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Boshoff HIM, Young K, Ahn YM, Yadav VD, Crowley BM, Yang L, Su J, Oh S, Arora K, Andrews J, Manikkam M, Sutphin M, Smith AJ, Weiner DM, Piazza MK, Fleegle JD, Gomez F, Dayao EK, Prideaux B, Zimmerman M, Kaya F, Sarathy J, Tan VY, Via LE, Tschirret-Guth R, Lenaerts AJ, Robertson GT, Dartois V, Olsen DB, Barry CE. Mtb-Selective 5-Aminomethyl Oxazolidinone Prodrugs: Robust Potency and Potential Liabilities. ACS Infect Dis 2024; 10:1679-1695. [PMID: 38581700 DOI: 10.1021/acsinfecdis.4c00025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2024]
Abstract
Linezolid is a drug with proven human antitubercular activity whose use is limited to highly drug-resistant patients because of its toxicity. This toxicity is related to its mechanism of action─linezolid inhibits protein synthesis in both bacteria and eukaryotic mitochondria. A highly selective and potent series of oxazolidinones, bearing a 5-aminomethyl moiety (in place of the typical 5-acetamidomethyl moiety of linezolid), was identified. Linezolid-resistant mutants were cross-resistant to these molecules but not vice versa. Resistance to the 5-aminomethyl molecules mapped to an N-acetyl transferase (Rv0133) and these mutants remained fully linezolid susceptible. Purified Rv0133 was shown to catalyze the transformation of the 5-aminomethyl oxazolidinones to their corresponding N-acetylated metabolites, and this transformation was also observed in live cells of Mycobacterium tuberculosis. Mammalian mitochondria, which lack an appropriate N-acetyltransferase to activate these prodrugs, were not susceptible to inhibition with the 5-aminomethyl analogues. Several compounds that were more potent than linezolid were taken into C3HeB/FeJ mice and were shown to be highly efficacious, and one of these (9) was additionally taken into marmosets and found to be highly active. Penetration of these 5-aminomethyl oxazolidinone prodrugs into caseum was excellent. Unfortunately, these compounds were rapidly converted into the corresponding 5-alcohols by mammalian metabolism which retained antimycobacterial activity but resulted in substantial mitotoxicity.
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Affiliation(s)
- Helena I M Boshoff
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Katherine Young
- Merck & Co., Inc., West Point, Pennsylvania 19486, United States
| | - Yong-Mo Ahn
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Veena D Yadav
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | | | - Lihu Yang
- Merck & Co., Inc., West Point, Pennsylvania 19486, United States
| | - Jing Su
- Merck & Co., Inc., West Point, Pennsylvania 19486, United States
| | - Sangmi Oh
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Kriti Arora
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jenna Andrews
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Michelle Manikkam
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Michelle Sutphin
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Anthony J Smith
- Mycobacterial Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Ft Collins, Colorado 80521, United States
| | - Danielle M Weiner
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Michaela K Piazza
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Joel D Fleegle
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Felipe Gomez
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Emmannual K Dayao
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | - Brendan Prideaux
- Merck & Co., Inc., West Point, Pennsylvania 19486, United States
| | - Matthew Zimmerman
- Hackensack Meridian Health Center for Discovery & Innovation, Nutley, New Jersey 07110, United States
| | - Firat Kaya
- Hackensack Meridian Health Center for Discovery & Innovation, Nutley, New Jersey 07110, United States
| | - Jansy Sarathy
- Hackensack Meridian Health Center for Discovery & Innovation, Nutley, New Jersey 07110, United States
| | - Vee Yang Tan
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Laura E Via
- Tuberculosis Imaging Program, Division of Intramural Research, National Insititute of Allergy and Infectious Disease, National Insititutes of Health, Bethesda, Maryland 20892, United States
| | | | - Anne J Lenaerts
- Mycobacterial Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Ft Collins, Colorado 80521, United States
| | - Gregory T Robertson
- Mycobacterial Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Ft Collins, Colorado 80521, United States
