| 2015 |
Heat shock triggers nuclear translocation of mitochondrial SSBP1 in a manner dependent on the mitochondrial permeability transition pore ANT-VDAC1 complex and direct interaction with HSF1. In the nucleus, SSBP1 is recruited by HSF1 to promoters of genes encoding cytoplasmic/nuclear and mitochondrial chaperones, where the HSF1-SSBP1 complex enhances gene induction by facilitating recruitment of chromatin-remodelling factor BRG1, thereby supporting cell survival and mitochondrial membrane potential against proteotoxic stresses. |
Co-immunoprecipitation, chromatin immunoprecipitation (ChIP), live-cell imaging of nuclear translocation, loss-of-function experiments with specific phenotypic readouts (cell survival, mitochondrial membrane potential) |
Nature communications |
High |
25762445
|
| 2011 |
Human mtSSB uses distinct structural surface elements (removed from the ssDNA-binding groove) to functionally interact with and stimulate DNA polymerase γ (pol γ) and the mtDNA helicase independently; variants defective in stimulating pol γ retained helicase stimulation capacity and vice versa. Overexpression of defective variants in Drosophila S2 cells caused mtDNA depletion, confirming these functional interactions are required for proper mtDNA replication in animal cells. |
In vitro DNA polymerase activity assay, in vitro DNA unwinding assay, site-directed mutagenesis of surface residues, mtDNA copy number measurement in cultured cells with overexpression of variants |
The Journal of biological chemistry |
High |
21953457
|
| 2013 |
Alkyladenine DNA glycosylase (AAG) localizes to mitochondria and directly interacts with mtSSB (SSBP1). This interaction specifically inhibits AAG glycosylase activity on single-stranded DNA substrates but not double-stranded DNA substrates, and the interaction increases upon alkylating agent treatment. A putative surface motif on mtSSB may recruit UNG1 to DNA-bound mtSSB, potentially facilitating rapid processing of uracil once the dsDNA conformation is restored. |
Immunofluorescence localization, purification of mitochondrial extracts, direct binding assay (pulldown), in vitro glycosylase activity assay with ssDNA and dsDNA substrates |
DNA repair |
Medium |
23290262
|
| 2011 |
mtSSB (SSBP1) impedes uracil excision and oxidative demethylation of 3meC in single-stranded DNA by UNG1 and ABH1 respectively, and partially inhibits NEIL1-mediated excision. mtSSB also effectively inhibited nicking of ssDNA by APE1 and ABH1 and partially inhibited the lyase activity of NEIL1, suggesting it prevents formation of DNA breaks in ssDNA during replication. |
In vitro base excision and DNA repair enzyme activity assays with purified mtSSB and ssDNA/dsDNA substrates |
DNA repair |
Medium |
22153281
|
| 2019 |
mtSSB (SSBP1) is not restricted to nucleoids but also localizes to mitochondrial RNA granules. Depletion of mtSSB results in RNA processing defects, accumulation of mtRNA breakdown products, and increased levels of dsRNA and RNA:DNA hybrids, indicating that mtSSB participates in the GRSF1-mtRNA degradosome pathway for degradation of G-quadruplex-prone long non-coding mtRNAs. |
Immunofluorescence colocalization, siRNA-mediated depletion, RNA processing analysis, dsRNA detection, RNA:DNA hybrid detection |
Nucleic acids research |
Medium |
30715486
|
| 2020 |
Missense mutations in SSBP1 (R38Q and R107Q) affect dimer/tetramer formation and impair mtDNA replication, leading to mtDNA depletion. Crystal structure of SSBP1 revealed that both mutated arginine residues affect dimer interactions and distort the DNA-binding region. Patient fibroblasts validated that R38Q destabilizes SSBP1 dimer/tetramer formation and reduces mtDNA replication efficiency. Reduced mtDNA replication was also reproduced in vitro. |
Crystal structure determination, size exclusion chromatography (oligomeric state), patient-derived fibroblast assays, in vitro mtDNA replication assay, zebrafish ssbp1 knockdown rescue experiments |
The Journal of clinical investigation |
High |
31550237 31550240
|
| 2019 |
SSBP1 mutations R38Q, R107Q, and S141N affect arginine residues in the basic patch essential for single-strand DNA binding. Antisense-mediated knockdown of ssbp1 in zebrafish compromised differentiation of retinal ganglion cells, and a similar effect was achieved with mutated mRNAs, demonstrating dominant-negative effects of the disease variants. |
In silico structural analysis, zebrafish antisense knockdown, mRNA rescue experiments with wild-type and mutant mRNAs |
Annals of neurology |
Medium |
31298765
|
| 2018 |
SSBP1 was identified as a putative binding protein for N6-methyldeoxyadenosine (6mA) on mitochondrial DNA heavy-strand using 6mACE-seq crosslinking-based pulldown, linking 6mA modification with regulation of mtDNA replication by SSBP1. |
6mACE-seq (6mA-Crosslinking-Exonuclease-sequencing), genome-wide 6mA mapping, protein identification |
Nucleic acids research |
Low |
30412255
|
| 2007 |
C. elegans par2.1/mtssb-1 (ortholog of SSBP1) is essential for mtDNA replication and germline cell proliferation; RNAi depletion over generations caused sterility with arrested germline cell proliferation, reduced mitochondrial number, comprehensive transcriptional alterations including hypoxia response, and reduced apoptosis frequency in germline cells. |
