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Ceballos-Zúñiga F, Menéndez M, Pérez-Dorado I. New insights into the domain of unknown function (DUF) of EccC 5, the pivotal ATPase providing the secretion driving force to the ESX-5 secretion system. Acta Crystallogr D Struct Biol 2024; 80:397-409. [PMID: 38805245 PMCID: PMC11154593 DOI: 10.1107/s2059798324004248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/08/2024] [Indexed: 05/29/2024] Open
Abstract
Type VII secretion (T7S) systems, also referred to as ESAT-6 secretion (ESX) systems, are molecular machines that have gained great attention due to their implications in cell homeostasis and in host-pathogen interactions in mycobacteria. The latter include important human pathogens such as Mycobacterium tuberculosis (Mtb), the etiological cause of human tuberculosis, which constitutes a pandemic accounting for more than one million deaths every year. The ESX-5 system is exclusively found in slow-growing pathogenic mycobacteria, where it mediates the secretion of a large family of virulence factors: the PE and PPE proteins. The secretion driving force is provided by EccC5, a multidomain ATPase that operates using four globular cytosolic domains: an N-terminal domain of unknown function (EccC5DUF) and three FtsK/SpoIIIE ATPase domains. Recent structural and functional studies of ESX-3 and ESX-5 systems have revealed EccCDUF to be an ATPase-like fold domain with potential ATPase activity, the functionality of which is essential for secretion. Here, the crystal structure of the MtbEccC5DUF domain is reported at 2.05 Å resolution, which reveals a nucleotide-free structure with degenerated cis-acting and trans-acting elements involved in ATP binding and hydrolysis. This crystallographic study, together with a biophysical assessment of the interaction of MtbEccC5DUF with ATP/Mg2+, supports the absence of ATPase activity proposed for this domain. It is shown that this degeneration is also present in DUF domains from other ESX and ESX-like systems, which are likely to exhibit poor or null ATPase activity. Moreover, based on an in silico model of the N-terminal region of MtbEccC5DUF, it is hypothesized that MtbEccC5DUF is a degenerated ATPase domain that may have retained the ability to hexamerize. These observations draw attention to DUF domains as structural elements with potential implications in the opening and closure of the membrane pore during the secretion process via their involvement in inter-protomer interactions.
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Affiliation(s)
- Fernando Ceballos-Zúñiga
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry Blas Cabrera, Spanish Research Council, Serrano 119, 28006 Madrid, Spain
| | - Margarita Menéndez
- Department of Structure and Thermodynamics of Macromolecules, Institute of Physical Chemistry Blas Cabrera, Spanish Research Council, Serrano 119, 28006 Madrid, Spain
- CIBER of Respiratory Diseases, ISCIII, Sinesio Delgado 10, 28029 Madrid, Spain
| | - Inmaculada Pérez-Dorado
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry Blas Cabrera, Spanish Research Council, Serrano 119, 28006 Madrid, Spain
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2
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Turgeman-Grott I, Arsenault D, Yahav D, Feng Y, Miezner G, Naki D, Peri O, Papke RT, Gogarten JP, Gophna U. Neighboring inteins interfere with one another's homing capacity. PNAS NEXUS 2023; 2:pgad354. [PMID: 38024399 PMCID: PMC10643990 DOI: 10.1093/pnasnexus/pgad354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 10/16/2023] [Accepted: 10/25/2023] [Indexed: 12/01/2023]
Abstract
Inteins are mobile genetic elements that invade conserved genes across all domains of life and viruses. In some instances, a single gene will have several intein insertion sites. In Haloarchaea, the minichromosome maintenance (MCM) protein at the core of replicative DNA helicase contains four intein insertion sites within close proximity, where two of these sites (MCM-a and MCM-d) are more likely to be invaded. A haloarchaeon that harbors both MCM-a and MCM-d inteins, Haloferax mediterranei, was studied in vivo to determine intein invasion dynamics and the interactions between neighboring inteins. Additionally, invasion frequencies and the conservation of insertion site sequences in 129 Haloferacales mcm homologs were analyzed to assess intein distribution across the order. We show that the inteins at MCM-a and MCM-d recognize and cleave their respective target sites and, in the event that only one empty intein invasion site is present, readily initiate homing (i.e. single homing). However, when two inteins are present co-homing into an intein-free target sequence is much less effective. The two inteins are more effective when invading alleles that already contain an intein at one of the two sites. Our in vivo and computational studies also support that having a proline in place of a serine as the first C-terminal extein residue of the MCM-d insertion site prevents successful intein splicing, but does not stop recognition of the insertion site by the intein's homing endonuclease.
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Affiliation(s)
- Israela Turgeman-Grott
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801 Tel Aviv, Israel
| | - Danielle Arsenault
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06268-3125, USA
| | - Dekel Yahav
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801 Tel Aviv, Israel
| | - Yutian Feng
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06268-3125, USA
| | - Guy Miezner
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801 Tel Aviv, Israel
| | - Doron Naki
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801 Tel Aviv, Israel
| | - Omri Peri
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801 Tel Aviv, Israel
| | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06268-3125, USA
| | - Johann Peter Gogarten
- Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06268-3125, USA
- Institute for Systems Genomics, University of Connecticut, 67 North Eagleville Road, Storrs, CT 06268-3003, USA
| | - Uri Gophna
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801 Tel Aviv, Israel
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McKinzey DR, Li C, Gao Y, Trakselis MA. Activity, substrate preference and structure of the HsMCM8/9 helicase. Nucleic Acids Res 2023; 51:7330-7341. [PMID: 37309874 PMCID: PMC10415141 DOI: 10.1093/nar/gkad508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 06/14/2023] Open
Abstract
The minichromosomal maintenance proteins, MCM8 and MCM9, are more recent evolutionary additions to the MCM family, only cooccurring in selected higher eukaryotes. Mutations in these genes are directly linked to ovarian insufficiency, infertility, and several cancers. MCM8/9 appears to have ancillary roles in fork progression and recombination of broken replication forks. However, the biochemical activity, specificities and structures have not been adequately illustrated, making mechanistic determination difficult. Here, we show that human MCM8/9 (HsMCM8/9) is an ATP dependent DNA helicase that unwinds fork DNA substrates with a 3'-5' polarity. High affinity ssDNA binding occurs in the presence of nucleoside triphosphates, while ATP hydrolysis weakens the interaction with DNA. The cryo-EM structure of the HsMCM8/9 heterohexamer was solved at 4.3 Å revealing a trimer of heterodimer configuration with two types of interfacial AAA+ nucleotide binding sites that become more organized upon binding ADP. Local refinements of the N or C-terminal domains (NTD or CTD) improved the resolution to 3.9 or 4.1 Å, respectively, and shows a large displacement in the CTD. Changes in AAA+ CTD upon nucleotide binding and a large swing between the NTD and CTD likely implies that MCM8/9 utilizes a sequential subunit translocation mechanism for DNA unwinding.
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Affiliation(s)
- David R McKinzey
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA
| | - Chuxuan Li
- Department of Biosciences, Rice University, Houston, TX 77005, USA
| | - Yang Gao
- Department of Biosciences, Rice University, Houston, TX 77005, USA
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA
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4
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Yeast Stn1 promotes MCM to circumvent Rad53 control of the S phase checkpoint. Curr Genet 2022; 68:165-179. [PMID: 35150303 PMCID: PMC8976814 DOI: 10.1007/s00294-022-01228-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 11/17/2022]
Abstract
Treating yeast cells with the replication inhibitor hydroxyurea activates the S phase checkpoint kinase Rad53, eliciting responses that block DNA replication origin firing, stabilize replication forks, and prevent premature extension of the mitotic spindle. We previously found overproduction of Stn1, a subunit of the telomere-binding Cdc13–Stn1–Ten1 complex, circumvents Rad53 checkpoint functions in hydroxyurea, inducing late origin firing and premature spindle extension even though Rad53 is activated normally. Here, we show Stn1 overproduction acts through remarkably similar pathways compared to loss of RAD53, converging on the MCM complex that initiates origin firing and forms the catalytic core of the replicative DNA helicase. First, mutations affecting Mcm2 and Mcm5 block the ability of Stn1 overproduction to disrupt the S phase checkpoint. Second, loss of function stn1 mutations compensate rad53 S phase checkpoint defects. Third Stn1 overproduction suppresses a mutation in Mcm7. Fourth, stn1 mutants accumulate single-stranded DNA at non-telomeric genome locations, imposing a requirement for post-replication DNA repair. We discuss these interactions in terms of a model in which Stn1 acts as an accessory replication factor that facilitates MCM activation at ORIs and potentially also maintains MCM activity at replication forks advancing through challenging templates.
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Determining translocation orientations of nucleic acid helicases. Methods 2021; 204:160-171. [PMID: 34758393 PMCID: PMC9076756 DOI: 10.1016/j.ymeth.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 11/20/2022] Open
Abstract
Helicase enzymes translocate along an RNA or DNA template with a defined polarity to unwind, separate, or remodel duplex strands for a variety of genome maintenance processes. Helicase mutations are commonly associated with a variety of diseases including aging, cancer, and neurodegeneration. Biochemical characterization of these enzymes has provided a wealth of information on the kinetics of unwinding and substrate preferences, and several high-resolution structures of helicases alone and bound to oligonucleotides have been solved. Together, they provide mechanistic insights into the structural translocation and unwinding orientations of helicases. However, these insights rely on structural inferences derived from static snapshots. Instead, continued efforts should be made to combine structure and kinetics to better define active translocation orientations of helicases. This review explores many of the biochemical and biophysical methods utilized to map helicase binding orientation to DNA or RNA substrates and includes several time-dependent methods to unequivocally map the active translocation orientation of these enzymes to better define the active leading and trailing faces.
