Mutations of mitochondrial DNA polymerase γA are a frequent cause of autosomal dominant or recessive progressive external ophthalmoplegia

Lamantea, Eleonora; Tiranti, Valeria; Bordoni, Andreina; Toscano, Antonio; Bono, Francesco; Servidei, Serenella; Papadimitriou, A.; Spelbrink, Johannes N.; Silvestri, Laura; Casari, Giorgio; Comi, Giacomo P.; Zeviani, Massimo

doi:10.1002/ana.10278

Cited by 246 publications

(186 citation statements)

References 35 publications

(48 reference statements)

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“…Although the specific function of the conserved spacer sequences is not known, a missense mutation in the spacer region of Drosophila pol ␥-␣ causes mitochondrial and nervous system dysfunction and developmental lethality in the larval third instar (24). Furthermore, hereditary progressive external ophthalmoplegia is associated with mutations in human pol ␥-␣, some of which map to the spacer region (5,25,26).Here we examine the consequences of site-directed mutagenesis of conserved amino acid sequences in the spacer region of Drosophila pol ␥-␣. Mutant holoenzymes were expressed from baculovirus constructs in insect cells, purified to near homogeneity, and characterized biochemically.…”

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confidence: 99%

Mutations in the Spacer Region of Drosophila Mitochondrial DNA Polymerase Affect DNA Binding, Processivity, and the Balance between Pol and Exo Function

Luo

Kaguni

2005

Journal of Biological Chemistry

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The catalytic subunit (␣) of mitochondrial DNA polymerase (pol ␥) shares conserved DNA polymerase and 3 -5 exonuclease active site motifs with Escherichia coli DNA polymerase I and bacteriophage T7 DNA polymerase. A major difference between the prokaryotic and mitochondrial proteins is the size and sequence of the region between the exonuclease and DNA polymerase domains, referred to as the spacer in pol ␥-␣. Four ␥-specific conserved sequence elements are located within the spacer region of the catalytic subunit in eukaryotic species from yeast to humans. To elucidate the functional roles of the spacer region, we pursued deletion and site-directed mutagenesis of Drosophila pol ␥. Mutant proteins were expressed from baculovirus constructs in insect cells, purified to near homogeneity, and analyzed biochemically. We find that mutations in three of the four conserved sequence elements within the spacer alter enzyme activity, processivity, and/or DNA binding affinity. In addition, several mutations affect differentially DNA polymerase and exonuclease activity and/or functional interactions with mitochondrial singlestranded DNA-binding protein. Based on these results and crystallographic evidence showing that the templateprimer binds in a cleft between the exonuclease and DNA polymerase domains in family A DNA polymerases, we propose that conserved sequences within the spacer of pol ␥ may position the substrate with respect to the enzyme catalytic domains.The mitochondrion is the eukaryotic organelle that carries out oxidative phosphorylation, fulfilling cellular requirements for energy production. Disruption of mitochondrial energy metabolism can occur by genetic or biochemical mechanisms and is associated with human disorders including degenerative diseases, cancer, and aging (1). Mutations in both the mitochondrial genome and in nuclear genes whose products have mitochondrial functions are linked to mitochondrial disease syndromes. Nuclear genes include those encoding the adenine nucleotide translocator 1 (2), thymidine phosphorylase (3), mitochondrial DNA helicase (Twinkle) (4), and the catalytic subunit of mitochondrial DNA polymerase (pol 1 ␥) (5). Pol ␥ has also been shown to be a target of oxidative damage, which reduces DNA polymerase activity in the mitochondrial matrix (6).Pol ␥ is the only DNA polymerase known to be required for mitochondrial DNA replication in animals (7). It is a member of the family A DNA polymerase group (8, 9), of which Escherichia coli pol I is the prototype (10). The crystal structures of numerous family A DNA polymerases have been solved, revealing a high degree of structural similarity among its members (11)(12)(13)(14)(15)(16)(17). The interaction between DNA polymerase and template-primer DNA has also been revealed in molecular detail by structural determination of pol:DNA co-crystals and in biochemical studies. The pol domain comprises palm, fingers, and thumb subdomains that are separated from the 3Ј-5Ј exonuclease (exo) domain by a cleft that binds the template-primer. Wher...

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confidence: 99%

Mutations in the Spacer Region of Drosophila Mitochondrial DNA Polymerase Affect DNA Binding, Processivity, and the Balance between Pol and Exo Function

Luo

Kaguni

2005

Journal of Biological Chemistry

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“…Two families described by Van Goethem et al (2001) were compound heterozygous for missense POLG mutations (A467T and L304R in family B; A467T and R3P in family C), therefore suggesting the existence of arPEO. Lamantea et al (2002) reported on three families sharing the heterozygous T251I mutation in association with either R309L, or G848S or the 2345G ins . Furthermore, Van Goethem et al (2003a) described one further apparently sporadic case due to recessive inheritance of the common Belgian A467T mutation together with a so far private R627W.…”

