scholarly journals DNA Polymerase Gamma in Mitochondrial DNA Replication and Repair

2003 ◽  
Vol 3 ◽  
pp. 34-44 ◽  
Author(s):  
William C. Copeland ◽  
Matthew J. Longley
Keyword(s):  
Mitochondrial Dna ◽  
Dna Polymerase ◽  
Mitochondrial Diseases ◽  
Polymerase Activity ◽  
Catalytic Subunit ◽  
Animal Cells ◽  
Repair Synthesis ◽  
Mtdna Mutations ◽  
Tissue Degeneration ◽  
Dna Repair Synthesis

Mutations in mitochondrial DNA (mtDNA) are associated with aging, and they can cause tissue degeneration and neuromuscular pathologies known as mitochondrial diseases. Because DNA polymerase γ (pol γ) is the enzyme responsible for replication and repair of mitochondrial DNA, the burden of faithful duplication of mitochondrial DNA, both in preventing spontaneous errors and in DNA repair synthesis, falls on pol γ. Investigating the biological functions of pol γ and its inhibitors aids our understanding of the sources of mtDNA mutations. In animal cells, pol γ is composed of two subunits, a larger catalytic subunit of 125–140 kDa and second subunit of 35–55 kDa. The catalytic subunit contains DNA polymerase activity, 3’-5’ exonuclease activity, and a 5’-dRP lyase activity. The accessory subunit is required for highly processive DNA synthesis and increases the affinity of pol gamma to the DNA.

scholarly journals The tamas Gene, Identified as a Mutation That Disrupts Larval Behavior in Drosophila melanogaster, Codes for the Mitochondrial DNA Polymerase Catalytic Subunit (DNApol-γ125)

Genetics ◽  
1999 ◽  
Vol 153 (4) ◽  
pp. 1809-1824 ◽  
Author(s):  
Balaji Iyengar ◽  
John Roote ◽  
Ana Regina Campos
Keyword(s):  
Mitochondrial Dna ◽  
Drosophila Melanogaster ◽  
Mutant Strain ◽  
Dna Polymerase ◽  
Complementation Group ◽  
Behavioral Changes ◽  
Catalytic Subunit ◽  
Primary Deficit ◽  
Mitochondrial Dna Polymerase ◽  
Food Substrate

AbstractFrom a screen of pupal lethal lines of Drosophila melanogaster we identified a mutant strain that displayed a reproducible reduction in the larval response to light. Moreover, this mutant strain showed defects in the development of the adult visual system and failure to undergo behavioral changes characteristic of the wandering stage. The foraging third instar larvae remained in the food substrate for a prolonged period and died at or just before pupariation. Using a new assay for individual larval photobehavior we determined that the lack of response to light in these mutants was due to a primary deficit in locomotion. The mutation responsible for these phenotypes was mapped to the lethal complementation group l(2)34Dc, which we renamed tamas (translated from Sanskrit as “dark inertia”). Sequencing of mutant alleles demonstrated that tamas codes for the mitochondrial DNA polymerase catalytic subunit (DNApol-γ125).

scholarly journals Segregation of mitochondrial DNA (mtDNA) in human oocytes and in animal models of mtDNA disease: clinical implications

Reproduction ◽  
2002 ◽  
pp. 751-755 ◽  
Author(s):  
J Poulton ◽  
DR Marchington
Keyword(s):  
Mitochondrial Dna ◽  
Antenatal Diagnosis ◽  
Mitochondrial Diseases ◽  
Management Options ◽  
Mtdna Mutations ◽  
Mendelian Disorders ◽  
Leigh’S Syndrome ◽  
Normal Individuals ◽  
Substantial Progress ◽  
Chorionic Villous Sampling

Mitochondrial DNA (mtDNA) is almost entirely maternally inherited. Thousands of copies of mtDNA are present in every nucleated cell and in most normal individuals these are virtually identical (homoplasmy). mtDNA diseases may be caused by mutations in either mitochondrial or nuclear genes and, hence, give rise to maternal or autosomal patterns of inheritance. Antenatal diagnosis of mitochondrial diseases based on chorionic villous sampling is available for Mendelian disorders and the syndromes caused by mutations at bp 8993 (associated with Leigh's syndrome and neurogenic weakness, ataxia and retinitis pigmentosa (NARP)). However, prenatal diagnosis of many other maternally inherited mtDNA diseases is less reliable because it is not possible to predict with confidence the way in which heteroplasmic mtDNA mutations segregate within tissues and find clinical expression. This review focuses on the substantial progress in genetics that has been made recently, and on the management options that clinicians can offer to families.

