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Velázquez-Ruiz C, Blanco L, Martínez-Jiménez MI. 3'dNTP Binding Is Modulated during Primer Synthesis and Translesion by Human PrimPol. Int J Mol Sci 2023; 25:51. [PMID: 38203225 PMCID: PMC10778844 DOI: 10.3390/ijms25010051] [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: 11/30/2023] [Revised: 12/15/2023] [Accepted: 12/17/2023] [Indexed: 01/12/2024] Open
Abstract
PrimPol is a DNA primase/polymerase from the Archaeo-Eukaryotic Primase (AEP) superfamily that enables the progression of stalled replication forks by synthesizing DNA primers ahead of blocking lesions or abnormal structures in the ssDNA template. PrimPol's active site is formed by three AEP-conserved motifs: A, B and C. Motifs A and C of human PrimPol (HsPrimPol) harbor the catalytic residues (Asp114, Glu116, Asp280) acting as metal ligands, whereas motif B includes highly conserved residues (Lys165, Ser167 and His169), which are postulated to stabilize 3' incoming deoxynucleotides (dNTPs). Additionally, other putative nucleotide ligands are situated close to motif C: Lys297, almost invariant in the whole AEP superfamily, and Lys300, specifically conserved in eukaryotic PrimPols. Here, we demonstrate that His169 is absolutely essential for 3'dNTP binding and, hence, for both primase and polymerase activities of HsPrimPol, whereas Ser167 and Lys297 are crucial for the dimer synthesis initiation step during priming, but dispensable for subsequent dNTP incorporation on growing primers. Conversely, the elimination of Lys165 does not affect the overall primase function; however, it is required for damage avoidance via primer-template realignments. Finally, Lys300 is identified as an extra anchor residue to stabilize the 3' incoming dNTP. Collectively, these results demonstrate that individual ligands modulate the stabilization of 3' incoming dNTPs to optimize DNA primer synthesis efficiency during initiation and primer maturation.
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Affiliation(s)
| | - Luis Blanco
- Centro de Biología Molecular Severo Ochoa, (CSIC-UAM), c/Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain;
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2
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Schneider A, Bergsch J, Lipps G. The monomeric archaeal primase from Nanoarchaeum equitans harbours the features of heterodimeric archaeoeukaryotic primases and primes sequence-specifically. Nucleic Acids Res 2023; 51:5087-5105. [PMID: 37099378 PMCID: PMC10250227 DOI: 10.1093/nar/gkad261] [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: 09/13/2022] [Revised: 03/17/2023] [Accepted: 03/29/2023] [Indexed: 04/27/2023] Open
Abstract
The marine thermophilic archaeon Nanoarchaeum equitans possesses a monomeric primase encompassing the conserved domains of the small catalytic and the large regulatory subunits of archaeoeukaryotic heterodimeric primases in one protein chain. The recombinant protein primes on templates containing a triplet with a central thymidine, thus displaying a pronounced sequence specificity typically observed with bacterial type primases only. The N. equitans primase (NEQ395) is a highly active primase enzyme synthesizing short RNA primers. Termination occurs preferentially at about nine nucleotides, as determined by HPLC analysis and confirmed with mass spectrometry. Possibly, the compact monomeric primase NEQ395 represents the minimal archaeoeukaryotic primase and could serve as a functional and structural model of the heterodimeric archaeoeukaryotic primases, whose study is hindered by engagement in protein assemblies and rather low activity.