| | - Véronique Dartois
- Mycobacterial Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Ft Collins, Colorado 80521, United States
| | - David B Olsen
- Merck & Co., Inc., West Point, Pennsylvania 19486, United States
| | - Clifton E Barry
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institutes of Health, Bethesda, Maryland 20892, United States
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Tian D, Liu Y, Zhang Y, Liu Y, Xia Y, Xu B, Xu J, Yomo T. Implementation of Fluorescent-Protein-Based Quantification Analysis in L-Form Bacteria. Bioengineering (Basel) 2024; 11:81. [PMID: 38247958 PMCID: PMC10813599 DOI: 10.3390/bioengineering11010081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 01/23/2024] Open
Abstract
Cell-wall-less (L-form) bacteria exhibit morphological complexity and heterogeneity, complicating quantitative analysis of them under internal and external stimuli. Stable and efficient labeling is needed for the fluorescence-based quantitative cell analysis of L-forms during growth and proliferation. Here, we evaluated the expression of multiple fluorescent proteins (FPs) under different promoters in the Bacillus subtilis L-form strain LR2 using confocal microscopy and imaging flow cytometry. Among others, Pylb-derived NBP3510 showed a superior performance for inducing several FPs including EGFP and mKO2 in both the wild-type and L-form strains. Moreover, NBP3510 was also active in Escherichia coli and its L-form strain NC-7. Employing these established FP-labeled strains, we demonstrated distinct morphologies in the L-form bacteria in a quantitative manner. Given cell-wall-deficient bacteria are considered protocell and synthetic cell models, the generated cell lines in our work could be valuable for L-form-based research.
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Affiliation(s)
| | | | | | | | | | | | - Jian Xu
- Laboratory of Biology and Information Science, School of Life Sciences, East China Normal University, Shanghai 200062, China
| | - Tetsuya Yomo
- Laboratory of Biology and Information Science, School of Life Sciences, East China Normal University, Shanghai 200062, China
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3
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Inamoto T, Furuta K, Han C, Uneme M, Kano T, Ishikawa K, Kaito C. Short-chain fatty acids stimulate dendrite elongation in dendritic cells by inhibiting histone deacetylase. FEBS J 2023; 290:5794-5810. [PMID: 37646105 DOI: 10.1111/febs.16945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 07/08/2023] [Accepted: 08/29/2023] [Indexed: 09/01/2023]
Abstract
Dendritic cells activate immune responses by presenting pathogen-derived molecules. The dendrites of dendritic cells contribute to the incorporation of foreign antigens or presenting antigens to T cells. Short-chain fatty acids (SCFAs), such as acetic, propionic, butyric and valeric acids, have many effects on immune responses by activating specific receptors or inhibiting a histone deacetylase (HDAC), although their effect on dendrite formation in dendritic cells is unknown. In the present study, we aimed to investigate the effect of SCFAs on dendrite elongation using a dendritic cell line (DC2.4 cells) and mouse bone marrow-derived dendritic cells. We found that SCFAs induced dendrite elongation. The elongation was reduced by inhibitors of Src family kinase (SFK), phosphatidylinositol-3 kinase (PI3K), Rho family GTPases (Cdc42, Rac1) or actin polymerization, indicating that SCFAs promote dendrite elongation by activating actin polymerization via the SFK/PI3K/Rho family GTPase signaling pathway. We showed that agonists for SCFA receptors GPR43 and GPR109a did not promote dendrite elongation. By contrast, HDAC inhibitors, including trichostatin A, promoted dendrite elongation in DC2.4 cells, and the promoting activity of trichostatin A was decreased by inhibiting the SFK/PI3K/Rho family GTPase signaling pathway or actin polymerization. Furthermore, DC2.4 cells treated with valeric acid showed enhanced uptake of soluble proteins, insoluble beads and Staphylococcus aureus. We also found that treatment with valeric acid enhanced major histocompatibility complex class II-mediated antigen presentation in bone marrow-derived dendritic cells. These results suggest that SCFAs promote dendrite elongation by inhibiting HDAC, stimulating the SFK/PI3K/Rho family pathway and activating actin polymerization, resulting in increased antigen uptake and presentation in dendritic cells.
