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Lablaine A, Chamot S, Serrano M, Billaudeau C, Bornard I, Carballido-López R, Carlin F, Henriques AO, Broussolle V. A new fluorescence-based approach for direct visualization of coat formation during sporulation in Bacillus cereus. Sci Rep 2023; 13:15136. [PMID: 37704668 PMCID: PMC10499802 DOI: 10.1038/s41598-023-42143-9] [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: 05/12/2023] [Accepted: 09/06/2023] [Indexed: 09/15/2023] Open
Abstract
The human pathogenic bacteria Bacillus cereus, Bacillus anthracis and the entomopathogenic Bacillus thuringiensis form spores encased in a protein coat surrounded by a balloon-like exosporium. These structures mediate spore interactions with its environment, including the host immune system, control the transit of molecules that trigger germination and thus are essential for the spore life cycle. Formation of the coat and exosporium has been traditionally visualized by transmission electronic microscopy on fixed cells. Recently, we showed that assembly of the exosporium can be directly observed in live B. cereus cells by super resolution-structured illumination microscopy (SR-SIM) using the membrane MitoTrackerGreen (MTG) dye. Here, we demonstrate that the different steps of coat formation can also be visualized by SR-SIM using MTG and SNAP-cell TMR-star dyes during B. cereus sporulation. We used these markers to characterize a subpopulation of engulfment-defective B. cereus cells that develops at a suboptimal sporulation temperature. Importantly, we predicted and confirmed that synthesis and accumulation of coat material, as well as synthesis of the σK-dependent protein BxpB, occur in cells arrested during engulfment. These results suggest that, unlike the well-studied model organism Bacillus subtilis, the activity of σK is not strictly linked to the state of forespore development in B. cereus.
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Affiliation(s)
- Armand Lablaine
- INRAE, Avignon Université, UMR SQPOV, 84000, Avignon, France
- MICALIS Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | | | - Mónica Serrano
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-157, Oeiras, Portugal
| | - Cyrille Billaudeau
- MICALIS Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | | | - Rut Carballido-López
- MICALIS Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Frédéric Carlin
- INRAE, Avignon Université, UMR SQPOV, 84000, Avignon, France
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-157, Oeiras, Portugal
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2
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Parrell D, Kroos L. Channels modestly impact compartment-specific ATP levels during Bacillus subtilis sporulation and a rise in the mother cell ATP level is not necessary for Pro-σ K cleavage. Mol Microbiol 2020; 114:563-581. [PMID: 32515031 DOI: 10.1111/mmi.14560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 01/13/2023]
Abstract
Starvation of Bacillus subtilis initiates endosporulation involving formation of mother cell (MC) and forespore (FS) compartments. During engulfment, the MC membrane migrates around the FS and protein channels connect the two compartments. The channels are necessary for postengulfment FS gene expression, which relieves inhibition of SpoIVFB, an intramembrane protease that cleaves Pro-σK , releasing σK into the MC. SpoIVFB has an ATP-binding domain exposed to the MC cytoplasm, but the role of ATP in regulating Pro-σK cleavage has been unclear, as has the impact of the channels on MC and FS ATP levels. Using luciferase produced separately in each compartment to measure relative ATP concentrations during sporulation, we found that the MC ATP concentration rises about twofold coincident with increasing cleavage of Pro-σK , and the FS ATP concentration does not decline. Mutants lacking a channel protein or defective in channel protein turnover exhibited modest and varied effects on ATP levels, which suggested that low ATP concentration does not explain the lack of postengulfment FS gene expression in channel mutants. Furthermore, a rise in the MC ATP level was not necessary for Pro-σK cleavage by SpoIVFB, based on analysis of mutants that bypass the need for relief of SpoIVFB inhibition.
