| 1996 |
SSU72 was identified as a synthetic enhancer of a TFIIB (sua7-1) defect, causing a downstream shift in transcription start site selection at ADH1; the N terminus of Ssu72 was shown to be essential for function, and cysteine residues in this region are critical, suggesting involvement in assembly of the transcription preinitiation complex. |
Genetic epistasis (synthetic enhancement screen), mutational analysis, in vivo transcription start site mapping |
Molecular and cellular biology |
Medium |
8657130
|
| 1999 |
Functional interactions among TFIIB, Ssu72, and Sub1 in transcription start site selection were established; allele-specific interactions between ssu72-1 and sua7 alleles that affect start site accuracy were demonstrated, defining a functional relationship between Ssu72 and TFIIB. |
Allele-specific genetic interaction analysis, error-prone PCR mutagenesis screen, in vivo transcription assays |
Genetics |
Medium |
10511545
|
| 2000 |
Ssu72 physically interacts directly with purified RNA polymerase II via its Rpb2 subunit, as shown by co-immunoprecipitation; an rpb2 suppressor mutation (R512C) was identified that genetically interacts with ssu72-2, linking Ssu72 to the RNAP II core machinery during transcription initiation. |
Co-immunoprecipitation with purified RNAP II, suppressor genetic screen, sequence analysis |
Molecular and cellular biology |
Medium |
11046131
|
| 2002 |
Ssu72 is stably associated with yeast CPF and bridges CPF subunits Pta1 and Ydh1/Cft2p, TFIIB, and RNAP II via Rpb2; ssu72-2 mutants show defects in RNAP II transcription elongation and termination, and 6-azauracil (which slows elongation) suppresses the ssu72-2 growth defect, indicating Ssu72 exerts a negative influence on RNAP II elongation. |
Biochemical fractionation, protein interaction assays, genetic suppression with 6-AU, transcription analyses in ssu72-2 mutants |
Molecular cell |
Medium |
12453421
|
| 2003 |
Ssu72 is a component of the yeast CPF complex required for 3' end cleavage of pre-mRNA but dispensable for poly(A) addition and RNAP II termination; the in vitro cleavage defect caused by Ssu72 depletion is rescued by recombinant Ssu72; Ssu72 physically interacts with Pta1 subunit of CPF; Sub1 interactions with Pta1 are mutually exclusive with Ssu72 interactions. |
Biochemical depletion and reconstitution with recombinant protein, in vitro cleavage assay, co-immunoprecipitation, genetic interaction analysis |
Genes & development |
High |
12704082
|
| 2003 |
Ssu72 is a phosphatase resembling low-molecular-weight protein tyrosine phosphatases; recombinant Ssu72 cleaves the phosphotyrosine analogue p-nitrophenylphosphate; this activity is inhibited by PTPase-inhibiting agents; the CX5R signature motif catalytic cysteine is essential for activity in vitro and for viability in vivo; Ssu72 is proposed as the founding member of a new phosphatase subfamily. |
In vitro phosphatase assay with p-nitrophenylphosphate, site-directed mutagenesis of catalytic cysteine, inhibitor studies, secondary structure prediction |
The Journal of biological chemistry |
High |
12606538
|
| 2003 |
Ssu72 mutations disrupt both Nrd1-dependent (poly(A)-independent, snoRNA) termination and poly(A)-dependent termination of RNAP II, demonstrating that Ssu72 mediates both termination pathways; Ssu72 was identified in a genome-wide selection for factors influencing the SNR13 snoRNA terminator. |
Genome-wide genetic selection, analysis of snoRNA read-through termination, in vivo transcription assays |
Molecular and cellular biology |
Medium |
12944462
|
| 2003 |
Ssu72 is a phosphatase that physically interacts with CTD kinase Kin28 and functionally interacts with CTD phosphatase Fcp1; ssu72 mutants exhibit read-through transcription of snoRNAs and specific mRNAs, implicating Ssu72 in transcription termination of specific transcripts, possibly by promoting RNA polymerase pausing. |
Genome-wide expression analysis (DNA microarray), physical interaction assays, analysis of ssu72-ts69 mutant phenotype |