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Affiliation(s)
- Takuho Inamoto
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
| | - Kazuyuki Furuta
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
| | - Cheng Han
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
| | - Mio Uneme
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
| | - Tomonori Kano
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
| | - Kazuya Ishikawa
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
| | - Chikara Kaito
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan
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Lu Y, Chen F, Zhao Q, Cao Q, Chen R, Pan H, Wang Y, Huang H, Huang R, Liu Q, Li M, Bae T, Liang H, Lan L. Modulation of MRSA virulence gene expression by the wall teichoic acid enzyme TarO. Nat Commun 2023; 14:1594. [PMID: 36949052 PMCID: PMC10032271 DOI: 10.1038/s41467-023-37310-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 03/10/2023] [Indexed: 03/24/2023] Open
Abstract
Phenol-soluble modulins (PSMs) and Staphylococcal protein A (SpA) are key virulence determinants for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), an important human pathogen that causes a wide range of diseases. Here, using chemical and genetic approaches, we show that inhibition of TarO, the first enzyme in the wall teichoic acid (WTA) biosynthetic pathway, decreases the expression of genes encoding PSMs and SpA in the prototypical CA-MRSA strain USA300 LAC. Mechanistically, these effects are linked to the activation of VraRS two-component system that directly represses the expression of accessory gene regulator (agr) locus and spa. The activation of VraRS was due in part to the loss of the functional integrity of penicillin-binding protein 2 (PBP2) in a PBP2a-dependent manner. TarO inhibition can also activate VraRS in a manner independent of PBP2a. We provide multiple lines of evidence that accumulation of lipid-linked peptidoglycan precursors is a trigger for the activation of VraRS. In sum, our results reveal that WTA biosynthesis plays an important role in the regulation of virulence gene expression in CA-MRSA, underlining TarO as an attractive target for anti-virulence therapy. Our data also suggest that acquisition of PBP2a-encoding mecA gene can impart an additional regulatory layer for the modulation of key signaling pathways in S. aureus.
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Affiliation(s)
- Yunfu Lu
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Feifei Chen
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- College of Life Science, Northwest University, Xi'an, 710127, China
| | - Qingmin Zhao
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Qiao Cao
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- College of Life Science, Northwest University, Xi'an, 710127, China
| | - Rongrong Chen
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Huiwen Pan
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Yanhui Wang
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Haixin Huang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Ruimin Huang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Qian Liu
- Department of Laboratory Medicine, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Min Li
- Department of Laboratory Medicine, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Taeok Bae
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest, Gary, IN, 46408, USA
| | - Haihua Liang
- College of Life Science, Northwest University, Xi'an, 710127, China.
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Lefu Lan
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China.
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China.
- College of Life Science, Northwest University, Xi'an, 710127, China.