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Affiliation(s)
- Andy Schneider
- Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, 4132 Muttenz, Switzerland
| | - Jan Bergsch
- Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, 4132 Muttenz, Switzerland
| | - Georg Lipps
- Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, 4132 Muttenz, Switzerland
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3
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Zhao W, Xu W, Tang J, Kaushik S, Chang CEA, Zhao L. Key Amino Acid Residues of Mitochondrial Transcription Factor A Synergize with Abasic (AP) Site Dynamics To Facilitate AP-Lyase Reactions. ACS Chem Biol 2023; 18:1168-1179. [PMID: 36930463 PMCID: PMC10198963 DOI: 10.1021/acschembio.3c00047] [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] [Indexed: 03/18/2023]
Abstract
Human mitochondrial DNA (mtDNA) encodes 37 essential genes and plays a critical role in mitochondrial and cellular functions. mtDNA is susceptible to damage by endogenous and exogenous chemicals. Damaged mtDNA molecules are counteracted by the redundancy, repair, and degradation of mtDNA. In response to difficult-to-repair or excessive amounts of DNA lesions, mtDNA degradation is a crucial mitochondrial genome maintenance mechanism. Nevertheless, the molecular basis of mtDNA degradation remains incompletely understood. Recently, mitochondrial transcription factor A (TFAM) has emerged as a factor in degrading damaged mtDNA containing abasic (AP) sites. TFAM has AP-lyase activity, which cleaves DNA at AP sites. Human TFAM and its homologs contain a higher abundance of Glu than that of the proteome. To decipher the role of Glu in TFAM-catalyzed AP-DNA cleavage, we constructed TFAM variants and used biochemical assays, kinetic simulations, and molecular dynamics (MD) simulations to probe the functional importance of E187 near a key residue K186. Our previous studies showed that K186 is a primary residue to cleave AP-DNA via Schiff base chemistry. Here, we demonstrate that E187 facilitates β-elimination, key to AP-DNA strand scission. MD simulations showed that extrahelical confirmation of the AP lesion and the flexibility of E187 in TFAM-DNA complexes facilitate AP-lyase reactions. Together, highly abundant Lys and Glu residues in TFAM promote AP-DNA strand scission, supporting the role of TFAM in AP-DNA turnover and implying the breadth of this process across different species.
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Affiliation(s)
- Wenxin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Wenyan Xu
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Jin Tang
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Shivansh Kaushik
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Chia-En A. Chang
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California, 92521, United States
| | - Linlin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California, 92521, United States
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Urrutia KM, Xu W, Zhao L. The 5′-phosphate enhances the DNA-binding and exonuclease activities of human mitochondrial genome maintenance nuclease 1 (MGME1). J Biol Chem 2022; 298:102306. [PMID: 35934053 PMCID: PMC9460513 DOI: 10.1016/j.jbc.2022.102306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 11/15/2022] Open
Abstract
In higher eukaryotes, mitochondria play multiple roles in energy production, signaling, and biosynthesis. Mitochondria possess multiple copies of mitochondrial DNA (mtDNA), which encodes 37 genes that are essential for mitochondrial and cellular function. When mtDNA is challenged by endogenous and exogenous factors, mtDNA undergoes repair, degradation, and compensatory synthesis. mtDNA degradation is an emerging pathway in mtDNA damage response and maintenance. A key factor involved is the human mitochondrial genome maintenance exonuclease 1 (MGME1). Despite previous biochemical and functional studies, controversies exist regarding the polarity of MGME1-mediated DNA cleavage. Also, how DNA sequence may affect the activities of MGME1 remains elusive. Such information is not only fundamental to the understanding of MGME1 but critical for deciphering the mechanism of mtDNA degradation. Herein, we use quantitative assays to examine the effects of substrate structure and sequence on the DNA-binding and enzymatic activities of MGME1. We demonstrate that MGME1 binds to and cleaves from the 5′-end of single-stranded DNA substrates, especially in the presence of 5′-phosphate, which plays an important role in DNA binding and optimal cleavage by MGME1. In addition, MGME1 tolerates certain modifications at the terminal end, such as a 5′-deoxyribosephosphate intermediate formed in base excision repair. We show that MGME1 processes different sequences with varying efficiencies, with dT and dC sequences being the most and least efficiently digested, respectively. Our results provide insights into the enzymatic properties of MGME1 and a rationale for the coordination of MGME1 with the 3′–5′ exonuclease activity of DNA polymerase γ in mtDNA degradation.
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Affiliation(s)
- Kathleen M Urrutia
- Department of Chemistry, University of California, Riverside, Riverside, California, USA
| | - Wenyan Xu
- Department of Chemistry, University of California, Riverside, Riverside, California, USA
| | - Linlin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, California, USA; Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California, USA.