The EMBO journal |
Medium |
12660165
|
| 2004 |
Ssu72, a component of yeast CPF, is a CTD phosphatase with specificity for Ser5-P (not Ser2-P); Ssu72 catalyzes CTD Ser5-P dephosphorylation in association with Pta1 component of CPF; depletion of Ssu72 impairs transcription in vitro and this defect is rescued by recombinant catalytically active Ssu72; the essential role of Ssu72 in 3' end processing is independent of its catalytic activity. |
In vitro CTD phosphatase assay, in vitro transcription assay, complementation with recombinant protein, biochemical fractionation with CPF |
Molecular cell |
High |
15125841
|
| 2005 |
Human Ssu72 (hSsu72/HSPC182) was identified via yeast two-hybrid as a pRb-binding factor; interaction between hSsu72 and pRb was confirmed in transfected mammalian cells and involved multiple pRb domains; mammalian Ssu72 associates with TFIIB and yeast Pta1 and exhibits intrinsic phosphatase activity; endogenous and ectopically expressed mammalian Ssu72 resides primarily in the cytoplasm with only partial nuclear localization. |
Yeast two-hybrid, co-immunoprecipitation in transfected mammalian cells, in vitro phosphatase assay, subcellular fractionation and localization, siRNA knockdown |
Nucleic acids research |
Medium |
15659578
|
| 2006 |
Ssu72-R129A (ssu72-2) is catalytically impaired in vitro and causes accumulation of Ser5-P form of RNAP II in vivo; ssu72-2 exhibits impaired elongation efficiency in vitro; suppressors in RPB1 (R1281A) and RPB2 (R983G), as well as slow RNAP II alleles rpb2-4 and rpb2-10 and deletion of SPT4 (Spt4-Spt5 complex subunit), suppress ssu72-2, defining Ssu72 as a transcription elongation factor that facilitates the transition from initiation to elongation. |
In vitro CTD phosphatase assay, in vivo CTD phosphorylation analysis, in vitro transcription elongation assay, suppressor genetic screen, multiple allele analysis |
Molecular and cellular biology |
High |
17101794
|
| 2009 |
The N-terminal region (first 75 aa) of Pta1 is required for Ssu72 function: pta1-Δ75 mutant is defective for snoRNA termination, CTD Ser5-P dephosphorylation, and gene looping; the first 300 aa of Pta1 are sufficient for interaction with Ssu72; degron-mediated depletion of Pta1 leads to loss of Ssu72 protein; the Pta1 N-terminus has an inhibitory effect on 3'-end processing that is neutralized through interaction with Ssu72. |
Deletion mutagenesis, degron-mediated depletion, in vitro cleavage/polyadenylation assays, CTD phosphorylation analysis, protein interaction mapping |
Molecular and cellular biology |
High |
19188448
|
| 2010 |
Crystal structure of the human symplekin N-terminal domain (ARM/HEAT fold) in ternary complex with Ssu72 and a CTD Ser5-phosphopeptide resolved at 2.4 Å; the pSer5-Pro6 peptide bond is in the cis configuration in the Ssu72 active site; Ssu72 has similarity to low-MW phosphotyrosine protein phosphatase with unique active-site features; engineered mutations in the symplekin-Ssu72 interface abolish their interaction; symplekin N-terminal domain stimulates Ssu72 CTD phosphatase activity in vitro; symplekin N-terminal domain inhibits polyadenylation in vitro only when coupled to transcription, and catalytically active Ssu72 overcomes this inhibition. |
X-ray crystallography at 2.4 Å, site-directed mutagenesis, in vitro phosphatase assay, in vitro polyadenylation coupled to transcription |
Nature |
High |
20861839
|
| 2010 |
Crystal structure of Ssu72 in complex with a CTD Ser5-phosphopeptide reveals that the cis-Ser(P)5-Pro6 isomer is the preferred substrate; the cis-Ser(P)5-Pro6 isomer is the minor population in solution; Ess1 (Pin1 ortholog)-catalyzed cis-trans proline isomerization facilitates rapid Ser5-P dephosphorylation by Ssu72, providing the first structural evidence of a cis-proline-specific enzyme. |
X-ray crystallography, NMR analysis of cis/trans isomer populations, in vitro phosphatase kinetics with Ess1, mutagenesis |
The Journal of biological chemistry |
