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Zhang Z, Chen J, Yao M, Wang G. Structural Insight Into the Function of DnaB Helicase in Bacterial DNA Replication. Proteins 2024. [PMID: 39230358 DOI: 10.1002/prot.26746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 07/16/2024] [Accepted: 08/26/2024] [Indexed: 09/05/2024]
Abstract
In bacteria, chromosome replication is achieved by the coordinations of more than a dozen replisome enzymes. Replication initiation protein DnaA melts DNA duplex at replication origin (oriC) and forms a replication bubble, followed by loading of helicase DnaB with the help of loader protein DnaC. Then the DnaB helicase unwinds the dsDNA and supports the priming of DnaG and the polymerizing of DNA polymerase. The DnaB helicase functions as a platform coupling unwinding, priming, and polymerizing events. The multiple roles of DnaB helicase are underlined by its distinctive architecture and dynamics conformations. In this review, we will discuss the assembling of DnaB hexamer and the conformational changes upon binding of various partners, DnaB in states of closed dilated (CD), closed constricted (CC), closed helical (CH), and open helical (OH) are discussed. These multiple interfaces among DnaB and partners are potential targets for inhibitors design and novel peptide antibiotics development.
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Affiliation(s)
- Zhiming Zhang
- Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences, Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jiang Chen
- Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences, Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu, China
- University of Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, Sichuan University, Chengdu, China
| | - Maochun Yao
- Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences, Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ganggang Wang
- Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences, Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu, China
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Zabrady M, Zabrady K, Li AH, Doherty AJ. Reverse transcriptases prime DNA synthesis. Nucleic Acids Res 2023; 51:7125-7142. [PMID: 37279911 PMCID: PMC10415136 DOI: 10.1093/nar/gkad478] [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: 03/03/2023] [Revised: 05/11/2023] [Accepted: 05/19/2023] [Indexed: 06/08/2023] Open
Abstract
The discovery of reverse transcriptases (RTs) challenged the central dogma by establishing that genetic information can also flow from RNA to DNA. Although they act as DNA polymerases, RTs are distantly related to replicases that also possess de novo primase activity. Here we identify that CRISPR associated RTs (CARTs) directly prime DNA synthesis on both RNA and DNA. We demonstrate that RT-dependent priming is utilized by some CRISPR-Cas complexes to synthesise new spacers and integrate these into CRISPR arrays. Expanding our analyses, we show that primer synthesis activity is conserved in representatives of other major RT classes, including group II intron RT, telomerase and retroviruses. Together, these findings establish a conserved innate ability of RTs to catalyse de novo DNA primer synthesis, independently of accessory domains or alternative priming mechanisms, which likely plays important roles in a wide variety of biological pathways.
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Affiliation(s)
- Matej Zabrady
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Katerina Zabrady
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Arthur W H Li
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
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3
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Rice PA. Mobile genetic element-encoded putative DNA primases composed of A-family polymerase-SSB pairs. Front Mol Biosci 2023; 10:1113960. [PMID: 37006622 PMCID: PMC10061031 DOI: 10.3389/fmolb.2023.1113960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
Mobile genetic elements can encode a wide variety of genes that support their own stability and mobility as well as genes that provide accessory functions to their hosts. Such genes can be adopted from host chromosomes and can be exchanged with other mobile elements. Due to their accessory nature, the evolutionary trajectories of these genes can differ from those of essential host genes. The mobilome therefore provides a rich source of genetic innovation. We previously described a new type of primase encoded by S. aureus SCCmec elements that is composed of an A-family polymerase catalytic domain in complex with a small second protein that confers single-stranded DNA binding. Here we use new structure prediction methods in conjunction with sequence database searches to show that related primases are widespread among putative mobile genetic elements in the Bacillota. Structure predictions show that the second protein adopts an OB fold (common among single-stranded DNA binding (SSB) proteins) and these predictions were far more powerful than simple sequence comparisons in identifying its homologs. The protein-protein interaction surface varies among these polymerase-SSB complexes appear to have arisen repeatedly by exploiting partial truncations of the polymerase's N-terminal accessory domains.
