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Schumacher MA, Singh RR, Salinas R. Structure of the E. coli nucleoid-associated protein YejK reveals a novel DNA binding clamp. Nucleic Acids Res 2024:gkae459. [PMID: 38832628 DOI: 10.1093/nar/gkae459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/02/2024] [Accepted: 05/15/2024] [Indexed: 06/05/2024] Open
Abstract
Nucleoid-associated proteins (NAPs) play central roles in bacterial chromosome organization and DNA processes. The Escherichia coli YejK protein is a highly abundant, yet poorly understood NAP. YejK proteins are conserved among Gram-negative bacteria but show no homology to any previously characterized DNA-binding protein. Hence, how YejK binds DNA is unknown. To gain insight into YejK structure and its DNA binding mechanism we performed biochemical and structural analyses on the E. coli YejK protein. Biochemical assays demonstrate that, unlike many NAPs, YejK does not show a preference for AT-rich DNA and binds non-sequence specifically. A crystal structure revealed YejK adopts a novel fold comprised of two domains. Strikingly, each of the domains harbors an extended arm that mediates dimerization, creating an asymmetric clamp with a 30 Å diameter pore. The lining of the pore is electropositive and mutagenesis combined with fluorescence polarization assays support DNA binding within the pore. Finally, our biochemical analyses on truncated YejK proteins suggest a mechanism for YejK clamp loading. Thus, these data reveal YejK contains a newly described DNA-binding motif that functions as a novel clamp.
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Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC 27710, USA
| | - Rajiv R Singh
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC 27710, USA
| | - Raul Salinas
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC 27710, USA
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2
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Bouillet S, Bauer TS, Gottesman S. RpoS and the bacterial general stress response. Microbiol Mol Biol Rev 2024; 88:e0015122. [PMID: 38411096 PMCID: PMC10966952 DOI: 10.1128/mmbr.00151-22] [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] [Indexed: 02/28/2024] Open
Abstract
SUMMARYThe general stress response (GSR) is a widespread strategy developed by bacteria to adapt and respond to their changing environments. The GSR is induced by one or multiple simultaneous stresses, as well as during entry into stationary phase and leads to a global response that protects cells against multiple stresses. The alternative sigma factor RpoS is the central GSR regulator in E. coli and conserved in most γ-proteobacteria. In E. coli, RpoS is induced under conditions of nutrient deprivation and other stresses, primarily via the activation of RpoS translation and inhibition of RpoS proteolysis. This review includes recent advances in our understanding of how stresses lead to RpoS induction and a summary of the recent studies attempting to define RpoS-dependent genes and pathways.
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Affiliation(s)
- Sophie Bouillet
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, Bethesda, Maryland, USA
| | - Taran S. Bauer
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, Bethesda, Maryland, USA
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, Bethesda, Maryland, USA
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3
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Zhu W, Xi L, Qiao J, Du D, Wang Y, Morigen. Involvement of OxyR and Dps in the repression of replication initiation by DsrA small RNA in Escherichia coli. Gene 2023; 882:147659. [PMID: 37482259 DOI: 10.1016/j.gene.2023.147659] [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: 06/27/2023] [Revised: 07/14/2023] [Accepted: 07/19/2023] [Indexed: 07/25/2023]
Abstract
Regulation of the cell cycle process is an effective measure to ensure the stability and fidelity of genetic material during the reproduction of bacteria under different stresses. The small RNA DsrA helps bacteria adapt to environments by binding to multiple targets, but its association with the cell cycle remains unclear. Detection by flow cytometry, we first found that the knockout of dsrA promoted replication initiation, and corresponding overexpression of DsrA inhibited replication initiation in Escherichia coli. The absence of the chaperone protein Hfq, the DNA replication negative regulator protein Dps, or the transcription factor OxyR, was found to cause DsrA to no longer inhibit replication initiation. Excess DsrA promotes expression of the oxyR and dps gene, whereas β-galactosidase activity assay showed that deleting oxyR limited the enhancement of dps promoter transcriptional activity by DsrA. OxyR is a known positive regulator of Dps. Our data suggests that the effect of DsrA on replication initiation requires Hfq and that the upregulation of Dps expression by OxyR in response to DsrA levels may be a potential regulatory pathway for the negative regulation of DNA replication initiation.
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Affiliation(s)
- Weiwei Zhu
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China; State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen 361102, China
| | - Lingjun Xi
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China
| | - Jiaxin Qiao
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China
| | - Dongdong Du
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China
| | - Yao Wang
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China
| | - Morigen
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China.
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4
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Williams SM, Chatterji D. Dps Functions as a Key Player in Bacterial Iron Homeostasis. ACS OMEGA 2023; 8:34299-34309. [PMID: 37779979 PMCID: PMC10536872 DOI: 10.1021/acsomega.3c03277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/24/2023] [Indexed: 10/03/2023]
Abstract
Iron plays a vital role in the maintenance of life, being central to various cellular processes, from respiration to gene regulation. It is essential for iron to be stored in a nontoxic and readily available form. DNA binding proteins under starvation (Dps) belong to the ferritin family of iron storage proteins and are adept at storing iron in their hollow protein shells. Existing solely in prokaryotes, these proteins have the additional functions of DNA binding and protection from oxidative stress. Iron storage proteins play a functional role in storage, release, and transfer of iron and therefore are central to the optimal functioning of iron homeostasis. Here we review the multifarious properties of Dps through relevant biochemical and structural studies with a focus on iron storage and ferroxidation. We also examine the role of Dps as a possible candidate as an iron donor to iron-sulfur (Fe-S) clusters, which are ubiquitous to many biological processes.
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Affiliation(s)
- Sunanda Margrett Williams
- Institute
of Structural and Molecular Biology, Birkbeck,
University of London, Malet Street, London WC1E
7HX, United Kingdom
| | - Dipankar Chatterji
- Molecular
Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
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5
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Gupta A, Joshi A, Arora K, Mukhopadhyay S, Guptasarma P. The bacterial nucleoid-associated proteins, HU, and Dps, condense DNA into context-dependent biphasic or multiphasic complex coacervates. J Biol Chem 2023; 299:104637. [PMID: 36963493 PMCID: PMC10141540 DOI: 10.1016/j.jbc.2023.104637] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 02/27/2023] [Accepted: 03/08/2023] [Indexed: 03/26/2023] Open
Abstract
The bacterial chromosome, known as its nucleoid, is an amorphous assemblage of globular nucleoprotein domains. It exists in a state of phase separation from the cell's cytoplasm, as an irregularly-shaped, membrane-less, intracellular compartment. This state (the nature of which remains largely unknown) is maintained through bacterial generations ad infinitum. Here, we show that HU, and Dps, two of the most abundant nucleoid-associated proteins (NAPs) of Escherichia coli, undergo spontaneous complex coacervation with different forms of DNA/RNA, both individually and in each other's presence, to cause accretion and compaction of DNA/RNA into liquid-liquid phase separated (LLPS) condensates in vitro. Upon mixing with nucleic acids, HU-A and HU-B form (a) bi-phasic heterotypic mixed condensates in which HU-B helps to lower the Csat of HU-A; and also (b) multi-phasic heterotypic condensates, with Dps, in which de-mixed domains display different contents of HU and Dps. We believe that these modes of complex coacervation that are seen in vitro can serve as models for the in vivo relationships amongst NAPs in nucleoids, involving local and global variations in the relative abundances of the different NAPs, especially in de-mixed sub-domains that are characterized by differing grades of phase separation. Our results clearly demonstrate some quantitative, and some qualitative, differences in the coacervating abilities of different NAPs with DNA, potentially explaining (i) why E. coli has two isoforms of HU, and (ii) why changes in the abundances of HU and Dps facilitate the lag, logarithmic and stationary phases of E. coli growth.
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Affiliation(s)
- Archit Gupta
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.
| | - Ashish Joshi
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Kanika Arora
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Chemical Sciences; Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Purnananda Guptasarma
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.
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6
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Complementary Roles of Two DNA Protection Proteins from Deinococcus geothermalis. Int J Mol Sci 2022; 24:ijms24010469. [PMID: 36613913 PMCID: PMC9820295 DOI: 10.3390/ijms24010469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/17/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
The roles of two interrelated DNA protection protein in starved cells (Dps)-putative Dps Dgeo_0257 and Dgeo_0281-as orthologous proteins to DrDps1 for DNA binding, protection, and metal ion sensing were characterised in a Deinococcus geothermalis strain. Dgeo_0257 exhibited high DNA-binding affinity and formed a multimeric structure but lacked the conserved amino acid sequence for ferroxidase activity. In contrast, the Dgeo_0281 (DgDps1) protein was abundant in the early exponential phase, had a lower DNA-binding activity than Dgeo_0257, and was mainly observed in its monomeric or dimeric forms. Electrophoretic mobility shift assays demonstrated that both purified proteins bound nonspecifically to DNA, and their binding ability was affected by certain metal ions. For example, in the presence of ferrous and ferric ions, neither Dgeo_0257 nor Dgeo_0281 could readily bind to DNA. In contrast, both proteins exhibited more stable DNA binding in the presence of zinc and manganese ions. Mutants in which the dps gene was disrupted exhibited higher sensitivity to oxidative stress than the wild-type strain. Furthermore, the expression levels of each gene showed an opposite correlation under H2O2 treatment conditions. Collectively, these findings indicate that the putative Dps Dgeo_0257 and DgDps1 from D. geothermalis are involved in DNA binding and protection in complementary interplay ways compared to known Dps.