High |
21159777
|
| 2011 |
Crystal structures of Drosophila Ssu72 in apo form and in complex with vanadate (transition state analogue) at 2.35 Å reveal a phosphoryl-enzyme intermediate mechanism; Ssu72 has a core fold similar to low-MW PTPs with a unique 'cap' domain sheltering the active site; mutagenesis identified five residues (Met17, Pro46, Asp51, Tyr77, Met85) in the active-site groove essential for CTD substrate recognition. |
X-ray crystallography (apo and vanadate-bound), site-directed mutagenesis, differential scanning fluorimetry |
The Biochemical journal |
High |
21204787
|
| 2012 |
Ssu72 is identified as a Ser7-P phosphatase of the RNAP II CTD; phospho-Ser7 substitution with glutamate (phosphomimetic) is lethal; Ssu72 removal of Ser7-P is mechanistically coupled to removal of other CTD marks during transcription termination; inability to remove phospho-CTD marks prevents efficient Pol II termination. |
In vivo CTD phosphorylation analysis (mass spectrometry), lethal phosphomimetic mutant analysis, genome-wide termination assays, ChIP |
The Journal of biological chemistry |
High |
22235117
|
| 2012 |
Crystal structure of a ternary complex of human symplekin N-terminal domain, human Ssu72, and a pSer7 CTD peptide shows the peptide is bound in the Ssu72 active site with its backbone running in the opposite direction compared with the pSer5 peptide; Ssu72 pSer7 phosphatase activity is ~4000-fold lower than pSer5 phosphatase activity toward peptide substrate. |
X-ray crystallography, in vitro phosphatase kinetic assay comparing pSer5 and pSer7 substrates |
Genes & development |
High |
23070812
|
| 2013 |
Aurora B kinase directly interacts with and phosphorylates Ssu72 at Ser19 in vitro and in vivo; Aurora B-mediated phosphorylation of Ssu72 causes structural modification of Ssu72, downregulates its phosphatase activity, and triggers ubiquitin-dependent degradation of Ssu72; Ssu72 is identified as a new cohesin-binding phosphatase required for maintenance of chromosome arm cohesion; overexpression of the Aurora B phosphomimetic Ssu72 mutant prevents chromosome arm cohesion. |
In vitro kinase assay, in vivo phosphorylation analysis, ubiquitin-dependent degradation assay, cohesin co-immunoprecipitation, overexpression of phosphomimetic mutants, chromosome cohesion assays |
Nature communications |
High |
24149858
|
| 2013 |
Thr4 phosphorylation of the CTD reduces Ssu72 Ser5-P phosphatase activity 4-fold but does not abolish it; Ssu72 does not dephosphorylate pThr4; the CTD adopts an almost identical cis conformation for Ssu72 recognition whether Ser5 alone or both Thr4/Ser5 are phosphorylated, despite loss of an intramolecular hydrogen bond; kinetic and structural data established that Thr4 phosphorylation fine-tunes but does not abolish Ssu72 activity. |
X-ray crystallography (Drosophila Ssu72-symplekin complex with doubly phosphorylated CTD peptide), mass spectrometry, in vitro phosphatase kinetics |
ACS chemical biology |
High |
23844594
|
| 2014 |
Ssu72 dephosphorylates Ser5-P at the initiation-elongation transition in vivo; Ssu72 indirectly affects Ser2-P levels during elongation but does so independent of its catalytic activity; Ssu72 interacts with components of the initiation machinery yet is an integral component of CPF; Ssu72 is unique in having specificity for Ser5-P in one CTD orientation and Ser7-P in the opposite orientation. |
In vivo CTD phosphorylation analysis (ChIP with phospho-specific antibodies), catalytic mutant analysis, epistasis with initiation/elongation factors |
The Journal of biological chemistry |
Medium |
25339178
|
| 2014 |
HIV-1 Tat interacts directly with Ssu72 and strongly stimulates its CTD phosphatase activity; Ssu72 is essential for Tat:P-TEFb-mediated phosphorylation of the Ser5-P CTD in vitro; Ssu72 is recruited by Tat to the integrated HIV-1 proviral promoter in T cells (ChIP); Ssu72 stimulates nascent HIV-1 transcription in a phosphatase-dependent manner; Ssu72 predominantly co-localizes with Ser5-P RNAP II at promoters genome-wide. |
