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Wagner M, Döhlemann J, Geisel D, Sobetzko P, Serrania J, Lenz P, Becker A. Engineering a Sinorhizobium meliloti Chassis with Monopartite, Single Replicon Genome Configuration. ACS Synth Biol 2024; 13:2515-2532. [PMID: 39109796 DOI: 10.1021/acssynbio.4c00281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Multipartite bacterial genomes pose challenges for genome engineering and the establishment of additional replicons. We simplified the tripartite genome structure (3.65 Mbp chromosome, 1.35 Mbp megaplasmid pSymA, 1.68 Mbp chromid pSymB) of the nitrogen-fixing plant symbiont Sinorhizobium meliloti. Strains with bi- and monopartite genome configurations were generated by targeted replicon fusions. Our design preserved key genomic features such as replichore ratios, GC skew, KOPS, and coding sequence distribution. Under standard culture conditions, the growth rates of these strains and the wild type were nearly comparable, and the ability for symbiotic nitrogen fixation was maintained. Spatiotemporal replicon organization and segregation were maintained in the triple replicon fusion strain. Deletion of the replication initiator-encoding genes, including the oriVs of pSymA and pSymB from this strain, resulted in a monopartite genome with oriC as the sole origin of replication, a strongly unbalanced replichore ratio, slow growth, aberrant cellular localization of oriC, and deficiency in symbiosis. Suppressor mutation R436H in the cell cycle histidine kinase CckA and a 3.2 Mbp inversion, both individually, largely restored growth, but only the genomic rearrangement recovered the symbiotic capacity. These strains will facilitate the integration of secondary replicons in S. meliloti and thus be useful for genome engineering applications, such as generating hybrid genomes.
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Affiliation(s)
- Marcel Wagner
- Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
- Department of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Johannes Döhlemann
- Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
- Department of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - David Geisel
- Department of Physics, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Patrick Sobetzko
- Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
| | - Javier Serrania
- Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
- Department of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Peter Lenz
- Department of Physics, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
- Department of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany
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Tominaga K, Ozaki S, Sato S, Katayama T, Nishimura Y, Omae K, Iwasaki W. Frequent nonhomologous replacement of replicative helicase loaders by viruses in Vibrionaceae. Proc Natl Acad Sci U S A 2024; 121:e2317954121. [PMID: 38683976 PMCID: PMC11087808 DOI: 10.1073/pnas.2317954121] [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: 10/18/2023] [Accepted: 03/14/2024] [Indexed: 05/02/2024] Open
Abstract
Several microbial genomes lack textbook-defined essential genes. If an essential gene is absent from a genome, then an evolutionarily independent gene of unknown function complements its function. Here, we identified frequent nonhomologous replacement of an essential component of DNA replication initiation, a replicative helicase loader gene, in Vibrionaceae. Our analysis of Vibrionaceae genomes revealed two genes with unknown function, named vdhL1 and vdhL2, that were substantially enriched in genomes without the known helicase-loader genes. These genes showed no sequence similarities to genes with known function but encoded proteins structurally similar with a viral helicase loader. Analyses of genomic syntenies and coevolution with helicase genes suggested that vdhL1/2 encodes a helicase loader. The in vitro assay showed that Vibrio harveyi VdhL1 and Vibrio ezurae VdhL2 promote the helicase activity of DnaB. Furthermore, molecular phylogenetics suggested that vdhL1/2 were derived from phages and replaced an intrinsic helicase loader gene of Vibrionaceae over 20 times. This high replacement frequency implies the host's advantage in acquiring a viral helicase loader gene.
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Affiliation(s)
- Kento Tominaga
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba277-0882, Japan
| | - Shogo Ozaki
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka812-8582, Japan
| | - Shohei Sato
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka812-8582, Japan
| | - Tsutomu Katayama
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka812-8582, Japan
| | - Yuki Nishimura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba277-0882, Japan
| | - Kimiho Omae
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba277-0882, Japan
| | - Wataru Iwasaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba277-0882, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo113-0032, Japan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba277-0882, Japan
- Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba277-8564, Japan
- Institute for Quantitative Biosciences, The University of Tokyo, Tokyo113-0032, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo113-8657, Japan
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Zhang C, Joseph AM, Casini L, Collier J, Badrinarayanan A, Manley S. Chromosome organization shapes replisome dynamics in Caulobacter crescentus. Nat Commun 2024; 15:3460. [PMID: 38658616 PMCID: PMC11043382 DOI: 10.1038/s41467-024-47849-6] [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: 08/28/2023] [Accepted: 04/15/2024] [Indexed: 04/26/2024] Open
Abstract
DNA replication in bacteria takes place on highly compacted chromosomes, where segregation, transcription, and repair must occur simultaneously. Within this dynamic environment, colocalization of sister replisomes has been observed in many bacterial species, driving the hypothesis that a physical linker may tether them together. However, replisome splitting has also been reported in many of the same species, leaving the principles behind replisome organization a long-standing puzzle. Here, by tracking the replisome β-clamp subunit in live Caulobacter crescentus, we find that rapid DNA segregation can give rise to a second focus which resembles a replisome, but does not replicate DNA. Sister replisomes can remain colocalized, or split apart to travel along DNA separately upon disruption of chromosome inter-arm alignment. Furthermore, chromosome arm-specific replication-transcription conflicts differentially modify replication speed on the two arms, facilitate the decoupling of the two replisomes. With these observations, we conclude that the dynamic chromosome organization flexibly shapes the organization of sister replisomes, and we outline principles which can help to reconcile previously conflicting models of replisome architecture.