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Khan YA, White KI, Brunger AT. The AAA+ superfamily: a review of the structural and mechanistic principles of these molecular machines. Crit Rev Biochem Mol Biol 2021; 57:156-187. [PMID: 34632886 DOI: 10.1080/10409238.2021.1979460] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ATPases associated with diverse cellular activities (AAA+ proteins) are a superfamily of proteins found throughout all domains of life. The hallmark of this family is a conserved AAA+ domain responsible for a diverse range of cellular activities. Typically, AAA+ proteins transduce chemical energy from the hydrolysis of ATP into mechanical energy through conformational change, which can drive a variety of biological processes. AAA+ proteins operate in a variety of cellular contexts with diverse functions including disassembly of SNARE proteins, protein quality control, DNA replication, ribosome assembly, and viral replication. This breadth of function illustrates both the importance of AAA+ proteins in health and disease and emphasizes the importance of understanding conserved mechanisms of chemo-mechanical energy transduction. This review is divided into three major portions. First, the core AAA+ fold is presented. Next, the seven different clades of AAA+ proteins and structural details and reclassification pertaining to proteins in each clade are described. Finally, two well-known AAA+ proteins, NSF and its close relative p97, are reviewed in detail.
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Affiliation(s)
- Yousuf A Khan
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Center for Biomedical Informatics Research, Stanford University, Stanford, CA, USA
| | - K Ian White
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
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Wu B, Xi S. Bioinformatics analysis of the transcriptional expression of minichromosome maintenance proteins as potential indicators of survival in patients with cervical cancer. BMC Cancer 2021; 21:928. [PMID: 34404366 PMCID: PMC8371838 DOI: 10.1186/s12885-021-08674-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 08/10/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND As major regulators of DNA replication in eukaryotes, minichromosome maintenance (MCM) proteins play an important role in the initiation and extension of DNA replication. MCMs and their related genes may be new markers of cell proliferation activity, which is of great significance for the diagnosis and prognosis of cervical cancer. METHODS To explore the role of MCMs and their related genes in cervical cancer, various bioinformatics methods were performed. First, the ONCOMINE and UALCAN databases were used to analyze the mRNA expression of different MCMs. The Human Protein Atlas database was used to analyze the protein expression of MCMs in normal and tumor tissues. The potential clinical value of MCMs was evaluated using the UALCAN, Kaplan-Meier plotter and cBioPortal databases. Then, the related genes and key coexpressed genes of MCMs were screened using GEPIA2 and cBioPortal analysis. For these genes, we used Metascape and the DAVID database to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, construct the related molecular interaction network, and obtain the key subnetworks and related hub genes. The Kaplan-Meier plotter database was used for survival analysis of cervical cancer patients to evaluate and predict the potential clinical value of the hub genes. Moreover, multiple gene comparisons of the expression of MCMs and related genes in different cancer types also showed the clinical significance of these potential targets. RESULTS The mRNA and protein expression of MCMs increased in tumor tissue. Overexpression of MCM2/3/4/5/6/7/8/10 was found to be significantly associated with clinical cancer stage. Higher mRNA expression levels of MCM3/5/6/7/8 were found to be significantly associated with longer overall survival, and higher mRNA expression of MCM2/3/4/5/6/7/8 was associated with favorable OS. In addition, a high mutation rate of MCMs (71%) was observed. MCM2, MCM4, MCM8, MCM3 and MCM7 were the five genes with the most genetic alterations. In addition, the coexpressed genes and related genes of MCMs were successfully screened for enrichment analysis. These genes were significantly enriched in important pathways, such as the DNA replication, cell cycle, mismatch repair, spliceosome, and Fanconi anemia pathways. A protein-protein interaction network was successfully constructed, and a total of 13 hub genes (CDC45, ORC1, RPA1, CDT1, TARDBP, RBMX, SRSF3, SRSF1, RFC5, RFC2, MSH6, DTL, and MSH2) from 4 key subnetworks were obtained. These genes and MCM2/3/4/5/6/7/8 might have potential clinical value for the survival and prognosis of cervical cancer patients. CONCLUSIONS These findings promoted the understanding of the MCM protein family and clinically related molecular targets for cervical epithelial neoplasia and cervical cancer. Our results were helpful to evaluate the potential clinical value of MCMs and related genes in patients with cervical cancer.
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Affiliation(s)
- Baojie Wu
- Shanghai Zerun Biotechnology Co., Ltd., Pilot Department, Building 9, 1690 Zhangheng Road Pudong, Shanghai, 201203, China.
| | - Shuyi Xi
- Shanghai Zerun Biotechnology Co., Ltd., Pilot Department, Building 9, 1690 Zhangheng Road Pudong, Shanghai, 201203, China
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8
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Meagher M, Spence MN, Enemark EJ. Structure of a dimer of the Sulfolobus solfataricus MCM N-terminal domain reveals a potential role in MCM ring opening. Acta Crystallogr F Struct Biol Commun 2021; 77:177-186. [PMID: 34100776 PMCID: PMC8186412 DOI: 10.1107/s2053230x21005331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 05/20/2021] [Indexed: 11/11/2022] Open
Abstract
Cells strongly regulate DNA replication to ensure genomic stability and prevent several diseases, including cancers. Eukaryotes and archaea strictly control DNA-replication initiation by the regulated loading of hexameric minichromosome maintenance (MCM) rings to encircle both strands of the DNA double helix followed by regulated activation of the loaded rings such that they then encircle one DNA strand while excluding the other. Both steps involve an open/closed ring transformation, allowing DNA strands to enter or exit. Here, the crystal structure of a dimer of the N-terminal domain of Sulfolobus solfataricus MCM with an intersubunit interface that is more extensive than in closed-ring structures, while including common interactions to enable facile interconversion, is presented. It is shown that the identified interface could stabilize open MCM rings by compensating for lost interactions at an open neighbor interface and that the prior open-ring cryo-EM structure of MCM loading has a similar extended interface adjacent to its open interface.
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Affiliation(s)
- Martin Meagher
- Structural Biology, St Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Madison N. Spence
- Structural Biology, St Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Eric J. Enemark
- Structural Biology, St Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 516, Little Rock, AR 72205, USA
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9
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The replicative CMG helicase: the ideal target for cancer therapy. UKRAINIAN BIOCHEMICAL JOURNAL 2020. [DOI: 10.15407/ubj92.06.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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10
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Miller JM, Brambley CA, Marsee JD. Examination of the Role of Mg 2+ in the Mechanism of Nucleotide Binding to the Monomeric YME1L AAA+ Domain. Biochemistry 2020; 59:4303-4320. [PMID: 33155794 DOI: 10.1021/acs.biochem.0c00699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The first line of defense in the mitochondrial quality control network involves the stress response from a family of ATP-dependent proteases. We have reported that a solubilized version of the mitochondrial inner membrane ATP-dependent protease YME1L displays nucleotide binding kinetics that are sensitive to the reactive oxygen species hydrogen peroxide under a limiting ATP concentration. Our observations were consistent with an altered YME1L conformational ensemble leading to increased nucleotide binding site accessibility under oxidative stress conditions. To examine this hypothesis further, we report here the results of a comprehensive study of the thermodynamic and kinetic properties underlying the binding of nucleoside di- and triphosphate to the isolated YME1L AAA+ domain (YME1L-AAA+). A combination of fluorescence titrations, molecular dynamics, and stopped-flow fluorescence experiments have demonstrated similarity between nucleotide binding behaviors for YME1L under oxidative conditions and the isolated AAA+ domain. Our data demonstrate that YME1L-AAA+ binds ATP and ADP with affinities equal to ∼30 and 5 μM, respectively, in the absence of Mg2+. We note a negative heterotropic linkage effect between Mg2+ and ATP that arises as the MgCl2 concentration is increased such that the affinity of YME1L-AAA+ for ATP decreases to ∼60 μM in the presence of 10 mM MgCl2. Molecular dynamics methods allow for structural rationalization by revealing condition-dependent conformational populations for YME1L-AAA+. Taken together, these data suggest a preliminary model in which YME1L modulates its affinity for the nucleotide to stabilize against degradation or instability inherent to such stress conditions.
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Affiliation(s)
- Justin M Miller
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, Tennessee 37132, United States
| | - Chad A Brambley
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, Tennessee 37132, United States
| | - Justin D Marsee
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, Tennessee 37132, United States
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11
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Yuan Z, Li H. Molecular mechanisms of eukaryotic origin initiation, replication fork progression, and chromatin maintenance. Biochem J 2020; 477:3499-3525. [PMID: 32970141 PMCID: PMC7574821 DOI: 10.1042/bcj20200065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/29/2020] [Accepted: 09/04/2020] [Indexed: 12/13/2022]
Abstract
Eukaryotic DNA replication is a highly dynamic and tightly regulated process. Replication involves several dozens of replication proteins, including the initiators ORC and Cdc6, replicative CMG helicase, DNA polymerase α-primase, leading-strand DNA polymerase ε, and lagging-strand DNA polymerase δ. These proteins work together in a spatially and temporally controlled manner to synthesize new DNA from the parental DNA templates. During DNA replication, epigenetic information imprinted on DNA and histone proteins is also copied to the daughter DNA to maintain the chromatin status. DNA methyltransferase 1 is primarily responsible for copying the parental DNA methylation pattern into the nascent DNA. Epigenetic information encoded in histones is transferred via a more complex and less well-understood process termed replication-couple nucleosome assembly. Here, we summarize the most recent structural and biochemical insights into DNA replication initiation, replication fork elongation, chromatin assembly and maintenance, and related regulatory mechanisms.