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Affiliation(s)
- Daniel Parrell
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Lee Kroos
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
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3
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Ramos-Silva P, Serrano M, Henriques AO. From Root to Tips: Sporulation Evolution and Specialization in Bacillus subtilis and the Intestinal Pathogen Clostridioides difficile. Mol Biol Evol 2020; 36:2714-2736. [PMID: 31350897 PMCID: PMC6878958 DOI: 10.1093/molbev/msz175] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacteria of the Firmicutes phylum are able to enter a developmental pathway that culminates with the formation of highly resistant, dormant endospores. Endospores allow environmental persistence, dissemination and for pathogens, are also infection vehicles. In both the model Bacillus subtilis, an aerobic organism, and in the intestinal pathogen Clostridioides difficile, an obligate anaerobe, sporulation mobilizes hundreds of genes. Their expression is coordinated between the forespore and the mother cell, the two cells that participate in the process, and is kept in close register with the course of morphogenesis. The evolutionary mechanisms by which sporulation emerged and evolved in these two species, and more broadly across Firmicutes, remain largely unknown. Here, we trace the origin and evolution of sporulation using the genes known to be involved in the process in B. subtilis and C. difficile, and estimating their gain-loss dynamics in a comprehensive bacterial macroevolutionary framework. We show that sporulation evolution was driven by two major gene gain events, the first at the base of the Firmicutes and the second at the base of the B. subtilis group and within the Peptostreptococcaceae family, which includes C. difficile. We also show that early and late sporulation regulons have been coevolving and that sporulation genes entail greater innovation in B. subtilis with many Bacilli lineage-restricted genes. In contrast, C. difficile more often recruits new sporulation genes by horizontal gene transfer, which reflects both its highly mobile genome, the complexity of the gut microbiota, and an adjustment of sporulation to the gut ecosystem.
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Affiliation(s)
- Paula Ramos-Silva
- Instituto Gulbenkian de Ciência, Oeiras, Portugal.,Marine Biodiversity Group, Naturalis Biodiversity Center, Leiden, The Netherlands
| | - Mónica Serrano
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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4
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Nunes F, Fernandes C, Freitas C, Marini E, Serrano M, Moran CP, Eichenberger P, Henriques AO. SpoVID functions as a non-competitive hub that connects the modules for assembly of the inner and outer spore coat layers in Bacillus subtilis. Mol Microbiol 2018; 110:576-595. [PMID: 30168214 PMCID: PMC6282716 DOI: 10.1111/mmi.14116] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 08/22/2018] [Accepted: 08/27/2018] [Indexed: 01/20/2023]
Abstract
During sporulation in Bacillus subtilis, a group of mother cell‐specific proteins guides the assembly of the coat, a multiprotein structure that protects the spore and influences many of its environmental interactions. SafA and CotE behave as party hubs, governing assembly of the inner and outer coat layers. Targeting of coat proteins to the developing spore is followed by encasement. Encasement by SafA and CotE requires E, a region of 11 amino acids in the encasement protein SpoVID, with which CotE interacts directly. Here, we identified two single alanine substitutions in E that prevent binding of SafA, but not of CotE, to SpoVID, and block encasement. The substitutions result in the accumulation of SafA, CotE and their dependent proteins at the mother cell proximal spore pole, phenocopying a spoVID null mutant and suggesting that mislocalized SafA acts as an attractor for the rest of the coat. The requirement for E in SafA binding is bypassed by a peptide with the sequence of E provided in trans. We suggest that E allows binding of SafA to a second region in SpoVID, enabling CotE to interact with E and SpoVID to function as a non‐competitive hub during spore encasement.
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Affiliation(s)
- Filipa Nunes
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Catarina Fernandes
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Carolina Freitas
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Eleonora Marini
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Mónica Serrano
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Charles P Moran
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | | | - Adriano O Henriques
- Microbial Development Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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5
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Mearls EB, Jackter J, Colquhoun JM, Farmer V, Matthews AJ, Murphy LS, Fenton C, Camp AH. Transcription and translation of the sigG gene is tuned for proper execution of the switch from early to late gene expression in the developing Bacillus subtilis spore. PLoS Genet 2018; 14:e1007350. [PMID: 29702640 PMCID: PMC5942855 DOI: 10.1371/journal.pgen.1007350] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/09/2018] [Accepted: 04/03/2018] [Indexed: 12/01/2022] Open
Abstract
