Affinage

MMS19

MMS19 nucleotide excision repair protein homolog · UniProt Q96T76

Length
1030 aa
Mass
113.3 kDa
Annotated
2026-06-10
26 papers in source corpus 17 papers cited in narrative 17 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/7 claims corpus-supported (86%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MMS19 is a scaffold component of the cytosolic iron-sulfur protein assembly (CIA) machinery that targets Fe-S cluster insertion to a defined subset of apoproteins acting in DNA replication, repair, telomere maintenance, and methionine biosynthesis (PMID:22678362, PMID:22678361). It nucleates a core CIA targeting complex with MIP18/FAM96B and CIAO1, in which MIP18 bridges MMS19 and CIAO1 while IOP1/NARFL acts as a more peripheral upstream component; loss of any core subunit destabilizes the others and abolishes Fe-S transfer to recipient apoproteins (PMID:22678361, PMID:23585563). MMS19 binds CIAO1 and recipient Fe-S apoproteins simultaneously, functioning as the adapter that couples cluster donors to apoprotein acceptors (PMID:23150669). Beyond cluster delivery, MMS19 directly engages the XPD/XPB helicase subunits of TFIIH and assembles a distinct TFIIH-independent MMXD complex (MMS19-MIP18-XPD-CIAO1-FAM96B-ANT2) that localizes to the mitotic spindle and is required for accurate chromosome segregation (PMID:11071939, PMID:20797633). In yeast, Mms19 supports both nucleotide excision repair and RNA polymerase II transcription by maintaining cellular levels of the TFIIH subunits Rad3/XPD and Ssl2/XPB, with separable protein domains governing the repair versus transcription functions (PMID:8943333, PMID:18836076, PMID:16797255). In Drosophila, Mms19 additionally promotes mitosis by sequestering Xpd to free the CAK (Cdk7/Cyclin H/Mat1) complex for Cdk1 activation and by directly binding and stabilizing spindle microtubules (PMID:29361561, PMID:33211700). Human loss-of-function causes a lethal neurodegenerative disorder with microcephaly and brain malformations driven by global failure of cytosolic and nuclear Fe-S protein maturation (PMID:38411040).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 1996 High

    Established that Mms19 is required for both NER and Pol II transcription yet is not itself a TFIIH or holoenzyme subunit, defining it as an upstream regulatory factor rather than a core machine component.

    Evidence yeast mms19Δ genetic deletion with in vitro transcription/NER reconstitution and TFIIH complementation

    PMID:8943333

    Open questions at the time
    • Did not identify the molecular target through which Mms19 regulates TFIIH activity
    • No direct biochemical mechanism for the transcription defect
  2. 1997 Medium

    Clarified the scope of the repair defect, showing mms19 loss impairs both transcription-coupled and global-genome NER at the level of dimer removal.

    Evidence in vitro NER assay and strand-specific CPD removal analysis in yeast

    PMID:9321645

    Open questions at the time
    • Did not establish whether the defect is direct or secondary to TFIIH dysfunction
  3. 2000 Medium

    Provided the first physical link between human MMS19 and the repair machinery by demonstrating direct interaction with TFIIH helicase subunits XPB and XPD.

    Evidence co-immunoprecipitation and nuclear localization in human cells

    PMID:11071939

    Open questions at the time
    • Did not determine functional consequence of the XPB/XPD interaction
    • Single lab without reciprocal validation across systems
  4. 2001 Medium

    Suggested a transcriptional-coactivation role by linking MMS19 to nuclear receptor signaling via RAC3 and estrogen receptor AF-1 stimulation.

    Evidence in vivo/in vitro Co-IP and ER reporter assays in human cells

    PMID:11279242

    Open questions at the time
    • This activity has not been integrated with the later CIA/Fe-S function
    • Not independently confirmed
  5. 2006 Medium

    Mapped MMS19 into separable functional modules, showing distinct domains drive transcription versus NER and a C-terminal HEAT domain is essential for both.

    Evidence domain-deletion complementation of yeast phenotypes

    PMID:16797255

    Open questions at the time
    • Domain assignments not connected to specific binding partners
    • No structural model of the domains
  6. 2008 Medium

    Resolved the mechanism of the NER defect by showing Mms19 sustains Rad3/XPD protein levels, with Rad3 overexpression rescuing repair.

