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==Structural basis for processivity and antiviral drug toxicity in human mitochondrial DNA replicase==
==Structural basis for processivity and antiviral drug toxicity in human mitochondrial DNA replicase==
<StructureSection load='4ztu' size='340' side='right' caption='[[4ztu]], [[Resolution|resolution]] 3.30&Aring;' scene=''>
<StructureSection load='4ztu' size='340' side='right'caption='[[4ztu]], [[Resolution|resolution]] 3.30&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[4ztu]] is a 5 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4ZTU OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4ZTU FirstGlance]. <br>
<table><tr><td colspan='2'>[[4ztu]] is a 5 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4ZTU OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4ZTU FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=DCT:2,3-DIDEOXYCYTIDINE+5-TRIPHOSPHATE'>DCT</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.299&#8491;</td></tr>
<tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=DOC:2,3-DIDEOXYCYTIDINE-5-MONOPHOSPHATE'>DOC</scene></td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=DCT:2,3-DIDEOXYCYTIDINE+5-TRIPHOSPHATE'>DCT</scene>, <scene name='pdbligand=DOC:2,3-DIDEOXYCYTIDINE-5-MONOPHOSPHATE'>DOC</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4ztz|4ztz]]</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4ztu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ztu OCA], [https://pdbe.org/4ztu PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4ztu RCSB], [https://www.ebi.ac.uk/pdbsum/4ztu PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4ztu ProSAT]</span></td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">POLG, MDP1, POLG1, POLGA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN]), POLG2, MTPOLB ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN])</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4ztu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ztu OCA], [http://pdbe.org/4ztu PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4ztu RCSB], [http://www.ebi.ac.uk/pdbsum/4ztu PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4ztu ProSAT]</span></td></tr>
</table>
</table>
== Disease ==
== Disease ==
[[http://www.uniprot.org/uniprot/DPOG1_HUMAN DPOG1_HUMAN]] Defects in POLG are the cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal dominant type 1 (PEOA1) [MIM:[http://omim.org/entry/157640 157640]]. Progressive external ophthalmoplegia is characterized by progressive weakness of ocular muscles and levator muscle of the upper eyelid. In a minority of cases, it is associated with skeletal myopathy, which predominantly involves axial or proximal muscles and which causes abnormal fatigability and even permanent muscle weakness. Ragged-red fibers and atrophy are found on muscle biopsy. A large proportion of chronic ophthalmoplegias are associated with other symptoms, leading to a multisystemic pattern of this disease. Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism, and parkinsonism.<ref>PMID:12210792</ref> <ref>PMID:11897778</ref> <ref>PMID:15534189</ref> <ref>PMID:15351195</ref> <ref>PMID:17420318</ref> <ref>PMID:18575922</ref>  Defects in POLG are a cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal recessive (PEOB) [MIM:[http://omim.org/entry/258450 258450]]. PEOB is a severe form of progressive external ophthalmoplegia. It is clinically more heterogeneous than the autosomal dominant forms. Can be more severe.<ref>PMID:15351195</ref> <ref>PMID:11431686</ref> <ref>PMID:12975295</ref> <ref>PMID:12872260</ref> <ref>PMID:14635118</ref> <ref>PMID:12707443</ref> <ref>PMID:12565911</ref> <ref>PMID:15349879</ref> <ref>PMID:15477547</ref> <ref>PMID:15917273</ref> <ref>PMID:16634032</ref> <ref>PMID:16401742</ref> <ref>PMID:16621917</ref> <ref>PMID:16639411</ref>  Defects in POLG are a cause of sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO) [MIM:[http://omim.org/entry/607459 607459]]. SANDO is a systemic disorder resulting from mitochondrial dysfunction associated with mitochondrial depletion in skeletal muscle and peripheral nerve tissue. The clinical triad of symptoms consists of sensory ataxic neuropathy, dysarthria, and ophthalmoparesis. However, the phenotype varies widely, even within the same family, and can also include myopathy, seizures, and hearing loss. An atypical form of the disease is characterized by headaches and/or seizures manifesting in childhood or adolescence, followed by development of cerebellar and sensory ataxia, dysarthria, progressive external ophthalmoplegia, and myoclonus in early adulthood.