scholarly journals REPAIR DNA SYNTHESIS IN DIFFERENTIATED EMBRYONIC MUSCLE CELLS

1972 ◽  
Vol 52 (3) ◽  
pp. 589-597 ◽  
Author(s):  
Frank E. Stockdale ◽  
Michael C. O'neill
Keyword(s):  
Skeletal Muscle ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Uv Irradiation ◽  
Life Time ◽  
Muscle Cells ◽  
Polymerase Activity ◽  
Repair Synthesis ◽  
Entire Life ◽  
Embryonic Muscle

The differentiation of embryonic skeletal muscle cells is closely coupled with the cessation of normal DNA replication. Once these cells begin to differentiate, they normally never undergo semiconservative replication of DNA during the entire life time of the muscle cell. Cessation of DNA synthesis has been shown to be accompanied by a loss of 80–90% of the replicative DNA polymerase activity of these cells. Despite this loss the studies reported here demonstrate that muscle cells retain the ability to synthesize DNA of a repair type after UV irradiation. These results suggest that the control exercised over semiconservative DNA synthesis during differentiation of these cells does not extend to repair synthesis after UV irradiation.

scholarly journals The Second-Largest Subunit of the Mouse DNA Polymerase α-Primase Complex Facilitates Both Production and Nuclear Translocation of the Catalytic Subunit of DNA Polymerase α

1998 ◽  
Vol 18 (6) ◽  
pp. 3552-3562 ◽  
Author(s):  
Takeshi Mizuno ◽  
Nobutoshi Ito ◽  
Masayuki Yokoi ◽  
Akio Kobayashi ◽  
Katsuyuki Tamai ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Mammalian Cells ◽  
Nuclear Translocation ◽  
Expression System ◽  
Physiological Role ◽  
Polymerase Activity ◽  
Catalytic Subunit ◽  
Dna Polymerase Α ◽  
Localization Signal ◽  
Primase Complex

ABSTRACT DNA polymerase α-primase is a replication enzyme necessary for DNA replication in all eukaryotes examined so far. Mouse DNA polymerase α is made up of four subunits, the largest of which is the catalytic subunit with a molecular mass of 180 kDa (p180). This subunit exists as a tight complex with the second-largest subunit (p68), whose physiological role has remained unclear up until now. We set out to characterize these subunits individually or in combination by using a cDNA expression system in cultured mammalian cells. Coexpression of p68 markedly increased the protein level of p180, with the result that ectopically generated DNA polymerase activity was dramatically increased. Immunofluorescence analysis showed that while either singly expressed p180 or p68 was localized in the cytoplasm, cotransfection of both subunits resulted in colocalization in the nucleus. We identified a putative nuclear localization signal for p180 (residues 1419 to 1437) and found that interaction with p68 is essential for p180 to translocate into the nucleus. These results indicate that association of p180 with p68 is important for both protein synthesis of p180 and translocation into the nucleus, implying that p68 plays a pivotal role in the newly synthesized DNA polymerase α complex.

scholarly journals The Base Excision Repair Pathway in the Nematode Caenorhabditis elegans

2020 ◽  
Vol 8 ◽  
Author(s):  
Noha Elsakrmy ◽  
Qiu-Mei Zhang-Akiyama ◽  
Dindial Ramotar
Keyword(s):  
Dna Repair ◽  
Caenorhabditis Elegans ◽  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Dna Glycosylases ◽  
Repair Synthesis ◽  
C Elegans ◽  
Base Excision ◽  
Dna Repair Synthesis

Exogenous and endogenous damage to the DNA is inevitable. Several DNA repair pathways including base excision, nucleotide excision, mismatch, homologous and non-homologous recombinations are conserved across all organisms to faithfully maintain the integrity of the genome. The base excision repair (BER) pathway functions to repair single-base DNA lesions and during the process creates the premutagenic apurinic/apyrimidinic (AP) sites. In this review, we discuss the components of the BER pathway in the nematode Caenorhabditis elegans and delineate the different phenotypes caused by the deletion or the knockdown of the respective DNA repair gene, as well as the implications. To date, two DNA glycosylases have been identified in C. elegans, the monofunctional uracil DNA glycosylase-1 (UNG-1) and the bifunctional endonuclease III-1 (NTH-1) with associated AP lyase activity. In addition, the animal possesses two AP endonucleases belonging to the exonuclease-3 and endonuclease IV families and in C. elegans these enzymes are called EXO-3 and APN-1, respectively. In mammalian cells, the DNA polymerase, Pol beta, that is required to reinsert the correct bases for DNA repair synthesis is not found in the genome of C. elegans and the evidence indicates that this role could be substituted by DNA polymerase theta (POLQ), which is known to perform a function in the microhomology-mediated end-joining pathway in human cells. The phenotypes observed by the C. elegans mutant strains of the BER pathway raised many challenging questions including the possibility that the DNA glycosylases may have broader functional roles, as discuss in this review.

scholarly journals DNA repair synthesis during base excision repair in vitro is catalyzed by DNA polymerase epsilon and is influenced by DNA polymerases alpha and delta in Saccharomyces cerevisiae.