A cascade of alternative sigma factors directs developmental gene expression during spore formation by the bacterium Bacillus subtilis. As the spore develops, a tightly regulated switch occurs in which the early-acting sigma factor σF is replaced by the late-acting sigma factor σG. The gene encoding σG (sigG) is transcribed by σF and by σG itself in an autoregulatory loop; yet σG activity is not detected until σF-dependent gene expression is complete. This separation in σF and σG activities has been suggested to be due at least in part to a poorly understood intercellular checkpoint pathway that delays sigG expression by σF. Here we report the results of a careful examination of sigG expression during sporulation. Unexpectedly, our findings argue against the existence of a regulatory mechanism to delay sigG transcription by σF and instead support a model in which sigG is transcribed by σF with normal timing, but at levels that are very low. This low-level expression of sigG is the consequence of several intrinsic features of the sigG regulatory and coding sequence—promoter spacing, secondary structure potential of the mRNA, and start codon identity—that dampen its transcription and translation. Especially notable is the presence of a conserved hairpin in the 5’ leader sequence of the sigG mRNA that occludes the ribosome-binding site, reducing translation by up to 4-fold. Finally, we demonstrate that misexpression of sigG from regulatory and coding sequences lacking these features triggers premature σG activity in the forespore during sporulation, as well as inappropriate σG activity during vegetative growth. Altogether, these data indicate that transcription and translation of the sigG gene is tuned to prevent vegetative expression of σG and to ensure the precise timing of the switch from σF to σG in the developing spore. Global changes in gene expression occur during normal cellular growth and development, as well as during cancer cell transformation and bacterial pathogenesis. In this study we have investigated the molecular mechanisms that drive the switch from early to late developmental gene expression during spore formation by the model bacterium Bacillus subtilis. At early times, gene expression in the developing spore is directed by the transcription factor σF; at later times σF is replaced by σG. An important, yet poorly understood aspect of this σF-to-σG transition is how σG activation is delayed until the early, σF-directed phase of gene expression is complete. Here we have carefully examined expression of the gene encoding σG, sigG, and found that its transcription and translation are ordinarily dampened by several features of its regulatory and coding sequences. Moreover, we have found that this “tuning” of sigG expression is required for proper timing of the switch to σG. These results reframe our understanding of how sigG is regulated during B. subtilis sporulation and, more broadly, advance our understanding of how global changes in gene expression can be precisely executed at the molecular/genetic level.
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MESH Headings
- Bacillus subtilis/genetics
- Bacillus subtilis/physiology
- Bacterial Proteins/biosynthesis
- Bacterial Proteins/genetics
- Gene Expression Regulation, Bacterial
- Genes, Bacterial
- Inverted Repeat Sequences
- Models, Genetic
- Nucleic Acid Conformation
- Promoter Regions, Genetic
- Protein Biosynthesis
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sigma Factor/biosynthesis
- Sigma Factor/genetics
- Signal Transduction
- Spores, Bacterial/genetics
- Spores, Bacterial/physiology
- Transcription, Genetic
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Affiliation(s)
- Elizabeth B. Mearls
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | - Jacquelin Jackter
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | | | - Veronica Farmer
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | - Allison J. Matthews
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | - Laura S. Murphy
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | - Colleen Fenton
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | - Amy H. Camp
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
- * E-mail:
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6
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Martínez-Lumbreras S, Alfano C, Evans NJ, Collins KM, Flanagan KA, Atkinson RA, Krysztofinska EM, Vydyanath A, Jackter J, Fixon-Owoo S, Camp AH, Isaacson RL. Structural and Functional Insights into Bacillus subtilis Sigma Factor Inhibitor, CsfB. Structure 2018; 26:640-648.e5. [PMID: 29526435 PMCID: PMC5890618 DOI: 10.1016/j.str.2018.02.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/17/2017] [Accepted: 02/06/2018] [Indexed: 11/23/2022]
Abstract
Global changes in bacterial gene expression can be orchestrated by the coordinated activation/deactivation of alternative sigma (σ) factor subunits of RNA polymerase. Sigma factors themselves are regulated in myriad ways, including via anti-sigma factors. Here, we have determined the solution structure of anti-sigma factor CsfB, responsible for inhibition of two alternative sigma factors, σG and σE, during spore formation by Bacillus subtilis. CsfB assembles into a symmetrical homodimer, with each monomer bound to a single Zn2+ ion via a treble-clef zinc finger fold. Directed mutagenesis indicates that dimer formation is critical for CsfB-mediated inhibition of both σG and σE, and we have characterized these interactions in vitro. This work represents an advance in our understanding of how CsfB mediates inhibition of two alternative sigma factors to drive developmental gene expression in a bacterium.