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Affiliation(s)
- Zuanning Yuan
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, U.S.A
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, U.S.A
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12
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Bebel A, Walsh MA, Mir-Sanchis I, Rice PA. A novel DNA primase-helicase pair encoded by SCC mec elements. eLife 2020; 9:55478. [PMID: 32945259 PMCID: PMC7581432 DOI: 10.7554/elife.55478] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 09/17/2020] [Indexed: 01/18/2023] Open
Abstract
Mobile genetic elements (MGEs) are a rich source of new enzymes, and conversely, understanding the activities of MGE-encoded proteins can elucidate MGE function. Here, we biochemically characterize three proteins encoded by a conserved operon carried by the Staphylococcal Cassette Chromosome (SCCmec), an MGE that confers methicillin resistance to Staphylococcus aureus, creating MRSA strains. The first of these proteins, CCPol, is an active A-family DNA polymerase. The middle protein, MP, binds tightly to CCPol and confers upon it the ability to synthesize DNA primers de novo. The CCPol-MP complex is therefore a unique primase-polymerase enzyme unrelated to either known primase family. The third protein, Cch2, is a 3’-to-5’ helicase. Cch2 additionally binds specifically to a dsDNA sequence downstream of its gene that is also a preferred initiation site for priming by CCPol-MP. Taken together, our results suggest that this is a functional replication module for SCCmec.
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Affiliation(s)
- Aleksandra Bebel
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Melissa A Walsh
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Ignacio Mir-Sanchis
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Phoebe A Rice
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
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Abstract
Replicative DNA helicases are essential cellular enzymes that unwind duplex DNA in front of the replication fork during chromosomal DNA replication. Replicative helicases were discovered, beginning in the 1970s, in bacteria, bacteriophages, viruses, and eukarya, and, in the mid-1990s, in archaea. This year marks the 20th anniversary of the first report on the archaeal replicative helicase, the minichromosome maintenance (MCM) protein. This minireview summarizes 2 decades of work on the archaeal MCM.
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14
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Yuan Z, Georgescu R, Bai L, Zhang D, Li H, O'Donnell ME. DNA unwinding mechanism of a eukaryotic replicative CMG helicase. Nat Commun 2020; 11:688. [PMID: 32019936 PMCID: PMC7000775 DOI: 10.1038/s41467-020-14577-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 01/17/2020] [Indexed: 11/09/2022] Open
Abstract
High-resolution structures have not been reported for replicative helicases at a replication fork at atomic resolution, a prerequisite to understanding the unwinding mechanism. The eukaryotic replicative CMG (Cdc45, Mcm2-7, GINS) helicase contains a Mcm2-7 motor ring, with the N-tier ring in front and the C-tier motor ring behind. The N-tier ring is structurally divided into a zinc finger (ZF) sub-ring followed by the oligosaccharide/oligonucleotide-binding (OB) fold ring. Here we report the cryo-EM structure of CMG on forked DNA at 3.9 Å, revealing that parental DNA enters the ZF sub-ring and strand separation occurs at the bottom of the ZF sub-ring, where the lagging strand is blocked and diverted sideways by OB hairpin-loops of Mcm3, Mcm4, Mcm6, and Mcm7. Thus, instead of employing a specific steric exclusion process, or even a separation pin, unwinding is achieved via a "dam-and-diversion tunnel" mechanism that does not require specific protein-DNA interaction. The C-tier motor ring contains spirally configured PS1 and H2I loops of Mcms 2, 3, 5, 6 that translocate on the spirally-configured leading strand, and thereby pull the preceding DNA segment through the diversion tunnel for strand separation.
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Affiliation(s)
- Zuanning Yuan
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Roxana Georgescu
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.,DNA Replication Laboratory, The Rockefeller University, New York, NY, USA
| | - Lin Bai
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Dan Zhang
- DNA Replication Laboratory, The Rockefeller University, New York, NY, USA
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
| | - Michael E O'Donnell
- Howard Hughes Medical Institute, Chevy Chase, MD, USA. .,DNA Replication Laboratory, The Rockefeller University, New York, NY, USA.
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15
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Mohapatra S, Lin CT, Feng XA, Basu A, Ha T. Single-Molecule Analysis and Engineering of DNA Motors. Chem Rev 2019; 120:36-78. [DOI: 10.1021/acs.chemrev.9b00361] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | | | | | | | - Taekjip Ha
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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16
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Meagher M, Epling LB, Enemark EJ. DNA translocation mechanism of the MCM complex and implications for replication initiation. Nat Commun 2019; 10:3117. [PMID: 31308367 PMCID: PMC6629641 DOI: 10.1038/s41467-019-11074-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 06/18/2019] [Indexed: 12/12/2022] Open
Abstract
The DNA translocation activity of the minichromosome maintenance (MCM) complex powers DNA strand separation of the replication forks of eukaryotes and archaea. Here we illustrate an atomic level mechanism for this activity with a crystal structure of an archaeal MCM hexamer bound to single-stranded DNA and nucleotide cofactors. Sequence conservation indicates this rotary mechanism is fully possible for all eukaryotes and archaea. The structure definitively demonstrates the ring orients during translocation with the N-terminal domain leading, indicating that the translocation activity could also provide the physical basis of replication initiation where a double-hexamer idly encircling double-stranded DNA transforms to single-hexamers that encircle only one strand. In this mechanism, each strand binds to the N-terminal tier of one hexamer and the AAA+ tier of the other hexamer such that one ring pulls on the other, aligning equivalent interfaces to enable each hexamer to pull its translocation strand outside of the opposing hexamer.
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Affiliation(s)
- Martin Meagher
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 311, Memphis, TN, 38105, USA
| | - Leslie B Epling
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 311, Memphis, TN, 38105, USA.,Incyte Research Institute, 1801 Augustine Cut-off, Wilmington, DE, 19803, USA
| | - Eric J Enemark
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 311, Memphis, TN, 38105, USA.
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17
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Brambley CA, Marsee JD, Halper N, Miller JM. Characterization of Mitochondrial YME1L Protease Oxidative Stress-Induced Conformational State. J Mol Biol 2019; 431:1250-1266. [PMID: 30731091 DOI: 10.1016/j.jmb.2019.01.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/11/2019] [Accepted: 01/27/2019] [Indexed: 10/27/2022]
Abstract
Oxidative stress is a common challenge to mitochondrial function where reactive oxygen species are capable of significant organelle damage. The generation of mitochondrial reactive oxygen species occurs in the inner membrane and matrix compartments as a consequence of subunit function in the electron transport chain and citric acid cycle, respectively. Maintenance of mitochondrial proteostasis and stress response is facilitated by compartmentalized proteases that couple the energy of ATP hydrolysis to unfolding and the regulated removal of damaged, misfolded, or aggregated proteins. The mitochondrial protease YME1L functions in the maintenance of proteostasis in the intermembrane space. YME1L is an inner membrane-anchored hexameric protease with distinct N-terminal, transmembrane, AAA+ (ATPases associated with various cellular activities), and C-terminal M41 zinc-dependent protease domains. The effect of oxidative stress on enzymes such as YME1L tasked with maintaining proteostasis is currently unclear. We report here that recombinant YME1L undergoes a reversible conformational change in response to oxidative stress that involves the interaction of one hydrogen peroxide molecule per YME1L monomer with affinities equal to 31 ± 2 and 26 ± 1 mM for conditions lacking or including nucleotide, respectively. Our data also reveal that oxidative stress does not significantly impact nucleotide binding equilibria, but does stimulate a 2-fold increase in the rate constant for high-affinity ATP binding from (8.9 ± 0.2) × 105 M-1 s-1 to (1.5 ± 0.1) × 106 M-1 s-1. Taken together, these data may suggest a mechanism for the regulated processing of YME1L by other inner membrane proteases such as OMA1.
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Affiliation(s)
- Chad A Brambley
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA
| | - Justin D Marsee
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA
| | - Neal Halper
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA
| | - Justin M Miller
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA.
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18
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Griffin WC, Trakselis MA. The MCM8/9 complex: A recent recruit to the roster of helicases involved in genome maintenance. DNA Repair (Amst) 2019; 76:1-10. [PMID: 30743181 DOI: 10.1016/j.dnarep.2019.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/03/2019] [Indexed: 12/11/2022]
Abstract
There are several DNA helicases involved in seemingly overlapping aspects of homologous and homoeologous recombination. Mutations of many of these helicases are directly implicated in genetic diseases including cancer, rapid aging, and infertility. MCM8/9 are recent additions to the catalog of helicases involved in recombination, and so far, the evidence is sparse, making assignment of function difficult. Mutations in MCM8/9 correlate principally with primary ovarian failure/insufficiency (POF/POI) and infertility indicating a meiotic defect. However, they also act when replication forks collapse/break shuttling products into mitotic recombination and several mutations are found in various somatic cancers. This review puts MCM8/9 in context with other replication and recombination helicases to narrow down its genomic maintenance role. We discuss the known structure/function relationship, the mutational spectrum, and dissect the available cellular and organismal data to better define its role in recombination.