1993 ◽  
Vol 13 (2) ◽  
pp. 1051-1058 ◽  
Author(s):  
Z Wang ◽  
X Wu ◽  
E C Friedberg
Keyword(s):  
Dna Repair ◽  
Dna Polymerase ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Repair Synthesis ◽  
Dna Polymerase Epsilon ◽  
Nuclear Extracts ◽  
Polymerase Epsilon ◽  
Base Excision ◽  
Dna Repair Synthesis

Base excision repair is an important mechanism for correcting DNA damage produced by many physical and chemical agents. We have examined the effects of the REV3 gene and the DNA polymerase genes POL1, POL2, and POL3 of Saccharomyces cerevisiae on DNA repair synthesis is nuclear extracts. Deletional inactivation of REV3 did not affect repair synthesis in the base excision repair pathway. Repair synthesis in nuclear extracts of pol1, pol2, and pol3 temperature-sensitive mutants was normal at permissive temperatures. However, repair synthesis in pol2 nuclear extracts was defective at the restrictive temperature of 37 degrees C and could be complemented by the addition of purified yeast DNA polymerase epsilon. Repair synthesis in pol1 nuclear extracts was proficient at the restrictive temperature unless DNA polymerase alpha was inactivated prior to the initiation of DNA repair. Thermal inactivation of DNA polymerase delta in pol3 nuclear extracts enhanced DNA repair synthesis approximately 2-fold, an effect which could be specifically reversed by the addition of purified yeast DNA polymerase delta to the extract. These results demonstrate that DNA repair synthesis in the yeast base excision repair pathway is catalyzed by DNA polymerase epsilon but is apparently modulated by the presence of DNA polymerases alpha and delta.

scholarly journals Residues of Human Cytomegalovirus DNA Polymerase Catalytic Subunit UL54 That Are Necessary and Sufficient for Interaction with the Accessory Protein UL44

2004 ◽  
Vol 78 (1) ◽  
pp. 158-167 ◽  
Author(s):  
Arianna Loregian ◽  
Brent A. Appleton ◽  
James M. Hogle ◽  
Donald M. Coen
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerase ◽  
Human Cytomegalovirus ◽  
Rational Design ◽  
Polymerase Activity ◽  
Catalytic Subunit ◽  
New Drugs ◽  
Accessory Protein ◽  
C Terminus ◽  
Long Chain

ABSTRACT The human cytomegalovirus DNA polymerase contains a catalytic subunit, UL54, and an accessory protein, UL44. Recent studies suggested that UL54 might interact via its extreme C terminus with UL44 (A. Loregian, R. Rigatti, M. Murphy, E. Schievano, G. Palu', and H. S. Marsden, J. Virol. 77:8336-8344, 2003). To address this hypothesis, we quantitatively measured the binding of peptides corresponding to the extreme C terminus of UL54 to UL44 by using isothermal titration calorimetry. A peptide corresponding to the last 22 residues of UL54 was sufficient to bind specifically to UL44 in a 1:1 complex with a dissociation constant of ca. 0.7 μM. To define individual residues in this segment that are crucial for interacting with UL44, we engineered a series of mutations in the C-terminal region of UL54. The UL54 mutants were tested for their ability to interact with UL44 by glutathione S-transferase pulldown assays, for basal DNA polymerase activity, and for long-chain DNA synthesis in the presence of UL44. We observed that deletion of the C-terminal segment or substitution of alanine for Leu1227 or Phe1231 in UL54 greatly impaired both the UL54-UL44 interaction in pulldown assays and long-chain DNA synthesis without affecting basal polymerase activity, identifying these residues as important for subunit interaction. Thus, like the herpes simplex virus UL30-UL42 interaction, a few specific side chains in the C terminus of UL54 are crucial for UL54-UL44 interaction. However, the UL54 residues important for interaction with UL44 are hydrophobic and not basic. This information might aid in the rational design of new drugs for the treatment of human cytomegalovirus infection.

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