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Manthei KA, Munson LM, Nandakumar J, Simmons LA. Structural and biochemical characterization of the mitomycin C repair exonuclease MrfB. Nucleic Acids Res 2024; 52:6347-6359. [PMID: 38661211 PMCID: PMC11194089 DOI: 10.1093/nar/gkae308] [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: 02/18/2024] [Revised: 04/03/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024] Open
Abstract
Mitomycin C (MMC) repair factor A (mrfA) and factor B (mrfB), encode a conserved helicase and exonuclease that repair DNA damage in the soil-dwelling bacterium Bacillus subtilis. Here we have focused on the characterization of MrfB, a DEDDh exonuclease in the DnaQ superfamily. We solved the structure of the exonuclease core of MrfB to a resolution of 2.1 Å, in what appears to be an inactive state. In this conformation, a predicted α-helix containing the catalytic DEDDh residue Asp172 adopts a random coil, which moves Asp172 away from the active site and results in the occupancy of only one of the two catalytic Mg2+ ions. We propose that MrfB resides in this inactive state until it interacts with DNA to become activated. By comparing our structure to an AlphaFold prediction as well as other DnaQ-family structures, we located residues hypothesized to be important for exonuclease function. Using exonuclease assays we show that MrfB is a Mg2+-dependent 3'-5' DNA exonuclease. We show that Leu113 aids in coordinating the 3' end of the DNA substrate, and that a basic loop is important for substrate binding. This work provides insight into the function of a recently discovered bacterial exonuclease important for the repair of MMC-induced DNA adducts.
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Affiliation(s)
- Kelly A Manthei
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Lia M Munson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Lyle A Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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Manthei KA, Munson LM, Nandakumar J, Simmons LA. Structural and biochemical characterization of the mitomycin C repair exonuclease MrfB. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.15.580553. [PMID: 38405983 PMCID: PMC10889028 DOI: 10.1101/2024.02.15.580553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Mitomycin C (MMC) repair factor A (mrfA) and factor B (mrfB), encode a conserved helicase and exonuclease that repair DNA damage in the soil-dwelling bacterium Bacillus subtilis. Here we have focused on the characterization of MrfB, a DEDDh exonuclease in the DnaQ superfamily. We solved the structure of the exonuclease core of MrfB to a resolution of 2.1 Å, in what appears to be an inactive state. In this conformation, a predicted α-helix containing the catalytic DEDDh residue Asp172 adopts a random coil, which moves Asp172 away from the active site and results in the occupancy of only one of the two catalytic Mg2+ ions. We propose that MrfB resides in this inactive state until it interacts with DNA to become activated. By comparing our structure to an AlphaFold prediction as well as other DnaQ-family structures, we located residues hypothesized to be important for exonuclease function. Using exonuclease assays we show that MrfB is a Mg2+-dependent 3'-5' DNA exonuclease. We show that Leu113 aids in coordinating the 3' end of the DNA substrate, and that a basic loop is important for substrate binding. This work provides insight into the function of a recently discovered bacterial exonuclease important for the repair of MMC-induced DNA adducts.
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Affiliation(s)
- Kelly A. Manthei
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lia M. Munson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
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Jia J, Hilal T, Bohnsack KE, Chernev A, Tsao N, Bethmann J, Arumugam A, Parmely L, Holton N, Loll B, Mosammaparast N, Bohnsack MT, Urlaub H, Wahl MC. Extended DNA threading through a dual-engine motor module of the activating signal co-integrator 1 complex. Nat Commun 2023; 14:1886. [PMID: 37019967 PMCID: PMC10076317 DOI: 10.1038/s41467-023-37528-3] [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: 08/28/2022] [Accepted: 03/21/2023] [Indexed: 04/07/2023] Open
Abstract
Activating signal co-integrator 1 complex (ASCC) subunit 3 (ASCC3) supports diverse genome maintenance and gene expression processes, and contains tandem Ski2-like NTPase/helicase cassettes crucial for these functions. Presently, the molecular mechanisms underlying ASCC3 helicase activity and regulation remain unresolved. We present cryogenic electron microscopy, DNA-protein cross-linking/mass spectrometry as well as in vitro and cellular functional analyses of the ASCC3-TRIP4 sub-module of ASCC. Unlike the related spliceosomal SNRNP200 RNA helicase, ASCC3 can thread substrates through both helicase cassettes. TRIP4 docks on ASCC3 via a zinc finger domain and stimulates the helicase by positioning an ASC-1 homology domain next to the C-terminal helicase cassette of ASCC3, likely supporting substrate engagement and assisting the DNA exit. TRIP4 binds ASCC3 mutually exclusively with the DNA/RNA dealkylase, ALKBH3, directing ASCC3 for specific processes. Our findings define ASCC3-TRIP4 as a tunable motor module of ASCC that encompasses two cooperating NTPase/helicase units functionally expanded by TRIP4.
