scholarly journals The p97 cofactor Ubxn7 facilitates replisome disassembly during S-phase

2021 ◽  
Author(s):  
Zeynep Tarcan ◽  
Divyasree Poovathumkadavil ◽  
Aggeliki Skagia ◽  
Agnieszka Gambus
Keyword(s):  
Dna Replication ◽  
Molecular Mechanism ◽  
Protein Complexes ◽  
Ubiquitin Ligases ◽  
S Phase ◽  
E3 Ubiquitin Ligases ◽  
Replication Machinery ◽  
Replicative Helicase ◽  
Cellular Processes ◽  
Eukaryotic Dna

Complex cellular processes are driven by the regulated assembly and disassembly of large multi-protein complexes. In eukaryotic DNA replication, whilst we are beginning to understand the molecular mechanism for assembly of the replication machinery (replisome), we still know relatively little about the regulation of its disassembly at replication termination. Over recent years, the first elements of this process have emerged, revealing that the replicative helicase, at the heart of the replisome, is polyubiquitylated prior to unloading and that this unloading requires p97 segregase activity. Two different E3 ubiquitin ligases are now known to ubiquitylate the helicase under different conditions: Cul2Lrr1 and TRAIP. Here we have found two p97 cofactors, Ubxn7 and Faf1, which can interact with p97 during replisome disassembly in S-phase. Only Ubxn7 however facilitates efficient replisome disassembly through its interaction with both Cul2Lrr1 and p97. Our data therefore characterise Ubxn7 as the first substrate-specific p97 cofactor regulating replisome disassembly in vertebrates.

scholarly journals Mitotic replisome disassembly in vertebrates

2018 ◽  
Author(s):  
Sara Priego Moreno ◽  
Rebecca M. Jones ◽  
Divyasree Poovathumkadavil ◽  
Agnieszka Gambus
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Ubiquitin Ligase ◽  
S Phase ◽  
Replication Forks ◽  
Replication Machinery ◽  
Replicative Helicase ◽  
Egg Extract ◽  
Eukaryotic Dna ◽  
Higher Eukaryotes

ABSTRACTRecent years have brought a breakthrough in our understanding of the process of eukaryotic DNA replication termination. We have shown that the process of replication machinery (replisome) disassembly at the termination of DNA replication forks in S-phase of the cell cycle is driven through polyubiquitylation of one of the replicative helicase subunits Mcm7. Our previous work in C.elegans embryos suggested also an existence of a back-up pathway of replisome disassembly in mitosis. Here we show, that in Xenopus laevis egg extract, any replisome retained on chromatin after S-phase is indeed removed from chromatin in mitosis. This mitotic disassembly pathway depends on formation of K6 and K63 ubiquitin chains on Mcm7 by TRAIP ubiquitin ligase and activity of p97/VCP protein segregase. The mitotic replisome pathway is therefore conserved through evolution in higher eukaryotes. However, unlike in lower eukaryotes it does not require SUMO modifications. This process can also remove any helicases from chromatin, including “active” stalled ones, indicating a much wider application of this pathway than just a “back-up” for terminated helicases.

scholarly journals E3 ubiquitin ligase components in GtoPdb v.2021.3

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Elena Faccenda ◽  
Robert Layfield
Keyword(s):  
Cell Cycle Progression ◽  
Protein Complexes ◽  
Ubiquitin Ligases ◽  
E3 Ubiquitin Ligases ◽  
Post Translational Modification ◽  
Protein Substrates ◽  
Cellular Processes ◽  
Ubiquitin Molecule ◽  
E2 Enzymes ◽  
Ubiquitin Conjugating Enzymes

Ubiquitination (a.k.a. ubiquitylation) is a protein post-translational modification that typically requires the sequential action of three enzymes: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-conjugating enzymes), and E3 (ubiquitin ligases) [19]. Ubiquitination of proteins can target them for proteasomal degradation, or modulate cellular processes including cell cycle progression, transcriptional regulation, DNA repair and signal transduction. E3 ubiquitin ligases, of which there are >600 in humans, are a family of highly heterogeneous proteins and protein complexes that recruit ubiquitin-loaded E2 enzymes to mediate transfer of the ubiquitin molecule from the E2 to protein substrates. Target substrate specificity is determined by a substrate recognition subunit within the E3 complex.