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7
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Sudarev VV, Dolotova SM, Bukhalovich SM, Bazhenov SV, Ryzhykau YL, Uversky VN, Bondarev NA, Osipov SD, Mikhailov AE, Kuklina DD, Murugova TN, Manukhov IV, Rogachev AV, Gordeliy VI, Gushchin IY, Kuklin AI, Vlasov AV. Ferritin self-assembly, structure, function, and biotechnological applications. Int J Biol Macromol 2022; 224:319-343. [DOI: 10.1016/j.ijbiomac.2022.10.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/28/2022] [Accepted: 10/13/2022] [Indexed: 11/05/2022]
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8
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Jiang L, Peng Y, Seo J, Jeon D, Jo MG, Lee JH, Jeong JC, Kim CY, Park HC, Lee J. Subtercola endophyticus sp. nov., a cold-adapted bacterium isolated from Abies koreana. Sci Rep 2022; 12:12114. [PMID: 35840645 PMCID: PMC9287328 DOI: 10.1038/s41598-022-16116-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 07/05/2022] [Indexed: 11/09/2022] Open
Abstract
A novel Gram-stain-positive, aerobic bacterial strain, designated AK-R2A1-2 T, was isolated from the surface-sterilized needle leaves of an Abies koreana tree. Strain AK-R2A1-2 T had 97.3% and 96.7% 16S rRNA gene sequence similarities with Subtercola boreus K300T and Subtercola lobariae 9583bT, respectively, but formed a distinct phyletic lineage from these two strains. Growth of strain AK-R2A1-2 T was observed at 4–25 °C at pH 5.0–8.0. Strain AK-R2A1-2 T contained menaquinone 9 (MK-9) and menaquinone 10 (MK-10) as the predominant respiratory quinones. The major cellular fatty acids were anteiso-C15:0 and summed feature 8 (C18:1ω7c or/and C18:1ω6c), and the polar lipids included diphosphatidylglycerol (DPG) and three unknown aminolipids, AKL2, AKL3, and AKL4. The complete genome of strain AK-R2A1-2 T was sequenced to understand the genetic basis of its survival at low temperatures. Multiple copies of cold-associated genes involved in cold-active chaperon, stress response, and DNA repair supported survival of the strain at low temperatures. Strain AK-R2A1-2 T was also able to significantly improve rice seedling growth under low temperatures. Thus, this strain represents a novel species of the genus Subtercola, and the proposed name is Subtercola endophyticus sp. nov. The type strain is AK-R2A1-2 T (= KCTC 49721 T = GDMCC 1.2921 T).
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Affiliation(s)
- Lingmin Jiang
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Yuxin Peng
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Jiyoon Seo
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Doeun Jeon
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Mi Gyeong Jo
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Ju Huck Lee
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Jae Cheol Jeong
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Cha Young Kim
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea
| | - Hyeong Cheol Park
- Team of Vulnerable Ecological Research, Division of Climate and Ecology, Bureau of Conservation & Assessment Research, National Institute of Ecology (NIE), Seocheon, 33657, Republic of Korea
| | - Jiyoung Lee
- Korean Collection for Type Cultures (KCTC), Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Jeollabuk-do, 56212, Republic of Korea.
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9
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Abstract
The DNA-binding protein from starved cells, Dps, is a universally conserved prokaryotic ferritin that, in many species, also binds DNA. Dps homologs have been identified in the vast majority of bacterial species and several archaea. Dps also may play a role in the global regulation of gene expression, likely through chromatin reorganization. Dps has been shown to use both its ferritin and DNA-binding functions to respond to a variety of environmental pressures, including oxidative stress. One mechanism that allows Dps to achieve this is through a global nucleoid restructuring event during stationary phase, resulting in a compact, hexacrystalline nucleoprotein complex called the biocrystal that occludes damaging agents from DNA. Due to its small size, hollow spherical structure, and high stability, Dps is being developed for applications in biotechnology.
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10
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Amemiya HM, Goss TJ, Nye TM, Hurto RL, Simmons LA, Freddolino PL. Distinct heterochromatin-like domains promote transcriptional memory and silence parasitic genetic elements in bacteria. EMBO J 2022; 41:e108708. [PMID: 34961960 PMCID: PMC8804932 DOI: 10.15252/embj.2021108708] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 11/22/2021] [Accepted: 11/29/2021] [Indexed: 02/03/2023] Open
Abstract
There is increasing evidence that prokaryotes maintain chromosome structure, which in turn impacts gene expression. We recently characterized densely occupied, multi-kilobase regions in the E. coli genome that are transcriptionally silent, similar to eukaryotic heterochromatin. These extended protein occupancy domains (EPODs) span genomic regions containing genes encoding metabolic pathways as well as parasitic elements such as prophages. Here, we investigate the contributions of nucleoid-associated proteins (NAPs) to the structuring of these domains, by examining the impacts of deleting NAPs on EPODs genome-wide in E. coli and B. subtilis. We identify key NAPs contributing to the silencing of specific EPODs, whose deletion opens a chromosomal region for RNA polymerase binding at genes contained within that region. We show that changes in E. coli EPODs facilitate an extra layer of transcriptional regulation, which prepares cells for exposure to exotic carbon sources. Furthermore, we distinguish novel xenogeneic silencing roles for the NAPs Fis and Hfq, with the presence of at least one being essential for cell viability in the presence of domesticated prophages. Our findings reveal previously unrecognized mechanisms through which genomic architecture primes bacteria for changing metabolic environments and silences harmful genomic elements.
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Affiliation(s)
- Haley M Amemiya
- Cellular and Molecular Biology ProgramUniversity of Michigan Medical SchoolAnn ArborMIUSA,Department of Computational Medicine and BioinformaticsUniversity of Michigan Medical SchoolAnn ArborMIUSA,Present address:
Broad Institute of MIT and HarvardCambridgeMAUSA
| | - Thomas J Goss
- Department of Biological ChemistryUniversity of Michigan Medical SchoolAnn ArborMIUSA
| | - Taylor M Nye
- Department of Molecular, Cellular, and Developmental BiologyUniversity of MichiganAnn ArborMIUSA,Present address:
Department of Molecular MicrobiologyWashington University in St. Louis School of MedicineSt. LouisMOUSA
| | - Rebecca L Hurto
- Department of Biological ChemistryUniversity of Michigan Medical SchoolAnn ArborMIUSA
| | - Lyle A Simmons
- Department of Molecular, Cellular, and Developmental BiologyUniversity of MichiganAnn ArborMIUSA
| | - Peter L Freddolino
- Cellular and Molecular Biology ProgramUniversity of Michigan Medical SchoolAnn ArborMIUSA,Department of Computational Medicine and BioinformaticsUniversity of Michigan Medical SchoolAnn ArborMIUSA,Department of Biological ChemistryUniversity of Michigan Medical SchoolAnn ArborMIUSA
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11
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12
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Mulyanti D, Soewandhi SN, Riani C. Insertion of prpoD_rpoS fragment enhances expression of recombinant protein by dps auto-inducible promoter in Escherichia coli. Mol Biol Rep 2021; 48:5833-5845. [PMID: 34342815 DOI: 10.1007/s11033-021-06562-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 07/12/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Nowadays, recombinant therapeutic proteins have been widely produced and consumed. For the safety and effectiveness of the protein production, an auto-inducible expression vector is required to replace inducer interference, which is uneconomic and could be harmful. In this research, an auto-inducible expression plasmid, pCAD2_sod (a pBR322 derivate plasmid), which was under dps (RpoS-dependent gene) promoter control, was modified to provide RpoS at earlier phase. Hence, accumulates more target protein and resulting a new plasmid, pCAD2+_sod. pCAD2_sod had been constructed to automatically induces the expression of recombinant superoxide dismutase (SOD) from Staphylococcus equorum (rMnSODSeq) in the stationary growth phase of Escherichia coli. This work aimed to obtain pCAD2+_sod and determine the expression level of rMnSODSeq on mRNA and protein level. METHOD AND RESULTS A synthetic rpoS coding region under rpoD promoter control (prpoD_rpoS) was inserted to pCAD2_sod and generated pCAD2+_sod. The rMnSODSeq (24.3 kDa) produced from pCAD2+_sod was ~ 1.5 fold higher at 37 °C and more intense at 43 °C compared to that from pCAD2_sod, likewise shifted to earlier phase (after 1 h of incubation), as shown in the SDS-PAGE. The dismutase activity was also retained after zymography assay. The mRNA level from pCAD2+_sod was determined by qPCR and gave quantification cycle (Cq) values of cDNA lowest among others. It made the relative quantification (RQ) of the mRNA expression towards rho reference gene were high. CONCLUSIONS The prpoD_rpoS insertion shifts and increases the rMnSODSeq production from stationary to exponential phase. The pCAD2+_sod plasmid is potential for further recombinant protein productions.
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Affiliation(s)
- Dina Mulyanti
- School of Pharmacy, Bandung Institute of Technology, Ganesha 10, Bandung, 40132, Indonesia.,Department of Pharmacy, Bandung Islamic University, Ranggagading 8, Bandung, 40116, Indonesia
| | | | - Catur Riani
- School of Pharmacy, Bandung Institute of Technology, Ganesha 10, Bandung, 40132, Indonesia.
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Kędzierska B, Potrykus K, Szalewska-Pałasz A, Wodzikowska B. Insights into Transcriptional Repression of the Homologous Toxin-Antitoxin Cassettes yefM-yoeB and axe-txe. Int J Mol Sci 2020; 21:ijms21239062. [PMID: 33260607 PMCID: PMC7730913 DOI: 10.3390/ijms21239062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 11/16/2022] Open
Abstract
Transcriptional repression is a mechanism which enables effective gene expression switch off. The activity of most of type II toxin-antitoxin (TA) cassettes is controlled in this way. These cassettes undergo negative autoregulation by the TA protein complex which binds to the promoter/operator sequence and blocks transcription initiation of the TA operon. Precise and tight control of this process is vital to avoid uncontrolled expression of the toxin component. Here, we employed a series of in vivo and in vitro experiments to establish the molecular basis for previously observed differences in transcriptional activity and repression levels of the pyy and pat promoters which control expression of two homologous TA systems, YefM-YoeB and Axe-Txe, respectively. Transcriptional fusions of promoters with a lux reporter, together with in vitro transcription, EMSA and footprinting assays revealed that: (1) the different sequence composition of the -35 promoter element is responsible for substantial divergence in strengths of the promoters; (2) variations in repression result from the TA repressor complex acting at different steps in the transcription initiation process; (3) transcription from an additional promoter upstream of pat also contributes to the observed inefficient repression of axe-txe module. This study provides evidence that even closely related TA cassettes with high sequence similarity in the promoter/operator region may employ diverse mechanisms for transcriptional regulation of their genes.