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Affiliation(s)
- Junqiao Jia
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Takustr. 6, D-14195, Berlin, Germany
- Harvard Medical School, Department of Cell Biology, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Tarek Hilal
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Takustr. 6, D-14195, Berlin, Germany
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Research Center of Electron Microscopy, Fabeckstr. 36a, D-14195, Berlin, Germany
| | - Katherine E Bohnsack
- Universitätsmedizin Göttingen, Department of Molecular Biology, Humboldallee 23, D-37073, Göttingen, Germany
| | - Aleksandar Chernev
- Max-Planck-Institut für Multidisziplinäre Naturwissenschaften, Bioanalytical Mass Spectrometry, Am Fassberg 11, D-37077, Göttingen, Germany
| | - Ning Tsao
- Washington University School of Medicine, Department of Pathology & Immunology and Center for Genome Integrity, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Juliane Bethmann
- Max-Planck-Institut für Multidisziplinäre Naturwissenschaften, Bioanalytical Mass Spectrometry, Am Fassberg 11, D-37077, Göttingen, Germany
- Universitätsmedizin Göttingen, Institut für Klinische Chemie, Bioanalytik, Robert-Koch-Straße 40, D-35075, Göttingen, Germany
| | - Aruna Arumugam
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Takustr. 6, D-14195, Berlin, Germany
| | - Lane Parmely
- Washington University School of Medicine, Department of Pathology & Immunology and Center for Genome Integrity, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Nicole Holton
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Takustr. 6, D-14195, Berlin, Germany
| | - Bernhard Loll
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Takustr. 6, D-14195, Berlin, Germany
| | - Nima Mosammaparast
- Washington University School of Medicine, Department of Pathology & Immunology and Center for Genome Integrity, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - Markus T Bohnsack
- Universitätsmedizin Göttingen, Department of Molecular Biology, Humboldallee 23, D-37073, Göttingen, Germany
- Georg-August-Universität, Göttingen Center for Molecular Biosciences, Justus-von-Liebig-Weg 11, D-37077, Göttingen, Germany
- Max-Planck-Institut für Multidisziplinäre Naturwissenschaften, Am Fassberg 11, D-37077, Göttingen, Germany
| | - Henning Urlaub
- Max-Planck-Institut für Multidisziplinäre Naturwissenschaften, Bioanalytical Mass Spectrometry, Am Fassberg 11, D-37077, Göttingen, Germany
- Universitätsmedizin Göttingen, Institut für Klinische Chemie, Bioanalytik, Robert-Koch-Straße 40, D-35075, Göttingen, Germany
| | - Markus C Wahl
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Laboratory of Structural Biochemistry, Takustr. 6, D-14195, Berlin, Germany.
- Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography, Albert-Einstein-Str. 15, D-12489, Berlin, Germany.
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Abstract
Bacteria are continuously exposed to numerous endogenous and exogenous DNA-damaging agents. To maintain genome integrity and ensure cell survival, bacteria have evolved several DNA repair pathways to correct different types of DNA damage and non-canonical bases, including strand breaks, nucleotide modifications, cross-links, mismatches and ribonucleotide incorporations. Recent advances in genome-wide screens, the availability of thousands of whole-genome sequences and advances in structural biology have enabled the rapid discovery and characterization of novel bacterial DNA repair pathways and new enzymatic activities. In this Review, we discuss recent advances in our understanding of base excision repair and nucleotide excision repair, and we discuss several new repair processes including the EndoMS mismatch correction pathway and the MrfAB excision repair system.