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Affiliation(s)
- Chen Zhang
- Laboratory of Experimental Biophysics, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Asha Mary Joseph
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Laurent Casini
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Justine Collier
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Anjana Badrinarayanan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Suliana Manley
- Laboratory of Experimental Biophysics, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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Santiago-Collazo G, Brown PJB, Randich AM. The divergent early divisome: is there a functional core? Trends Microbiol 2024; 32:231-240. [PMID: 37741788 DOI: 10.1016/j.tim.2023.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 09/25/2023]
Abstract
The bacterial divisome is a complex nanomachine that drives cell division and separation. The essentiality of these processes leads to the assumption that proteins with core roles will be strictly conserved across all bacterial genomes. However, recent studies in diverse proteobacteria have revealed considerable variation in the early divisome compared with Escherichia coli. While some proteins are highly conserved, their specific functions and interacting partners vary. Meanwhile, different subphyla use clade-specific proteins with analogous functions. Thus, instead of focusing on gene conservation, we must also explore how key functions are maintained during early division by diverging protein networks. An enhanced awareness of these complex genetic networks will clarify the physical and evolutionary constraints of bacterial division.
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Affiliation(s)
- Gustavo Santiago-Collazo
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri-Columbia, Columbia, MO, USA
| | - Pamela J B Brown
- Division of Biological Sciences, College of Arts and Sciences, University of Missouri-Columbia, Columbia, MO, USA
| | - Amelia M Randich
- Department of Biology, College of Arts and Sciences, University of Scranton, Scranton, PA, USA.
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Ozaki S, Wang D, Wakasugi Y, Itani N, Katayama T. The Caulobacter crescentus DciA promotes chromosome replication through topological loading of the DnaB replicative helicase at replication forks. Nucleic Acids Res 2022; 50:12896-12912. [PMID: 36484102 PMCID: PMC9825169 DOI: 10.1093/nar/gkac1146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/04/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
The replicative DNA helicase translocates on single-stranded DNA to drive replication forks during chromosome replication. In most bacteria the ubiquitous replicative helicase, DnaB, co-evolved with the accessory subunit DciA, but how they function remains incompletely understood. Here, using the model bacterium Caulobacter crescentus, we demonstrate that DciA plays a prominent role in DNA replication fork maintenance. Cell cycle analyses using a synchronized Caulobacter cell population showed that cells devoid of DciA exhibit a severe delay in fork progression. Biochemical characterization revealed that the DnaB helicase in its default state forms a hexamer that inhibits self-loading onto single-stranded DNA. We found that upon binding to DciA, the DnaB hexamer undergoes conformational changes required for encircling single-stranded DNA, thereby establishing the replication fork. Further investigation of the functional structure of DciA revealed that the C-terminus of DciA includes conserved leucine residues responsible for DnaB binding and is essential for DciA in vivo functions. We propose that DciA stimulates loading of DnaB onto single strands through topological isomerization of the DnaB structure, thereby ensuring fork progression. Given that the DnaB-DciA modules are widespread among eubacterial species, our findings suggest that a common mechanism underlies chromosome replication.
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Affiliation(s)
| | | | | | - Naoto Itani
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
| | - Tsutomu Katayama
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
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Gogou C, Japaridze A, Dekker C. Mechanisms for Chromosome Segregation in Bacteria. Front Microbiol 2021; 12:685687. [PMID: 34220773 PMCID: PMC8242196 DOI: 10.3389/fmicb.2021.685687] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/19/2021] [Indexed: 11/13/2022] Open
Abstract
The process of DNA segregation, the redistribution of newly replicated genomic material to daughter cells, is a crucial step in the life cycle of all living systems. Here, we review DNA segregation in bacteria which evolved a variety of mechanisms for partitioning newly replicated DNA. Bacterial species such as Caulobacter crescentus and Bacillus subtilis contain pushing and pulling mechanisms that exert forces and directionality to mediate the moving of newly synthesized chromosomes to the bacterial poles. Other bacteria such as Escherichia coli lack such active segregation systems, yet exhibit a spontaneous de-mixing of chromosomes due to entropic forces as DNA is being replicated under the confinement of the cell wall. Furthermore, we present a synopsis of the main players that contribute to prokaryotic genome segregation. We finish with emphasizing the importance of bottom-up approaches for the investigation of the various factors that contribute to genome segregation.
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Affiliation(s)
- Christos Gogou
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Aleksandre Japaridze
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
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