Direct protein interaction assay, in vitro CTD phosphatase assay with Tat stimulation, ChIP, ChIP-seq, GRO-seq, in vivo transcription analysis |
Genes & development |
High |
25319827
|
| 2014 |
Vertebrate (chicken) Ssu72 exhibits Ser5- and Ser7-specific CTD phosphatase activity in vitro; conditional inactivation of Ssu72 in DT40 cells causes defects in 3'-end formation of U2 and U4 snRNAs and GAPDH mRNA; Ssu72 inactivation increases efficiency of 3'-end formation of non-polyadenylated replication-dependent histone mRNA; Ssu72 depletion causes significant increases in both Ser5 and Ser7 phosphorylation of Pol II CTD at affected genes. |
Conditional knockout in DT40 cells, in vitro phosphatase assay, RT-PCR and Northern blot for 3'-end formation, ChIP with CTD phospho-specific antibodies |
PloS one |
High |
25166011
|
| 2015 |
Liver-specific conditional knockout of Ssu72 in mice results in aberrant hepatocyte chromosome polyploidization, deregulation of cell cycle progression by overriding the G1 restriction point, and promotion of DNA endoreplication through G2/M arrest; Ssu72 depletion is associated with impaired liver damage response and markers of liver injury (fibrosis, steatosis, steatohepatitis). |
Conditional knockout mouse model (liver-specific), cell cycle analysis, flow cytometry, histopathology |
Hepatology (Baltimore, Md.) |
Medium |
26458163
|
| 2017 |
Ssu72 overexpression suppresses STAT3 activation and Th17 cell responses in vitro; systemic infusion of Ssu72 attenuates experimental autoimmune arthritis by reducing STAT3 activity and Th17 cell differentiation, associated with reduced p-STAT3 levels. |
In vitro overexpression assays, systemic protein infusion in arthritis mouse model, p-STAT3 measurement, Th17 differentiation assays |
Scientific reports |
Medium |
28710354
|
| 2019 |
Ssu72 phosphatase is responsible for terminating the cycle of telomere replication in fission yeast; Ssu72 controls recruitment of Stn1 to telomeres by regulating Stn1 phosphorylation at Ser74 within its conserved OB-fold domain; ssu72Δ mutants exhibit defective lagging-strand DNA synthesis with long 3'-ssDNA overhangs; human SSU72 regulates telomerase activation by controlling recruitment of hSTN1 to telomeres. |
Genetic deletion, telomere ChIP for Stn1 recruitment, in vitro phosphatase assay, telomere length and overhang analysis, human cell telomerase assays |
The EMBO journal |
High |
30796050
|
| 2019 |
Human Ssu72 is physically associated with early RNAP II elongation complexes and enters the transcription cycle during PIC formation; Ssu72 phosphatase activity on early elongation complexes is strictly limited to complexes containing RNA shorter than 28 nt; when PICs are washed before initiation, this 28 nt cutoff is lost, suggesting trans-acting factors regulate Ssu72 activity during the initiation-to-pausing transition. |
Biochemical fractionation of RNAP II transcription complexes, in vitro transcription elongation assay, phosphatase activity assay on isolated complexes, salt wash experiments |
PloS one |
Medium |
30901332
|
| 2020 |
In fission yeast, Pin1 prolyl isomerase directly recruits Ssu72 phosphatase to facilitate dephosphorylation of the RNAP II CTD for transcription elongation; in response to oxidative stress, Pin1 promotes dissociation of Sty1 MAPK from the CTD and recruits Ssu72 to dephosphorylate Ser5-P CTD, enabling productive transcription elongation. |
Protein interaction assays, genetic analysis (pin1Δ), in vivo ChIP, in vitro assays, analysis in fission yeast and human cancer cells |
Nucleic acids research |
Medium |
33410907
|
| 2020 |
Transcriptome profiling in fission yeast pin1Δ overlaps 77–100% with the effects of Ssu72 inactivation, supporting Pin1 as a positive effector of 3' processing/termination that acts via its ability to generate cis-Pro6 substrate for Ssu72; CTD-S7A mutation is de-repressive for PHO genes and this effect is erased by pin1Δ in a Ssu72-dependent manner. |