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Affiliation(s)
- Katherine J Wozniak
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Lyle A Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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Structural basis for broad anti-phage immunity by DISARM. Nat Commun 2022; 13:2987. [PMID: 35624106 PMCID: PMC9142583 DOI: 10.1038/s41467-022-30673-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/12/2022] [Indexed: 11/08/2022] Open
Abstract
In the evolutionary arms race against phage, bacteria have assembled a diverse arsenal of antiviral immune strategies. While the recently discovered DISARM (Defense Island System Associated with Restriction-Modification) systems can provide protection against a wide range of phage, the molecular mechanisms that underpin broad antiviral targeting but avoiding autoimmunity remain enigmatic. Here, we report cryo-EM structures of the core DISARM complex, DrmAB, both alone and in complex with an unmethylated phage DNA mimetic. These structures reveal that DrmAB core complex is autoinhibited by a trigger loop (TL) within DrmA and binding to DNA substrates containing a 5′ overhang dislodges the TL, initiating a long-range structural rearrangement for DrmAB activation. Together with structure-guided in vivo studies, our work provides insights into the mechanism of phage DNA recognition and specific activation of this widespread antiviral defense system. DISARM (Defense Island System Associated with Restriction Modification) systems can provide bacteria with protection against a wide range of phage. Here, Bravo et al. determine cryo-EM structures of the core DISARM complex that shed light onto phage DNA recognition and activation of this widespread defense system.
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Grass LM, Wollenhaupt J, Barthel T, Parfentev I, Urlaub H, Loll B, Klauck E, Antelmann H, Wahl MC. Large-scale ratcheting in a bacterial DEAH/RHA-type RNA helicase that modulates antibiotics susceptibility. Proc Natl Acad Sci U S A 2021; 118:e2100370118. [PMID: 34290142 PMCID: PMC8325345 DOI: 10.1073/pnas.2100370118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Many bacteria harbor RNA-dependent nucleoside-triphosphatases of the DEAH/RHA family, whose molecular mechanisms and cellular functions are poorly understood. Here, we show that the Escherichia coli DEAH/RHA protein, HrpA, is an ATP-dependent 3 to 5' RNA helicase and that the RNA helicase activity of HrpA influences bacterial survival under antibiotics treatment. Limited proteolysis, crystal structure analysis, and functional assays showed that HrpA contains an N-terminal DEAH/RHA helicase cassette preceded by a unique N-terminal domain and followed by a large C-terminal region that modulates the helicase activity. Structures of an expanded HrpA helicase cassette in the apo and RNA-bound states in combination with cross-linking/mass spectrometry revealed ratchet-like domain movements upon RNA engagement, much more pronounced than hitherto observed in related eukaryotic DEAH/RHA enzymes. Structure-based functional analyses delineated transient interdomain contact sites that support substrate loading and unwinding, suggesting that similar conformational changes support RNA translocation. Consistently, modeling studies showed that analogous dynamic intramolecular contacts are not possible in the related but helicase-inactive RNA-dependent nucleoside-triphosphatase, HrpB. Our results indicate that HrpA may be an interesting target to interfere with bacterial tolerance toward certain antibiotics and suggest possible interfering strategies.
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Affiliation(s)
- Lena M Grass
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Jan Wollenhaupt
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
| | - Tatjana Barthel
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry, Max-Planck-Institut für biophysikalische Chemie, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max-Planck-Institut für biophysikalische Chemie, D-37077 Göttingen, Germany
- Bioanalytics, Institute of Clinical Chemistry, Universitätsmedizin Göttingen, D-37075 Göttingen, Germany
| | - Bernhard Loll
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Eberhard Klauck
- Microbiology, Institute of Biology, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Haike Antelmann
- Microbiology, Institute of Biology, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany;
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, D-12489 Berlin, Germany
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