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Affiliation(s)
- Phoebe A. Rice
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, United States
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Verdú C, Pérez-Arnaiz P, Peropadre A, Berenguer J, Mencía M. Deletion of the primase-polymerases encoding gene, located in a mobile element in Thermus thermophilus HB27, leads to loss of function mutation of addAB genes. Front Microbiol 2022; 13:1005862. [DOI: 10.3389/fmicb.2022.1005862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 11/08/2022] [Indexed: 12/03/2022] Open
Abstract
DNA primase-polymerases (Ppol) have been shown to play active roles in DNA repair and damage tolerance, both in prokaryotes and eukaryotes. The ancestral thermophilic bacterium Thermus thermophilus strain HB27 encodes a Ppol protein among the genes present in mobile element ICETh2, absent in other T. thermophilus strains. Using different strategies we ablated the function of Ppol in HB27 cells, either by knocking out the gene through insertional mutagenesis, markerless deletion or through abolition of its catalytic activity. Whole genome sequencing of this diverse collection of Ppol mutants showed spontaneous loss of function mutation in the helicase-nuclease AddAB in every ppol mutant isolated. Given that AddAB is a major player in recombinational repair in many prokaryotes, with similar activity to the proteobacterial RecBCD complex, we have performed a detailed characterization of the ppol mutants in combination with addAB mutants. The results show that knockout addAB mutants are more sensitive to DNA damage agents than the wild type, and present a dramatic three orders of magnitude increase in natural transformation efficiencies with both plasmid and lineal DNA, whereas ppol mutants show defects in plasmid stability. Interestingly, DNA-integrity comet assays showed that the genome of all the ppol and/or addAB mutants was severely affected by widespread fragmentation, however, this did not translate in neat loss of viability of the strains. All these data support that Ppol appears to keep in balance the activity of AddAB as a part of the DNA housekeeping maintenance in T. thermophilus HB27, thus, playing a key role in its genome stability.
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Periago J, Mason C, Griep MA. Theoretical Development of DnaG Primase as a Novel Narrow-Spectrum Antibiotic Target. ACS OMEGA 2022; 7:8420-8428. [PMID: 35309427 PMCID: PMC8928506 DOI: 10.1021/acsomega.1c05928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 02/01/2022] [Indexed: 06/01/2023]
Abstract
The widespread use of antibiotics to treat infections is one of the reasons that global mortality rates have fallen over the past 80 years. However, antibiotic use is also responsible for the concomitant rise in antibiotic resistance because it results in dysbiosis in which commensal and pathogenic bacteria are both greatly reduced. Therefore, narrow-range antibiotics are a promising direction for reducing antibiotic resistance because they are more discriminate. As a step toward addressing this problem, the goal of this study was to identify sites on DnaG primase that are conserved within Gram-positive bacteria and different from the equivalent sites in Gram-negative bacteria. Based on sequence and structural analysis, the primase C-terminal helicase-binding domain (CTD) was identified as most promising. Although the primase CTD sequences are very poorly conserved, they have highly conserved protein folds, and Gram-positive bacterial primases fold into a compact state that creates a small molecule binding site adjacent to a groove. The small molecule would stabilize the protein in its compact state, which would interfere with the helicase binding. This is important because primase CTD must be in its open conformation to bind to its cognate helicase at the replication fork.