    Evidence genetic deletion/overexpression with Western blot and UV-sensitivity rescue in yeast

    PMID:18836076

    Open questions at the time
    • Did not explain why Mms19 loss destabilizes Rad3 (later linked to Fe-S maturation)
    • Single-lab study
  7. 2010 High

    Identified the MMXD complex as a TFIIH-independent assembly of MMS19, MIP18, CIAO1, FAM96B and XPD that localizes to the spindle and is required for proper chromosome segregation.

    Evidence reciprocal Co-IP, immunofluorescence and siRNA mitotic phenotyping in human cells

    PMID:20797633

    Open questions at the time
    • Did not define how the complex acts on the spindle mechanistically
    • Relationship of MMXD to Fe-S maturation not yet established
  8. 2012 High

    Defined MMS19's central biological role as a CIA targeting-complex adapter that delivers Fe-S clusters to DNA-metabolism apoproteins, unifying the prior repair and transcription phenotypes as downstream consequences of Fe-S maturation failure.

    Evidence co-IP, MS interactome, RNAi/KO phenotyping and an Mms19 knockout mouse (preimplantation lethal), reported by two independent labs

    PMID:22678361 PMID:22678362

    Open questions at the time
    • Did not resolve the structural basis of cluster transfer
    • Selectivity rules for which apoproteins are served not fully defined
  9. 2013 Medium

    Refined complex architecture, establishing a tight MMS19-MIP18-CIAO1 core (with MIP18 bridging) and IOP1 as an external component, and showing MMS19 contacts apoprotein recipients directly.

    Evidence in vivo/in vitro Co-IP and knockdown stability analysis in human cells (and JBC interactome mapping)

    PMID:23150669 PMID:23585563

    Open questions at the time
    • No atomic-resolution structure of the core complex
    • Mechanism of apoprotein recognition unresolved
  10. 2018 Medium

    Revealed a mitotic-kinase mechanism in which Mms19 sequesters Xpd to free CAK for Cdk1 activation, connecting Mms19 to mitotic progression independent of cluster delivery.

    Evidence Drosophila genetic rescue by CAK overexpression plus Co-IP physical interaction

    PMID:29361561

    Open questions at the time
    • Not demonstrated in mammalian cells
    • Single-lab study
  11. 2020 Medium

    Showed Mms19 stabilizes spindle and astral microtubules both indirectly via the mitotic kinase cascade/TACC-Msps recruitment and directly by binding microtubules.

    Evidence Drosophila loss-of-function phenotyping, kinase-cascade rescue and direct MT-binding assay

    PMID:33211700

    Open questions at the time
    • Direct MT binding not confirmed for human MMS19
    • Structural basis of MT binding unknown
  12. 2024 Medium

    Linked MMS19 to human disease, showing homozygous in-frame deletions cause a lethal neurodegenerative syndrome driven by global cytosolic/nuclear Fe-S maturation failure.

    Evidence genome sequencing, patient-fibroblast multi-omics and zebrafish knockout

    PMID:38411040

    Open questions at the time
    • Genotype-phenotype relationship across mutation types not established
    • Tissue-specific vulnerability mechanism unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • How MMS19 mechanistically transfers Fe-S clusters and selects among recipient apoproteins, and whether its mitotic spindle/microtubule roles are conserved in humans and separable from cluster delivery, remain open.
  • No structure of the CIA targeting complex bound to an apoprotein
  • Mammalian validation of the CAK/microtubule mechanism lacking
  • Reconciliation of the reported mitochondrial localization with cytosolic/nuclear roles unresolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 4 GO:0008092 cytoskeletal protein binding 1
Localization
GO:0005829 cytosol 2 GO:0005856 cytoskeleton 2 GO:0005634 nucleus 1
Pathway
R-HSA-73894 DNA Repair 3 R-HSA-1640170 Cell Cycle 2 R-HSA-74160 Gene expression (Transcription) 1
Complex memberships
CIA targeting complex (MMS19-MIP18-CIAO1)MMXD complex