Transcriptional profiling (RNA-seq), genetic epistasis analysis (pin1Δ × ssu72 inactivation), CTD mutant analysis |
Nucleic acids research |
Medium |
32282918
|
| 2020 |
Following GM-CSF stimulation, Ssu72 directly binds to the GM-CSF receptor β-chain in alveolar macrophages, preventing its phosphorylation; Ssu72-deficient AMs show higher phosphorylation of GM-CSFR β-chain and downstream molecules; JAK2 inhibitor restores normal signaling in Ssu72-deficient AMs; LysM-Cre and CD11c-Cre conditional knockouts establish Ssu72 as required for AM development, maturation, and mitochondrial function. |
Co-immunoprecipitation (Ssu72-GM-CSFR β-chain binding), conditional knockout mice (LysM-Cre and CD11c-Cre), phosphorylation analysis, JAK2 inhibitor rescue, adoptive transfer experiments |
The Journal of allergy and clinical immunology |
High |
32910932
|
| 2021 |
Ssu72 is activated by TCR and IL-2R signaling pathways and localizes at the cell membrane; Ssu72 forms a complex with PLCγ1; Ssu72 deficiency in T cells impairs PLCγ1 downstream signaling and results in failure of Foxp3 induction and Treg development; T-cell-specific Ssu72 deletion disrupts CD4+ T-cell differentiation into Tregs via overproduction of IL-2 and IFNγ. |
Conditional T-cell KO (Foxp3-Cre, CD4-Cre), co-immunoprecipitation (Ssu72-PLCγ1 complex), cytokine analysis, Foxp3 induction assays, mucosal tolerance patient samples |
Cellular & molecular immunology |
Medium |
33850312
|
| 2021 |
Ssu72 phosphatase directly binds ZAP-70 in T cells (shown by affinity purification-mass spectrometry and in vitro assay); recombinant Ssu72 reduces tyrosine phosphorylation of ZAP-70 via phosphatase activity in vitro; Ssu72-deficient T cells show increased ZAP-70 phosphorylation and hyperresponsiveness; CD4-Cre Ssu72 fl/fl mice develop spontaneous inflammation with altered T cell subset distribution. |
Affinity purification-mass spectrometry, in vitro phosphatase assay (recombinant Ssu72 on ZAP-70), conditional T-cell KO, phosphorylation analysis |
Proceedings of the National Academy of Sciences of the United States of America |
High |
34452999
|
| 2021 |
Liver-specific deletion of Ssu72 leads to Ssu72-mediated hypo-phosphorylation of HNF4α, a master hepatocyte regulator; loss of Ssu72 induces mature hepatocyte-to-progenitor cell conversion (dedifferentiation) orchestrated through HNF4α; Ssu72-deficient mice show high incidence of NAFLD and NASH, and increased probability of HCC in chemical/metabolic HCC models. |
Conditional liver-specific KO mice, phosphorylation analysis of HNF4α, hepatic progenitor cell assays, chemical and metabolic HCC induction models, histopathology |
Cell death and differentiation |
Medium |
34616001
|
| 2022 |
Avian influenza NS1 protein directly binds to SSU72; NS1-mediated degradation of SSU72 induces transcriptional readthrough (TRT) at genes on the complementary strand; SSU72 overexpression reduces TRT and alleviates mouse lung injury post-AIV infection; SSU72 restoration suppresses TRT-mediated disruption of STAT1/2 expression, defining an NS1-SSU72-trans-TRT-STAT1/2 axis. |
Co-immunoprecipitation (NS1-SSU72 binding), SSU72 overexpression in cell lines and mouse lungs, TRT quantification, patient PBMC analysis, STAT1/2 expression analysis |
Cellular & molecular immunology |
Medium |
35332300
|
| 2023 |
Ssu72 phosphatase dephosphorylates eIF2α in brown adipocytes; adipocyte-specific Ssu72 deletion causes hyperphosphorylation of eIF2α, alteration of cytosolic mRNA translation programs, reduced translation of mitochondrial OXPHOS subunits, mitochondrial dysfunction and defective thermogenesis; cold exposure increases Ssu72 expression in BAT; restoration of Ssu72 expression rescues metabolic dysfunction. |
Adipocyte-specific conditional KO, in vitro phosphatase assay (eIF2α dephosphorylation), polysome profiling/translation analysis, mitochondrial function assays, cold tolerance test, Ssu72 re-expression rescue |
Nature communications |
High |
36841836
|