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14
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Network Rewiring: Physiological Consequences of Reciprocally Exchanging the Physical Locations and Growth-Phase-Dependent Expression Patterns of the Salmonella fis and dps Genes. mBio 2020; 11:mBio.02128-20. [PMID: 32900812 PMCID: PMC7482072 DOI: 10.1128/mbio.02128-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We assessed the impact on Salmonella physiology of reciprocally translocating the genes encoding the Fis and Dps nucleoid-associated proteins (NAPs) and of inverting their growth-phase production patterns such that Fis was produced in stationary phase (like Dps) and Dps was produced in exponential phase (like Fis). Changes to peak binding of Fis were detected by ChIP-seq on the chromosome, as were widespread impacts on the transcriptome, especially when Fis production mimicked Dps production. Virulence gene expression and the expression of a virulence phenotype were altered. Overall, these radical changes to NAP gene expression were well tolerated, revealing the robust and well-buffered nature of global gene regulation networks in the bacterium. The Fis nucleoid-associated protein controls the expression of a large and diverse regulon of genes in Gram-negative bacteria. Fis production is normally maximal in bacteria during the early exponential phase of batch culture growth, becoming almost undetectable by the onset of stationary phase. We tested the effect on the Fis regulatory network in Salmonella of moving the complete fis gene from its usual location near the origin of chromosomal replication to the position normally occupied by the dps gene in the right macrodomain of the chromosome, and vice versa, creating the gene exchange (GX) strain. In a parallel experiment, we tested the effect of rewiring the Fis regulatory network by placing the fis open reading frame under the control of the stationary-phase-activated dps promoter at the dps genetic location within the right macrodomain, and vice versa, creating the open reading frame exchange (OX) strain. Chromatin immunoprecipitation sequencing (ChIP-seq) was used to measure global Fis protein binding levels and to determine gene expression patterns. Strain GX showed few changes compared with the wild type, although we did detect increased Fis binding at Ter, accompanied by reduced binding at Ori. Strain OX displayed a more pronounced version of this distorted Fis protein-binding pattern together with numerous alterations in the expression of genes in the Fis regulon. OX, but not GX, had a reduced ability to infect cultured mammalian cells. These findings illustrate the inherent robustness of the Fis regulatory network with respect to the effects of rewiring based on gene repositioning alone and emphasize the importance of fis expression signals in phenotypic determination.
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15
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Yousuf M, Iuliani I, Veetil RT, Seshasayee A, Sclavi B, Cosentino Lagomarsino M. Early fate of exogenous promoters in E. coli. Nucleic Acids Res 2020; 48:2348-2356. [PMID: 31960057 PMCID: PMC7049719 DOI: 10.1093/nar/gkz1196] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/05/2019] [Accepted: 12/20/2019] [Indexed: 01/12/2023] Open
Abstract
Gene gain by horizontal gene transfer is a major pathway of genome innovation in bacteria. The current view posits that acquired genes initially need to be silenced and that a bacterial chromatin protein, H-NS, plays a role in this silencing. However, we lack direct observation of the early fate of a horizontally transferred gene to prove this theory. We combine sequencing, flow cytometry and sorting, followed by microscopy to monitor gene expression and its variability after large-scale random insertions of a reporter gene in a population of Escherichia coli bacteria. We find that inserted promoters have a wide range of gene-expression variability related to their location. We find that high-expression clones carry insertions that are not correlated with H-NS binding. Conversely, binding of H-NS correlates with silencing. Finally, while most promoters show a common level of extrinsic noise, some insertions show higher noise levels. Analysis of these high-noise clones supports a scenario of switching due to transcriptional interference from divergent ribosomal promoters. Altogether, our findings point to evolutionary pathways where newly-acquired genes are not necessarily silenced, but may immediately explore a wide range of expression levels to probe the optimal ones.
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Affiliation(s)
- Malikmohamed Yousuf
- LBPA, UMR 8113, CNRS, ENS Paris-Saclay, 61 Avenue du President Wilson, 94235 Cachan, France
- Current Affiliation: Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Ilaria Iuliani
- LBPA, UMR 8113, CNRS, ENS Paris-Saclay, 61 Avenue du President Wilson, 94235 Cachan, France
- Current Affiliation: LCQB, UMR 7238, Sorbonne Université, 4 Place Jussieu, 75005 Paris, France
| | - Reshma T Veetil
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, Karnataka, India
- School of Life science, The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru 560064, Karnataka, India
| | - Aswin Sai Narain Seshasayee
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, Karnataka, India
| | - Bianca Sclavi
- LBPA, UMR 8113, CNRS, ENS Paris-Saclay, 61 Avenue du President Wilson, 94235 Cachan, France
- Current Affiliation: LCQB, UMR 7238, Sorbonne Université, 4 Place Jussieu, 75005 Paris, France
| | - Marco Cosentino Lagomarsino
- Sorbonne Université, Campus Pierre and Marie Curie, 4 Place Jussieu, 75005 Paris, France
- CNRS, UMR7238, 4 Place Jussieu, 75005 Paris, France
- Current Affiliation: IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, 20143 Milan, Italy
- Current Affiliation: Physics Department, University of Milan, and I.N.F.N., Via Celoria 16, 20133 Milan, Italy
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16
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The quorum sensing transcription factor AphA directly regulates natural competence in Vibrio cholerae. PLoS Genet 2019; 15:e1008362. [PMID: 31658256 PMCID: PMC6855506 DOI: 10.1371/journal.pgen.1008362] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/14/2019] [Accepted: 10/16/2019] [Indexed: 01/30/2023] Open
Abstract
Many bacteria use population density to control gene expression via quorum sensing. In Vibrio cholerae, quorum sensing coordinates virulence, biofilm formation, and DNA uptake by natural competence. The transcription factors AphA and HapR, expressed at low and high cell density respectively, play a key role. In particular, AphA triggers the entire virulence cascade upon host colonisation. In this work we have mapped genome-wide DNA binding by AphA. We show that AphA is versatile, exhibiting distinct modes of DNA binding and promoter regulation. Unexpectedly, whilst HapR is known to induce natural competence, we demonstrate that AphA also intervenes. Most notably, AphA is a direct repressor of tfoX, the master activator of competence. Hence, production of AphA markedly suppressed DNA uptake; an effect largely circumvented by ectopic expression of tfoX. Our observations suggest dual regulation of competence. At low cell density AphA is a master repressor whilst HapR activates the process at high cell density. Thus, we provide deep mechanistic insight into the role of AphA and highlight how V. cholerae utilises this regulator for diverse purposes. Cholera remains a devastating diarrhoeal disease responsible for millions of cases, thousands of deaths, and a $3 billion financial burden every year. Although notorious for causing human disease, the microorganism responsible for cholera is predominantly a resident of aquatic environments. Here, the organism survives in densely packed communities on the surfaces of crustaceans. Remarkably, in this situation, the microbe can feast on neighbouring cells and acquire their DNA. This provides a useful food source and an opportunity to obtain new genetic information. In this paper, we have investigated how acquisition of DNA from the local environment is regulated. We show that a “switch” within the microbial cell, known to activate disease processes in the human host, also controls DNA uptake. Our results explain why DNA scavenging only occurs in suitable environments and illustrates how interactions between common regulatory switches affords precise control of microbial behaviours.
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17
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Kettles RA, Tschowri N, Lyons KJ, Sharma P, Hengge R, Webber MA, Grainger DC. The Escherichia coli MarA protein regulates the ycgZ-ymgABC operon to inhibit biofilm formation. Mol Microbiol 2019; 112:1609-1625. [PMID: 31518447 PMCID: PMC6900184 DOI: 10.1111/mmi.14386] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Escherichia coli marRAB operon is a paradigm for chromosomally encoded antibiotic resistance. The operon exerts its effect via an encoded transcription factor called MarA that modulates efflux pump and porin expression. In this work, we show that MarA is also a regulator of biofilm formation. Control is mediated by binding of MarA to the intergenic region upstream of the ycgZ-ymgABC operon. The operon, known to influence the formation of curli fibres and colanic acid, is usually expressed during periods of starvation. Hence, the ycgZ-ymgABC promoter is recognised by σ38 (RpoS)-associated RNA polymerase (RNAP). Surprisingly, MarA does not influence σ38 -dependent transcription. Instead, MarA drives transcription by the housekeeping σ70 -associated RNAP. The effects of MarA on ycgZ-ymgABC expression are coupled with biofilm formation by the rcsCDB phosphorelay system, with YcgZ, YmgA and YmgB forming a complex that directly interacts with the histidine kinase domain of RcsC.
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Affiliation(s)
- Rachel A Kettles
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Natalia Tschowri
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Kevin J Lyons
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Prateek Sharma
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Regine Hengge
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Mark A Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - David C Grainger
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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18
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Structural basis for transcription activation by Crl through tethering of σ S and RNA polymerase. Proc Natl Acad Sci U S A 2019; 116:18923-18927. [PMID: 31484766 DOI: 10.1073/pnas.1910827116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In bacteria, a primary σ-factor associates with the core RNA polymerase (RNAP) to control most transcription initiation, while alternative σ-factors are used to coordinate expression of additional regulons in response to environmental conditions. Many alternative σ-factors are negatively regulated by anti-σ-factors. In Escherichia coli, Salmonella enterica, and many other γ-proteobacteria, the transcription factor Crl positively regulates the alternative σS-regulon by promoting the association of σS with RNAP without interacting with promoter DNA. The molecular mechanism for Crl activity is unknown. Here, we determined a single-particle cryo-electron microscopy structure of Crl-σS-RNAP in an open promoter complex with a σS-regulon promoter. In addition to previously predicted interactions between Crl and domain 2 of σS (σS 2), the structure, along with p-benzoylphenylalanine cross-linking, reveals that Crl interacts with a structural element of the RNAP β'-subunit that we call the β'-clamp-toe (β'CT). Deletion of the β'CT decreases activation by Crl without affecting basal transcription, highlighting the functional importance of the Crl-β'CT interaction. We conclude that Crl activates σS-dependent transcription in part through stabilizing σS-RNAP by tethering σS 2 and the β'CT. We propose that Crl, and other transcription activators that may use similar mechanisms, be designated σ-activators.
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19
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Abstract
The global regulatory protein CsrA coordinates gene expression in response to physiological cues reflecting cellular stress and nutrition. CsrA binding to the 5' segments of mRNA targets affects their translation, RNA stability, and/or transcript elongation. Recent studies identified probable mRNA targets of CsrA that are involved in iron uptake and storage in Escherichia coli, suggesting an unexplored role for CsrA in regulating iron homeostasis. Here, we assessed the impact of CsrA on iron-related gene expression, cellular iron, and growth under various iron levels. We investigated five new targets of CsrA regulation, including the genes for 4 ferritin or ferritin-like iron storage proteins (ISPs) and the stress-inducible Fe-S repair protein, SufA. CsrA bound with high affinity and specificity to ftnB, bfr, and dps mRNAs and inhibited their translation, while it modestly activated ftnA expression. Furthermore, CsrA was found to regulate cellular iron levels and support growth by repressing the expression of genes for ISPs, most importantly, ferritin B (FtnB) and bacterioferritin (Bfr). Iron starvation did not substantially affect cellular levels of CsrA or its small RNA (sRNA) antagonists, CsrB and CsrC. csrA disruption led to increased resistance to the lethal effects of H2O2 during exponential growth, consistent with a regulatory role in oxidative stress resistance. We propose that during exponential growth and under minimal stress, CsrA represses the deleterious expression of the ISPs that function under oxidative stress and stationary-phase conditions (FtnB, Bfr, and Dps), thus ensuring that cellular iron is available to processes that are required for growth.IMPORTANCE Iron is an essential micronutrient for nearly all living organisms but is toxic in excess. Consequently, the maintenance of iron homeostasis is a critical biological process, and the genes involved in this function are tightly regulated. Here, we explored a new role for the bacterial RNA binding protein CsrA in the regulation of iron homeostasis. CsrA was shown to be a key regulator of iron storage genes in Escherichia coli, with consequential effects on cellular iron levels and growth. Our findings establish a model in which robust CsrA activity during the exponential phase of growth leads to repression of genes whose products sequester iron or divert it to unnecessary stress response processes. In so doing, CsrA supports E. coli growth under iron-limiting laboratory conditions and may promote fitness in the competitive iron-limited environment of the host large intestine.