<ref>PMID:12565911</ref> <ref>PMID:15477547</ref> <ref>PMID:15917273</ref> <ref>PMID:16621917</ref> <ref>PMID:16639411</ref> <ref>PMID:14745080</ref> <ref>PMID:16080118</ref> <ref>PMID:15824347</ref> <ref>PMID:16919951</ref>  Defects in POLG are the cause of mitochondrial DNA depletion syndrome type 4A (MTDPS4A) [MIM:[http://omim.org/entry/203700 203700]]; also called Alpers diffuse degeneration of cerebral gray matter with hepatic cirrhosis. An autosomal recessive hepatocerebral syndrome. The typical course of the disease includes severe developmental delay, intractable seizures, liver failure, and death in childhood. Refractory seizures, cortical blindness, progressive liver dysfunction, and acute liver failure after exposure to valproic acid are considered diagnostic features. The neuropathological hallmarks are neuronal loss, spongiform degeneration, and astrocytosis of the visual cortex. Liver biopsy results show steatosis, often progressing to cirrhosis.<ref>PMID:16621917</ref> <ref>PMID:16639411</ref> <ref>PMID:15122711</ref> <ref>PMID:15929042</ref> <ref>PMID:15689359</ref> <ref>PMID:18828154</ref>  Defects in POLG are the cause of mitochondrial DNA depletion syndrome type 4B (MTDPS4B) [MIM:[http://omim.org/entry/613662 613662]]; also known as mitochondrial DNA depletion syndrome 4B MNGIE type or mitochondrial neurogastrointestinal encephalopathy syndrome POLG-related. An autosomal recessive progressive multisystem disorder clinically characterized by chronic gastrointestinal dysmotility and pseudo-obstruction, cachexia, progressive external ophthalmoplegia, axonal sensory ataxic neuropathy, and muscle weakness.  Defects in POLG are a cause of Leigh syndrome (LS) [MIM:[http://omim.org/entry/256000 256000]]. LS is a severe neurological disorder characterized by bilaterally symmetrical necrotic lesions in subcortical brain regions.<ref>PMID:18828154</ref> [[http://www.uniprot.org/uniprot/DPOG2_HUMAN DPOG2_HUMAN]] Defects in POLG2 are the cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal dominant type 4 (PEOA4) [MIM:[http://omim.org/entry/610131 610131]]. Progressive external ophthalmoplegia is characterized by progressive weakness of ocular muscles and levator muscle of the upper eyelid. In a minority of cases, it is associated with skeletal myopathy, which predominantly involves axial or proximal muscles and which causes abnormal fatigability and even permanent muscle weakness. Ragged-red fibers and atrophy are found on muscle biopsy. A large proportion of chronic ophthalmoplegias are associated with other symptoms, leading to a multisystemic pattern of this disease. Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism, and parkinsonism.<ref>PMID:16685652</ref> 
[https://www.uniprot.org/uniprot/DPOG1_HUMAN DPOG1_HUMAN] Defects in POLG are the cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal dominant type 1 (PEOA1) [MIM:[https://omim.org/entry/157640 157640]. Progressive external ophthalmoplegia is characterized by progressive weakness of ocular muscles and levator muscle of the upper eyelid. In a minority of cases, it is associated with skeletal myopathy, which predominantly involves axial or proximal muscles and which causes abnormal fatigability and even permanent muscle weakness. Ragged-red fibers and atrophy are found on muscle biopsy. A large proportion of chronic ophthalmoplegias are associated with other symptoms, leading to a multisystemic pattern of this disease. Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism, and parkinsonism.<ref>PMID:12210792</ref> <ref>PMID:11897778</ref> <ref>PMID:15534189</ref> <ref>PMID:15351195</ref> <ref>PMID:17420318</ref> <ref>PMID:18575922</ref>  Defects in POLG are a cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal recessive (PEOB) [MIM:[https://omim.org/entry/258450 258450]. PEOB is a severe form of progressive external ophthalmoplegia. It is clinically more heterogeneous than the autosomal dominant forms. Can be more severe.<ref>PMID:15351195</ref> <ref>PMID:11431686</ref> <ref>PMID:12975295</ref> <ref>PMID:12872260</ref> <ref>PMID:14635118</ref> <ref>PMID:12707443</ref> <ref>PMID:12565911</ref> <ref>PMID:15349879</ref> <ref>PMID:15477547</ref> <ref>PMID:15917273</ref> <ref>PMID:16634032</ref> <ref>PMID:16401742</ref> <ref>PMID:16621917</ref> <ref>PMID:16639411</ref>  Defects in POLG are a cause of sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO) [MIM:[https://omim.org/entry/607459 607459]. SANDO is a systemic disorder resulting from mitochondrial dysfunction associated with mitochondrial depletion in skeletal muscle and peripheral nerve tissue. The clinical triad of symptoms consists of sensory ataxic neuropathy, dysarthria, and ophthalmoparesis. However, the phenotype varies widely, even within the same family, and can also include myopathy, seizures, and hearing loss. An atypical form of the disease is characterized by headaches and/or seizures manifesting in childhood or adolescence, followed by development of cerebellar and sensory ataxia, dysarthria, progressive external ophthalmoplegia, and myoclonus in early adulthood.