Evidence

Reading pass · 17 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2012 MMS19 is a member of the cytosolic iron-sulfur protein assembly (CIA) machinery, functioning as part of a CIA targeting complex that specifically interacts with and facilitates iron-sulfur (Fe-S) cluster insertion into apoproteins involved in methionine biosynthesis, DNA replication, DNA repair, and telomere maintenance. MMS19 serves as an adapter between early-acting CIA components (CIAO1, IOP1/NARFL, MIP18/FAM96B) and a subset of cellular Fe-S proteins. Co-immunoprecipitation, mass spectrometry, in vitro binding assays, RNAi knockdown with defined cellular phenotypes (Fe-S protein instability) Science High 22678361 22678362
2012 MMS19 forms a complex with the CIA proteins CIAO1, IOP1, and MIP18 in the cytoplasm, and also binds directly to multiple nuclear Fe-S proteins involved in DNA metabolism. Knockout of Mms19 in mice causes preimplantation lethality, and loss of MMS19 leads to failure of Fe-S cluster transfer to target proteins and consequent Fe-S protein instability. Co-immunoprecipitation, siRNA knockdown, Mms19 knockout mouse model Science High 22678361
2010 MMS19 forms a complex with XPD (a TFIIH subunit) and MIP18, FAM96B, CIAO1, and ANT2, designated the MMXD complex, that does not contain other TFIIH subunits. MMS19, MIP18, and XPD localize to the mitotic spindle during mitosis. siRNA knockdown of MMS19, MIP18, or XPD leads to improper chromosome segregation and accumulation of nuclei with abnormal shapes. Co-immunoprecipitation, siRNA knockdown, immunofluorescence localization to mitotic spindle Molecular Cell High 20797633
2012 MMS19 simultaneously binds CIAO1 and Fe-S proteins, confirming its role as a central CIA component bridging cluster donor proteins and apoprotein recipients. MIP18 also interacts with both CIAO1 and Fe-S proteins by binding Fe-S cluster coordinating regions. ANT2 interacts with Fe-S apoproteins and MMS19 within the CIA complex but not with the individual proteins. Co-immunoprecipitation, mass spectrometry-based interactome analysis, in vitro binding The Journal of Biological Chemistry Medium 23150669
2013 MMS19, MIP18, and CIAO1 form a tight 'core' CIA complex, while IOP1 is an 'external' component. Deficiency in any core component leads to down-regulation of all core components; IOP1 knockdown does not affect core component levels. MIP18 bridges MMS19 and CIAO1, and MMS19 interacts directly with target Fe-S apoproteins. Co-immunoprecipitation (in vivo and in vitro), siRNA knockdown with Western blot quantification The Journal of Biological Chemistry Medium 23585563
2000 Human MMS19 (hMMS19) directly interacts with the XPB and XPD helicase subunits of the NER-transcription factor TFIIH, as shown by co-immunoprecipitation. hMMS19 is localized to the nucleus, consistent with a repair function. Co-immunoprecipitation, nuclear localization by subcellular fractionation/immunofluorescence Nucleic Acids Research Medium 11071939
2001 Human MMS19 interacts with the N-terminal PAS-A/B domain of the nuclear receptor coactivator RAC3 in vivo and in vitro via a conserved C-terminal domain of hMMS19. hMMS19 also interacts with estrogen receptors in a ligand-independent manner but not with retinoic acid receptor or thyroid hormone receptor. Overexpression of full-length hMMS19 enhances ER-mediated transcriptional activation by stimulating AF-1 activity of ERα but not AF-2 activity. Co-immunoprecipitation (in vivo and in vitro), overexpression/dominant-negative assays, transcriptional reporter assay The Journal of Biological Chemistry Medium 11279242
1996 Yeast MMS19 is required for both nucleotide excision repair (NER) and RNA polymerase II transcription. mms19Δ cell extracts are deficient in Pol II transcription; this defect is corrected by addition of purified TFIIH but not by purified Mms19 protein. Mms19 is not a component of TFIIH or Pol II holoenzyme, but affects their activity as an upstream regulatory element. Genetic deletion (mms19Δ), in vitro transcription and NER reconstitution assays, complementation with purified TFIIH Molecular and Cellular Biology High 8943333