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20
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Retnoningrum DS, Santika IWM, Kesuma S, Ekowati SA, Riani C. Construction and Characterization of a Medium Copy Number Expression Vector Carrying Auto-Inducible dps Promoter to Overproduce a Bacterial Superoxide Dismutase in Escherichia coli. Mol Biotechnol 2019; 61:231-240. [PMID: 30721405 DOI: 10.1007/s12033-018-00151-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Medium copy number expression vector and auto-inducible promoter could be a solution for producing recombinant therapeutic proteins in industrial scale regarding plasmid stability, cost, and product quality. This work aimed to construct a medium copy number pBR322-based expression vector carrying auto-inducible promoter, determine its ability to express heterologous gene, and study its segregational stability. Three stationary-phase promoters of Escherichia coli genes (gadA, dps and sbmC) were used to produce a superoxide dismutase from Staphylococcus equorum (rMnSODSeq) coding region from pBR322Δtet (pBR322-mini). Four plasmids were constructed with different promoters, i.e., T7 (pBMsod), gadA (pMCDsod), dps (pCADsod), and sbmC (pCDSsod) using pBR322-mini as backbone. Results showed that rMnSODSeq expression from pBMsod was significantly higher than that from pJExpress414sod (high copy number plasmid). Meanwhile, rMnSODSeq from pCADsod (auto-inducible promoter) was as high as from pBMsod (IPTG-inducible T7 promoter). rMnSODSeq expressed from pCADsod when bacterial cells entered stationary phase appeared as an active protein band of 23.5 kDa when analyzed by zymography and SDS-PAGE. pCADsod displayed the highest stability compared with pBMsod and pJEXpress414sod by plasmid retention assay. We demonstrate the use of an auto-inducible dps promoter to express high level of heterologous protein, an SOD of S. equorum, from a stable expression vector with medium copy number.
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Affiliation(s)
- Debbie Soefie Retnoningrum
- Laboratory of Pharmaceutical Biotechnology, School of Pharmacy, Institut Teknologi Bandung, Bandung, 40132, Indonesia.
| | - I Wayan Martadi Santika
- Laboratory of Pharmaceutical Biotechnology, School of Pharmacy, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - Suryanata Kesuma
- Laboratory of Pharmaceutical Biotechnology, School of Pharmacy, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - Syahdu Ayu Ekowati
- Laboratory of Pharmaceutical Biotechnology, School of Pharmacy, Institut Teknologi Bandung, Bandung, 40132, Indonesia
| | - Catur Riani
- Laboratory of Pharmaceutical Biotechnology, School of Pharmacy, Institut Teknologi Bandung, Bandung, 40132, Indonesia
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21
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Flores-Ríos R, Quatrini R, Loyola A. Endogenous and Foreign Nucleoid-Associated Proteins of Bacteria: Occurrence, Interactions and Effects on Mobile Genetic Elements and Host's Biology. Comput Struct Biotechnol J 2019; 17:746-756. [PMID: 31303979 PMCID: PMC6606824 DOI: 10.1016/j.csbj.2019.06.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/05/2019] [Accepted: 06/11/2019] [Indexed: 02/08/2023] Open
Abstract
Mobile Genetic Elements (MGEs) are mosaics of functional gene modules of diverse evolutionary origin and are generally divergent from the hosts´ genetic background. Existing biases in base composition and codon usage of these elements` genes impose transcription and translation limitations that may affect the physical and regulatory integration of MGEs in new hosts. Stable appropriation of the foreign DNA depends on a number of host factors among which are the Nucleoid-Associated Proteins (NAPs). These small, basic, highly abundant proteins bind and bend DNA, altering its topology and folding, thereby affecting all known essential DNA metabolism related processes. Both chromosomally- (endogenous) and MGE- (foreign) encoded NAPs have been shown to exist in bacteria. While the role of host-encoded NAPs in xenogeneic silencing of both episomal (plasmids) and integrative MGEs (pathogenicity islands and prophages) is well acknowledged, less is known about the role of MGE-encoded NAPs in the foreign elements biology or their influence on the host's chromosome expression dynamics. Here we review existing literature on the topic, present examples on the positive and negative effects that endogenous and foreign NAPs exert on global transcriptional gene expression, MGE integrative and excisive recombination dynamics, persistence and transfer to suitable hosts and discuss the nature and relevance of synergistic and antagonizing higher order interactions between diverse types of NAPs.
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Affiliation(s)
| | - Raquel Quatrini
- Fundación Ciencia y Vida, Avenida Zañartu 1482, Ñuñoa, Santiago, Chile.,Millennium Nucleus in the Biology of Intestinal Microbiota, Santiago, Chile
| | - Alejandra Loyola
- Fundación Ciencia y Vida, Avenida Zañartu 1482, Ñuñoa, Santiago, Chile
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22
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Browning DF, Butala M, Busby SJW. Bacterial Transcription Factors: Regulation by Pick "N" Mix. J Mol Biol 2019; 431:4067-4077. [PMID: 30998934 DOI: 10.1016/j.jmb.2019.04.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/03/2019] [Accepted: 04/08/2019] [Indexed: 10/27/2022]
Abstract
Transcription in most bacteria is tightly regulated in order to facilitate bacterial adaptation to different environments, and transcription factors play a key role in this. Here we give a brief overview of the essential features of bacterial transcription factors and how they affect transcript initiation at target promoters. We focus on complex promoters that are regulated by combinations of activators and repressors, combinations of repressors only, or combinations of activators. At some promoters, transcript initiation is regulated by nucleoid-associated proteins, which often work together with transcription factors. We argue that the distinction between nucleoid-associated proteins and transcription factors is blurred and that they likely share common origins.
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Affiliation(s)
- Douglas F Browning
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Matej Butala
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Stephen J W Busby
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
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23
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The Escherichia coli multiple antibiotic resistance activator protein represses transcription of the lac operon. Biochem Soc Trans 2019; 47:671-677. [PMID: 30850424 DOI: 10.1042/bst20180498] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/30/2019] [Accepted: 02/04/2019] [Indexed: 11/17/2022]
Abstract
In Escherichia coli, the marRAB operon is a determinant for antibiotic resistance. Such phenotypes require the encoded transcription factor MarA that activates efflux pump expression. To better understand all genes controlled by MarA, we recently mapped binding of the regulator across the E. coli genome. As expected, many MarA targets were adjacent to genes encoding stress response systems. Surprisingly, one MarA-binding site overlapped the lac operon regulatory region. Here, we show that MarA specifically targets this locus and can block transcription of the lac genes. Repression is mediated by binding of MarA to a site overlapping the lacP1 promoter -35 element. Control of the lac operon by MarA does not impact antibiotic resistance.
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24
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Chen J, Wassarman KM, Feng S, Leon K, Feklistov A, Winkelman JT, Li Z, Walz T, Campbell EA, Darst SA. 6S RNA Mimics B-Form DNA to Regulate Escherichia coli RNA Polymerase. Mol Cell 2017; 68:388-397.e6. [PMID: 28988932 DOI: 10.1016/j.molcel.2017.09.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/11/2017] [Accepted: 09/05/2017] [Indexed: 01/25/2023]
Abstract
Noncoding RNAs (ncRNAs) regulate gene expression in all organisms. Bacterial 6S RNAs globally regulate transcription by binding RNA polymerase (RNAP) holoenzyme and competing with promoter DNA. Escherichia coli (Eco) 6S RNA interacts specifically with the housekeeping σ70-holoenzyme (Eσ70) and plays a key role in the transcriptional reprogramming upon shifts between exponential and stationary phase. Inhibition is relieved upon 6S RNA-templated RNA synthesis. We report here the 3.8 Å resolution structure of a complex between 6S RNA and Eσ70 determined by single-particle cryo-electron microscopy and validation of the structure using footprinting and crosslinking approaches. Duplex RNA segments have A-form C3' endo sugar puckers but widened major groove widths, giving the RNA an overall architecture that mimics B-form promoter DNA. Our results help explain the specificity of Eco 6S RNA for Eσ70 and show how an ncRNA can mimic B-form DNA to directly regulate transcription by the DNA-dependent RNAP.
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Affiliation(s)
- James Chen
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Karen M Wassarman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Shili Feng
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Katherine Leon
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Andrey Feklistov
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Jared T Winkelman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Zongli Li
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA.
| | - Seth A Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA.
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25
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Antipov SS, Tutukina MN, Preobrazhenskaya EV, Kondrashov FA, Patrushev MV, Toshchakov SV, Dominova I, Shvyreva US, Vrublevskaya VV, Morenkov OS, Sukharicheva NA, Panyukov VV, Ozoline ON. The nucleoid protein Dps binds genomic DNA of Escherichia coli in a non-random manner. PLoS One 2017; 12:e0182800. [PMID: 28800583 PMCID: PMC5553809 DOI: 10.1371/journal.pone.0182800] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 07/25/2017] [Indexed: 11/18/2022] Open
Abstract
Dps is a multifunctional homododecameric protein that oxidizes Fe2+ ions accumulating them in the form of Fe2O3 within its protein cavity, interacts with DNA tightly condensing bacterial nucleoid upon starvation and performs some other functions. During the last two decades from discovery of this protein, its ferroxidase activity became rather well studied, but the mechanism of Dps interaction with DNA still remains enigmatic. The crucial role of lysine residues in the unstructured N-terminal tails led to the conventional point of view that Dps binds DNA without sequence or structural specificity. However, deletion of dps changed the profile of proteins in starved cells, SELEX screen revealed genomic regions preferentially bound in vitro and certain affinity of Dps for artificial branched molecules was detected by atomic force microscopy. Here we report a non-random distribution of Dps binding sites across the bacterial chromosome in exponentially growing cells and show their enrichment with inverted repeats prone to form secondary structures. We found that the Dps-bound regions overlap with sites occupied by other nucleoid proteins, and contain overrepresented motifs typical for their consensus sequences. Of the two types of genomic domains with extensive protein occupancy, which can be highly expressed or transcriptionally silent only those that are enriched with RNA polymerase molecules were preferentially occupied by Dps. In the dps-null mutant we, therefore, observed a differentially altered expression of several targeted genes and found suppressed transcription from the dps promoter. In most cases this can be explained by the relieved interference with Dps for nucleoid proteins exploiting sequence-specific modes of DNA binding. Thus, protecting bacterial cells from different stresses during exponential growth, Dps can modulate transcriptional integrity of the bacterial chromosome hampering RNA biosynthesis from some genes via competition with RNA polymerase or, vice versa, competing with inhibitors to activate transcription.
