A coordinated haptic mechanism ensures efficient DNA sampling by the 8-oxoguanine glycosylase OGG1.

Martinez, M.; D'Augustin, O.; Chousianiti, D. M.; Gaudon, V.; Quevedo, A. G.; Bigot, N.; Chapuis, C.; Di Guilmi, A. M.; Hubert, J. F.; Castaing, B.; Campalans, A.; Huet, S.

doi:10.1101/2025.10.08.681224

bioRxiv · 10.1101/2025.10.08.681224

A coordinated haptic mechanism ensures efficient DNA sampling by the 8-oxoguanine glycosylase OGG1.

Martinez, M.·D'Augustin, O.·Chousianiti, D. M.·Gaudon, V.·Quevedo, A. G.·Bigot, N.·Chapuis, C.·Di Guilmi, A. M.·Hubert, J. F.·Castaing, B.·Campalans, A.·Huet, S.

View original source ↗Export metadata ↓

Abstract

7,8-Dihydro-8-oxoguanine (8-oxoG) is the most frequent base modification occurring upon oxidative stress. This highly mutagenic lesion is specifically recognized and excised by the DNA glycosylase OGG1 when paired with cytosine, initiating the base excision repair pathway. Since 8-oxoG neither significantly impacts the structure of the double helix nor blocks transcription and replication processes, its detection requires a careful inspection of each base pair by OGG1. By monitoring this lesion search process both in vitro and in living cells, we demonstrate that it involves a tight coordination between several conserved amino acids encircling the DNA helix. More specifically, we show that the N149-151 motif, on the target strand, as well as residues R154 and R204, on the opposite strand, both regulate OGG1 engagement on the DNA to ensure fast Y203-mediated base unstacking, a prerequisite for efficient 8-oxoG detection. These findings highlight the early mechanisms that enable OGG1 to maintain rapid sampling kinetics while preserving high specificity for 8-oxoG in the context of the complex architecture displayed by the DNA within the cell nucleus.

Source connections

Published article ↗

Explore related subjects

genetics Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Martinez, M., D'Augustin, O., Chousianiti, D. M., Gaudon, V., Quevedo, A. G., Bigot, N., Chapuis, C., Di Guilmi, A. M., Hubert, J. F., Castaing, B., Campalans, A., Huet, S.. 2025-10-08. A coordinated haptic mechanism ensures efficient DNA sampling by the 8-oxoguanine glycosylase OGG1.. https://doi.org/10.1101/2025.10.08.681224

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

OPA1 controls mitochondrial dysfunction-driven liver fibrosis in MASLD

Progressive hepatic fibrosis is the principal determinant of morbidity and mortality in metabolic dysfunction-associated steatotic liver disease and steatohepatitis (MASLD/MASH). Mitochondrial dysfunction is a hallmark of MASH, and the release of mitochondrial damage-associated molecular patterns (mito-DAMPs) from injured hepatocytes can promote fibrosis. However, how mitochondrial dynamics and quality control shape the fibrotic response in MASLD/MASH remains unclear. Here, through large-scale genomic analyses of mitochondrial genes governing mitophagy, fusion and fission in human MASLD, with a power-equivalent sample size of approximately 700,000 individuals, we identify a strong association between hepatic fibrosis and the mitochondrial fusion factor dynamin-like GTPase optic atrophy 1 (OPA1). OPA1 transcripts and protein abundance in the liver epithelium were progressively dysregulated with advancing fibrosis. In mice, hepatocyte-specific OPA1 loss alone was sufficient to induce hepatic stellate cell activation and fibrosis in zone 3, promoted the release of mito-DAMPs into the circulation and exacerbated fibrosis in experimental MASH. These findings identify OPA1 as a central regulator of the hepatic fibrotic response and connect defective mitochondrial homeostasis to mito-DAMP release, hepatic stellate cell activation and fibrosis in MASLD.

genetics↗

bioRxiv2026

Temporal control of mitochondrial mutagenesis reveals the fate of mtDNA mutations with age

Mutations in the mitochondrial genome (mtDNA) play a critical role in the aging process and a wide variety of age-related diseases. However, it remains unclear when the mutations that drive physiological decline arise. To answer this question, we generated a new mouse model in which mitochondrial mutagenesis can be confined to a defined window of time. Surprisingly, we found that mutations that arise during the first two months of life are sufficient to drive a wide variety of age-related pathologies, and that the severity of this pathology is broadly regulated by distinct, tissue-specific selective pressures that control the fate of mtDNA mutations with age. Further, we found that selection against deleterious variants can be modulated by manipulation of mitochondrial fusion in vitro and in vivo. These observations raise the possibility that in some tissues, the pace of aging is pre-determined by events that occur early in life and that interventions targeting mitochondrial fusion may be able to slow down or reverse the expansion of these pathogenic variants. These results carry far-reaching implications for strategies aimed at preventing or delaying age-related decline.

genetics↗

bioRxiv2026

Innate immune stress pathway activation underlies heterochromatin dysfunction pathology

Heterochromatin loss disrupts nuclear architecture, gene regulation and repetitive element silencing, and is associated with diverse human diseases. However, mechanisms linking heterochromatin dysfunction to pathological phenotypes remain unclear. Using genetic interaction screening and genomic analyses in C. elegans, we identify secondary activation of the Intracellular Pathogen Response (IPR), an innate immune stress pathway, as a major contributor to heterochromatin mutant phenotypes. Constitutive IPR activation phenocopies slow growth and indirect transcriptional changes observed in these mutants. Depletion of genetic enhancers further increased, whereas suppressor RNAi attenuated IPR activation, with direct heterochromatin targets remaining substantially deregulated. Notably, many suppressors encode active chromatin components, and mild reduction of RNA polymerase II activity ameliorates growth defects in C. elegans HP1 mutants and human HP1-deficient cells. Our findings reveal secondary stress response activation as an important mechanism linking heterochromatin dysfunction to pathology and identify transcriptional dampening as a potential therapeutic strategy for mitigating these effects.

genetics↗