92 Disease mutations in the human mitochondrial DNA polymerase thumb subdomain impart severe defects in mtDNA replication

Kasiviswanathan, Rajesh; Longley, Matthew J.; Chan, Sherine S.L.; Copeland, William C.

doi:10.1016/j.mito.2009.12.085

Cited by 7 publications

(30 citation statements)

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“…Polymerase active site mutations G923D and A957S are found in PEO patients and have been shown to exhibit 21% and 23% polymerase activity, respectively (Graziewicz et al 2004). Analysis of a cluster of Alpers mutations in the thumb domain has shown a striking correlation with the severity of the defect and the degree of conservation of amino acid sequences among various eukaryotes (Kasiviswanathan et al 2009). Mutations in the most conserved sites represented by G848S, T851A, R852C, and R853Q exhibited less than 1% WTenzyme activity (Kasiviswanathan et al 2009).…”

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

“…Analysis of a cluster of Alpers mutations in the thumb domain has shown a striking correlation with the severity of the defect and the degree of conservation of amino acid sequences among various eukaryotes (Kasiviswanathan et al 2009). Mutations in the most conserved sites represented by G848S, T851A, R852C, and R853Q exhibited less than 1% WTenzyme activity (Kasiviswanathan et al 2009). Mutations in codons for less conserved amino acids (Gln879 and Thr885) resulted in only moderate reduction in activity (Kasiviswanathan et al 2009).…”

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

“…Mutations in the most conserved sites represented by G848S, T851A, R852C, and R853Q exhibited less than 1% WTenzyme activity (Kasiviswanathan et al 2009). Mutations in codons for less conserved amino acids (Gln879 and Thr885) resulted in only moderate reduction in activity (Kasiviswanathan et al 2009). Haplotype analysis of the Finnish population demonstrates a carrier frequency of 1:125 for a common polymerase domain mutation, W748S (Hakonen et al 2005).…”

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

“…By measuring a base substitution in mtDNA that confers erythromycin resistance, it was shown that mtDNA mutant frequency is increased by some disease-associated mutations (Baruffini et al 2006(Baruffini et al , 2007(Baruffini et al , 2011Stumpf et al 2010). However, biochemical evidence of several mutants showed that the incorporation of an incorrect nucleotide is not more kinetically favorable (Kasiviswanathan et al 2009;Szczepanowska and Foury 2010). Therefore, it is still unclear what causes the increase in mutagenesis in these mutant strains.…”

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

See 3 more Smart Citations

Clinical and Molecular Features of POLG-Related Mitochondrial Disease

Stumpf

Saneto

Copeland

2013

Cold Spring Harbor Perspectives in Biology

117

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Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

Section: Molecular Characterization Of Defects In Polymerase Activitymentioning

confidence: 99%

See 2 more Smart Citations

Clinical and Molecular Features of POLG-Related Mitochondrial Disease

Stumpf

Saneto

Copeland

2013

Cold Spring Harbor Perspectives in Biology

117

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“…These data suggest that the mutant polymerase binds to mtDNA and not only is unable to replicate but either directly or indirectly inhibits the wild-type polymerase. Interestingly, human R853Q and T851A do not incorporate the incorrect nucleotide at a higher frequency than wild-type, indicating that these mutations do not affect fidelity [52]. These mutations are severely compromised for polymerase activity and so it is unlikely that they are participating in any mtDNA replication.…”

Section: Saccharomyces Cerevisiae Identifies Mutations That Cause Mtdmentioning

confidence: 99%

Mitochondrial DNA replication and disease: insights from DNA polymerase γ mutations

Stumpf

Copeland

2010

Cell. Mol. Life Sci.

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DNA polymerase γ (pol γ), encoded by POLG, is responsible for replicating human mitochondrial DNA. About 150 mutations in the human POLG have been identified in patients with mitochondrial diseases such as Alpers syndrome, progressive external ophthalmoplegia, and ataxia-neuropathy syndromes. Because many of the mutations are described in single citations with no genotypic family history, it is important to ascertain which mutations cause or contribute to mitochondrial disease. The vast majority of data about POLG mutations has been generated from biochemical characterizations of recombinant pol γ. However, recently, the study of mitochondrial dysfunction in Saccharomyces cerevisiae and mouse models provides important in vivo evidence for the role of POLG mutations in disease. Also, the published 3D-structure of the human pol γ assists in explaining some of the biochemical and genetic properties of the mutants. This review summarizes the current evidence that identifies and explains disease-causing POLG mutations.

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Synergistic Effects of the in cis T251I and P587L Mitochondrial DNA Polymerase γ Disease Mutations

DeBalsi

Longley

Hoff

et al. 2017

Journal of Biological Chemistry

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Human mitochondrial DNA (mtDNA) polymerase γ (Pol γ) is the only polymerase known to replicate the mitochondrial genome. The Pol γ holoenzyme consists of the p140 catalytic subunit (POLG) and the p55 homodimeric accessory subunit (POLG2), which enhances binding of Pol γ to DNA and promotes processivity of the holoenzyme. Mutations within impede maintenance of mtDNA and cause mitochondrial diseases. Two common mutations usually found in patients primarily with progressive external ophthalmoplegia generate T251I and P587L amino acid substitutions. To determine whether T251I or P587L is the primary pathogenic allele or whether both substitutions are required to cause disease, we overproduced and purified WT, T251I, P587L, and T251I + P587L double variant forms of recombinant Pol γ. Biochemical characterization of these variants revealed impaired DNA binding affinity, reduced thermostability, diminished exonuclease activity, defective catalytic activity, and compromised DNA processivity, even in the presence of the p55 accessory subunit. However, physical association with p55 was unperturbed, suggesting intersubunit affinities similar to WT. Notably, although the single mutants were similarly impaired, a dramatic synergistic effect was found for the double mutant across all parameters. In conclusion, our analyses suggest that individually both T251I and P587L substitutions functionally impair Pol γ, with greater pathogenicity predicted for the single P587L variant. Combining T251I and P587L induces extreme thermal lability and leads to synergistic nucleotide and DNA binding defects, which severely impair catalytic activity and correlate with presentation of disease in patients.

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92 Disease mutations in the human mitochondrial DNA polymerase thumb subdomain impart severe defects in mtDNA replication

Cited by 7 publications

References 0 publications

Clinical and Molecular Features of POLG-Related Mitochondrial Disease

Clinical and Molecular Features of POLG-Related Mitochondrial Disease

Mitochondrial DNA replication and disease: insights from DNA polymerase γ mutations

Synergistic Effects of the in cis T251I and P587L Mitochondrial DNA Polymerase γ Disease Mutations

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