<ref>PMID:12565911</ref> <ref>PMID:15477547</ref> <ref>PMID:15917273</ref> <ref>PMID:16621917</ref> <ref>PMID:16639411</ref> <ref>PMID:14745080</ref> <ref>PMID:16080118</ref> <ref>PMID:15824347</ref> <ref>PMID:16919951</ref>  Defects in POLG are the cause of mitochondrial DNA depletion syndrome type 4A (MTDPS4A) [MIM:[https://omim.org/entry/203700 203700]; also called Alpers diffuse degeneration of cerebral gray matter with hepatic cirrhosis. An autosomal recessive hepatocerebral syndrome. The typical course of the disease includes severe developmental delay, intractable seizures, liver failure, and death in childhood. Refractory seizures, cortical blindness, progressive liver dysfunction, and acute liver failure after exposure to valproic acid are considered diagnostic features. The neuropathological hallmarks are neuronal loss, spongiform degeneration, and astrocytosis of the visual cortex. Liver biopsy results show steatosis, often progressing to cirrhosis.<ref>PMID:16621917</ref> <ref>PMID:16639411</ref> <ref>PMID:15122711</ref> <ref>PMID:15929042</ref> <ref>PMID:15689359</ref> <ref>PMID:18828154</ref>  Defects in POLG are the cause of mitochondrial DNA depletion syndrome type 4B (MTDPS4B) [MIM:[https://omim.org/entry/613662 613662]; also known as mitochondrial DNA depletion syndrome 4B MNGIE type or mitochondrial neurogastrointestinal encephalopathy syndrome POLG-related. An autosomal recessive progressive multisystem disorder clinically characterized by chronic gastrointestinal dysmotility and pseudo-obstruction, cachexia, progressive external ophthalmoplegia, axonal sensory ataxic neuropathy, and muscle weakness.  Defects in POLG are a cause of Leigh syndrome (LS) [MIM:[https://omim.org/entry/256000 256000]. LS is a severe neurological disorder characterized by bilaterally symmetrical necrotic lesions in subcortical brain regions.<ref>PMID:18828154</ref>  
== Function ==
== Function ==
[[http://www.uniprot.org/uniprot/DPOG1_HUMAN DPOG1_HUMAN]] Involved in the replication of mitochondrial DNA. Associates with mitochondrial DNA. [[http://www.uniprot.org/uniprot/DPOG2_HUMAN DPOG2_HUMAN]] Mitochondrial polymerase processivity subunit. Stimulates the polymerase and exonuclease activities, and increases the processivity of the enzyme. Binds to ss-DNA.
[https://www.uniprot.org/uniprot/DPOG1_HUMAN DPOG1_HUMAN] Involved in the replication of mitochondrial DNA. Associates with mitochondrial DNA.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The human DNA polymerase gamma (Pol gamma) is responsible for DNA replication in mitochondria. Pol gamma is particularly susceptible to inhibition by dideoxynucleoside-based inhibitors designed to fight viral infection. Here, we report crystal structures of the replicating Pol gamma-DNA complex bound to either substrate or zalcitabine, an inhibitor used for HIV reverse transcriptase. The structures reveal that zalcitabine binds to the Pol gamma active site almost identically to the substrate dCTP, providing a structural basis for Pol gamma-mediated drug toxicity. When compared to the apo form, Pol gamma undergoes intra- and inter-subunit conformational changes upon formation of the ternary complex with primer/template DNA and substrate. We also find that the accessory subunit Pol gammaB, which lacks intrinsic enzymatic activity and does not contact the primer/template DNA directly, serves as an allosteric regulator of holoenzyme activities. The structures presented here suggest a mechanism for processivity of the holoenzyme and provide a model for understanding the deleterious effects of Pol gamma mutations in human disease. Crystal structures of the mitochondrial DNA polymerase, Pol gamma, in complex with substrate or antiviral inhibitor zalcitabine provide a basis for understanding Pol gamma-mediated drug toxicity.


Structural basis for processivity and antiviral drug toxicity in human mitochondrial DNA replicase.,Szymanski MR, Kuznetsov VB, Shumate C, Meng Q, Lee YS, Patel G, Patel S, Yin YW EMBO J. 2015 Jul 14;34(14):1959-70. doi: 10.15252/embj.201591520. Epub 2015 Jun, 8. PMID:26056153<ref>PMID:26056153</ref>
==See Also==
 
*[[DNA polymerase 3D structures|DNA polymerase 3D structures]]
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4ztu" style="background-color:#fffaf0;"></div>
== References ==
== References ==
<references/>
<references/>
__TOC__
__TOC__
</StructureSection>
</StructureSection>
[[Category: Human]]
[[Category: Homo sapiens]]
[[Category: Kuznestov, V B]]
[[Category: Large Structures]]
[[Category: Lee, Y S]]
[[Category: Synthetic construct]]
[[Category: Meng, Q]]
[[Category: Kuznestov VB]]
[[Category: Patel, G]]
[[Category: Lee Y-S]]
[[Category: Patel, S S]]
[[Category: Meng Q]]
[[Category: Shumate, C K]]
[[Category: Patel G]]
[[Category: Szymanski, M R]]
[[Category: Patel SS]]
[[Category: Yin, Y W]]
[[Category: Shumate CK]]
[[Category: Dna binding protein-dna complex]]
[[Category: Szymanski MR]]
[[Category: Dna polymerase holoenzyme]]
[[Category: Yin YW]]
[[Category: Mitochondria]]

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