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Affiliation(s)
- S. S. Antipov
- Department of Functional Genomics and Cellular Stress, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
- Department of Cell Biology, Pushchino State Institute of Natural Sciences, Pushchino, Moscow Region, Russian Federation
- Department of Biophysics and Biotechnology, Voronezh State University, Voronezh, Russian Federation
- Department of Genomics of Microorganisms, Immanuel Kant Baltic Federal University, Kaliningrad, Russian Federation
| | - M. N. Tutukina
- Department of Functional Genomics and Cellular Stress, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG) Barcelona, Spain
- Department of Evolutionary Genomics, Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Department of Structural and Functional Genomics,–Pushchino Research Center of the Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - E. V. Preobrazhenskaya
- Department of Functional Genomics and Cellular Stress, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - F. A. Kondrashov
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG) Barcelona, Spain
- Department of Evolutionary Genomics, Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 23 Pg. Lluís Companys, Barcelona, Spain
| | - M. V. Patrushev
- Department of Genomics of Microorganisms, Immanuel Kant Baltic Federal University, Kaliningrad, Russian Federation
| | - S. V. Toshchakov
- Department of Genomics of Microorganisms, Immanuel Kant Baltic Federal University, Kaliningrad, Russian Federation
| | - I. Dominova
- Department of Genomics of Microorganisms, Immanuel Kant Baltic Federal University, Kaliningrad, Russian Federation
| | - U. S. Shvyreva
- Department of Functional Genomics and Cellular Stress, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - V. V. Vrublevskaya
- Department of Cell Culture and Cell Engeneering, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - O. S. Morenkov
- Department of Cell Culture and Cell Engeneering, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - N. A. Sukharicheva
- Department of Functional Genomics and Cellular Stress, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - V. V. Panyukov
- Department of Structural and Functional Genomics,–Pushchino Research Center of the Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
- Department of Bioinformatics, Institute of Mathematical Problems of Biology—the Branch of Keldysh Institute of Applied Mathematics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
| | - O. N. Ozoline
- Department of Functional Genomics and Cellular Stress, Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
- Department of Cell Biology, Pushchino State Institute of Natural Sciences, Pushchino, Moscow Region, Russian Federation
- Department of Structural and Functional Genomics,–Pushchino Research Center of the Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation
- * E-mail:
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26
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de la Campa AG, Ferrándiz MJ, Martín-Galiano AJ, García MT, Tirado-Vélez JM. The Transcriptome of Streptococcus pneumoniae Induced by Local and Global Changes in Supercoiling. Front Microbiol 2017; 8:1447. [PMID: 28824578 PMCID: PMC5534458 DOI: 10.3389/fmicb.2017.01447] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/17/2017] [Indexed: 01/28/2023] Open
Abstract
The bacterial chromosome is compacted in a manner optimal for DNA transactions to occur. The degree of compaction results from the level of DNA-supercoiling and the presence of nucleoid-binding proteins. DNA-supercoiling is homeostatically maintained by the opposing activities of relaxing DNA topoisomerases and negative supercoil-inducing DNA gyrase. DNA-supercoiling acts as a general cis regulator of transcription, which can be superimposed upon other types of more specific trans regulatory mechanism. Transcriptomic studies on the human pathogen Streptococcus pneumoniae, which has a relatively small genome (∼2 Mb) and few nucleoid-binding proteins, have been performed under conditions of local and global changes in supercoiling. The response to local changes induced by fluoroquinolone antibiotics, which target DNA gyrase subunit A and/or topoisomerase IV, involves an increase in oxygen radicals which reduces cell viability, while the induction of global supercoiling changes by novobiocin (a DNA gyrase subunit B inhibitor), or by seconeolitsine (a topoisomerase I inhibitor), has revealed the existence of topological domains that specifically respond to such changes. The control of DNA-supercoiling in S. pneumoniae occurs mainly via the regulation of topoisomerase gene transcription: relaxation triggers the up-regulation of gyrase and the down-regulation of topoisomerases I and IV, while hypernegative supercoiling down-regulates the expression of topoisomerase I. Relaxation affects 13% of the genome, with the majority of the genes affected located in 15 domains. Hypernegative supercoiling affects 10% of the genome, with one quarter of the genes affected located in 12 domains. However, all the above domains overlap, suggesting that the chromosome is organized into topological domains with fixed locations. Based on its response to relaxation, the pneumococcal chromosome can be said to be organized into five types of domain: up-regulated, down-regulated, position-conserved non-regulated, position-variable non-regulated, and AT-rich. The AT content is higher in the up-regulated than in the down-regulated domains. Genes within the different domains share structural and functional characteristics. It would seem that a topology-driven selection pressure has defined the chromosomal location of the metabolism, virulence and competence genes, which suggests the existence of topological rules that aim to improve bacterial fitness.
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Affiliation(s)
- Adela G de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain.,Presidencia, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - María J Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - Antonio J Martín-Galiano
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - María T García
- Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad ComplutenseMadrid, Spain
| | - Jose M Tirado-Vélez
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
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Structure and function of bacterial H-NS protein. Biochem Soc Trans 2017; 44:1561-1569. [PMID: 27913665 DOI: 10.1042/bst20160190] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 08/05/2016] [Accepted: 08/09/2016] [Indexed: 01/10/2023]
Abstract
The histone-like nucleoid structuring (H-NS) protein is a major component of the folded chromosome in Escherichia coli and related bacteria. Functions attributed to H-NS include management of genome evolution, DNA condensation, and transcription. The wide-ranging influence of H-NS is remarkable given the simplicity of the protein, a small peptide, possessing rudimentary determinants for self-association, hetero-oligomerisation and DNA binding. In this review, I will discuss our understanding of H-NS with a focus on these structural elements. In particular, I will consider how these interaction surfaces allow H-NS to exert its different effects.
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28
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Feijoo-Siota L, Rama JLR, Sánchez-Pérez A, Villa TG. Considerations on bacterial nucleoids. Appl Microbiol Biotechnol 2017; 101:5591-5602. [PMID: 28664324 DOI: 10.1007/s00253-017-8381-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 12/21/2022]
Abstract
The classic genome organization of the bacterial chromosome is normally envisaged with all its genetic markers linked, thus forming a closed genetic circle of duplex stranded DNA (dsDNA) and several proteins in what it is called as "the bacterial nucleoid." This structure may be more or less corrugated depending on the physiological state of the bacterium (i.e., resting state or active growth) and is not surrounded by a double membrane as in eukayotic cells. The universality of the closed circle model in bacteria is however slowly changing, as new data emerge in different bacterial groups such as in Planctomycetes and related microorganisms, species of Borrelia, Streptomyces, Agrobacterium, or Phytoplasma. In these and possibly other microorganisms, the existence of complex formations of intracellular membranes or linear chromosomes is typical; all of these situations contributing to weakening the current cellular organization paradigm, i.e., prokaryotic vs eukaryotic cells.
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Affiliation(s)
- Lucía Feijoo-Siota
- Department of Microbiology, Biotechnology Unit, Faculty of Pharmacy, University of Santiago de Compostela, 15706, Santiago de Compostela, Spain
| | - José Luis R Rama
- Department of Microbiology, Biotechnology Unit, Faculty of Pharmacy, University of Santiago de Compostela, 15706, Santiago de Compostela, Spain
| | - Angeles Sánchez-Pérez
- Discipline of Physiology and Bosch Institute, School of Medical Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Tomás G Villa
- Department of Microbiology, Biotechnology Unit, Faculty of Pharmacy, University of Santiago de Compostela, 15706, Santiago de Compostela, Spain.
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29
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Godfrey RE, Lee DJ, Busby SJW, Browning DF. Regulation of nrf operon expression in pathogenic enteric bacteria: sequence divergence reveals new regulatory complexity. Mol Microbiol 2017; 104:580-594. [PMID: 28211111 PMCID: PMC5434802 DOI: 10.1111/mmi.13647] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2017] [Indexed: 12/11/2022]
Abstract
The Escherichia coli K‐12 nrf operon encodes a periplasmic nitrite reductase, the expression of which is driven from a single promoter, pnrf. Expression from pnrf is activated by the FNR transcription factor in response to anaerobiosis and further increased in response to nitrite by the response regulator proteins, NarL and NarP. FNR‐dependent transcription is suppressed by the binding of two nucleoid associated proteins, IHF and Fis. As Fis levels increase in cells grown in rich medium, the positioning of its binding site, overlapping the promoter −10 element, ensures that pnrf is sharply repressed. Here, we investigate the expression of the nrf operon promoter from various pathogenic enteric bacteria. We show that pnrf from enterohaemorrhagic E. coli is more active than its K‐12 counterpart, exhibits substantial FNR‐independent activity and is insensitive to nutrient quality, due to an improved −10 element. We also demonstrate that the Salmonella enterica serovar Typhimurium core promoter is more active than previously thought, due to differences around the transcription start site, and that its expression is repressed by downstream sequences. We identify the CsrA RNA binding protein as being responsible for this, and show that CsrA differentially regulates the E. coli K‐12 and Salmonella nrf operons.
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Affiliation(s)
- Rita E Godfrey
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - David J Lee
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.,Department of Life Sciences, School of Health Sciences, Birmingham City University, Birmingham, B15 3TN, UK
| | - Stephen J W Busby
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Douglas F Browning
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
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30
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Horizontally acquired AT-rich genes in Escherichia coli cause toxicity by sequestering RNA polymerase. Nat Microbiol 2017; 2:16249. [PMID: 28067866 DOI: 10.1038/nmicrobiol.2016.249] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/08/2016] [Indexed: 11/09/2022]
Abstract
Horizontal gene transfer permits rapid dissemination of genetic elements between individuals in bacterial populations. Transmitted DNA sequences may encode favourable traits. However, if the acquired DNA has an atypical base composition, it can reduce host fitness. Consequently, bacteria have evolved strategies to minimize the harmful effects of foreign genes. Most notably, xenogeneic silencing proteins bind incoming DNA that has a higher AT content than the host genome. An enduring question has been why such sequences are deleterious. Here, we showed that the toxicity of AT-rich DNA in Escherichia coli frequently results from constitutive transcription initiation within the coding regions of genes. Left unchecked, this causes titration of RNA polymerase and a global downshift in host gene expression. Accordingly, a mutation in RNA polymerase that diminished the impact of AT-rich DNA on host fitness reduced transcription from constitutive, but not activator-dependent, promoters.