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Affiliation(s)
- Wezley C Griffin
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA.
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19
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Graham BW, Bougoulias ME, Dodge KL, Thaxton CT, Olaso D, Tao Y, Young NL, Marshall AG, Trakselis MA. Control of Hexamerization, Assembly, and Excluded Strand Specificity for the Sulfolobus solfataricus MCM Helicase. Biochemistry 2018; 57:5672-5682. [DOI: 10.1021/acs.biochem.8b00766] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian W. Graham
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Michael E. Bougoulias
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Katie L. Dodge
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Carly T. Thaxton
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Danae Olaso
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Yeqing Tao
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Nicolas L. Young
- Verna & Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030-3411, United States
| | - Alan G. Marshall
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306, United States
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Michael A. Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
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20
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Tamberg N, Tahk S, Koit S, Kristjuhan K, Kasvandik S, Kristjuhan A, Ilves I. Keap1-MCM3 interaction is a potential coordinator of molecular machineries of antioxidant response and genomic DNA replication in metazoa. Sci Rep 2018; 8:12136. [PMID: 30108253 PMCID: PMC6092318 DOI: 10.1038/s41598-018-30562-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/02/2018] [Indexed: 01/19/2023] Open
Abstract
Coordination of DNA replication and cellular redox homeostasis mechanisms is essential for the sustained genome stability due to the sensitivity of replicating DNA to oxidation. However, substantial gaps remain in our knowledge of underlying molecular pathways. In this study, we characterise the interaction of Keap1, a central antioxidant response regulator in Metazoa, with the replicative helicase subunit protein MCM3. Our analysis suggests that structural determinants of the interaction of Keap1 with its critical downstream target - Nrf2 master transactivator of oxidative stress response genes – may have evolved in evolution to mimic the conserved helix-2-insert motif of MCM3. We show that this has led to a competition between MCM3 and Nrf2 proteins for Keap1 binding, and likely recruited MCM3 for the competitive binding dependent modulation of Keap1 controlled Nrf2 activities. We hypothesise that such mechanism could help to adjust the Keap1-Nrf2 antioxidant response pathway according to the proliferative and replicative status of the cell, with possible reciprocal implications also for the regulation of cellular functions of MCM3. Altogether this suggests about important role of Keap1-MCM3 interaction in the cross-talk between replisome and redox homeostasis machineries in metazoan cells.
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Affiliation(s)
- Nele Tamberg
- Institute of Technology, University of Tartu, Tartu, 50411, Estonia
| | - Siret Tahk
- Institute of Technology, University of Tartu, Tartu, 50411, Estonia
| | - Sandra Koit
- Institute of Technology, University of Tartu, Tartu, 50411, Estonia
| | - Kersti Kristjuhan
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, 51010, Estonia
| | - Sergo Kasvandik
- Institute of Technology, University of Tartu, Tartu, 50411, Estonia
| | - Arnold Kristjuhan
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, 51010, Estonia
| | - Ivar Ilves
- Institute of Technology, University of Tartu, Tartu, 50411, Estonia.
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21
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Ou X, Wang M, Mao S, Cao J, Cheng A, Zhu D, Chen S, Jia R, Liu M, Yang Q, Wu Y, Zhao X, Zhang S, Liu Y, Yu Y, Zhang L, Chen X, Peppelenbosch MP, Pan Q. Incompatible Translation Drives a Convergent Evolution and Viral Attenuation During the Development of Live Attenuated Vaccine. Front Cell Infect Microbiol 2018; 8:249. [PMID: 30073153 PMCID: PMC6058041 DOI: 10.3389/fcimb.2018.00249] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/02/2018] [Indexed: 11/13/2022] Open
Abstract
Live attenuated vaccines are widely used to protect humans or animals from pathogen infections. We have previously developed a chicken embryo-attenuated Duck Hepatitis A Virus genotype 1 (DHAV-1) vaccine (CH60 strain). This study aims to understand the mechanisms that drive a virulent strain to an attenuated virus. Here, we systematically compared five DHAV-1 chicken embryo attenuated strains and 68 virulent strains. Phylogenetic analysis indicated that duck virulent strains isolated from different geographic regions of China undergo a convergent evolution in the chicken embryos. Comparative analysis indicated that the codon usage bias of the attenuated strains were shaped by chicken codons usage bias, which essentially contributed to viral adaption in the unsuitable host driven by incompatible translation. Of note, the missense mutations in coding region and mutations in untranslated regions may also contribute to viral attenuation of DHAV-1 to some extent. Importantly, we have experimentally confirmed that the expression levels of four viral proteins (2A3pro, 2A3pro, 3Cpro, and 3Dpro) in the liver and kidney of ducks infected with an attenuated strain are significantly lower than that infected with a virulent strain, despite with similar virus load. Thus, the key mechanisms of viral attenuation revealed by this study may lead to innovative and easy approaches in designing live attenuated vaccines.
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Affiliation(s)
- Xumin Ou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, Netherlands
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Jingyu Cao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Dekang Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yunya Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yanling Yu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaoyue Chen
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Maikel P Peppelenbosch
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, Netherlands
| | - Qiuwei Pan
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, Netherlands
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22
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Zhai Y, Tye BK. Structure of the MCM2-7 Double Hexamer and Its Implications for the Mechanistic Functions of the Mcm2-7 Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1042:189-205. [PMID: 29357059 DOI: 10.1007/978-981-10-6955-0_9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The eukaryotic minichromosome maintenance 2-7 complex is the core of the inactive MCM replication licensing complex and the catalytic core of the Cdc45-MCM-GINS replicative helicase. The years of effort to determine the structure of parts or the whole of the heterohexameric complex by X-ray crystallography and conventional cryo-EM produced limited success. Modern cryo-EM technology ushered in a new era of structural biology that allowed the determination of the structure of the inactive double hexamer at an unprecedented resolution of 3.8 Å. This review will focus on the fine details observed in the Mcm2-7 double hexameric complex and their implications for the function of the Mcm2-7 hexamer in its different roles during DNA replication.
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Affiliation(s)
- Yuanliang Zhai
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
- Institute for Advanced Study, Hong Kong University of Science and Technology, Hong Kong, China
| | - Bik-Kwoon Tye
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China.
- Department of Molecular Biology and Genetics, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA.
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23
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Seo YS, Kang YH. The Human Replicative Helicase, the CMG Complex, as a Target for Anti-cancer Therapy. Front Mol Biosci 2018; 5:26. [PMID: 29651420 PMCID: PMC5885281 DOI: 10.3389/fmolb.2018.00026] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/12/2018] [Indexed: 12/14/2022] Open
Abstract
DNA helicases unwind or rearrange duplex DNA during replication, recombination and repair. Helicases of many pathogenic organisms such as viruses, bacteria, and protozoa have been studied as potential therapeutic targets to treat infectious diseases, and human DNA helicases as potential targets for anti-cancer therapy. DNA replication machineries perform essential tasks duplicating genome in every cell cycle, and one of the important functions of these machineries are played by DNA helicases. Replicative helicases are usually multi-subunit protein complexes, and the minimal complex active as eukaryotic replicative helicase is composed of 11 subunits, requiring a functional assembly of two subcomplexes and one protein. The hetero-hexameric MCM2-7 helicase is activated by forming a complex with Cdc45 and the hetero-tetrameric GINS complex; the Cdc45-Mcm2-7-GINS (CMG) complex. The CMG complex can be a potential target for a treatment of cancer and the feasibility of this replicative helicase as a therapeutic target has been tested recently. Several different strategies have been implemented and are under active investigations to interfere with helicase activity of the CMG complex. This review focuses on the molecular function of the CMG helicase during DNA replication and its relevance to cancers based on data published in the literature. In addition, current efforts made to identify small molecules inhibiting the CMG helicase to develop anti-cancer therapeutic strategies were summarized, with new perspectives to advance the discovery of the CMG-targeting drugs.
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Affiliation(s)
- Yeon-Soo Seo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Young-Hoon Kang
- Core Protein Resources Center, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
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24
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The ring-shaped hexameric helicases that function at DNA replication forks. Nat Struct Mol Biol 2018; 25:122-130. [PMID: 29379175 DOI: 10.1038/s41594-018-0024-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 11/27/2017] [Indexed: 11/08/2022]
Abstract
DNA replication requires separation of genomic duplex DNA strands, an operation that is performed by a hexameric ring-shaped helicase in all domains of life. The structures and chemomechanical actions of these fascinating machines are coming into sharper focus. Although there is no evolutionary relationship between the hexameric helicases of bacteria and those of archaea and eukaryotes, they share many fundamental features. Here we review recent studies of these two groups of hexameric helicases and the unexpected distinctions they have also unveiled.