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MESH Headings
- Amino Acid Sequence
- Bacillus subtilis/chemistry
- Bacillus subtilis/genetics
- Bacillus subtilis/metabolism
- Binding Sites
- Cations, Divalent
- Cloning, Molecular
- Crystallography, X-Ray
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression Regulation, Bacterial
- Genetic Vectors/chemistry
- Genetic Vectors/metabolism
- Models, Molecular
- Mutation
- Protein Binding
- Protein Conformation, alpha-Helical
- Protein Conformation, beta-Strand
- Protein Interaction Domains and Motifs
- Protein Isoforms/antagonists & inhibitors
- Protein Isoforms/chemistry
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Multimerization
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Repressor Proteins/chemistry
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Sequence Alignment
- Sequence Homology, Amino Acid
- Sigma Factor/antagonists & inhibitors
- Sigma Factor/chemistry
- Sigma Factor/genetics
- Sigma Factor/metabolism
- Spores, Bacterial/chemistry
- Spores, Bacterial/genetics
- Spores, Bacterial/metabolism
- Zinc/chemistry
- Zinc/metabolism
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Affiliation(s)
| | - Caterina Alfano
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK; Structural Biology and Biophysics Unit, Fondazione Ri.MED, Via Bandiera, 11, 90133 Palermo, Italy
| | - Nicola J Evans
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Katherine M Collins
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Kelly A Flanagan
- Department of Biological Sciences, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
| | - R Andrew Atkinson
- Centre for Biomolecular Spectroscopy and Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Ewelina M Krysztofinska
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Anupama Vydyanath
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Jacquelin Jackter
- Department of Biological Sciences, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
| | - Sarah Fixon-Owoo
- Department of Biological Sciences, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
| | - Amy H Camp
- Department of Biological Sciences, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
| | - Rivka L Isaacson
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK.
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7
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Wang Erickson AF, Deighan P, Chen S, Barrasso K, Garcia CP, Martínez-Lumbreras S, Alfano C, Krysztofinska EM, Thapaliya A, Camp AH, Isaacson RL, Hochschild A, Losick R. A novel RNA polymerase-binding protein that interacts with a sigma-factor docking site. Mol Microbiol 2017; 105:652-662. [PMID: 28598017 PMCID: PMC5558796 DOI: 10.1111/mmi.13724] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2017] [Indexed: 11/30/2022]
Abstract
Sporulation in Bacillus subtilis is governed by a cascade of alternative RNA polymerase sigma factors. We previously identified a small protein Fin that is produced under the control of the sporulation sigma factor σF to create a negative feedback loop that inhibits σF -directed gene transcription. Cells deleted for fin are defective for spore formation and exhibit increased levels of σF -directed gene transcription. Based on pull-down experiments, chemical crosslinking, bacterial two-hybrid experiments and nuclear magnetic resonance chemical shift analysis, we now report that Fin binds to RNA polymerase and specifically to the coiled-coil region of the β' subunit. The coiled-coil is a docking site for sigma factors on RNA polymerase, and evidence is presented that the binding of Fin and σF to RNA polymerase is mutually exclusive. We propose that Fin functions by a mechanism distinct from that of classic sigma factor antagonists (anti-σ factors), which bind directly to a target sigma factor to prevent its association with RNA polymerase, and instead functions to inhibit σF by competing for binding to the β' coiled-coil.