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PrimPol: A Breakthrough among DNA Replication Enzymes and a Potential New Target for Cancer Therapy. Biomolecules 2022; 12:biom12020248. [PMID: 35204749 PMCID: PMC8961649 DOI: 10.3390/biom12020248] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/29/2022] [Accepted: 02/02/2022] [Indexed: 02/01/2023] Open
Abstract
DNA replication can encounter blocking obstacles, leading to replication stress and genome instability. There are several mechanisms for evading this blockade. One mechanism consists of repriming ahead of the obstacles, creating a new starting point; in humans, PrimPol is responsible for carrying out this task. PrimPol is a primase that operates in both the nucleus and mitochondria. In contrast with conventional primases, PrimPol is a DNA primase able to initiate DNA synthesis de novo using deoxynucleotides, discriminating against ribonucleotides. In vitro, PrimPol can act as a DNA primase, elongating primers that PrimPol itself sythesizes, or as translesion synthesis (TLS) DNA polymerase, elongating pre-existing primers across lesions. However, the lack of evidence for PrimPol polymerase activity in vivo suggests that PrimPol only acts as a DNA primase. Here, we provide a comprehensive review of human PrimPol covering its biochemical properties and structure, in vivo function and regulation, and the processes that take place to fill the gap-containing lesion that PrimPol leaves behind. Finally, we explore the available data on human PrimPol expression in different tissues in physiological conditions and its role in cancer.
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6
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Human PrimPol Discrimination against Dideoxynucleotides during Primer Synthesis. Genes (Basel) 2021; 12:genes12101487. [PMID: 34680882 PMCID: PMC8535229 DOI: 10.3390/genes12101487] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/17/2021] [Accepted: 09/22/2021] [Indexed: 12/02/2022] Open
Abstract
PrimPol is required to re-prime DNA replication at both nucleus and mitochondria, thus facilitating fork progression during replicative stress. ddC is a chain-terminating nucleotide that has been widely used to block mitochondrial DNA replication because it is efficiently incorporated by the replicative polymerase Polγ. Here, we show that human PrimPol discriminates against dideoxynucleotides (ddNTP) when elongating a primer across 8oxoG lesions in the template, but also when starting de novo synthesis of DNA primers, and especially when selecting the 3′nucleotide of the initial dimer. PrimPol incorporates ddNTPs with a very low efficiency compared to dNTPs even in the presence of activating manganese ions, and only a 40-fold excess of ddNTP would significantly disturb PrimPol primase activity. This discrimination against ddNTPs prevents premature termination of the primers, warranting their use for elongation. The crystal structure of human PrimPol highlights Arg291 residue as responsible for the strong dNTP/ddNTP selectivity, since it interacts with the 3′-OH group of the incoming deoxynucleotide, absent in ddNTPs. Arg291, shown here to be critical for both primase and polymerase activities of human PrimPol, would contribute to the preferred binding of dNTPs versus ddNTPs at the 3′elongation site, thus avoiding synthesis of abortive primers.
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Rechkoblit O, Johnson RE, Gupta YK, Prakash L, Prakash S, Aggarwal AK. Structural basis of DNA synthesis opposite 8-oxoguanine by human PrimPol primase-polymerase. Nat Commun 2021; 12:4020. [PMID: 34188055 PMCID: PMC8241999 DOI: 10.1038/s41467-021-24317-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 06/14/2021] [Indexed: 11/30/2022] Open
Abstract
PrimPol is a human DNA polymerase-primase that localizes to mitochondria and nucleus and bypasses the major oxidative lesion 7,8-dihydro-8-oxoguanine (oxoG) via translesion synthesis, in mostly error-free manner. We present structures of PrimPol insertion complexes with a DNA template-primer and correct dCTP or erroneous dATP opposite the lesion, as well as extension complexes with C or A as a 3′−terminal primer base. We show that during the insertion of C and extension from it, the active site is unperturbed, reflecting the readiness of PrimPol to accommodate oxoG(anti). The misinsertion of A opposite oxoG(syn) also does not alter the active site, and is likely less favorable due to lower thermodynamic stability of the oxoG(syn)•A base-pair. During the extension step, oxoG(syn) induces an opening of its base-pair with A or misalignment of the 3′-A primer terminus. Together, the structures show how PrimPol accurately synthesizes DNA opposite oxidatively damaged DNA in human cells. The human DNA primase and DNA polymerase PrimPol replicates through the major oxidative DNA damage lesion 7,8-dihydro-8-oxoguanine (oxoG) via translesion synthesis in a mostly error-free manner thus suppressing oxoG-induced mutagenesis in mitochondria and the nucleus. Here, the authors present crystal structures of PrimPol in complex with an oxoG lesion in different contexts that provide mechanistic insights into how PrimPol performs predominantly accurate synthesis on oxidative-damaged DNAs in human cells.