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31
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Milosavljevic V, Jelinkova P, Jimenez Jimenez AM, Moulick A, Haddad Y, Buchtelova H, Krizkova S, Heger Z, Kalina L, Richtera L, Kopel P, Adam V. Alternative Synthesis Route of Biocompatible Polyvinylpyrrolidone Nanoparticles and Their Effect on Pathogenic Microorganisms. Mol Pharm 2016; 14:221-233. [PMID: 27943679 DOI: 10.1021/acs.molpharmaceut.6b00807] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herein we describe a novel alternative synthesis route of polyvinylpyrrolidone nanoparticles using salting-out method at a temperature close to polyvinylpyrrolidone decomposition. At elevated temperatures, the stability of polyvinylpyrrolidone decreases and the opening of pyrrolidone ring fractions occurs. This leads to cross-linking process, where separate units of polyvinylpyrrolidone interact among themselves and rearrange to form nanoparticles. The formation/stability of these nanoparticles was confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, mass spectrometry, infrared spectroscopy, and spectrophotometry. The obtained nanoparticles possess exceptional biocompatibility. No toxicity and genotoxicity was found in normal human prostate epithelium cells (PNT1A) together with their high hemocompatibility. The antimicrobial effects of polyvinylpyrrolidone nanoparticles were tested on bacterial strains isolated from the wounds of patients suffering from hard-to-heal infections. Molecular analysis (qPCR) confirmed that the treatment can induce the regulation of stress-related survival genes. Our results strongly suggest that the polyvinylpyrrolidone nanoparticles have great potential to be developed into a novel antibacterial compound.
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Affiliation(s)
- Vedran Milosavljevic
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic
| | - Pavlina Jelinkova
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic
| | - Ana Maria Jimenez Jimenez
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Amitava Moulick
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Yazan Haddad
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Hana Buchtelova
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic
| | - Sona Krizkova
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Zbynek Heger
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Lukas Kalina
- Materials Research Centre, Faculty of Chemistry, Brno University of Technology , Purkynova 118, Brno CZ-612 00, Czech Republic
| | - Lukas Richtera
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Pavel Kopel
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
| | - Vojtech Adam
- Department of Chemistry and Biochemistry, Mendel University in Brno , Zemedelska 1, CZ-613 00 Brno, Czech Republic.,Central European Institute of Technology, Brno University of Technology , Technicka 3058/10, CZ-616 00 Brno, Czech Republic
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32
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Ghosh IN, Landick R. OptSSeq: High-Throughput Sequencing Readout of Growth Enrichment Defines Optimal Gene Expression Elements for Homoethanologenesis. ACS Synth Biol 2016; 5:1519-1534. [PMID: 27404024 DOI: 10.1021/acssynbio.6b00121] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The optimization of synthetic pathways is a central challenge in metabolic engineering. OptSSeq (Optimization by Selection and Sequencing) is one approach to this challenge. OptSSeq couples selection of optimal enzyme expression levels linked to cell growth rate with high-throughput sequencing to track enrichment of gene expression elements (promoters and ribosome-binding sites) from a combinatorial library. OptSSeq yields information on both optimal and suboptimal enzyme levels, and helps identify constraints that limit maximal product formation. Here we report a proof-of-concept implementation of OptSSeq using homoethanologenesis, a two-step pathway consisting of pyruvate decarboxylase (Pdc) and alcohol dehydrogenase (Adh) that converts pyruvate to ethanol and is naturally optimized in the bacterium Zymomonas mobilis. We used OptSSeq to determine optimal gene expression elements and enzyme levels for Z. mobilis Pdc, AdhA, and AdhB expressed in Escherichia coli. By varying both expression signals and gene order, we identified an optimal solution using only Pdc and AdhB. We resolved current uncertainty about the functions of the Fe2+-dependent AdhB and Zn2+-dependent AdhA by showing that AdhB is preferred over AdhA for rapid growth in both E. coli and Z. mobilis. Finally, by comparing predictions of growth-linked metabolic flux to enzyme synthesis costs, we established that optimal E. coli homoethanologenesis was achieved by our best pdc-adhB expression cassette and that the remaining constraints lie in the E. coli metabolic network or inefficient Pdc or AdhB function in E. coli. OptSSeq is a general tool for synthetic biology to tune enzyme levels in any pathway whose optimal function can be linked to cell growth or survival.
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Affiliation(s)
- Indro Neil Ghosh
- DOE
Great Lakes Bioenergy Research Center, University of Wisconsin—Madison, Madison, Wisconsin 53726, United States
| | - Robert Landick
- DOE
Great Lakes Bioenergy Research Center, University of Wisconsin—Madison, Madison, Wisconsin 53726, United States
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33
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Flint A, Stintzi A, Saraiva LM. Oxidative and nitrosative stress defences of Helicobacter and Campylobacter species that counteract mammalian immunity. FEMS Microbiol Rev 2016; 40:938-960. [PMID: 28201757 PMCID: PMC5091033 DOI: 10.1093/femsre/fuw025] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/29/2016] [Accepted: 07/02/2016] [Indexed: 12/18/2022] Open
Abstract
Helicobacter and Campylobacter species are Gram-negative microaerophilic host-associated heterotrophic bacteria that invade the digestive tract of humans and animals. Campylobacter jejuni is the major worldwide cause of foodborne gastroenteritis in humans, while Helicobacter pylori is ubiquitous in over half of the world's population causing gastric and duodenal ulcers. The colonisation of the gastrointestinal system by Helicobacter and Campylobacter relies on numerous cellular defences to sense the host environment and respond to adverse conditions, including those imposed by the host immunity. An important antimicrobial tool of the mammalian innate immune system is the generation of harmful oxidative and nitrosative stresses to which pathogens are exposed during phagocytosis. This review summarises the regulators, detoxifying enzymes and subversion mechanisms of Helicobacter and Campylobacter that ultimately promote the successful infection of humans.
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Affiliation(s)
- Annika Flint
- Ottawa Institute of Systems Biology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Alain Stintzi
- Ottawa Institute of Systems Biology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Lígia M. Saraiva
- Instituto de Tecnologia Química e Biológica, NOVA, Av. da República, 2780-157 Oeiras, Portugal
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34
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Tan L, Moriel DG, Totsika M, Beatson SA, Schembri MA. Differential Regulation of the Surface-Exposed and Secreted SslE Lipoprotein in Extraintestinal Pathogenic Escherichia coli. PLoS One 2016; 11:e0162391. [PMID: 27598999 PMCID: PMC5012682 DOI: 10.1371/journal.pone.0162391] [Citation(s) in RCA: 8] [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: 02/14/2016] [Accepted: 08/22/2016] [Indexed: 11/19/2022] Open
Abstract
Extra-intestinal pathogenic Escherichia coli (ExPEC) are responsible for diverse infections including meningitis, sepsis and urinary tract infections. The alarming rise in anti-microbial resistance amongst ExPEC complicates treatment and has highlighted the need for alternative preventive measures. SslE is a lipoprotein secreted by a dedicated type II secretion system in E. coli that was first identified as a potential vaccine candidate using reverse genetics. Although the function and protective efficacy of SslE has been studied, the molecular mechanisms that regulate SslE expression remain to be fully elucidated. Here, we show that while the expression of SslE can be detected in E. coli culture supernatants, different strains express and secrete different amounts of SslE when grown under the same conditions. While the histone-like transcriptional regulator H-NS strongly represses sslE at ambient temperatures, the variation in SslE expression at human physiological temperature suggested a more complex mode of regulation. Using a genetic screen to identify novel regulators of sslE in the high SslE-expressing strain UTI89, we defined a new role for the nucleoid-associated regulator Fis and the ribosome-binding GTPase TypA as positive regulators of sslE transcription. We also showed that Fis-mediated enhancement of sslE transcription is dependent on a putative Fis-binding sequence located upstream of the -35 sequence in the core promoter element, and provide evidence to suggest that Fis may work in complex with H-NS to control SslE expression. Overall, this study has defined a new mechanism for sslE regulation and increases our understanding of this broadly conserved E. coli vaccine antigen.
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Affiliation(s)
- Lendl Tan
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, QLD 4072, Brisbane, Australia
| | - Danilo G. Moriel
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, QLD 4072, Brisbane, Australia
| | - Makrina Totsika
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, QLD 4059, Brisbane, Australia
| | - Scott A. Beatson
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, QLD 4072, Brisbane, Australia
| | - Mark A. Schembri
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, QLD 4072, Brisbane, Australia
- * E-mail:
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35
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Bergkessel M, Basta DW, Newman DK. The physiology of growth arrest: uniting molecular and environmental microbiology. Nat Rev Microbiol 2016; 14:549-62. [PMID: 27510862 PMCID: PMC10069271 DOI: 10.1038/nrmicro.2016.107] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Most bacteria spend the majority of their time in prolonged states of very low metabolic activity and little or no growth, in which electron donors, electron acceptors and/or nutrients are limited, but cells are poised to undergo rapid division cycles when resources become available. These non-growing states are far less studied than other growth states, which leaves many questions regarding basic bacterial physiology unanswered. In this Review, we discuss findings from a small but diverse set of systems that have been used to investigate how growth-arrested bacteria adjust metabolism, regulate transcription and translation, and maintain their chromosomes. We highlight major questions that remain to be addressed, and suggest that progress in answering them will be aided by recent methodological advances and by dialectic between environmental and molecular microbiology perspectives.
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36
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37
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Melkina OE, Goryanin II, Zavilgelsky GB. The DNA-mimic antirestriction proteins ArdA ColIB-P9, Arn T4, and Ocr T7 as activators of H-NS-dependent gene transcription. Microbiol Res 2016; 192:283-291. [PMID: 27664747 DOI: 10.1016/j.micres.2016.07.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 07/16/2016] [Accepted: 07/28/2016] [Indexed: 11/16/2022]
Abstract
The antirestriction proteins ArdA ColIb-P9, Arn T4 and Ocr T7 specifically inhibit type I and type IV restriction enzymes and belong to the family of DNA-mimic proteins because their three-dimensional structure is similar to the double-helical B-form DNA. It is proposed that the DNA-mimic proteins are able to bind nucleoid protein H-NS and alleviate H-NS-silencing of the transcription of bacterial genes. Escherichia coli lux biosensors were constructed by inserting H-NS-dependent promoters into a vector, thereby placing each fragment upstream of the promoterless Photorhabdus luminescens luxCDABE operon. It was demonstrated that the DNA-mimic proteins ArdA, Arn and Ocr activate the transcription of H-NS-dependent promoters of the lux operon of marine luminescent bacteria (mesophilic Aliivibrio fischeri and psychrophilic Aliivibrio logei), and the dps gene from E. coli. It was also demonstrated that the ArdA antirestriction protein, the genes of which are located on transmissive plasmids ColIb-P9, R64, PK101, decreases levels of H-NS silencing of the PluxC promoter during conjugation in the recipient bacteria.