scholarly journals Functional Significance of the E3 Ubiquitin Ligases in Disease and Therapeutics

2021 ◽  
Author(s):  
Julius Tieroyaare Dongdem ◽  
Cletus Adiyaga Wezena
Keyword(s):  
Therapeutic Potential ◽  
Protein Complexes ◽  
Ring Finger ◽  
Ubiquitin Ligases ◽  
E3 Ubiquitin Ligases ◽  
Phd Finger ◽  
E3 Ligases ◽  
Cellular Processes ◽  
Future Drug ◽  
Ubiquitin Conjugating Enzyme

E3 ubiquitin ligases of which there are >600 putative in humans, constitute a family of highly heterogeneous proteins and protein complexes that are the ultimate enzymes responsible for the recruitment of an ubiquitin loaded E2 ubiquitin-conjugating enzyme, recognise the appropriate protein substrate and directly or indirectly transfer the ubiquitin load onto the substrate. The aftermath of an E3 ligase activity is usually the formation of an isopeptide bond between the free carboxylate group of ubiquitin’s C-terminal Gly76 and an ε-amino group of the substrate’s Lys, even though non-canonical ubiquitylation on non-amine groups of target proteins have been observed. E3 ligases are grouped into four distinct families: HECT, RING-finger/U-box, RBR and PHD-finger. E3 ubiquitin ligases play critical roles in subcellular signalling cascades in eukaryotes. Dysfunctional E3 ubiquitin ligases therefore tend to inflict dramatic effects on human health and may result in the development of various diseases including Parkinson’s, Amyotrophic Lateral Sclerosis, Alzheimer’s, cancer, etc. Being regulators of numerous cellular processes, some E3 ubiquitin ligases have become potential targets for therapy. This chapter will present a comprehensive review of up-to-date findings in E3 ligases, their role in the pathology of disease and therapeutic potential for future drug development.

scholarly journals E3 ubiquitin ligase components (version 2019.5) in the IUPHAR/BPS Guide to Pharmacology Database

2019 ◽  
Vol 2019 (5) ◽  
Author(s):  
Elena Faccenda ◽  
Robert Layfield
Keyword(s):  
Cell Cycle Progression ◽  
Protein Complexes ◽  
Ubiquitin Ligases ◽  
E3 Ubiquitin Ligases ◽  
Post Translational Modification ◽  
Protein Substrates ◽  
Cellular Processes ◽  
Ubiquitin Molecule ◽  
E2 Enzymes ◽  
Ubiquitin Conjugating Enzymes

Ubiquitination (a.k.a. ubiquitylation) is a protein post-translational modification that typically requires the sequential action of three enzymes: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-conjugating enzymes), and E3 (ubiquitin ligases) [16]. Ubiquitination of proteins can target them for proteasomal degradation, or modulate cellular processes including cell cycle progression, transcriptional regulation, DNA repair and signal transduction. E3 ubiquitin ligases, of which there are >600 in humans, are a family of highly heterogeneous proteins and protein complexes that recruit ubiquitin-loaded E2 enzymes to mediate transfer of the ubiquitin molecule from the E2 to protein substrates. Target substrate specificity is determined by a substrate recognition subunit within the E3 complex.

scholarly journals DDB2 regulates DNA replication through PCNA-independent degradation of CDT2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaojun Wu ◽  
Min Yu ◽  
Zhuxia Zhang ◽  
Feng Leng ◽  
Yue Ma ◽  
...  
Keyword(s):  
Dna Replication ◽  
Cancer Therapy ◽  
Target Genes ◽  
Ubiquitin Ligases ◽  
Ovarian Teratoma ◽  
Control Group ◽  
E3 Ubiquitin Ligases ◽  
Small Interfering Rnas ◽  
Interacting Protein