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25
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Miller JM, Chaudhary H, Marsee JD. Phylogenetic analysis predicts structural divergence for proteobacterial ClpC proteins. J Struct Biol 2017; 201:52-62. [PMID: 29129755 DOI: 10.1016/j.jsb.2017.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 11/06/2017] [Accepted: 11/08/2017] [Indexed: 12/29/2022]
Abstract
Regulated proteolysis is required in all organisms for the removal of misfolded or degradation-tagged protein substrates in cellular quality control pathways. The molecular machines that catalyze this process are known as ATP-dependent proteases with examples that include ClpAP and ClpCP. Clp/Hsp100 subunits form ring-structures that couple the energy of ATP binding and hydrolysis to protein unfolding and subsequent translocation of denatured protein into the compartmentalized ClpP protease for degradation. Copies of the clpA, clpC, clpE, clpK, and clpL genes are present in all characterized bacteria and their gene products are highly conserved in structure and function. However, the evolutionary relationship between these proteins remains unclear. Here we report a comprehensive phylogenetic analysis that suggests divergent evolution yielded ClpA from an ancestral ClpC protein and that ClpE/ClpL represent intermediates between ClpA/ClpC. This analysis also identifies a group of proteobacterial ClpC proteins that are likely not functional in regulated proteolysis. Our results strongly suggest that bacterial ClpC proteins should not be assumed to all function identically due to the structural differences identified here.
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Affiliation(s)
- Justin M Miller
- Middle Tennessee State University, Department of Chemistry, 1301 East Main Street, Murfreesboro, TN 37132, United States.
| | - Hamza Chaudhary
- Middle Tennessee State University, Department of Chemistry, 1301 East Main Street, Murfreesboro, TN 37132, United States
| | - Justin D Marsee
- Middle Tennessee State University, Department of Chemistry, 1301 East Main Street, Murfreesboro, TN 37132, United States
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26
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Riera A, Barbon M, Noguchi Y, Reuter LM, Schneider S, Speck C. From structure to mechanism-understanding initiation of DNA replication. Genes Dev 2017; 31:1073-1088. [PMID: 28717046 PMCID: PMC5538431 DOI: 10.1101/gad.298232.117] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In this Review, Riera et al. review recent structural and biochemical insights that start to explain how specific proteins recognize DNA replication origins, load the replicative helicase on DNA, unwind DNA, synthesize new DNA strands, and reassemble chromatin. DNA replication results in the doubling of the genome prior to cell division. This process requires the assembly of 50 or more protein factors into a replication fork. Here, we review recent structural and biochemical insights that start to explain how specific proteins recognize DNA replication origins, load the replicative helicase on DNA, unwind DNA, synthesize new DNA strands, and reassemble chromatin. We focus on the minichromosome maintenance (MCM2–7) proteins, which form the core of the eukaryotic replication fork, as this complex undergoes major structural rearrangements in order to engage with DNA, regulate its DNA-unwinding activity, and maintain genome stability.
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Affiliation(s)
- Alberto Riera
- DNA Replication Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Marta Barbon
- DNA Replication Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom.,Medical Research Council (MRC) London Institute of Medical Sciences (LMS), London W12 0NN, United Kingdom
| | - Yasunori Noguchi
- DNA Replication Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - L Maximilian Reuter
- DNA Replication Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Sarah Schneider
- DNA Replication Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Christian Speck
- DNA Replication Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom.,Medical Research Council (MRC) London Institute of Medical Sciences (LMS), London W12 0NN, United Kingdom
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27
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Lõoke M, Maloney MF, Bell SP. Mcm10 regulates DNA replication elongation by stimulating the CMG replicative helicase. Genes Dev 2017; 31:291-305. [PMID: 28270517 PMCID: PMC5358725 DOI: 10.1101/gad.291336.116] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/31/2017] [Indexed: 11/25/2022]
Abstract
Activation of the Mcm2-7 replicative DNA helicase is the committed step in eukaryotic DNA replication initiation. Although Mcm2-7 activation requires binding of the helicase-activating proteins Cdc45 and GINS (forming the CMG complex), an additional protein, Mcm10, drives initial origin DNA unwinding by an unknown mechanism. We show that Mcm10 binds a conserved motif located between the oligonucleotide/oligosaccharide fold (OB-fold) and A subdomain of Mcm2. Although buried in the interface between these domains in Mcm2-7 structures, mutations predicted to separate the domains and expose this motif restore growth to conditional-lethal MCM10 mutant cells. We found that, in addition to stimulating initial DNA unwinding, Mcm10 stabilizes Cdc45 and GINS association with Mcm2-7 and stimulates replication elongation in vivo and in vitro. Furthermore, we identified a lethal allele of MCM10 that stimulates initial DNA unwinding but is defective in replication elongation and CMG binding. Our findings expand the roles of Mcm10 during DNA replication and suggest a new model for Mcm10 function as an activator of the CMG complex throughout DNA replication.
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Affiliation(s)
- Marko Lõoke
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 USA
| | - Michael F Maloney
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 USA.,Microbiology Graduate Program, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 USA
| | - Stephen P Bell
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 USA
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28
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Eukaryotic Replicative Helicase Subunit Interaction with DNA and Its Role in DNA Replication. Genes (Basel) 2017; 8:genes8040117. [PMID: 28383499 PMCID: PMC5406864 DOI: 10.3390/genes8040117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 03/23/2017] [Accepted: 03/31/2017] [Indexed: 01/30/2023] Open
Abstract
The replicative helicase unwinds parental double-stranded DNA at a replication fork to provide single-stranded DNA templates for the replicative polymerases. In eukaryotes, the replicative helicase is composed of the Cdc45 protein, the heterohexameric ring-shaped Mcm2-7 complex, and the tetrameric GINS complex (CMG). The CMG proteins bind directly to DNA, as demonstrated by experiments with purified proteins. The mechanism and function of these DNA-protein interactions are presently being investigated, and a number of important discoveries relating to how the helicase proteins interact with DNA have been reported recently. While some of the protein-DNA interactions directly relate to the unwinding function of the enzyme complex, other protein-DNA interactions may be important for minichromosome maintenance (MCM) loading, origin melting or replication stress. This review describes our current understanding of how the eukaryotic replicative helicase subunits interact with DNA structures in vitro, and proposed models for the in vivo functions of replicative helicase-DNA interactions are also described.
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Maric M, Mukherjee P, Tatham MH, Hay R, Labib K. Ufd1-Npl4 Recruit Cdc48 for Disassembly of Ubiquitylated CMG Helicase at the End of Chromosome Replication. Cell Rep 2017; 18:3033-3042. [PMID: 28355556 PMCID: PMC5382235 DOI: 10.1016/j.celrep.2017.03.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/28/2017] [Accepted: 03/03/2017] [Indexed: 12/20/2022] Open
Abstract
Disassembly of the Cdc45-MCM-GINS (CMG) DNA helicase is the key regulated step during DNA replication termination in eukaryotes, involving ubiquitylation of the Mcm7 helicase subunit, leading to a disassembly process that requires the Cdc48 "segregase". Here, we employ a screen to identify partners of budding yeast Cdc48 that are important for disassembly of ubiquitylated CMG helicase at the end of chromosome replication. We demonstrate that the ubiquitin-binding Ufd1-Npl4 complex recruits Cdc48 to ubiquitylated CMG. Ubiquitylation of CMG in yeast cell extracts is dependent upon lysine 29 of Mcm7, which is the only detectable site of ubiquitylation both in vitro and in vivo (though in vivo other sites can be modified when K29 is mutated). Mutation of K29 abrogates in vitro recruitment of Ufd1-Npl4-Cdc48 to the CMG helicase, supporting a model whereby Ufd1-Npl4 recruits Cdc48 to ubiquitylated CMG at the end of chromosome replication, thereby driving the disassembly reaction.
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Affiliation(s)
- Marija Maric
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Progya Mukherjee
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Michael H Tatham
- Gene Regulation and Expression Division, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Ronald Hay
- Gene Regulation and Expression Division, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Karim Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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Zhai Y, Cheng E, Wu H, Li N, Yung PYK, Gao N, Tye BK. Open-ringed structure of the Cdt1-Mcm2-7 complex as a precursor of the MCM double hexamer. Nat Struct Mol Biol 2017; 24:300-308. [PMID: 28191894 DOI: 10.1038/nsmb.3374] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 01/09/2017] [Indexed: 12/17/2022]
Abstract
The minichromosome maintenance complex (MCM) hexameric complex (Mcm2-7) forms the core of the eukaryotic replicative helicase. During G1 phase, two Cdt1-Mcm2-7 heptamers are loaded onto each replication origin by the origin-recognition complex (ORC) and Cdc6 to form an inactive MCM double hexamer (DH), but the detailed loading mechanism remains unclear. Here we examine the structures of the yeast MCM hexamer and Cdt1-MCM heptamer from Saccharomyces cerevisiae. Both complexes form left-handed coil structures with a 10-15-Å gap between Mcm5 and Mcm2, and a central channel that is occluded by the C-terminal domain winged-helix motif of Mcm5. Cdt1 wraps around the N-terminal regions of Mcm2, Mcm6 and Mcm4 to stabilize the whole complex. The intrinsic coiled structures of the precursors provide insights into the DH formation, and suggest a spring-action model for the MCM during the initial origin melting and the subsequent DNA unwinding.