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Affiliation(s)
- Anna F. Wang Erickson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Padraig Deighan
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115
- Department of Biology, Emmanuel College, 400 The Fenway, Boston, MA 02115
| | - Shanshan Chen
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Kelsey Barrasso
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115
- Department of Biology, Emmanuel College, 400 The Fenway, Boston, MA 02115
| | - Cinthia P. Garcia
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115
- Department of Biology, Emmanuel College, 400 The Fenway, Boston, MA 02115
| | | | - Caterina Alfano
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, United Kingdom
| | - Ewelina M. Krysztofinska
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, United Kingdom
| | - Arjun Thapaliya
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, United Kingdom
| | - Amy H. Camp
- Department of Biological Sciences, Mount Holyoke College, South Hadley, MA 01075
| | - Rivka L. Isaacson
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, United Kingdom
| | - Ann Hochschild
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115
| | - Richard Losick
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
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8
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Li L, Mu L, Wang X, Yu J, Hu R, Li Z. A novel expression vector for the secretion of abaecin in Bacillus subtilis. Braz J Microbiol 2017; 48:809-814. [PMID: 28651889 PMCID: PMC5628310 DOI: 10.1016/j.bjm.2017.01.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 01/03/2017] [Accepted: 01/31/2017] [Indexed: 11/03/2022] Open
Abstract
This study aimed to describe a Bacillus subtilis expression system based on genetically modified B. subtilis. Abaecin, an antimicrobial peptide obtained from Apis mellifera, can enhance the effect of pore-forming peptides from other species on the inhibition of bacterial growth. For the exogenous expression, the abaecin gene was fused with a tobacco etch virus protease cleavage site, a promoter Pglv, and a mature beta-glucanase signal peptide. Also, a B. subtilis expression system was constructed. The recombinant abaecin gene was expressed and purified as a recombinant protein in the culture supernatant. The purified abaecin did not inhibit the growth of Escherichia coli strain K88. Cecropin A and hymenoptaecin exhibited potent bactericidal activities at concentrations of 1 and 1.5μM. Combinatorial assays revealed that cecropin A and hymenoptaecin had sublethal concentrations of 0.3 and 0.5μM. This potentiating functional interaction represents a promising therapeutic strategy. It provides an opportunity to address the rising threat of multidrug-resistant pathogens that are recalcitrant to conventional antibiotics.
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Affiliation(s)
- Li Li
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
| | - Lan Mu
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, Inner Mongolia, China
| | - Xiaojuan Wang
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, Inner Mongolia, China
| | - Jingfeng Yu
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, Inner Mongolia, China
| | - Ruiping Hu
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, Inner Mongolia, China.
| | - Zhen Li
- College of Horticulture, China Agricultural University, Haidian District, Beijing, China
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9
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Highly Signal-Responsive Gene Regulatory Network Governing Myxococcus Development. Trends Genet 2016; 33:3-15. [PMID: 27916428 DOI: 10.1016/j.tig.2016.10.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 10/14/2016] [Accepted: 10/24/2016] [Indexed: 11/20/2022]
Abstract
The bacterium Myxococcus xanthus undergoes multicellular development when starved. Thousands of cells build mounds in which some differentiate into spores. This remarkable feat and the genetic tractability of Myxococcus provide a unique opportunity to understand the evolution of gene regulatory networks (GRNs). Recent work has revealed a GRN involving interconnected cascades of signal-responsive transcriptional activators. Initially, starvation-induced intracellular signals direct changes in gene expression. Subsequently, self-generated extracellular signals provide morphological cues that regulate certain transcriptional activators. However, signals for many of the activators remain to be discovered. A key insight is that activators often work combinatorially, allowing signal integration. The Myxococcus GRN differs strikingly from those governing sporulation of Bacillus and Streptomyces, suggesting that Myxococcus evolved a highly signal-responsive GRN to enable complex multicellular development.
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10
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Serrano M, Kint N, Pereira FC, Saujet L, Boudry P, Dupuy B, Henriques AO, Martin-Verstraete I. A Recombination Directionality Factor Controls the Cell Type-Specific Activation of σK and the Fidelity of Spore Development in Clostridium difficile. PLoS Genet 2016; 12:e1006312. [PMID: 27631621 PMCID: PMC5025042 DOI: 10.1371/journal.pgen.1006312] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/21/2016] [Indexed: 01/05/2023] Open
Abstract
The strict anaerobe Clostridium difficile is the most common cause of nosocomial diarrhea, and the oxygen-resistant spores that it forms have a central role in the infectious cycle. The late stages of sporulation require the mother cell regulatory protein σK. In Bacillus subtilis, the onset of σK activity requires both excision of a prophage-like element (skinBs) inserted in the sigK gene and proteolytical removal of an inhibitory pro-sequence. Importantly, the rearrangement is restricted to the mother cell because the skinBs recombinase is produced specifically in this cell. In C. difficile, σK lacks a pro-sequence but a skinCd element is present. The product of the skinCd gene CD1231 shares similarity with large serine recombinases. We show that CD1231 is necessary for sporulation and skinCd excision. However, contrary to B. subtilis, expression of CD1231 is observed in vegetative cells and in both sporangial compartments. Nevertheless, we show that skinCd excision is under the control of mother cell regulatory proteins σE and SpoIIID. We then demonstrate that σE and SpoIIID control the expression of the skinCd gene CD1234, and that this gene is required for sporulation and skinCd excision. CD1231 and CD1234 appear to interact and both proteins are required for skinCd excision while only CD1231 is necessary for skinCd integration. Thus, CD1234 is a recombination directionality factor that delays and restricts skinCd excision to the terminal mother cell. Finally, while the skinCd element is not essential for sporulation, deletion of skinCd results in premature activity of σK and in spores with altered surface layers. Thus, skinCd excision is a key element controlling the onset of σK activity and the fidelity of spore development.