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Affiliation(s)
- Olga E Melkina
- Laboratory of Bacterial Genetics, State Research Institute of Genetics and Selection of Industrial Microorganisms (GosNIIgenetika), 1-st Dorozhniy Pr., 1, Moscow 117545, Russia
| | - Ignatiy I Goryanin
- Laboratory of Bacterial Genetics, State Research Institute of Genetics and Selection of Industrial Microorganisms (GosNIIgenetika), 1-st Dorozhniy Pr., 1, Moscow 117545, Russia; Laboratory of Molecular Genetics, Moscow Institute of Physics and Technology, 9 Instituitsky per., Dolgoprudny, Moscow Region 141700, Russia
| | - Gennadii B Zavilgelsky
- Laboratory of Bacterial Genetics, State Research Institute of Genetics and Selection of Industrial Microorganisms (GosNIIgenetika), 1-st Dorozhniy Pr., 1, Moscow 117545, Russia.
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38
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Haycocks JRJ, Grainger DC. Unusually Situated Binding Sites for Bacterial Transcription Factors Can Have Hidden Functionality. PLoS One 2016; 11:e0157016. [PMID: 27258043 PMCID: PMC4892627 DOI: 10.1371/journal.pone.0157016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/23/2016] [Indexed: 01/13/2023] Open
Abstract
A commonly accepted paradigm of molecular biology is that transcription factors control gene expression by binding sites at the 5' end of a gene. However, there is growing evidence that transcription factor targets can occur within genes or between convergent genes. In this work, we have investigated one such target for the cyclic AMP receptor protein (CRP) of enterotoxigenic Escherichia coli. We show that CRP binds between two convergent genes. When bound, CRP regulates transcription of a small open reading frame, which we term aatS, embedded within one of the adjacent genes. Our work demonstrates that non-canonical sites of transcription factor binding can have hidden functionality.
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Affiliation(s)
- James R. J. Haycocks
- Institute of Microbiology and Infection, School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - David C. Grainger
- Institute of Microbiology and Infection, School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail:
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39
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De Martino M, Ershov D, van den Berg PJ, Tans SJ, Meyer AS. Single-Cell Analysis of the Dps Response to Oxidative Stress. J Bacteriol 2016; 198:1662-1674. [PMID: 27021559 PMCID: PMC4959295 DOI: 10.1128/jb.00239-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/20/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Microorganisms have developed an elaborate spectrum of mechanisms to respond and adapt to environmental stress conditions. Among these is the expression of dps, coding for the DNA-binding protein from starved cells. Dps becomes the dominant nucleoid-organizing protein in stationary-phase Escherichia coli cells and is required for robust survival under stress conditions, including carbon or nitrogen starvation, oxidative stress, metal exposure, and irradiation. To study the complex regulation of Dps in E. coli, we utilized time-lapse fluorescence microscopy imaging to examine the kinetics, input encoding, and variability of the Dps response in single cells. In the presence of an oxidative stressor, we observed a single pulse of activation of Dps production. Increased concentrations of H2O2 led to increased intensity and duration of the pulse. While lower concentrations of H2O2 robustly activated the Dps response with little effect on the growth rate, higher concentrations of H2O2 resulted in dramatically lower and highly varied growth rates. A comparison of cells exposed to the same concentration of H2O2 revealed that increased levels of Dps expression did not confer a growth advantage, indicating that recovery from stress may rely primarily upon variation in the amount of damage caused to individual cells. IMPORTANCE We show for the first time the response of the DNA-binding protein from starved cells (Dps) to oxidative stress in single cells of E. coli Through time-lapse fluorescence microscopy, a single pulse of Dps production is observed in cells exposed to H2O2, with a duration and intensity of induction proportional to the concentration of the applied stress. More intense Dps expression did not provide a growth benefit to the bacteria, suggesting that healing from oxidative stress may largely depend upon the amount of damage in each individual cell.
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Affiliation(s)
- Michela De Martino
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | | | - Peter J van den Berg
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | | | - Anne S Meyer
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
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Brandi A, Giangrossi M, Giuliodori AM, Falconi M. An Interplay among FIS, H-NS, and Guanosine Tetraphosphate Modulates Transcription of the Escherichia coli cspA Gene under Physiological Growth Conditions. Front Mol Biosci 2016; 3:19. [PMID: 27252944 PMCID: PMC4877382 DOI: 10.3389/fmolb.2016.00019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 05/01/2016] [Indexed: 11/13/2022] Open
Abstract
CspA, the most characterized member of the csp gene family of Escherichia coli, is highly expressed not only in response to cold stress, but also during the early phase of growth at 37°C. Here, we investigate at molecular level the antagonistic role played by the nucleoid proteins FIS and H-NS in the regulation of cspA expression under non-stress conditions. By means of both probing experiments and immunological detection, we demonstrate in vitro the existence of binding sites for these proteins on the cspA regulatory region, in which FIS and H-NS bind simultaneously to form composite DNA-protein complexes. While the in vitro promoter activity of cspA is stimulated by FIS and repressed by H-NS, a compensatory effect is observed when both proteins are added in the transcription assay. Consistently with these findings, inactivation of fis and hns genes reversely affect the in vivo amount of cspA mRNA. In addition, by means of strains expressing a high level of the alarmone guanosine tetraphosphate ((p)ppGpp) and in vitro transcription assays, we show that the cspA promoter is sensitive to (p)ppGpp inhibition. The (p)ppGpp-mediated expression of fis and hns genes is also analyzed, thus clarifying some aspects of the regulatory loop governing cspA transcription.
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Affiliation(s)
- Anna Brandi
- Laboratory of Genetics, School of Bioscience and Veterinary Medicine, University of Camerino Camerino, Italy
| | - Mara Giangrossi
- Laboratory of Genetics, School of Bioscience and Veterinary Medicine, University of Camerino Camerino, Italy
| | - Anna M Giuliodori
- Laboratory of Genetics, School of Bioscience and Veterinary Medicine, University of Camerino Camerino, Italy
| | - Maurizio Falconi
- Laboratory of Genetics, School of Bioscience and Veterinary Medicine, University of Camerino Camerino, Italy
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41
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Meyer AS, Grainger DC. The Escherichia coli Nucleoid in Stationary Phase. ADVANCES IN APPLIED MICROBIOLOGY 2016; 83:69-86. [PMID: 23651594 DOI: 10.1016/b978-0-12-407678-5.00002-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Compaction of DNA is an essential phenomenon that affects all facets of cellular biology. Surprisingly, given the abundance and apparent simplicity of bacteria, our understanding of chromosome organization in these ancient organisms is inadequate. In this chapter we will focus on arguably the best understood aspect of DNA folding in the model bacterium Escherichia coli: the supercondensation of the chromosome that occurs during periods of starvation and stress.
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Affiliation(s)
- Anne S Meyer
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
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Moore JM, Magnan D, Mojica AK, Núñez MAB, Bates D, Rosenberg SM, Hastings PJ. Roles of Nucleoid-Associated Proteins in Stress-Induced Mutagenic Break Repair in Starving Escherichia coli. Genetics 2015; 201:1349-62. [PMID: 26500258 PMCID: PMC4676537 DOI: 10.1534/genetics.115.178970] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 10/18/2015] [Indexed: 01/02/2023] Open
Abstract
The mutagenicity of DNA double-strand break repair in Escherichia coli is controlled by DNA-damage (SOS) and general (RpoS) stress responses, which let error-prone DNA polymerases participate, potentially accelerating evolution during stress. Either base substitutions and indels or genome rearrangements result. Here we discovered that most small basic proteins that compact the genome, nucleoid-associated proteins (NAPs), promote or inhibit mutagenic break repair (MBR) via different routes. Of 15 NAPs, H-NS, Fis, CspE, and CbpA were required for MBR; Dps inhibited MBR; StpA and Hha did neither; and five others were characterized previously. Three essential genes were not tested. Using multiple tests, we found the following: First, Dps, which reduces reactive oxygen species (ROS), inhibited MBR, implicating ROS in MBR. Second, CbpA promoted F' plasmid maintenance, allowing MBR to be measured in an F'-based assay. Third, Fis was required for activation of the SOS DNA-damage response and could be substituted in MBR by SOS-induced levels of DinB error-prone DNA polymerase. Thus, Fis promoted MBR by allowing SOS activation. Fourth, H-NS represses ROS detoxifier sodB and was substituted in MBR by deletion of sodB, which was not otherwise mutagenic. We conclude that normal ROS levels promote MBR and that H-NS promotes MBR by maintaining ROS. CspE positively regulates RpoS, which is required for MBR. Four of five previously characterized NAPs promoted stress responses that enhance MBR. Hence, most NAPs affect MBR, the majority via regulatory functions. The data show that a total of six NAPs promote MBR by regulating stress responses, indicating the importance of nucleoid structure and function to the regulation of MBR and of coupling mutagenesis to stress, creating genetic diversity responsively.
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Affiliation(s)
- Jessica M Moore
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, 77030 Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030
| | - David Magnan
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - Ana K Mojica
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030 Undergraduate Program on Genomic Sciences, National Autonomous University of Mexico, Cuernavaca, 62210, Morelos, Mexico
| | - María Angélica Bravo Núñez
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, 77030 Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
| | - David Bates
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, 77030
| | - Susan M Rosenberg
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, 77030 Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, 77030
| | - P J Hastings
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030
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Abstract
This review provides a brief review of the current understanding of the structure-function relationship of the Escherichia coli nucleoid developed after the overview by Pettijohn focusing on the physical properties of nucleoids. Isolation of nucleoids requires suppression of DNA expansion by various procedures. The ability to control the expansion of nucleoids in vitro has led to purification of nucleoids for chemical and physical analyses and for high-resolution imaging. Isolated E. coli genomes display a number of individually intertwined supercoiled loops emanating from a central core. Metabolic processes of the DNA double helix lead to three types of topological constraints that all cells must resolve to survive: linking number, catenates, and knots. The major species of nucleoid core protein share functional properties with eukaryotic histones forming chromatin; even the structures are different from histones. Eukaryotic histones play dynamic roles in the remodeling of eukaryotic chromatin, thereby controlling the access of RNA polymerase and transcription factors to promoters. The E. coli genome is tightly packed into the nucleoid, but, at each cell division, the genome must be faithfully replicated, divided, and segregated. Nucleoid activities such as transcription, replication, recombination, and repair are all affected by the structural properties and the special conformations of nucleoid. While it is apparent that much has been learned about the nucleoid, it is also evident that the fundamental interactions organizing the structure of DNA in the nucleoid still need to be clearly defined.