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Affiliation(s)
- Yuanliang Zhai
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Erchao Cheng
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Hao Wu
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Ningning Li
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Philip Yuk Kwong Yung
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Ning Gao
- Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Bik-Kwoon Tye
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Department of Molecular Biology and Genetics, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA
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Cannone G, Visentin S, Palud A, Henneke G, Spagnolo L. Structure of an octameric form of the minichromosome maintenance protein from the archaeon Pyrococcus abyssi. Sci Rep 2017; 7:42019. [PMID: 28176822 PMCID: PMC5296750 DOI: 10.1038/srep42019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 01/05/2017] [Indexed: 12/12/2022] Open
Abstract
Cell division is a complex process that requires precise duplication of genetic material. Duplication is concerted by replisomes. The Minichromosome Maintenance (MCM) replicative helicase is a crucial component of replisomes. Eukaryotic and archaeal MCM proteins are highly conserved. In fact, archaeal MCMs are powerful tools for elucidating essential features of MCM function. However, while eukaryotic MCM2-7 is a heterocomplex made of different polypeptide chains, the MCM complexes of many Archaea form homohexamers from a single gene product. Moreover, some archaeal MCMs are polymorphic, and both hexameric and heptameric architectures have been reported for the same polypeptide. Here, we present the structure of the archaeal MCM helicase from Pyrococcus abyssi in its single octameric ring assembly. To our knowledge, this is the first report of a full-length octameric MCM helicase.
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Affiliation(s)
- Giuseppe Cannone
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
- School of Biological Sciences and Max Born Crescent, Edinburgh EH9 3JR, UK
- Centre for Science at extreme conditions, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3JR, UK
| | - Silvia Visentin
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
- School of Biological Sciences and Max Born Crescent, Edinburgh EH9 3JR, UK
- ISIS neutron source, Science and Technologies Research Council, Rutherford Appleton Laboratories, Harwell, OX11 0QX United Kingdom
| | - Adeline Palud
- IFREMER, Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, ZI de la pointe du diable CS 10070 29280 Plouzané, France
- Université de Bretagne Occidentale, Laboratoire de Microbiologie des Environnements Extrêmes, UMR6197, rue Dumont d’Urville 29280 Plouzané, France
- CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, UMR6197, rue Dumont d’Urville 29280 Plouzané, France
| | - Ghislaine Henneke
- IFREMER, Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, ZI de la pointe du diable CS 10070 29280 Plouzané, France
- Université de Bretagne Occidentale, Laboratoire de Microbiologie des Environnements Extrêmes, UMR6197, rue Dumont d’Urville 29280 Plouzané, France
- CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, UMR6197, rue Dumont d’Urville 29280 Plouzané, France
| | - Laura Spagnolo
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
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Parker MW, Botchan MR, Berger JM. Mechanisms and regulation of DNA replication initiation in eukaryotes. Crit Rev Biochem Mol Biol 2017; 52:107-144. [PMID: 28094588 DOI: 10.1080/10409238.2016.1274717] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cellular DNA replication is initiated through the action of multiprotein complexes that recognize replication start sites in the chromosome (termed origins) and facilitate duplex DNA melting within these regions. In a typical cell cycle, initiation occurs only once per origin and each round of replication is tightly coupled to cell division. To avoid aberrant origin firing and re-replication, eukaryotes tightly regulate two events in the initiation process: loading of the replicative helicase, MCM2-7, onto chromatin by the origin recognition complex (ORC), and subsequent activation of the helicase by its incorporation into a complex known as the CMG. Recent work has begun to reveal the details of an orchestrated and sequential exchange of initiation factors on DNA that give rise to a replication-competent complex, the replisome. Here, we review the molecular mechanisms that underpin eukaryotic DNA replication initiation - from selecting replication start sites to replicative helicase loading and activation - and describe how these events are often distinctly regulated across different eukaryotic model organisms.
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Affiliation(s)
- Matthew W Parker
- a Department of Biophysics and Biophysical Chemistry , Johns Hopkins University School of Medicine , Baltimore , MD , USA
| | - Michael R Botchan
- b Department of Molecular and Cell Biology , University of California Berkeley , Berkeley , CA , USA
| | - James M Berger
- a Department of Biophysics and Biophysical Chemistry , Johns Hopkins University School of Medicine , Baltimore , MD , USA
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Bai L, Yuan Z, Sun J, Georgescu R, O'Donnell ME, Li H. Architecture of the Saccharomyces cerevisiae Replisome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:207-228. [PMID: 29357060 DOI: 10.1007/978-981-10-6955-0_10] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Eukaryotic replication proteins are highly conserved, and thus study of Saccharomyces cerevisiae replication can inform about this central process in higher eukaryotes including humans. The S. cerevisiae replisome is a large and dynamic assembly comprised of ~50 proteins. The core of the replisome is composed of 31 different proteins including the 11-subunit CMG helicase; RFC clamp loader pentamer; PCNA clamp; the heteroligomeric DNA polymerases ε, δ, and α-primase; and the RPA heterotrimeric single strand binding protein. Many additional protein factors either travel with or transiently associate with these replisome proteins at particular times during replication. In this chapter, we summarize several recent structural studies on the S. cerevisiae replisome and its subassemblies using single particle electron microscopy and X-ray crystallography. These recent structural studies have outlined the overall architecture of a core replisome subassembly and shed new light on the mechanism of eukaryotic replication.
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Affiliation(s)
- Lin Bai
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Zuanning Yuan
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, USA
- Biochemistry and Structural Biology Graduate Program, Stony Brook University, Stony Brook, NY, USA
| | - Jingchuan Sun
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Roxana Georgescu
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA
| | - Michael E O'Donnell
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
| | - Huilin Li
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, USA.
- Biochemistry and Structural Biology Graduate Program, Stony Brook University, Stony Brook, NY, USA.
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34
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The excluded DNA strand is SEW important for hexameric helicase unwinding. Methods 2016; 108:79-91. [DOI: 10.1016/j.ymeth.2016.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/07/2016] [Accepted: 04/07/2016] [Indexed: 02/04/2023] Open
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Staphylococcal SCCmec elements encode an active MCM-like helicase and thus may be replicative. Nat Struct Mol Biol 2016; 23:891-898. [PMID: 27571176 PMCID: PMC5052118 DOI: 10.1038/nsmb.3286] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 08/05/2016] [Indexed: 01/07/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a public-health threat worldwide. Although the mobile genomic island responsible for this phenotype, staphylococcal cassette chromosome (SCC), has been thought to be nonreplicative, we predicted DNA-replication-related functions for some of the conserved proteins encoded by SCC. We show that one of these, Cch, is homologous to the self-loading initiator helicases of an unrelated family of genomic islands, that it is an active 3'-to-5' helicase and that the adjacent ORF encodes a single-stranded DNA-binding protein. Our 2.9-Å crystal structure of intact Cch shows that it forms a hexameric ring. Cch, like the archaeal and eukaryotic MCM-family replicative helicases, belongs to the pre-sensor II insert clade of AAA+ ATPases. Additionally, we found that SCC elements are part of a broader family of mobile elements, all of which encode a replication initiator upstream of their recombinases. Replication after excision would enhance the efficiency of horizontal gene transfer.
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36
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Fundamental Characteristics of AAA+ Protein Family Structure and Function. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2016; 2016:9294307. [PMID: 27703410 PMCID: PMC5039278 DOI: 10.1155/2016/9294307] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 07/21/2016] [Indexed: 12/22/2022]
Abstract
Many complex cellular events depend on multiprotein complexes known as molecular machines to efficiently couple the energy derived from adenosine triphosphate hydrolysis to the generation of mechanical force. Members of the AAA+ ATPase superfamily (ATPases Associated with various cellular Activities) are critical components of many molecular machines. AAA+ proteins are defined by conserved modules that precisely position the active site elements of two adjacent subunits to catalyze ATP hydrolysis. In many cases, AAA+ proteins form a ring structure that translocates a polymeric substrate through the central channel using specialized loops that project into the central channel. We discuss the major features of AAA+ protein structure and function with an emphasis on pivotal aspects elucidated with archaeal proteins.
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37
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Pellegrini L, Costa A. New Insights into the Mechanism of DNA Duplication by the Eukaryotic Replisome. Trends Biochem Sci 2016; 41:859-871. [PMID: 27555051 DOI: 10.1016/j.tibs.2016.07.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 07/20/2016] [Accepted: 07/22/2016] [Indexed: 11/26/2022]
Abstract
The DNA replication machinery, or replisome, is a macromolecular complex that combines DNA unwinding, priming and synthesis activities. In eukaryotic cells, the helicase and polymerases are multi-subunit, highly-dynamic assemblies whose structural characterization requires an integrated approach. Recent studies have combined single-particle electron cryo-microscopy and protein crystallography to gain insights into the mechanism of DNA duplication by the eukaryotic replisome. We review current understanding of how replication fork unwinding by the CMG helicase is coupled to leading-strand synthesis by polymerase (Pol) ɛ and lagging-strand priming by Pol α/primase, and discuss emerging principles of replisome organization.
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Affiliation(s)
- Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK.
| | - Alessandro Costa
- Macromolecular Machines Laboratory, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, UK.
