Biology subjects

Ogata, S.

Publications and source records attributed to Ogata, S..

3 recordsLinked to original sources

bioRxiv2026

Glutaredoxins rapidly reduce glutathione hydroper- and polysulfides

Hydropersulfides have gained attention in cell biology as excellent nucleophiles and membrane-protective radical scavengers. They form perthiyl radicals, which terminate radical chain reactions through self-recombination, leading to the formation of polysulfides. It is currently unknown how polysulfides are subsequently reduced again in non-enzymatic or enzymatic metabolic pathways. Here we used stopped-flow kinetic measurements in combination with mass spectrometry to show that the model class I glutaredoxin from the malaria parasite Plasmodium falciparum (PfGrx) rapidly reduces the polysulfides glutathione trisulfide (GS3G) and glutathione tetrasulfide (GS4G), yielding the glutathionylated enzyme and the corresponding glutathione hydropersulfide GSSH and hydrotrisulfide GS3H. The second-order rate constants of these enzymatic reductions [≥]107 M-1s-1 are even slightly higher than for glutathione disulfide (GSSG). In contrast, PfGrx was inactive or only moderately active using cystine or cysteine trisulfide as oxi-dants. GSSH and GS3H are further reduced by PfGrx with second-order rate constants on the order of 106-107 M-1s-1, yielding the glutathionylated enzyme as well as hydrogen sulfide (H2S) and hydrogen disulfide (H2S2), respectively. Thus, glutaredoxins specifically recognize the glutathione moiety of glutathione (hydro)polysulfides and glutathione hydropersulfide. Due to the rapid reduction of glutathionylated glutaredoxins by reduced glutathione (GSH), glutathione (hydro)per/polysulfides are efficiently converted to GSSG and H2S or the corresponding hydrogen polysulfides. As a consequence, the steady-state concentration of glutathione (hydro)per/polysulfides should be tightly controlled in subcellular compartments containing active glutaredoxins and high GSH concentrations.

biochemistry↗

bioRxiv2026

Sulfide:quinone oxidoreductase drives mitochondrial supersulfide metabolism to regulate bioenergetics and longevity in eukaryotes

Sulfide:quinone oxidoreductase (SQR) is a critical enzyme that maintains sulfur metabolism by oxidizing sulfide to supersulfides, currently defined as sulfur metabolites with six valence electrons and no charge that are covalently catenated with other sulfur atoms and excludes disulfides. While SQR is known to contribute to mitochondrial electron transport, its physiological impact on systemic energy metabolism and longevity remains largely undefined. In this study, we investigated the role of SQR in mitochondrial bioenergetics and aging using SQR-deficient Schizosaccharomyces pombe ({Delta}hmt2) and a mitochondria-selective SQR-deficient (Sqrdl{Delta}N/{Delta}N) mice model. Functional analysis demonstrated that{Delta} hmt2 grew normally in glucose but not in glycerol, indicating impaired mitochondrial respiration. It showed reduced membrane potential, ATP, and lifespan. Consistent with the yeast findings, Sqrdl{Delta}N/{Delta}N mice exhibited accumulated levels of hydrogen sulfide and persulfides, and demonstrated impaired mitochondrial energy metabolism. Furthermore, supersulfide donor supplementation selectively conferred lifespan extension in wild-type yeast, but not in SQR-deficient strain, and similarly improved mitochondrial function exclusively in wild-type mouse embryonic fibroblasts, with no benefit observed in SQR-mutant counterparts. Together, our findings demonstrate that mitochondrial SQR plays an essential role in sulfur respiration, critically supporting mitochondrial function and organismal longevity across eukaryotes. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/716515v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@d834forg.highwire.dtl.DTLVardef@127dc7dorg.highwire.dtl.DTLVardef@1fccb8eorg.highwire.dtl.DTLVardef@197e910_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDeveloped an SQR-deficient S. pombe ({Delta}hmt2) model that exhibits sulfur metabolism, mitochondrial dysfunction, and shortened chronological lifespan C_LIO_LISulfide and supersulfide donors prolong yeast lifespan in a SQR-dependent manner C_LIO_LIMitochondrial SQR is essential for membrane potential formation and ATP production in yeast and mammals C_LI

biochemistry↗

bioRxiv2025

Functional impact of pathogenic Runt domain mutations in Runx2 in vivo: Insights into the skeletal and dental anomalies of cleidocranial dysplasia

Runt-related transcription factor 2 (RUNX2) is essential for skeletogenesis, and mutations in its gene cause cleidocranial dysplasia (CCD), an autosomal dominant skeletal disorder. The evolutionarily conserved 128-amino acid Runt homology domain (RHD) of human RUNX2 is essential for DNA binding and heterodimerization, and serves as a mutation hotspot associated with severe CCD phenotypes. To elucidate the functional impact of pathogenic RHD mutations in vivo, we generated two novel mouse lines: one carrying a missense mutation, c.695G>A (p.R232Q) (Runx2m/+), corresponding to the human RUNX2 c.674G>A (p.R225Q), and the other harboring a frameshift mutation, c.697_698delGA (p.E233TfsTer9) (Runx2112/+), causing a premature stop codon. Homozygous Runx2m/mand Runx2112/112 mice lacked membranous ossification, whereas heterozygous Runx2m/+ and Runx2112/+ mice displayed typical CCD-like skeletal features, including an open anterior fontanelle and clavicle hypoplasia. Unexpectedly, heterozygotes carrying pathogenic mutations in RHD developed an accessory root-like protrusion at the furcation of three-rooted maxillary first molars, representing a previously unrecognized dental phenotype during root development. Dual luciferase assays revealed impaired transactivation of the p.R232Q mutant Runx2 on the osteocalcin enhancer/promoter. Wild-type Runx2 was robustly expressed in osteoblasts and hypertrophic chondrocytes during bone formation, but the mutant Runx2 exhibited reduced expression in hypertrophic chondrocytes and partially impaired nuclear localization, resulting in arrested osteoblast and chondrocyte maturation. Our mutant mouse model provides a valuable in vivo platform to study CCD pathogenesis, mechanisms of tooth root furcation, and therapeutic interventions targeting dysfunctional RHD.

genetics↗