD protein translated and removal of the putative mitochondrial targeting pre-sequence generates a protein of approx. 50.7 kDa in size. To address this,

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Section: Discussionsupporting

confidence: 81%

Section: Discussionsupporting

confidence: 80%

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Characterization of rat liver malonyl-CoA decarboxylase and the study of its role in regulating fatty acid metabolism

Dyck

Berthiaume

Thomas

et al. 2000

Biochemical Journal

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“…The synthesis of the p-hydroxyphenylalkanoic acid precursor could be catalysed by FAS (or an analogous enzyme) from p-hydroxybenzoyl-CoA as the starter with malonyl-CoA as the elongating substrate. FASs are known to have seldom-used but inherent capabilities to use starters other than acetyl-CoA and substrates other than malonyl-CoA to generate unusual fatty acids (Courchesne-Smith et al, 1992), and benzoyl-CoA appears to be elongated to very long-chain fatty acids by M. bovis BCG extracts (N. D. Fernandes and P. E. Kolattukudy, unpublished).…”

Section: Biosynthesis Of Phthiocerol and Phenolphthiocerolmentioning

confidence: 99%

Biochemistry and molecular genetics of cell‐wall lipid biosynthesis in mycobacteria

Kolattukudy

Fernandes

Azad

et al. 1997

Molecular Microbiology

170

149

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SummaryTuberculosis and other mycobacterial infections are the most serious infectious diseases in terms of human fatalities. The high content of unique cellwall lipids helps these organisms to resist antimicrobial drugs and host defences. The biosynthesis of these lipids is discussed briefly. The recent advances in recombinant DNA technology have begun to help to elucidate the nature of some of the enzymes involved in this process and the genes that encode them. Gene disruption and other molecular genetic technologies are beginning to provide new approaches to test for the biological functions of these gene products and may lead to identification of new antimycobacterial drug targets.

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“…Thus, if translation initiated at M1, a mitochondrial protein could be produced, whereas translation initiated at M2 would presumably produce the nonmitochondrial, nuclear form. Alternate translation initiation has been shown to result in the production of both mitochondrial and nonmitochondrial proteins from the same gene in both yeasts (1,35,45) and vertebrates (6,39).…”

mentioning

confidence: 99%

The Human DNA Ligase III Gene Encodes Nuclear and Mitochondrial Proteins

Lakshmipathy

Campbell

1999

Molecular and Cellular Biology

215

170

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We provide evidence that the human DNA ligase III gene encodes a mitochondrial form of this enzyme. First, the DNA ligase III cDNA contains an in-frame ATG located upstream from the putative translation initiation start site. The DNA sequence between these two ATG sites encodes an amphipathic helix similar to previously identified mitochondrial targeting peptides. Second, recombinant green fluorescent protein harboring this sequence at its amino terminus was efficiently targeted to the mitochondria of Cos-1 monkey kidney cells. In contrast, native green fluorescent protein distributed to the cytosol. Third, a series of hemagglutinin-DNA ligase III minigene constructs were introduced into Cos-1 cells, and immunocytochemistry was used to determine subcellular localization of the epitope-tagged DNA ligase III protein. These experiments revealed that inactivation of the upstream ATG resulted in nuclear accumulation of the DNA ligase III protein, whereas inactivation of the downstream ATG abolished nuclear localization and led to accumulation within the mitochondrial compartment. Fourth, mitochondrial protein extracts prepared from human cells overexpressing antisense DNA ligase III mRNA possessed substantially less DNA ligase activity than did mitochondrial extracts prepared from control cells. DNA end-joining activity was also substantially reduced in extracts prepared from antisense mRNA-expressing cells. From these results, we conclude that the human DNA ligase III gene encodes both nuclear and mitochondrial enzymes. DNA ligase plays a central role in DNA replication, recombination, and DNA repair. Thus, identification of a mitochondrial form of this enzyme provides a tool with which to dissect mammalian mitochondrial genome dynamics.For some time it was thought that the mammalian mitochondria lacked the capacity to repair damaged DNA (18). This hypothesis had its origin in the observation that pyrimidine dimers produced within the mitochondrial DNA (mtDNA) of cultured cells were not repaired, in marked contrast to similar lesions produced in the nuclear genomes of these same cells (4,15,21). However, it is now clear that this organelle is not entirely deficient in DNA repair activity. For example, it appears that base excision repair of oxidized DNA occurs in mtDNA of mammalian cells (8,23,34,40). In addition, a number of studies have revealed that mammalian cultured cells can repair mtDNA damage caused by a number of chemical agents, including cisplatin (15), bleomycin (33), streptozotocin (22), and 4-nitroquinoline (36). More recently, it was shown that mammalian mitochondrial extracts possess DNA nonhomologous end-joining and homologous recombination activities (14, 41). Taken together, these findings indicate that mammalian mitochondria likely possess a number of DNA repair pathways. A series of recent observations suggest that mutations to the mitochondrial genome may be associated with a variety of human pathologies (5, 9, 10, 38, 49), thus highlighting the need for a greater understanding of the molecular...

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Cytoplasmic accumulation of a normally mitochondrial malonyl-CoA decarboxylase by the use of an alternate transcription start site

Cited by 31 publications

References 39 publications

Characterization of rat liver malonyl-CoA decarboxylase and the study of its role in regulating fatty acid metabolism

Characterization of rat liver malonyl-CoA decarboxylase and the study of its role in regulating fatty acid metabolism

Biochemistry and molecular genetics of cell‐wall lipid biosynthesis in mycobacteria

The Human DNA Ligase III Gene Encodes Nuclear and Mitochondrial Proteins

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