9y4c | pdb_00009y4c

Strand displacement state I of Human mitochondrial DNA polymerase gamma ternary complex

spinqualitylabelsall models 9y4c, resolution 3.23Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9y4c is a 4 chain structure with sequence from Homo sapiens and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.23Å Ligands: CA, DTP 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 Accurate replication of mitochondrial genome (mtDNA) integrity, which is essential for cellular metabolism and energy supply, relies primarily on DNA polymerase gamma (Pol gamma), Twinkle helicase, and mitochondrial single-stranded DNA binding protein (mtSSB). Twinkle alone exhibits little helicase activity while reports indicate that Pol gamma displays from modest to limited unwinding activity. This led us to dissect Pol gamma strand displacement activity using structural, biochemical and in silico approaches. Here, we show that human Pol gamma carries out robust strand displacement synthesis at physiological concentrations of divalent metal ions which reveals that distinct metal-binding sites can independently regulate DNA synthesis and unwinding activities. We further showed that Pol gamma can displace RNA/DNA hybrid with comparable efficiency as DNA/DNA duplex, representing a key implication on RNA primer removal to preserve mtDNA integrity. Our cryo-electron microscopy structures of Pol gamma complexed with a template containing downstream dsDNA and an incoming nucleotide revealed the structural mechanism for the strand displacement activity. We identified four conformational states that represent successive stages of DNA unwinding, accompanied by coordinated rearrangement of the downstream DNA and Pol gamma elements that mediate strand displacement. This work establishes biochemical and structural mechanisms of Pol gamma strand displacement activity, providing fundamental insight into human mitochondrial DNA replication and integrity. Pol gamma possesses separate metal binding sites for polymerase and strand displacement functions.,Baruch-Torres N, Park J, Mora-Garduno J, Roy A, Singh A, Cisneros GA, Brieba LG, Patel SS, Yin YW bioRxiv [Preprint]. 2026 Jan 25:2026.01.25.701366. doi: , 10.64898/2026.01.25.701366. PMID:41648309 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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