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5
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Fuse N, Okamori C, Okaji R, Tang C, Hirai K, Kurata S. Transcriptome features of innate immune memory in Drosophila. PLoS Genet 2022; 18:e1010005. [PMID: 36252180 PMCID: PMC9612818 DOI: 10.1371/journal.pgen.1010005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 10/27/2022] [Accepted: 10/03/2022] [Indexed: 11/21/2022] Open
Abstract
Immune memory is the ability of organisms to elicit potentiated immune responses at secondary infection. Current studies have revealed that similar to adaptive immunity, innate immunity exhibits memory characteristics (called "innate immune memory"). Although epigenetic reprogramming plays an important role in innate immune memory, the underlying mechanisms have not been elucidated, especially at the individual level. Here, we established experimental systems for detecting innate immune memory in Drosophila melanogaster. Training infection with low-pathogenic bacteria enhanced the survival rate of the flies at subsequent challenge infection with high-pathogenic bacteria. Among low-pathogenic bacteria, Micrococcus luteus (Ml) and Salmonella typhimurium (St) exerted apparent training effects in the fly but exhibited different mechanisms of action. Ml exerted training effects even after its clearance from flies, while live St persisted in the flies for a prolonged duration. RNA sequencing (RNA-Seq) analysis revealed that Ml training enhanced the expression of the immune-related genes under the challenge condition but not under the non-challenge condition. In contrast, St training upregulated the expression of the immune-related genes independent of challenge. These results suggest that training effects with Ml and St are due to memory and persistence of immune responses, respectively. Furthermore, we searched for the gene involved in immune memory, and identified a candidate gene, Ada2b, which encodes a component of the histone modification complex. The Ada2b mutant suppressed Ml training effects on survival and disrupted the expression of some genes under the training + challenge condition. These results suggest that the gene expression regulated by Ada2b may contribute to innate immune memory in Drosophila.
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Affiliation(s)
- Naoyuki Fuse
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
- * E-mail: (NF); (SK)
| | - Chisaki Okamori
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Ryoma Okaji
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Chang Tang
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Kikuko Hirai
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Shoichiro Kurata
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
- * E-mail: (NF); (SK)
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Structural and Functional Analysis of Toxin and Small RNA Gene Promoter Regions in Bacillus anthracis. J Bacteriol 2022; 204:e0020022. [PMID: 36043862 PMCID: PMC9487513 DOI: 10.1128/jb.00200-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It was previously demonstrated that anthrax toxin activator (AtxA) binds directly to the σA-like promoter region of pagA (encoding protective antigen, PA) immediately upstream of the RNA polymerase binding site. In this study, using electrophoretic mobility shift assays and in vivo analyses, we identified AtxA-binding sites in the promoter regions of the lef and cya genes (encoding lethal and edema factors, respectively) and of two Bacillus anthracis small RNAs (XrrA and XrrB). Activities of all four newly studied promoters were enhanced in the presence of CO2/bicarbonate and AtxA, as previously seen for the pagA promoter. Notably, the cya promoter was less activated by AtxA and CO2/bicarbonate conditions. The putative promoter of a recently described third small RNA, XrrC, showed a negligible response to AtxA and CO2/bicarbonate. RNA polymerase binding sites of the newly studied promoters show no consensus and differ from the σA-like promoter region of pagA. In silico analysis of the probable AtxA binding sites in the studied promoters revealed several palindromes. All the analyzed palindromes showed very little overlap with the σA-like pagA promoter. It remains unclear as to how AtxA and DNA-dependent RNA-polymerase identify such diverse DNA-sequences and differentially regulate promoter activation of the studied genes. IMPORTANCE Anthrax toxin activator (AtxA) is the major virulence regulator of Bacillus anthracis, the causative agent of anthrax. Understanding AtxA's mechanism of regulation could facilitate the development of therapeutics for B. anthracis infection. We provide evidence that AtxA binds to the promoters of the cya, lef, xrrA, and xrrB genes. In vivo assays confirmed the activities of all four promoters were enhanced in the presence of AtxA and CO2/bicarbonate, as previously seen for the pagA promoter. The cya and lef genes encode important toxin components. The xrrA and xrrB genes encode sRNAs with a suggested function as cell physiology regulators. Our data provides further evidence for the direct regulatory role of AtxA that was previously shown with the pagA promoter.