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Affiliation(s)
- Mónica Serrano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Nicolas Kint
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France
- University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Fátima C. Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Laure Saujet
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France
- University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Pierre Boudry
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France
- University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Bruno Dupuy
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France
- University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Adriano O. Henriques
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail: (AOH); (IMV)
| | - Isabelle Martin-Verstraete
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France
- University Paris Diderot, Sorbonne Paris Cité, Paris, France
- * E-mail: (AOH); (IMV)
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Slager J, Veening JW. Hard-Wired Control of Bacterial Processes by Chromosomal Gene Location. Trends Microbiol 2016; 24:788-800. [PMID: 27364121 PMCID: PMC5034851 DOI: 10.1016/j.tim.2016.06.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/31/2016] [Accepted: 06/08/2016] [Indexed: 12/23/2022]
Abstract
Bacterial processes, such as stress responses and cell differentiation, are controlled at many different levels. While some factors, such as transcriptional regulation, are well appreciated, the importance of chromosomal gene location is often underestimated or even completely neglected. A combination of environmental parameters and the chromosomal location of a gene determine how many copies of its DNA are present at a given time during the cell cycle. Here, we review bacterial processes that rely, completely or partially, on the chromosomal location of involved genes and their fluctuating copy numbers. Special attention will be given to the several different ways in which these copy-number fluctuations can be used for bacterial cell fate determination or coordination of interdependent processes in a bacterial cell.
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Affiliation(s)
- Jelle Slager
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
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A Membrane-Embedded Amino Acid Couples the SpoIIQ Channel Protein to Anti-Sigma Factor Transcriptional Repression during Bacillus subtilis Sporulation. J Bacteriol 2016; 198:1451-63. [PMID: 26929302 DOI: 10.1128/jb.00958-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/22/2016] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED SpoIIQ is an essential component of a channel connecting the developing forespore to the adjacent mother cell during Bacillus subtilis sporulation. This channel is generally required for late gene expression in the forespore, including that directed by the late-acting sigma factor σ(G) Here, we present evidence that SpoIIQ also participates in a previously unknown gene regulatory circuit that specifically represses expression of the gene encoding the anti-sigma factor CsfB, a potent inhibitor of σ(G) The csfB gene is ordinarily transcribed in the forespore only by the early-acting sigma factor σ(F) However, in a mutant lacking the highly conserved SpoIIQ transmembrane amino acid Tyr-28, csfB was also aberrantly transcribed later by σ(G), the very target of CsfB inhibition. This regulation of csfB by SpoIIQ Tyr-28 is specific, given that the expression of other σ(F)-dependent genes was unaffected. Moreover, we identified a conserved element within the csfB promoter region that is both necessary and sufficient for SpoIIQ Tyr-28-mediated inhibition. These results indicate that SpoIIQ is a bifunctional protein that not only generally promotes σ(G)activity in the forespore as a channel component but also specifically maximizes σ(G)activity as part of a gene regulatory circuit that represses σ(G)-dependent expression of its own inhibitor, CsfB. Finally, we demonstrate that SpoIIQ Tyr-28 is required for the proper localization and stability of the SpoIIE phosphatase, raising the possibility that these two multifunctional proteins cooperate to fine-tune developmental gene expression in the forespore at late times. IMPORTANCE Cellular development is orchestrated by gene regulatory networks that activate or repress developmental genes at the right time and place. Late gene expression in the developing Bacillus subtilis spore is directed by the alternative sigma factor σ(G) The activity of σ(G)requires a channel apparatus through which the adjacent mother cell provides substrates that generally support gene expression. Here we report that the channel protein SpoIIQ also specifically maximizes σ(G)activity as part of a previously unknown regulatory circuit that prevents σ(G)from activating transcription of the gene encoding its own inhibitor, the anti-sigma factor CsfB. The discovery of this regulatory circuit significantly expands our understanding of the gene regulatory network controlling late gene expression in the developing B. subtilis spore.
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