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38
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Meagher M, Enemark EJ. Structure of a double hexamer of the Pyrococcus furiosus minichromosome maintenance protein N-terminal domain. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2016; 72:545-51. [PMID: 27380371 DOI: 10.1107/s2053230x1600858x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 05/27/2016] [Indexed: 11/11/2022]
Abstract
The crystal structure of the N-terminal domain of the Pyrococcus furiosus minichromosome maintenance (MCM) protein as a double hexamer is described. The MCM complex is a ring-shaped helicase that unwinds DNA at the replication fork of eukaryotes and archaea. Prior to replication initiation, the MCM complex assembles as an inactive double hexamer at specific sites of DNA. The presented structure is highly consistent with previous MCM double-hexamer structures and shows two MCM hexamers with a head-to-head interaction mediated by the N-terminal domain. Minor differences include a diminished head-to-head interaction and a slightly reduced inter-hexamer rotation.
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Affiliation(s)
- Martin Meagher
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Eric J Enemark
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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39
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Simon AC, Sannino V, Costanzo V, Pellegrini L. Structure of human Cdc45 and implications for CMG helicase function. Nat Commun 2016; 7:11638. [PMID: 27189187 PMCID: PMC4873980 DOI: 10.1038/ncomms11638] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/14/2016] [Indexed: 01/05/2023] Open
Abstract
Cell division cycle protein 45 (Cdc45) is required for DNA synthesis during genome duplication, as a component of the Cdc45-MCM-GINS (CMG) helicase. Despite its essential biological function, its biochemical role in DNA replication has remained elusive. Here we report the 2.1-Å crystal structure of human Cdc45, which confirms its evolutionary link with the bacterial RecJ nuclease and reveals several unexpected features that underpin its function in eukaryotic DNA replication. These include a long-range interaction between N- and C-terminal DHH domains, blocking access to the DNA-binding groove of its RecJ-like fold, and a helical insertion in its N-terminal DHH domain, which appears poised for replisome interactions. In combination with available electron microscopy data, we validate by mutational analysis the mechanism of Cdc45 association with the MCM ring and GINS co-activator, critical for CMG assembly. These findings provide an indispensable molecular basis to rationalize the essential role of Cdc45 in genomic duplication. The cell cycle division protein Cdc45 is required for genome duplication in eukaryotes. Here, the authors determine the crystal structure of human Cdc45 and combine it with functional data to improve our understanding of its role in DNA replication.
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Affiliation(s)
- Aline C Simon
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Vincenzo Sannino
- DNA Metabolism Laboratory, FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy
| | - Vincenzo Costanzo
- DNA Metabolism Laboratory, FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
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Abid Ali F, Costa A. The MCM Helicase Motor of the Eukaryotic Replisome. J Mol Biol 2016; 428:1822-32. [PMID: 26829220 DOI: 10.1016/j.jmb.2016.01.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/23/2016] [Indexed: 10/22/2022]
Abstract
The MCM motor of the CMG helicase powers ahead of the eukaryotic replication machinery to unwind DNA, in a process that requires ATP hydrolysis. The reconstitution of DNA replication in vitro has established the succession of events that lead to replication origin activation by the MCM and recent studies have started to elucidate the structural basis of duplex DNA unwinding. Despite the exciting progress, how the MCM translocates on DNA remains a matter of debate.
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Affiliation(s)
- Ferdos Abid Ali
- Architecture and Dynamics of Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, United Kingdom
| | - Alessandro Costa
- Architecture and Dynamics of Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, United Kingdom.
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41
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Cheng K, Xu H, Chen X, Wang L, Tian B, Zhao Y, Hua Y. Structural basis for DNA 5´-end resection by RecJ. eLife 2016; 5:e14294. [PMID: 27058167 PMCID: PMC4846377 DOI: 10.7554/elife.14294] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/07/2016] [Indexed: 12/18/2022] Open
Abstract
The resection of DNA strand with a 5´ end at double-strand breaks is an essential step in recombinational DNA repair. RecJ, a member of DHH family proteins, is the only 5´ nuclease involved in the RecF recombination pathway. Here, we report the crystal structures of Deinococcus radiodurans RecJ in complex with deoxythymidine monophosphate (dTMP), ssDNA, the C-terminal region of single-stranded DNA-binding protein (SSB-Ct) and a mechanistic insight into the RecF pathway. A terminal 5´-phosphate-binding pocket above the active site determines the 5´-3´ polarity of the deoxy-exonuclease of RecJ; a helical gateway at the entrance to the active site admits ssDNA only; and the continuous stacking interactions between protein and nine nucleotides ensure the processive end resection. The active site of RecJ in the N-terminal domain contains two divalent cations that coordinate the nucleophilic water. The ssDNA makes a 180° turn at the scissile phosphate. The C-terminal domain of RecJ binds the SSB-Ct, which explains how RecJ and SSB work together to efficiently process broken DNA ends for homologous recombination.
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Affiliation(s)
- Kaiying Cheng
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
| | - Hong Xu
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
| | - Xuanyi Chen
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
| | - Liangyan Wang
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
| | - Bing Tian
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
| | - Ye Zhao
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
| | - Yuejin Hua
- Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China
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42
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Graham BW, Tao Y, Dodge KL, Thaxton CT, Olaso D, Young NL, Marshall AG, Trakselis MA. DNA Interactions Probed by Hydrogen-Deuterium Exchange (HDX) Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Confirm External Binding Sites on the Minichromosomal Maintenance (MCM) Helicase. J Biol Chem 2016; 291:12467-12480. [PMID: 27044751 DOI: 10.1074/jbc.m116.719591] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 11/06/2022] Open
Abstract
The archaeal minichromosomal maintenance (MCM) helicase from Sulfolobus solfataricus (SsoMCM) is a model for understanding structural and mechanistic aspects of DNA unwinding. Although interactions of the encircled DNA strand within the central channel provide an accepted mode for translocation, interactions with the excluded strand on the exterior surface have mostly been ignored with regard to DNA unwinding. We have previously proposed an extension of the traditional steric exclusion model of unwinding to also include significant contributions with the excluded strand during unwinding, termed steric exclusion and wrapping (SEW). The SEW model hypothesizes that the displaced single strand tracks along paths on the exterior surface of hexameric helicases to protect single-stranded DNA (ssDNA) and stabilize the complex in a forward unwinding mode. Using hydrogen/deuterium exchange monitored by Fourier transform ion cyclotron resonance MS, we have probed the binding sites for ssDNA, using multiple substrates targeting both the encircled and excluded strand interactions. In each experiment, we have obtained >98.7% sequence coverage of SsoMCM from >650 peptides (5-30 residues in length) and are able to identify interacting residues on both the interior and exterior of SsoMCM. Based on identified contacts, positively charged residues within the external waist region were mutated and shown to generally lower DNA unwinding without negatively affecting the ATP hydrolysis. The combined data globally identify binding sites for ssDNA during SsoMCM unwinding as well as validating the importance of the SEW model for hexameric helicase unwinding.
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Affiliation(s)
- Brian W Graham
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Yeqing Tao
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306
| | - Katie L Dodge
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798
| | - Carly T Thaxton
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798
| | - Danae Olaso
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798
| | - Nicolas L Young
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310
| | - Alan G Marshall
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306; National High Magnetic Field Laboratory, Tallahassee, Florida 32310
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798.
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Abid Ali F, Renault L, Gannon J, Gahlon HL, Kotecha A, Zhou JC, Rueda D, Costa A. Cryo-EM structures of the eukaryotic replicative helicase bound to a translocation substrate. Nat Commun 2016; 7:10708. [PMID: 26888060 PMCID: PMC4759635 DOI: 10.1038/ncomms10708] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/12/2016] [Indexed: 02/06/2023] Open
Abstract
The Cdc45-MCM-GINS (CMG) helicase unwinds DNA during the elongation step of eukaryotic genome duplication and this process depends on the MCM ATPase function. Whether CMG translocation occurs on single- or double-stranded DNA and how ATP hydrolysis drives DNA unwinding remain open questions. Here we use cryo-electron microscopy to describe two subnanometre resolution structures of the CMG helicase trapped on a DNA fork. In the predominant state, the ring-shaped C-terminal ATPase of MCM is compact and contacts single-stranded DNA, via a set of pre-sensor 1 hairpins that spiral around the translocation substrate. In the second state, the ATPase module is relaxed and apparently substrate free, while DNA intimately contacts the downstream amino-terminal tier of the MCM motor ring. These results, supported by single-molecule FRET measurements, lead us to suggest a replication fork unwinding mechanism whereby the N-terminal and AAA+ tiers of the MCM work in concert to translocate on single-stranded DNA.