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Affiliation(s)
- Olga Rechkoblit
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Robert E Johnson
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Yogesh K Gupta
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Greehey Children's Cancer Research Institute & Department of Biochemistry and Structural Biology, University of Texas Health at San Antonio, San Antonio, TX, USA
| | - Louise Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Satya Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Aneel K Aggarwal
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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8
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Identifying the role of PrimPol in TDF-induced toxicity and implications of its loss of function mutation in an HIV+ patient. Sci Rep 2020; 10:9343. [PMID: 32518272 PMCID: PMC7283272 DOI: 10.1038/s41598-020-66153-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 05/14/2020] [Indexed: 12/25/2022] Open
Abstract
A key component of antiretroviral therapy (ART) for HIV patients is the nucleoside reverse transcriptase inhibitor (NRTI) is tenofovir. Recent reports of tenofovir toxicity in patients taking ART for HIV cannot be explained solely on the basis of off-target inhibition of mitochondrial DNA polymerase gamma (Polγ). PrimPol was discovered as a primase-polymerase localized to the mitochondria with repriming and translesion synthesis capabilities and, therefore, a potential contributor to mitochondrial toxicity. We established a possible role of PrimPol in tenofovir-induced toxicity in vitro and show that tenofovir-diphosphate incorporation by PrimPol is dependent on the n-1 nucleotide. We identified and characterized a PrimPol mutation, D114N, in an HIV+ patient on tenofovir-based ART with mitochondrial toxicity. This mutant form of PrimPol, targeting a catalytic metal ligand, was unable to synthesize primers, likely due to protein instability and weakened DNA binding. We performed cellular respiration and toxicity assays using PrimPol overexpression and shRNA knockdown strains in renal proximal tubular epithelial cells. The PrimPol-knockdown strain was hypersensitive to tenofovir treatment, indicating that PrimPol protects against tenofovir-induced mitochondrial toxicity. We show that a major cellular role of PrimPol is protecting against toxicity caused by ART and individuals with inactivating mutations may be predisposed to these effects.
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Sakhabutdinova AR, Mirsaeva LR, Oscorbin IP, Filipenko ML, Garafutdinov RR. Elimination of DNA Multimerization Arising from Isothermal Amplification in the Presence of Bst Exo– DNA Polymerase. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2020. [DOI: 10.1134/s1068162020010082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Oliveira MT, Pontes CDB, Ciesielski GL. Roles of the mitochondrial replisome in mitochondrial DNA deletion formation. Genet Mol Biol 2020; 43:e20190069. [PMID: 32141473 PMCID: PMC7197994 DOI: 10.1590/1678-4685-gmb-2019-0069] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 08/12/2019] [Indexed: 01/07/2023] Open
Abstract
Mitochondrial DNA (mtDNA) deletions are a common cause of human mitochondrial
diseases. Mutations in the genes encoding components of the mitochondrial
replisome, such as DNA polymerase gamma (Pol γ) and the mtDNA helicase Twinkle,
have been associated with the accumulation of such deletions and the development
of pathological conditions in humans. Recently, we demonstrated that changes in
the level of wild-type Twinkle promote mtDNA deletions, which implies that not
only mutations in, but also dysregulation of the stoichiometry between the
replisome components is potentially pathogenic. The mechanism(s) by which
alterations to the replisome function generate mtDNA deletions is(are) currently
under debate. It is commonly accepted that stalling of the replication fork at
sites likely to form secondary structures precedes the deletion formation. The
secondary structural elements can be bypassed by the replication-slippage
mechanism. Otherwise, stalling of the replication fork can generate single- and
double-strand breaks, which can be repaired through recombination leading to the
elimination of segments between the recombination sites. Here, we discuss
aberrances of the replisome in the context of the two debated outcomes, and
suggest new mechanistic explanations based on replication restart and template
switching that could account for all the deletion types reported for
patients.
