5c51

Probing the Structural and Molecular Basis of Nucleotide Selectivity by Human Mitochondrial DNA Polymerase gamma

spinqualitylabelsall models 5c51, resolution 3.43Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5c51 is a 5 chain structure with sequence from DNA launch vector pDE-GFP2, Homo sapiens and Virus Chimp162. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.426Å Ligands: 1RY, DOC, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease DPOG1_HUMAN Defects in POLG are the cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal dominant type 1 (PEOA1) [MIM: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. Defects in POLG are a cause of progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal recessive (PEOB) [MIM:258450. PEOB is a severe form of progressive external ophthalmoplegia. It is clinically more heterogeneous than the autosomal dominant forms. Can be more severe. Defects in POLG are a cause of sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO) [MIM: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. Defects in POLG are the cause of mitochondrial DNA depletion syndrome type 4A (MTDPS4A) [MIM: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. Defects in POLG are the cause of mitochondrial DNA depletion syndrome type 4B (MTDPS4B) [MIM: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:256000. LS is a severe neurological disorder characterized by bilaterally symmetrical necrotic lesions in subcortical brain regions. Function DPOG1_HUMAN Involved in the replication of mitochondrial DNA. Associates with mitochondrial DNA. Publication Abstract from PubMed Nucleoside analog reverse transcriptase inhibitors (NRTIs) are the essential components of highly active antiretroviral (HAART) therapy targeting HIV reverse transcriptase (RT). NRTI triphosphates (NRTI-TP), the biologically active forms, act as chain terminators of viral DNA synthesis. Unfortunately, NRTIs also inhibit human mitochondrial DNA polymerase (Pol gamma), causing unwanted mitochondrial toxicity. Understanding the structural and mechanistic differences between Pol gamma and RT in response to NRTIs will provide invaluable insight to aid in designing more effective drugs with lower toxicity. The NRTIs emtricitabine [(-)-2,3'-dideoxy-5-fluoro-3'-thiacytidine, (-)-FTC] and lamivudine, [(-)-2,3'-dideoxy-3'-thiacytidine, (-)-3TC] are both potent RT inhibitors, but Pol gamma discriminates against (-)-FTC-TP by two orders of magnitude better than (-)-3TC-TP. Furthermore, although (-)-FTC-TP is only slightly more potent against HIV RT than its enantiomer (+)-FTC-TP, it is discriminated by human Pol gamma four orders of magnitude more efficiently than (+)-FTC-TP. As a result, (-)-FTC is a much less toxic NRTI. Here, we present the structural and kinetic basis for this striking difference by identifying the discriminator residues of drug selectivity in both viral and human enzymes responsible for substrate selection and inhibitor specificity. For the first time, to our knowledge, this work illuminates the mechanism of (-)-FTC-TP differential selectivity and provides a structural scaffold for development of novel NRTIs with lower toxicity. Probing the structural and molecular basis of nucleotide selectivity by human mitochondrial DNA polymerase gamma.,Sohl CD, Szymanski MR, Mislak AC, Shumate CK, Amiralaei S, Schinazi RF, Anderson KS, Yin YW Proc Natl Acad Sci U S A. 2015 Jul 14;112(28):8596-601. doi:, 10.1073/pnas.1421733112. Epub 2015 Jun 29. PMID:26124101 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also DNA polymerase 3D structures

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