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Oki K, Yamagami T, Nagata M, Mayanagi K, Shirai T, Adachi N, Numata T, Ishino S, Ishino Y. DNA polymerase D temporarily connects primase to the CMG-like helicase before interacting with proliferating cell nuclear antigen. Nucleic Acids Res 2021; 49:4599-4612. [PMID: 33849056 PMCID: PMC8096248 DOI: 10.1093/nar/gkab243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 11/17/2022] Open
Abstract
The eukaryotic replisome is comprised of three family-B DNA polymerases (Polα, δ and ϵ). Polα forms a stable complex with primase to synthesize short RNA-DNA primers, which are subsequently elongated by Polδ and Polϵ in concert with proliferating cell nuclear antigen (PCNA). In some species of archaea, family-D DNA polymerase (PolD) is the only DNA polymerase essential for cell viability, raising the question of how it alone conducts the bulk of DNA synthesis. We used a hyperthermophilic archaeon, Thermococcus kodakarensis, to demonstrate that PolD connects primase to the archaeal replisome before interacting with PCNA. Whereas PolD stably connects primase to GINS, a component of CMG helicase, cryo-EM analysis indicated a highly flexible PolD-primase complex. A conserved hydrophobic motif at the C-terminus of the DP2 subunit of PolD, a PIP (PCNA-Interacting Peptide) motif, was critical for the interaction with primase. The dissociation of primase was induced by DNA-dependent binding of PCNA to PolD. Point mutations in the alternative PIP-motif of DP2 abrogated the molecular switching that converts the archaeal replicase from de novo to processive synthesis mode.
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Affiliation(s)
- Keisuke Oki
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Takeshi Yamagami
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Mariko Nagata
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Kouta Mayanagi
- Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Tsuyoshi Shirai
- Department of Bioscience, Nagahama Institute of Bio-Science and Technology, Tamura 1266, Nagahama, Shiga 526-0829, Japan
| | - Naruhiko Adachi
- Structure Biology Research Center, Institute of Materials Structural Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Tomoyuki Numata
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
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Bergsch J, Devillier JC, Jeschke G, Lipps G. Stringent Primer Termination by an Archaeo-Eukaryotic DNA Primase. Front Microbiol 2021; 12:652928. [PMID: 33927705 PMCID: PMC8076596 DOI: 10.3389/fmicb.2021.652928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/19/2021] [Indexed: 11/23/2022] Open
Abstract
Priming of single stranded templates is essential for DNA replication. In recent years, significant progress was made in understanding how DNA primase fulfils this fundamental function, particularly with regard to the initiation. Equally intriguing is the unique property of archeao-eukaryotic primases to terminate primer formation at a well-defined unit length. The apparent ability to “count” the number of bases incorporated prior to primer release is not well understood, different mechanisms having been proposed for different species. We report a mechanistic investigation of primer termination by the pRN1 primase from Sulfolobus islandicus. Using an HPLC-based assay we determined structural features of the primer 5′-end that are required for consistent termination. Mutations within the unstructured linker connecting the catalytic domain to the template binding domain allowed us to assess the effect of altered linker length and flexibility on primer termination.
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Affiliation(s)
- Jan Bergsch
- Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland.,Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Jean-Christophe Devillier
- Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland.,Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Georg Lipps
- Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland
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Singh J, Pikaard CS. Reconstitution of siRNA Biogenesis In Vitro: Novel Reaction Mechanisms and RNA Channeling in the RNA-Directed DNA Methylation Pathway. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2020; 84:195-201. [PMID: 32350049 DOI: 10.1101/sqb.2019.84.039842] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Eukaryotes deploy RNA-mediated gene silencing pathways to guard their genomes against selfish genetic elements, such as transposable elements and invading viruses. In plants, RNA-directed DNA methylation (RdDM) is used to silence selfish elements at the level of transcription. This process involves 24-nt short interfering RNAs (siRNAs) and longer noncoding RNAs to which the siRNAs base-pair. Recently, we showed that 24-nt siRNA biogenesis could be recapitulated in the test tube using purified enzymes, yielding biochemical answers to numerous questions left unresolved by prior genetic and genomic studies. Interestingly, each enzyme has activities that program what happens in the next step, thus channeling the RNAs within the RdDM pathway and restricting their diversion into alternative pathways. However, a similar mechanistic understanding is lacking for other important steps of the RdDM pathway. We discuss some of the steps most in need of biochemical investigation and important questions still in need of answers.
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Affiliation(s)
- Jasleen Singh
- Department of Molecular and Cellular Biochemistry and Department of Biology, Bloomington, Indiana 47405, USA
| | - Craig S Pikaard
- Department of Molecular and Cellular Biochemistry and Department of Biology, Bloomington, Indiana 47405, USA.,Howard Hughes Medical Institute, Indiana University, Bloomington, Indiana 47405, USA
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