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Affiliation(s)
- Marcos T Oliveira
- Universidade Estadual Paulista Júlio de Mesquita Filho, Faculdade de Ciências Agrárias e Veterinárias, Departamento de Tecnologia, Jaboticabal, SP, Brazil
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Blanco L, Calvo PA, Diaz-Talavera A, Carvalho G, Calero N, Martínez-Carrón A, Velázquez-Ruiz C, Villadangos S, Guerra S, Martínez-Jiménez MI. Mechanism of DNA primer synthesis by human PrimPol. Enzymes 2019; 45:289-310. [PMID: 31627881 DOI: 10.1016/bs.enz.2019.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PrimPol is the second primase discovered in eukaryotic cells, whose function is to restart the stalled replication forks during both mitochondrial and nuclear DNA replication. This chapter revises our current knowledge about the mechanism of synthesis of DNA primers by human PrimPol, and the importance of its distinctive Zn-finger domain (ZnFD). After PrimPol forms a binary complex with ssDNA, the formation of the pre-ternary complex strictly requires the presence of Mn2+ ions to stabilize the interaction of the incoming deoxynucleotide at the 3'-site. The capacity to bind both ssDNA template and 3'-deoxynucleotide was shown to reside in the AEP core of PrimPol, with ZnFD being dispensable at these two early steps of the primase reaction. Sugar selection favoring dNTPs versus NTPs at the 3' site is mediated by a specific tyrosine (Tyr100) acting as a steric gate. Besides, a specific glutamate residue (Glu116) conforming a singular A motif (DxE) promotes the use of Mn2+ to stabilize the pre-ternary complex. Mirroring the function of the PriL subunit of dimeric AEP primases, the ZnFD of PrimPol is crucial to stabilize the initiating 5'-nucleotide, specifically interacting with the gamma-phosphate. Such an interaction is crucial to optimize dimer formation and the subsequent translocation events leading to the processive synthesis of a mature DNA primer. Finally, the capacity of PrimPol to tolerate lesions is discussed in the context of its DNA primase function, and its potential as a TLS primase.
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Affiliation(s)
- Luis Blanco
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain.
| | - Patricia A Calvo
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | | | - Gustavo Carvalho
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Nieves Calero
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | | | | | | | - Susana Guerra
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
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Calvo PA, Sastre-Moreno G, Perpiñá C, Guerra S, Martínez-Jiménez MI, Blanco L. The invariant glutamate of human PrimPol DxE motif is critical for its Mn 2+-dependent distinctive activities. DNA Repair (Amst) 2019; 77:65-75. [PMID: 30889508 DOI: 10.1016/j.dnarep.2019.03.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/05/2019] [Accepted: 03/13/2019] [Indexed: 10/27/2022]
Abstract
PrimPol is a human primase/polymerase specialized in downstream repriming of stalled forks during both nuclear and mitochondrial DNA replication. Like most primases and polymerases, PrimPol requires divalent metal cations, as Mg2+ or Mn2+, used as cofactors for catalysis. However, little is known about the consequences of using these two metal cofactors in combination, which would be the most physiological scenario during PrimPol-mediated reactions, and the individual contribution of the putative carboxylate residues (Asp114, Glu116 and Asp280) acting as metal ligands. By site-directed mutagenesis in human PrimPol, we confirmed the catalytic relevance of these three carboxylates, and identified Glu116 as a relevant enhancer of distinctive PrimPol reactions, which are highly dependent on Mn2+. Herein, we evidenced that PrimPol Glu116 contributes to error-prone tolerance of 8oxodG more markedly when both Mg2+ and Mn2+ ions are present. Moreover, Glu116 was important for TLS events mediated by primer/template realignments, and crucial to achieving an optimal primase activity, processes in which Mn2+ is largely preferred. EMSA analysis of PrimPol:ssDNA:dNTP pre-ternary complex indicated a critical role of each metal ligand, and a significant impairment when Glu116 was changed to a more conventional aspartate. These data suggest that PrimPol active site requires a specific motif A (DxE) to favor the use of Mn2+ ions in order to achieve optimal incoming nucleotide stabilization, especially required during primer synthesis.
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Affiliation(s)
- Patricia A Calvo
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) c/Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Guillermo Sastre-Moreno
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) c/Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Cristina Perpiñá
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) c/Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Susana Guerra
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) c/Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - María I Martínez-Jiménez
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) c/Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Luis Blanco
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) c/Nicolás Cabrera 1, Cantoblanco, 28049, Madrid, Spain.
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