RNAi depletion across generations, mtDNA copy number measurement, cell cytology, transcriptome microarray analysis |
Experimental cell research |
Medium |
17900564
|
| 2022 |
SSBP1 promotes ferroptosis in glomerular podocytes under high fructose conditions by interacting with DNA-dependent protein kinase (DNA-PK) and p53, activating DNA-PK to phosphorylate p53 at serine 15, promoting nuclear accumulation of p53 and subsequent inhibition of SLC7A11 expression. |
Co-immunoprecipitation (SSBP1-DNA-PK-p53 complex), siRNA knockdown, western blotting for p53 phosphorylation, nuclear fractionation, ferroptosis assays |
Redox biology |
Medium |
35390676
|
| 2018 |
mtSSB (SSBP1) expression in colorectal cancer is induced by IL-6/STAT3 signaling via upregulation of the transcription factor FOXP1, which was identified as a new transcriptional regulator of mtSSB. Elevated mtSSB increased mitochondrial biogenesis and ROS production, which induced TERT expression and telomere elongation via the Akt/mTOR pathway. |
Reporter assays, ChIP for FOXP1 binding to mtSSB promoter, overexpression/knockdown, in vitro proliferation assays, in vivo xenograft, telomerase activity assays |
International journal of cancer |
Medium |
30415472
|
| 2024 |
The disease-associated R107Q mutation in mtSSB (SSBP1) does not destabilize tetramers in vitro, but significantly reduces intramolecular ssDNA compaction ability and increases ssDNA dissociation rate compared to wild-type. Real-time competition experiments showed a marked advantage of wild-type mtSSB over R107Q mutant for ssDNA binding. Molecular modeling suggested R107Q creates an electronegative spot that disrupts an ssDNA-interacting electropositive patch, reducing potential mtSSB-ssDNA interaction sites. |
Single-molecule manipulation/visualization, in vitro ssDNA compaction assay, ssDNA dissociation kinetics measurement, real-time competition binding assay, molecular modeling |
Nucleic acids research |
High |
38742632
|
| 2021 |
Molecular dynamics simulations of wild-type and 31 variant SSBP1 tetramers showed that all disease-associated variants form stable tetramers with stronger intermonomer interactions, reduced solvent accessible surface areas, and net loss of positive surface charge. Structural modeling identified potential DNA binding surfaces and hotspots, suggesting disease variants alter DNA binding/wrapping rather than abolishing binding altogether or destabilizing tetramers. |
Molecular dynamics simulations, structural alignment, phosphate binding simulations |
DNA repair |
Low |
34464898
|
| 2019 |
A heterozygous start loss mutation in SSBP1, co-segregating with hearing loss in a multigenerational family carrying the m.1555A>G mtDNA variant, reduced steady-state SSBP1 protein levels and caused mtDNA depletion and multiple deletions in skeletal muscle, demonstrating that SSBP1 haploinsufficiency can compound an intra-mitochondrial translation defect in a tissue-specific manner. |
Exome sequencing, SSBP1 protein level quantification by western blot, mtDNA copy number and deletion analysis in skeletal muscle biopsy |
Brain : a journal of neurology |
Medium |
29182774
|
| 2024 |
HMGB3 recruits and interacts with SSBP1 (demonstrated by co-immunoprecipitation combined with mass spectrometry), inducing SSBP1 nuclear translocation. This nuclear translocation reprograms mitochondrial metabolism, elevates cytoplasmic ROS, and activates the PI3K/Akt signaling pathway through PTEN downregulation, promoting tumor cell EMT and brain metastasis. |
Co-immunoprecipitation with mass spectrometry, western blotting, nuclear fractionation, gain-of-function and loss-of-function experiments, in vivo brain metastasis model |
Cancer communications (London, England) |
Medium |
41194553
|
| 2025 |
SSBP1 promotes K48-linked ubiquitination of MAVS (mitochondrial antiviral signaling protein) by recruiting Smurf1 E3 ubiquitin ligase, thereby promoting proteasomal degradation of MAVS and suppressing antiviral innate immune responses during bovine ephemeral fever virus infection. |
Co-immunoprecipitation, ubiquitination assay (K48-linkage specific), proteasome inhibitor rescue, SSBP1 knockdown/overexpression with viral replication readout |
Veterinary microbiology |
Medium |
40848354
|
| 2024 |
mtSSB (SSBP1) binding to DNA likely outcompetes the Zinc-binding domain (ZBD) of the Twinkle helicase for DNA interactions, alleviating ZBD-mediated downregulation of Twinkle's DNA unwinding kinetics. This places mtSSB as a positive regulator of Twinkle helicase activity at the mtDNA replication fork by relieving an auto-inhibitory constraint. |
Single-molecule manipulation and visualization, biochemical unwinding assays, real-time kinetics measurements |
bioRxivpreprint |
Medium |
|
| 2023 |
STAT3 acts as a transcriptional repressor of SSBP1; chromatin immunoprecipitation (ChIP) and dual luciferase reporter assays demonstrated that STAT3 binds the SSBP1 promoter region and inhibits SSBP1 transcription. The compound sanguinarine inhibits JAK/STAT3 signaling, relieving STAT3 repression of SSBP1 and increasing SSBP1 expression, which disrupts mitochondrial function and induces apoptosis in osteosarcoma cells. |
Chromatin immunoprecipitation (ChIP), dual luciferase reporter assay, western blotting, flow cytometry (apoptosis, cell cycle, ROS) |
British journal of pharmacology |
Medium |
37501645
|