Human EXOG Possesses Strong AP Hydrolysis Activity: Implication on Mitochondrial DNA Base Excision Repair.

Most oxidative damage on mitochondrial DNA is corrected by the base excision repair (BER) pathway. However, the enzyme that catalyzes the rate-limiting reaction─deoxyribose phosphate (dRP) removal─in the multienzymatic reaction pathway has not been completely determined in mitochondria. Also unclear is how a logical order of enzymatic reactions is ensured.

In vitro reconstitution reveals a key role of human mitochondrial EXOG in RNA primer processing.

The removal of RNA primers is essential for mitochondrial DNA (mtDNA) replication. Several nucleases have been implicated in RNA primer removal in human mitochondria, however, no conclusive mechanism has been elucidated. Here, we reconstituted minimal in vitro system capable of processing RNA primers into ligatable DNA ends.

Whole exome sequencing identifies a homozygous POLG2 missense variant in an adult patient presenting with optic atrophy, movement disorders, premature ovarian failure and mitochondrial DNA depletion.

POLG2 associated disorders belong to the group of mitochondrial DNA (mtDNA) diseases and present with a heterogeneous clinical spectrum, various age of onset, and disease severity. We report a 39-year old female presenting with childhood-onset and progressive neuroophthalmic manifestation with optic atrophy, mixed polyneuropathy, spinal and cerebellar ataxia and generalized chorea associated with mtDNA depletion. Whole-exome sequencing identified an ultra-rare homozygous missense mutation located at Chr17: 062474101-C > A (p.

Defining the crucial domain and amino acid residues in bacterial Lon protease for DNA binding and processing of DNA-interacting substrates.

Lon protease previously has been shown to interact with DNA, but the role of this interaction for Lon proteolytic activity has not been characterized. In this study, we used truncated Lon constructs, bioinformatics analysis, and site-directed mutagenesis to identify Lon domains and residues crucial for Lon binding with DNA and effects on Lon proteolytic activity. We found that deletion of Lon's ATPase domain abrogated interactions with DNA.

Proteolysis in plasmid DNA stable maintenance in bacterial cells.

Plasmids, as extrachromosomal genetic elements, need to work out strategies that promote independent replication and stable maintenance in host bacterial cells. Their maintenance depends on constant formation and dissociation of nucleoprotein complexes formed on plasmid DNA. Plasmid replication initiation proteins (Rep) form specific complexes on direct repeats (iterons) localized within the plasmid replication origin.