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Affiliation(s)
- Ferdos Abid Ali
- Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, UK
| | - Ludovic Renault
- Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, UK
- National Institute for Biological Standards and Control, Microscopy and Imaging, Blanche Lane, South Mimms EN6 3QG, UK
| | - Julian Gannon
- Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, UK
| | - Hailey L. Gahlon
- Section of Virology and Single Molecule Imaging Group, Department of Medicine, MRC Clinical Centre, Imperial College London, London W12 0NN, UK
| | - Abhay Kotecha
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Jin Chuan Zhou
- Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, UK
| | - David Rueda
- Section of Virology and Single Molecule Imaging Group, Department of Medicine, MRC Clinical Centre, Imperial College London, London W12 0NN, UK
| | - Alessandro Costa
- Macromolecular Machines, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms EN6 3LD, UK
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Yuan Z, Bai L, Sun J, Georgescu R, Liu J, O'Donnell ME, Li H. Structure of the eukaryotic replicative CMG helicase suggests a pumpjack motion for translocation. Nat Struct Mol Biol 2016; 23:217-24. [PMID: 26854665 PMCID: PMC4812828 DOI: 10.1038/nsmb.3170] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/06/2016] [Indexed: 01/06/2023]
Abstract
The CMG helicase is composed of Cdc45, Mcm2-7 and GINS. Here we report the structure of the Saccharomyces cerevisiae CMG, determined by cryo-EM at a resolution of 3.7-4.8 Å. The structure reveals that GINS and Cdc45 scaffold the N tier of the helicase while enabling motion of the AAA+ C tier. CMG exists in two alternating conformations, compact and extended, thus suggesting that the helicase moves like an inchworm. The N-terminal regions of Mcm2-7, braced by Cdc45-GINS, form a rigid platform upon which the AAA+ C domains make longitudinal motions, nodding up and down like an oil-rig pumpjack attached to a stable platform. The Mcm ring is remodeled in CMG relative to the inactive Mcm2-7 double hexamer. The Mcm5 winged-helix domain is inserted into the central channel, thus blocking entry of double-stranded DNA and supporting a steric-exclusion DNA-unwinding model.
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Affiliation(s)
- Zuanning Yuan
- Department of Biochemistry &Cell Biology, Stony Brook University, Stony Brook, New York, USA.,Biology Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Lin Bai
- Biology Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Jingchuan Sun
- Biology Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Roxana Georgescu
- DNA Replication Laboratory, Rockefeller University, New York, New York, USA.,Howard Hughes Medical Institute, Rockefeller University, New York, New York, USA
| | - Jun Liu
- Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Michael E O'Donnell
- DNA Replication Laboratory, Rockefeller University, New York, New York, USA.,Howard Hughes Medical Institute, Rockefeller University, New York, New York, USA
| | - Huilin Li
- Department of Biochemistry &Cell Biology, Stony Brook University, Stony Brook, New York, USA.,Biology Department, Brookhaven National Laboratory, Upton, New York, USA
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45
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Archaeal DNA Replication Origins and Recruitment of the MCM Replicative Helicase. DNA REPLICATION ACROSS TAXA 2016; 39:169-90. [DOI: 10.1016/bs.enz.2016.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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46
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Archaeal MCM Proteins as an Analog for the Eukaryotic Mcm2-7 Helicase to Reveal Essential Features of Structure and Function. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2015; 2015:305497. [PMID: 26539061 PMCID: PMC4619765 DOI: 10.1155/2015/305497] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/05/2015] [Indexed: 11/18/2022]
Abstract
In eukaryotes, the replicative helicase is the large multisubunit CMG complex consisting of the Mcm2–7 hexameric ring, Cdc45, and the tetrameric GINS complex. The Mcm2–7 ring assembles from six different, related proteins and forms the core of this complex. In archaea, a homologous MCM hexameric ring functions as the replicative helicase at the replication fork. Archaeal MCM proteins form thermostable homohexamers, facilitating their use as models of the eukaryotic Mcm2–7 helicase. Here we review archaeal MCM helicase structure and function and how the archaeal findings relate to the eukaryotic Mcm2–7 ring.
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47
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Froelich CA, Nourse A, Enemark EJ. MCM ring hexamerization is a prerequisite for DNA-binding. Nucleic Acids Res 2015; 43:9553-63. [PMID: 26365238 PMCID: PMC4627082 DOI: 10.1093/nar/gkv914] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 09/01/2015] [Indexed: 11/22/2022] Open
Abstract
The hexameric Minichromosome Maintenance (MCM) protein complex forms a ring that unwinds DNA at the replication fork in eukaryotes and archaea. Our recent crystal structure of an archaeal MCM N-terminal domain bound to single-stranded DNA (ssDNA) revealed ssDNA associating across tight subunit interfaces but not at the loose interfaces, indicating that DNA-binding is governed not only by the DNA-binding residues of the subunits (MCM ssDNA-binding motif, MSSB) but also by the relative orientation of the subunits. We now extend these findings by showing that DNA-binding by the MCM N-terminal domain of the archaeal organism Pyrococcus furiosus occurs specifically in the hexameric oligomeric form. We show that mutants defective for hexamerization are defective in binding ssDNA despite retaining all the residues observed to interact with ssDNA in the crystal structure. One mutation that exhibits severely defective hexamerization and ssDNA-binding is at a conserved phenylalanine that aligns with the mouse Mcm4(Chaos3) mutation associated with chromosomal instability, cancer, and decreased intersubunit association.
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Affiliation(s)
- Clifford A Froelich
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 311, Memphis, TN 38105, USA
| | - Amanda Nourse
- Molecular Interaction Analysis Shared Resource, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 311, Memphis, TN 38105, USA
| | - Eric J Enemark
- Department of Structural Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 311, Memphis, TN 38105, USA
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48
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Abstract
DNA replication in eukaryotes is strictly regulated by several mechanisms. A central step in this replication is the assembly of the heterohexameric minichromosome maintenance (MCM2-7) helicase complex at replication origins during G1 phase as an inactive double hexamer. Here, using cryo-electron microscopy, we report a near-atomic structure of the MCM2-7 double hexamer purified from yeast G1 chromatin. Our structure shows that two single hexamers, arranged in a tilted and twisted fashion through interdigitated amino-terminal domain interactions, form a kinked central channel. Four constricted rings consisting of conserved interior β-hairpins from the two single hexamers create a narrow passageway that tightly fits duplex DNA. This narrow passageway, reinforced by the offset of the two single hexamers at the double hexamer interface, is flanked by two pairs of gate-forming subunits, MCM2 and MCM5. These unusual features of the twisted and tilted single hexamers suggest a concerted mechanism for the melting of origin DNA that requires structural deformation of the intervening DNA.
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49
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Itou H, Shirakihara Y, Araki H. The quaternary structure of the eukaryotic DNA replication proteins Sld7 and Sld3. ACTA ACUST UNITED AC 2015; 71:1649-56. [PMID: 26249346 DOI: 10.1107/s1399004715010457] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/31/2015] [Indexed: 11/10/2022]
Abstract
The initiation of eukaryotic chromosomal DNA replication requires the formation of an active replicative helicase at the replication origins of chromosomes. Yeast Sld3 and its metazoan counterpart treslin are the hub proteins mediating protein associations critical for formation of the helicase. The Sld7 protein interacts with Sld3, and the complex formed is thought to regulate the function of Sld3. Although Sld7 is a non-essential DNA replication protein that is found in only a limited range of yeasts, its depletion slowed the growth of cells and caused a delay in the S phase. Recently, the Mdm2-binding protein was found to bind to treslin in humans, and its depletion causes defects in cells similar to the depletion of Sld7 in yeast, suggesting their functional relatedness and importance during the initiation step of DNA replication. Here, the crystal structure of Sld7 in complex with Sld3 is presented. Sld7 comprises two structural domains. The N-terminal domain of Sld7 binds to Sld3, and the C-terminal domains connect two Sld7 molecules in an antiparallel manner. The quaternary structure of the Sld3-Sld7 complex shown from the crystal structures appears to be suitable to activate two helicase molecules loaded onto replication origins in a head-to-head manner.
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Affiliation(s)
- Hiroshi Itou
- Structural Biology Center, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Yasuo Shirakihara
- Structural Biology Center, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Hiroyuki Araki
- Division of Microbial Genetics, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
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50
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Petojevic T, Pesavento JJ, Costa A, Liang J, Wang Z, Berger JM, Botchan MR. Cdc45 (cell division cycle protein 45) guards the gate of the Eukaryote Replisome helicase stabilizing leading strand engagement. Proc Natl Acad Sci U S A 2015; 112:E249-58. [PMID: 25561522 PMCID: PMC4311868 DOI: 10.1073/pnas.1422003112] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
DNA replication licensing is now understood to be the pathway that leads to the assembly of double hexamers of minichromosome maintenance (Mcm2-7) at origin sites. Cell division control protein 45 (Cdc45) and GINS proteins activate the latent Mcm2-7 helicase by inducing allosteric changes through binding, forming a Cdc45/Mcm2-7/GINS (CMG) complex that is competent to unwind duplex DNA. The CMG has an active gate between subunits Mcm2 and Mcm5 that opens and closes in response to nucleotide binding. The consequences of inappropriate Mcm2/5 gate actuation and the role of a side channel formed between GINS/Cdc45 and the outer edge of the Mcm2-7 ring for unwinding have remained unexplored. Here we uncover a novel function for Cdc45. Cross-linking studies trace the path of the DNA with the CMG complex at a fork junction between duplex and single strands with the bound CMG in an open or closed gate conformation. In the closed state, the lagging strand does not pass through the side channel, but in the open state, the leading strand surprisingly interacts with Cdc45. Mutations in the recombination protein J fold of Cdc45 that ablate this interaction diminish helicase activity. These data indicate that Cdc45 serves as a shield to guard against occasional slippage of the leading strand from the core channel.
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Affiliation(s)
- Tatjana Petojevic
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720; Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - James J Pesavento
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720
| | - Alessandro Costa
- Clare Hall Laboratories, London Research Institute, South Mimms, Herts EN6 3LD, United Kingdom; and
| | - Jingdan Liang
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720
| | - Zhijun Wang
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720
| | - James M Berger
- Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205
| | - Michael R Botchan
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720;
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