Abstract Background Targeting ubiquitin-dependent proteolysis is one of the strategies in cancer therapy. CRLCDT2 and CRLDDB2 are two key E3 ubiquitin ligases involved in DNA replication and DNA damage repair. But CDT2 and DDB2 are opposite prognostic factors in kinds of cancers, and the underlining mechanism needs to be elucidated. Methods Small interfering RNAs were used to determine the function of target genes. Co-immunoprecipitation (Co-IP) was performed to detect the interaction between DDB2 and CDT2. Immunofluorescence assays and fluorescence activating cell sorting (FACS) were used to measure the change of DNA content. In vivo ubiquitination assay was carried out to clarify the ubiquitination of CDT2 mediated by DDB2. Cell synchronization was performed to arrest cells at G1/S and S phase. The mechanism involved in DDB2-mediated CDT2 degradation was investigated by constructing plasmids with mutant variants and measured by Western blot. Immunohistochemistry was performed to determine the relationship between DDB2 and CDT2. Paired two-side Student’s t-test was used to measure the significance of the difference between control group and experimental group. Results Knockdown of DDB2 stabilized CDT2, while over-expression of DDB2 enhanced ubiquitination of CDT2, and subsequentially degradation of CDT2. Although both DDB2 and CDT2 contain PIP (PCNA-interacting protein) box, PIP box is dispensable for DDB2-mediated CDT2 degradation. Knockdown of PCNA had negligible effects on the stability of CDT2, but promoted accumulation of CDT1, p21 and SET8. Silencing of DDB2 arrested cell cycle in G1 phase, destabilized CDT1 and reduced the chromatin loading of MCMs, thereby blocked the formation of polyploidy induced by ablation of CDT2. In breast cancer and ovarian teratoma tissues, high level of DDB2 was along with lower level of CDT2. Conclusions We found that CRL4DDB2 is the novel E3 ubiquitin ligases of CDT2, and DDB2 regulates DNA replication through indirectly regulates CDT1 protein stability by degrading CDT2 and promotes the assembly of pre-replication complex. Our results broaden the horizon for understanding the opposite function of CDT2 and DDB2 in tumorigenesis, and may provide clues for drug discovery in cancer therapy.

scholarly journals Cryo-EM of dynamic protein complexes in eukaryotic DNA replication

2016 ◽  
Vol 26 (1) ◽  
pp. 40-51 ◽  
Author(s):  
Jingchuan Sun ◽  
Zuanning Yuan ◽  
Lin Bai ◽  
Huilin Li
Keyword(s):  
Dna Replication ◽  
Protein Complexes ◽  
Eukaryotic Dna

scholarly journals BM28, a human member of the MCM2-3-5 family, is displaced from chromatin during DNA replication.

1995 ◽  
Vol 129 (6) ◽  
pp. 1433-1445 ◽  
Author(s):  
I T Todorov ◽  
A Attaran ◽  
S E Kearsey
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Posttranslational Modifications ◽  
S Phase ◽  
Present Evidence ◽  
Nuclear Binding ◽  
Eukaryotic Dna ◽  
Triton X ◽  
Related Proteins ◽  
Phase Proceeds