2008 Yeast Mms19 functions in NER by sustaining adequate cellular concentration of the TFIIH component Rad3 (XPD homologue). In mms19 mutant cells, Rad3 and Ssl2 (XPB homologue) protein levels are significantly reduced (up to 3.5-fold for Rad3). Overexpression of Rad3 from a plasmid restores proficient NER and UV resistance in mms19 mutants, while overexpression of Ssl2 has no effect on repair. Genetic deletion and overexpression, Western blot quantification, UV sensitivity complementation assay PNAS Medium 18836076
1997 Yeast mms19 deletion mutant cell-free extracts are deficient for NER in vitro, and the mutant is defective in both transcription-coupled and global genome NER in vivo, as demonstrated by inability to remove cyclobutane-pyrimidine dimers from both transcribed and non-transcribed sequences. In vitro NER assay, nucleotide-level CPD removal analysis (in vivo strand-specific repair) Nucleic Acids Research Medium 9321645
2006 Deletion analysis of MMS19 domains reveals three structurally distinct domains with separable functions: domain A is required for transcription but not NER; domain B is required for NER but not transcription; the C-terminal HEAT repeat domain (domain C) is essential for both NER and transcription functions. Domain deletion analysis with complementation of yeast mms19Δ mutant phenotypes (UV sensitivity, thermosensitivity) DNA Repair Medium 16797255
2018 Drosophila Mms19 functions in mitosis by allowing CAK (Cdk7/Cyclin H/Mat1) to become fully active as a Cdk1-activating kinase. Mms19 physically and genetically interacts with Xpd, and this interaction prevents Xpd from binding to the CAK complex; Xpd bound to Mms19 frees CAK to phosphorylate Cdk1 and facilitate progression to metaphase. Mitotic defects in Mms19-deficient Drosophila cells can be rescued by overexpression of the CAK complex. Genetic rescue (CAK overexpression in Mms19 mutants), physical interaction studies (Co-IP), loss-of-function with mitotic phenotype readout Development Medium 29361561
2020 Drosophila Mms19 promotes spindle and astral microtubule (MT) growth, MT stability, and bundling in neural stem cells through two mechanisms: (1) by stimulating the mitotic kinase cascade to trigger localization of the TACC/Msps MT regulatory complex to the centrosome, and (2) by directly binding to microtubules to stimulate MT stability and bundling. Loss-of-function with mitotic phenotype quantification, kinase cascade rescue experiments, direct MT-binding assay PLoS Genetics Medium 33211700
2016 Human DNA polymerase ε catalytic subunit (POLE1) phosphorylated at serine-1940 interacts with MMS19, but this interaction is not essential: mutation of serine-1940 to alanine caused no defect in proliferation or survival, even after DNA damage. The POLE1-CIAO1 interaction is independent of serine-1940 phosphorylation. Co-immunoprecipitation, site-directed mutagenesis, cell survival assay DNA Repair Medium 27235625
2017 MMS19 localizes to the inner membrane of mitochondria and participates in mitochondrial DNA (mtDNA) oxidative damage repair. MMS19 knockdown leads to decreased mtDNA copy number, diminished mtDNA repair capacity, and elevated mtDNA common deletion after oxidative stress. Immunoprecipitation-mass spectrometry identified interaction of MMS19 with ANT2, a mitochondrial ATP metabolism protein. Subcellular fractionation/mitochondrial localization, siRNA knockdown, immunoprecipitation-mass spectrometry Biochemistry and Cell Biology Low 29035693
2023 The transcription factor c-MYC directly activates MMS19 expression in bladder cancer cells, as demonstrated by ChIP and luciferase reporter assays, establishing c-MYC as a transcriptional regulator of MMS19. Chromatin immunoprecipitation (ChIP), luciferase reporter assay Tissue & Cell Low 37201439
2024 Patients with MMS19 homozygous in-frame deletion mutations develop a lethal neurodegenerative phenotype with microcephaly, brain malformations, and recurrent infections. Patient-derived fibroblasts show profound alterations in proteome, metabolome, and lipidome, consistent with general failure of cytosolic and nuclear Fe-S protein maturation. MMS19 deficiency was confirmed to be detrimental in zebrafish models. Genome sequencing, patient fibroblast proteomics/metabolomics/lipidomics, zebrafish knockout model Genetics in Medicine Medium 38411040