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confidence: 99%

POLG mutations in sporadic mitochondrial disorders with multiple mtDNA deletions

et al. 2003

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The accumulation of multiple mitochondrial DNA (mtDNA) deletions in stable tissues is a distinctive feature of several autosomal disorders, characterized by Progressive External Ophthalmoplegia (PEO), ptosis, and proximal myopathy. At least three nuclear genes are responsible for these disorders: ANT1 and C10orf2 cause autosomal dominant PEO, while mutations of DNA polymerase γA (POLG1 or POLG) gene on chromosome 15q25 causes both autosomal dominant and recessive forms of PEO. To investigate the contribution of these genes to the sporadic cases of PEO with multiple mtDNA deletions, we studied 31 mitochondrial myopathy patients without any family history for the disorder: 23 had PEO with myopathy, with or without the additional features of pigmentary retinopathy, ataxia, neurosensorial hypoacusia and diabetes mellitus, 7 presented isolated myopathy and one a peripheral neuropathy with ptosis. In all patients Southern blot of muscle DNA showed multiple mtDNA deletions; screening for ANT1 and C10ORF2 genes was negative. POLG analysis revealed mutations in eight patients; in six of them the mutations were allelic, while two patients were heterozygous. Five mutations were new, namely one stop codon (c.2407C>T / p.R709X) and four missense mutations (c.1085G>C / p.G268A; c.1967G>A / p.R562Q; c.2702G>C / p.R807P; c.3076C>T / p.H932W). A high degree of conservation was observed for all the new missense mutations. Only patients presenting PEO as part of their clinical phenotype had POLG mutations, in seven of them together with myopathic signs and in one with a sensori-motor peripheral neuropathy.

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“…POLG encodes the catalytic subunit of the mitochondrial DNA polymerase g and is also associated with recessive, multisystemic PEO (26), which tends to have a more complex/ severe phenotype than dominant forms. PEOA2 (OMIM #609283) corresponds to ANT1 on chromosome 4q34 -35, which is limited to about 4% of adPEO cases (23). Mutations in twinkle (C10ORF2) on chromosome 10q24 (PEOA3; OMIM #609286), are identified in approximately 35% of adPEO (23,27) cases.…”

Section: Progressive External Opthalmoplegia (Peo)mentioning

confidence: 99%

“…PEOA2 (OMIM #609283) corresponds to ANT1 on chromosome 4q34 -35, which is limited to about 4% of adPEO cases (23). Mutations in twinkle (C10ORF2) on chromosome 10q24 (PEOA3; OMIM #609286), are identified in approximately 35% of adPEO (23,27) cases. The twinkle gene product appears to be a mitochondrial DNA helicase by homology with the phage T7 primase/helicase (27).…”

Section: Progressive External Opthalmoplegia (Peo)mentioning

confidence: 99%

The adenine nucleotide translocase type 1 (ANT1): A new factor in mitochondrial disease

Sharer

2005

IUBMB Life (International Union of Biochemistry and Molecular B

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Mitochondrial disorders of oxidative phosphorylation (OXPHOS) comprise a growing list of potentially lethal diseases caused by mutations in either mitochondrial (mtDNA) or nuclear DNA (nDNA). Two such conditions, autosomal dominant progressive external ophthalmoplegia (adPEO) and Senger's Syndrome, are associated with dysfunction of the heart and muscle‐specific isoform of the adenine nucleotide translocase (ANT1), a nDNA gene product that facilitates transport of ATP and ADP across the inner mitochondrial membrane. AdPEO is a mtDNA deletion disorder broadly characterized by pathology involving the eyes, skeletal muscle, and central nervous system. In addition to ANT1, mutations in at least two other nuclear genes, twinkle and POLG, have been shown to cause mtDNA destabilization associated with adPEO. Senger's syndrome is an autosomal recessive condition characterized by congenital heart defects, abnormalities of skeletal muscle mitochondria, cataracts, and elevated circulatory levels of lactic acid. This syndrome is associated with severe depletion of ANT1, which may be the result of an as yet unidentified ANT1‐specific transcriptional or translational processing error. ANT1 has also been associated with a third condition, autosomal dominant facioscapulohumeral muscular dystrophy (FSHD), an adult onset disorder characterized by variable muscle weakness in the face, feet, shoulders, and hips. FSHD patients possess specific DNA deletions on chromosome 4, which appear to cause derepression of several nearby genes, including ANT1. Early development of FSHD may involve mitochondrial dysfunction and increased oxidative stress, possibly associated with overexpression of ANT1. IUBMB Life, 57: 607‐614, 2005

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Mutations of mitochondrial DNA polymerase γA are a frequent cause of autosomal dominant or recessive progressive external ophthalmoplegia

Cited by 246 publications

References 35 publications

Mutations in the Spacer Region of Drosophila Mitochondrial DNA Polymerase Affect DNA Binding, Processivity, and the Balance between Pol and Exo Function

Mutations in the Spacer Region of Drosophila Mitochondrial DNA Polymerase Affect DNA Binding, Processivity, and the Balance between Pol and Exo Function

POLG mutations in sporadic mitochondrial disorders with multiple mtDNA deletions

The adenine nucleotide translocase type 1 (ANT1): A new factor in mitochondrial disease

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