We have recently cloned and characterized a human member (BM28) of the MCM2-3-5 family of putative relication factors (Todorov, I.T., R. Pepperkok, R.N. Philipova, S. Kearsey, W. Ansorge, and D. Werner. 1994. J. Cell Sci. 107:253-265). While this protein is located in the nucleus throughout interphase, we report here a dramatic alteration in its nuclear binding during the cell cycle. BM28 is retained in the nucleus after Triton X-100 extraction in G1 and early S phase cells, but is progressively lost as S phase proceeds, and little BM28 is retained in detergent-extracted G2 nuclei. BM28 that is resistant to extraction in G1 nuclei is removed by DNase I digestion, suggesting that the protein is chromatin associated. In addition, we present evidence for variations in the electrophoretic mobility of BM28 that may reflect posttranslational modifications of BM28 during the cell cycle. During mitosis, BM28 is present as a fast-migrating form, but on entry into G1, the protein is converted into a slow-migrating form. With the onset of S phase, the slow-migrating form is progressively converted into the fast form. BM28 is phosphorylated at all stages of the cell cycle, but during interphase the fast form is hyperphosphorylated compared with the slow form. These apparent changes in modification may reflect or effect changes in the nuclear binding of BM28. The behavior of BM28 is not dissimilar to related proteins in Saccharomyces cerevisiae, such as Mcm2p, which are excluded from the nucleus after DNA replication. We speculate that BM28 may be involved in the control that limits eukaryotic DNA replication to one round per cell cycle.

scholarly journals Multivalent interaction of ESCO2 with the replication machinery is required for cohesion

2019 ◽  
Author(s):  
Dawn Bender ◽  
Eulália Maria Lima Da Silva ◽  
Jingrong Chen ◽  
Annelise Poss ◽  
Lauren Gawey ◽  
...  
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Cohesin Complex ◽  
Replication Machinery ◽  
Replicative Helicase ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Mcm Helicase ◽  
N Terminus ◽  
Processivity Factor

AbstractThe tethering together of sister chromatids by the cohesin complex ensures their accurate alignment and segregation during cell division. In vertebrates, the establishment of cohesion between sister chromatids requires the activity of the ESCO2 acetyltransferase, which modifies the Smc3 subunit of cohesin. It was shown recently that ESCO2 promotes cohesion through interaction with the MCM replicative helicase. However, ESCO2 does not significantly colocalize with the MCM helicase, suggesting there may be additional interactions that are important for ESCO2 function. Here we show that ESCO2 is recruited to replication factories, the sites of DNA replication. We show that ESCO2 contains multiple conserved PCNA-interaction motifs in its N-terminus, and that each of these motifs are essential to ESCO2’s ability to establish sister chromatid cohesion. We propose that multiple PCNA interaction motifs embedded in a largely flexible and disordered region of the protein underlie the ability of ESCO2 to establish cohesion between sister chromatids precisely as they are born during DNA replication.SummaryCohesin modification by the ESCO2 acetyltransferase is required for cohesion between sister chromatids. Here we identify multiple motifs in ESCO2 that mediate its interaction with the replication processivity factor PCNA, and show that their mutation abrogates the ability of ESCO2 to ensure cohesion.

scholarly journals The F-Box Protein Dia2 Regulates DNA Replication

2006 ◽  
Vol 17 (4) ◽  
pp. 1540-1548 ◽  
Author(s):  
Deanna M. Koepp ◽  
Andrew C. Kile ◽  
Swarna Swaminathan ◽  
Veronica Rodriguez-Rivera
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Protein Complexes ◽  
S Phase ◽  
Cycle Progression ◽  
Origin Binding Protein ◽  
Cold Sensitive ◽  
F Box Protein

Ubiquitin-mediated proteolysis plays a key role in many pathways inside the cell and is particularly important in regulating cell cycle transitions. SCF (Skp1/Cul1/F-box protein) complexes are modular ubiquitin ligases whose specificity is determined by a substrate-binding F-box protein. Dia2 is a Saccharomyces cerevisiae F-box protein previously described to play a role in invasive growth and pheromone response pathways. We find that deletion of DIA2 renders cells cold-sensitive and subject to defects in cell cycle progression, including premature S-phase entry. Consistent with a role in regulating DNA replication, the Dia2 protein binds replication origins. Furthermore, the dia2 mutant accumulates DNA damage in both S and G2/M phases of the cell cycle. These defects are likely a result of the absence of SCFDia2 activity, as a Dia2 ΔF-box mutant shows similar phenotypes. Interestingly, prolonging G1-phase in dia2 cells prevents the accumulation of DNA damage in S-phase. We propose that Dia2 is an origin-binding protein that plays a role in regulating DNA replication.

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