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 MMS19 assembles iron-sulfur proteins required for DNA metabolism and genomic integrity. Science (New York, N.Y.) 232 22678362
2012 MMS19 links cytoplasmic iron-sulfur cluster assembly to DNA metabolism. Science (New York, N.Y.) 194 22678361
2010 MMXD, a TFIIH-independent XPD-MMS19 protein complex involved in chromosome segregation. Molecular cell 104 20797633
1979 Three additional genes involved in pyrimidine dimer removal in Saccharomyces cerevisiae: RAD7, RAD14 and MMS19. Molecular & general genetics : MGG 63 392238
2001 The human homologue of the yeast DNA repair and TFIIH regulator MMS19 is an AF-1-specific coactivator of estrogen receptor. The Journal of biological chemistry 54 11279242
1996 Dual requirement for the yeast MMS19 gene in DNA repair and RNA polymerase II transcription. Molecular and cellular biology 49 8943333
2012 The mammalian proteins MMS19, MIP18, and ANT2 are involved in cytoplasmic iron-sulfur cluster protein assembly. The Journal of biological chemistry 39 23150669
2009 Nucleotide excision repair pathway polymorphisms and pancreatic cancer risk: evidence for role of MMS19L. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 39 19318433
2013 IOP1 protein is an external component of the human cytosolic iron-sulfur cluster assembly (CIA) machinery and functions in the MMS19 protein-dependent CIA pathway. The Journal of biological chemistry 37 23585563
2016 The cytosolic Fe-S cluster assembly component MET18 is required for the full enzymatic activity of ROS1 in active DNA demethylation. Scientific reports 35 27193999
2008 Mms19 protein functions in nucleotide excision repair by sustaining an adequate cellular concentration of the TFIIH component Rad3. Proceedings of the National Academy of Sciences of the United States of America 25 18836076
1997 Saccharomyces cerevisiae mms19 mutants are deficient in transcription-coupled and global nucleotide excision repair. Nucleic acids research 22 9321645
2000 Cloning of a human homolog of the yeast nucleotide excision repair gene MMS19 and interaction with transcription repair factor TFIIH via the XPB and XPD helicases. Nucleic acids research 21 11071939
2006 Identification of MMS19 domains with distinct functions in NER and transcription. DNA repair 18 16797255
2001 Cloning the human and mouse MMS19 genes and functional complementation of a yeast mms19 deletion mutant. Nucleic acids research 16 11328871
2013 The association of XPG and MMS19L polymorphisms response to chemotherapy in osteosarcoma. Pakistan journal of medical sciences 12 24353725
2018 Mms19 is a mitotic gene that permits Cdk7 to be fully active as a Cdk-activating kinase. Development (Cambridge, England) 11 29361561
2024 CIAO1 and MMS19 deficiency: A lethal neurodegenerative phenotype caused by cytosolic Fe-S cluster protein assembly disorders. Genetics in medicine : official journal of the American College of Medical Genetics 9 38411040
2023 The c-MYC transcription factor conduces to resistance to cisplatin by regulating MMS19 in bladder cancer cells. Tissue & cell 8 37201439
2017 MET18 Deficiency Increases the Sensitivity of Yeast to Oxidative Stress and Shortens Replicative Lifespan by Inhibiting Catalase Activity. BioMed research international 7 28828388
2017 MMS19 localizes to mitochondria and protects the mitochondrial genome from oxidative damage. Biochemistry and cell biology = Biochimie et biologie cellulaire 6 29035693
2016 Human DNA polymerase ε is phosphorylated at serine-1940 after DNA damage and interacts with the iron-sulfur complex chaperones CIAO1 and MMS19. DNA repair 5 27235625
2016 MMS19 as a potential predictive marker of adjuvant chemotherapy benefit in resected non-small cell lung cancer. Cancer biomarkers : section A of Disease markers 4 27802208
2020 Mms19 promotes spindle microtubule assembly in Drosophila neural stem cells. PLoS genetics 3 33211700
2025 Mitochondrial Mayhem: How cigarette smoke induces placental dysfunction through MMS19 degradation. Ecotoxicology and environmental safety 2 39823666
2024 Only bioactive forms of PTH (n-oxPTH and Met18(ox)-PTH) inhibit synthesis of sclerostin - evidence from in vitro and human studies. Pflugers Archiv : European journal of physiology 2 38393416

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