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Gerganova V, Berger M, Zaldastanishvili E, Sobetzko P, Lafon C, Mourez M, Travers A, Muskhelishvili G. Chromosomal position shift of a regulatory gene alters the bacterial phenotype. Nucleic Acids Res 2015; 43:8215-26. [PMID: 26170236 PMCID: PMC4751926 DOI: 10.1093/nar/gkv709] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 06/30/2015] [Indexed: 12/31/2022] Open
Abstract
Recent studies strongly suggest that in bacterial cells the order of genes along the chromosomal origin-to-terminus axis is determinative for regulation of the growth phase-dependent gene expression. The prediction from this observation is that positional displacement of pleiotropic genes will affect the genetic regulation and hence, the cellular phenotype. To test this prediction we inserted the origin-proximal dusB-fis operon encoding the global regulator FIS in the vicinity of replication terminus on both arms of the Escherichia coli chromosome. We found that the lower fis gene dosage in the strains with terminus-proximal dusB-fis operons was compensated by increased fis expression such that the intracellular concentration of FIS was homeostatically adjusted. Nevertheless, despite unchanged FIS levels the positional displacement of dusB-fis impaired the competitive growth fitness of cells and altered the state of the overarching network regulating DNA topology, as well as the cellular response to environmental stress, hazardous substances and antibiotics. Our finding that the chromosomal repositioning of a regulatory gene can determine the cellular phenotype unveils an important yet unexplored facet of the genetic control mechanisms and paves the way for novel approaches to manipulate bacterial physiology.
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Affiliation(s)
- Veneta Gerganova
- Jacobs University Bremen, School of Engineering and Science, Bremen, 28758, Germany
| | - Michael Berger
- Institut für Hygiene, Universitätsklinikum Münster, Münster, 48149, Germany
| | | | - Patrick Sobetzko
- Philipps-Universität Marburg, LOEWE-Zentrum für Synthetische Mikrobiologie, Department of Chromosome Biology, Marburg, 35032, Germany
| | - Corinne Lafon
- SANOFI/ TSU Infectious Diseases, Toulouse, 31036, France
| | - Michael Mourez
- SANOFI/ TSU Infectious Diseases, Toulouse, 31036, France
| | - Andrew Travers
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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Schaefer J, Engl C, Zhang N, Lawton E, Buck M. Genome wide interactions of wild-type and activator bypass forms of σ54. Nucleic Acids Res 2015; 43:7280-91. [PMID: 26082500 PMCID: PMC4551910 DOI: 10.1093/nar/gkv597] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/25/2015] [Indexed: 01/05/2023] Open
Abstract
Enhancer-dependent transcription involving the promoter specificity factor σ54 is widely distributed amongst bacteria and commonly associated with cell envelope function. For transcription initiation, σ54-RNA polymerase yields open promoter complexes through its remodelling by cognate AAA+ ATPase activators. Since activators can be bypassed in vitro, bypass transcription in vivo could be a source of emergent gene expression along evolutionary pathways yielding new control networks and transcription patterns. At a single test promoter in vivo bypass transcription was not observed. We now use genome-wide transcription profiling, genome-wide mutagenesis and gene over-expression strategies in Escherichia coli, to (i) scope the range of bypass transcription in vivo and (ii) identify genes which might alter bypass transcription in vivo. We find little evidence for pervasive bypass transcription in vivo with only a small subset of σ54 promoters functioning without activators. Results also suggest no one gene limits bypass transcription in vivo, arguing bypass transcription is strongly kept in check. Promoter sequences subject to repression by σ54 were evident, indicating loss of rpoN (encoding σ54) rather than creating rpoN bypass alleles would be one evolutionary route for new gene expression patterns. Finally, cold-shock promoters showed unusual σ54-dependence in vivo not readily correlated with conventional σ54 binding-sites.
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Affiliation(s)
- Jorrit Schaefer
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Christoph Engl
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK Institute for Global Food Security, Queen's University Belfast, Belfast BT9 5BN, UK
| | - Nan Zhang
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Edward Lawton
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Martin Buck
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
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46
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Expression of different bacterial cytotoxins is controlled by two global transcription factors, CRP and Fis, that co-operate in a shared-recruitment mechanism. Biochem J 2015; 466:323-35. [DOI: 10.1042/bj20141315] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Expression of related autotransporter toxin genes in pathogenic Escherichia coli and Shigella sonnei require the CRP and Fis global regulators. At promoters controlling toxin production, CRP is suboptimally positioned and Fis compensates for this impediment by facilitating RNA polymerase recruitment.
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47
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Gene regulation by H-NS as a function of growth conditions depends on chromosomal position in Escherichia coli. G3-GENES GENOMES GENETICS 2015; 5:605-14. [PMID: 25701587 PMCID: PMC4390576 DOI: 10.1534/g3.114.016139] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Cellular adaptation to changing environmental conditions requires the coordinated regulation of expression of large sets of genes by global regulatory factors such as nucleoid associated proteins. Although in eukaryotic cells genomic position is known to play an important role in regulation of gene expression, it remains to be established whether in bacterial cells there is an influence of chromosomal position on the efficiency of these global regulators. Here we show for the first time that genome position can affect transcription activity of a promoter regulated by the histone-like nucleoid-structuring protein (H-NS), a global regulator of bacterial transcription and genome organization. We have used as a local reporter of H-NS activity the level of expression of a fluorescent reporter protein under control of an H-NS−regulated promoter (Phns) at different sites along the genome. Our results show that the activity of the Phns promoter depends on whether it is placed within the AT-rich regions of the genome that are known to be bound preferentially by H-NS. This modulation of gene expression moreover depends on the growth phase and the growth rate of the cells, reflecting the changes taking place in the relative abundance of different nucleoid proteins and the inherent heterogeneous organization of the nucleoid. Genomic position can thus play a significant role in the adaptation of the cells to environmental changes, providing a fitness advantage that can explain the selection of a gene’s position during evolution.
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48
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van der Valk RA, Vreede J, Crémazy F, Dame RT. Genomic Looping: A Key Principle of Chromatin Organization. J Mol Microbiol Biotechnol 2015; 24:344-59. [DOI: 10.1159/000368851] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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49
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Bacterial histone-like proteins: roles in stress resistance. Curr Genet 2015; 61:489-92. [DOI: 10.1007/s00294-015-0478-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 01/30/2015] [Indexed: 12/16/2022]
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50
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Lévi-Meyrueis C, Monteil V, Sismeiro O, Dillies MA, Kolb A, Monot M, Dupuy B, Duarte SS, Jagla B, Coppée JY, Beraud M, Norel F. Repressor activity of the RpoS/σS-dependent RNA polymerase requires DNA binding. Nucleic Acids Res 2015; 43:1456-68. [PMID: 25578965 PMCID: PMC4330354 DOI: 10.1093/nar/gku1379] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The RpoS/σ(S) sigma subunit of RNA polymerase (RNAP) activates transcription of stationary phase genes in many Gram-negative bacteria and controls adaptive functions, including stress resistance, biofilm formation and virulence. In this study, we address an important but poorly understood aspect of σ(S)-dependent control, that of a repressor. Negative regulation by σ(S) has been proposed to result largely from competition between σ(S) and other σ factors for binding to a limited amount of core RNAP (E). To assess whether σ(S) binding to E alone results in significant downregulation of gene expression by other σ factors, we characterized an rpoS mutant of Salmonella enterica serovar Typhimurium producing a σ(S) protein proficient for Eσ(S) complex formation but deficient in promoter DNA binding. Genome expression profiling and physiological assays revealed that this mutant was defective for negative regulation, indicating that gene repression by σ(S) requires its binding to DNA. Although the mechanisms of repression by σ(S) are likely specific to individual genes and environmental conditions, the study of transcription downregulation of the succinate dehydrogenase operon suggests that σ competition at the promoter DNA level plays an important role in gene repression by Eσ(S).
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Affiliation(s)
- Corinne Lévi-Meyrueis
- Institut Pasteur, Laboratoire Systèmes Macromoléculaires et Signalisation, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France CNRS ERL3526, rue du Docteur Roux, 75015 Paris, France Université Paris Sud XI, 15, rue Georges Clémenceau, 91405 Orsay Cedex, France
| | - Véronique Monteil
- Institut Pasteur, Laboratoire Systèmes Macromoléculaires et Signalisation, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France CNRS ERL3526, rue du Docteur Roux, 75015 Paris, France
| | - Odile Sismeiro
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et génétique, rue du Docteur Roux, 75015 Paris, France
| | - Marie-Agnès Dillies
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et génétique, rue du Docteur Roux, 75015 Paris, France
| | - Annie Kolb
- Institut Pasteur, Laboratoire Systèmes Macromoléculaires et Signalisation, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France CNRS ERL3526, rue du Docteur Roux, 75015 Paris, France
| | - Marc Monot
- Institut Pasteur, Laboratoire Pathogenèse des bactéries anaérobies, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France
| | - Bruno Dupuy
- Institut Pasteur, Laboratoire Pathogenèse des bactéries anaérobies, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France
| | - Sara Serradas Duarte
- Institut Pasteur, Laboratoire Systèmes Macromoléculaires et Signalisation, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France CNRS ERL3526, rue du Docteur Roux, 75015 Paris, France
| | - Bernd Jagla
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et génétique, rue du Docteur Roux, 75015 Paris, France
| | - Jean-Yves Coppée
- Institut Pasteur, Plate-forme Transcriptome et Epigénome, Département Génomes et génétique, rue du Docteur Roux, 75015 Paris, France
| | - Mélanie Beraud
- Institut Pasteur, Laboratoire Systèmes Macromoléculaires et Signalisation, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France CNRS ERL3526, rue du Docteur Roux, 75015 Paris, France Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, rue du Docteur Roux, 75015 Paris, France
| | - Françoise Norel
- Institut Pasteur, Laboratoire Systèmes Macromoléculaires et Signalisation, Département de Microbiologie, rue du Docteur Roux, 75015 Paris, France CNRS ERL3526, rue du Docteur Roux, 75015 Paris, France
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