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Oliveira Paiva AM, Friggen AH, Douwes R, Wittekoek B, Smits WK. Practical observations on the use of fluorescent reporter systems in Clostridioides difficile. Antonie van Leeuwenhoek 2022; 115:297-323. [PMID: 35039954 DOI: 10.1007/s10482-021-01691-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/19/2021] [Indexed: 12/18/2022]
Abstract
Fluorescence microscopy is a valuable tool to study a broad variety of bacterial cell components and dynamics thereof. For Clostridioides difficile, the fluorescent proteins CFPopt, mCherryOpt and phiLOV2.1, and the self-labelling tags SNAPCd and HaloTag, hereafter collectively referred as fluorescent systems, have been described to explore different cellular pathways. In this study, we sought to characterize previously used fluorescent systems in C. difficile cells. We performed single cell analyses using fluorescence microscopy of exponentially growing C. difficile cells harbouring different fluorescent systems, either expressing these separately in the cytosol or fused to the C-terminus of HupA, under defined conditions. We show that the intrinsic fluorescence of C. difficile cells increases during growth, independent of sigB or spo0A. However, when C. difficile cells are exposed to environmental oxygen autofluorescence is enhanced. Cytosolic overexpression of the different fluorescent systems alone, using the same expression signals, showed heterogeneous expression of the fluorescent systems. High levels of mCherryOpt were toxic for C. difficile cells limiting the applicability of this fluorophore as a transcriptional reporter. When fused to HupA, a C. difficile histone-like protein, the fluorescent systems behaved similarly and did not affect the HupA overproduction phenotype. The present study compares several commonly used fluorescent systems for application as transcriptional or translational reporters in microscopy and summarizes the limitations and key challenges for live-cell imaging of C. difficile. Due to independence of molecular oxygen and fluorescent signal, SNAPCd appears the most suitable candidate for live-cell imaging in C. difficile to date.
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Affiliation(s)
- Ana M Oliveira Paiva
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, Leiden, The Netherlands.,Center for Microbial Cell Biology, Leiden, The Netherlands.,Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France
| | - Annemieke H Friggen
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, Leiden, The Netherlands.,Center for Microbial Cell Biology, Leiden, The Netherlands
| | - Roxanne Douwes
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, Leiden, The Netherlands
| | - Bert Wittekoek
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, Leiden, The Netherlands
| | - Wiep Klaas Smits
- Department of Medical Microbiology, Section Experimental Bacteriology, Leiden University Medical Center, Leiden, The Netherlands. .,Center for Microbial Cell Biology, Leiden, The Netherlands.
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8
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Anaerobic Fungal Mevalonate Pathway Genomic Biases Lead to Heterologous Toxicity Underpredicted by Codon Adaptation Indices. Microorganisms 2021; 9:microorganisms9091986. [PMID: 34576881 PMCID: PMC8468974 DOI: 10.3390/microorganisms9091986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 12/19/2022] Open
Abstract
Anaerobic fungi are emerging biotechnology platforms with genomes rich in biosynthetic potential. Yet, the heterologous expression of their biosynthetic pathways has had limited success in model hosts like E. coli. We find one reason for this is that the genome composition of anaerobic fungi like P. indianae are extremely AT-biased with a particular preference for rare and semi-rare AT-rich tRNAs in E coli, which are not explicitly predicted by standard codon adaptation indices (CAI). Native P. indianae genes with these extreme biases create drastic growth defects in E. coli (up to 69% reduction in growth), which is not seen in genes from other organisms with similar CAIs. However, codon optimization rescues growth, allowing for gene evaluation. In this manner, we demonstrate that anaerobic fungal homologs such as PI.atoB are more active than S. cerevisiae homologs in a hybrid pathway, increasing the production of mevalonate up to 2.5 g/L (more than two-fold) and reducing waste carbon to acetate by ~90% under the conditions tested. This work demonstrates the bioproduction potential of anaerobic fungal enzyme homologs and how the analysis of codon utilization enables the study of otherwise difficult to express genes that have applications in biocatalysis and natural product discovery.
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Kuchina A, Brettner LM, Paleologu L, Roco CM, Rosenberg AB, Carignano A, Kibler R, Hirano M, DePaolo RW, Seelig G. Microbial single-cell RNA sequencing by split-pool barcoding. Science 2020; 371:science.aba5257. [PMID: 33335020 DOI: 10.1126/science.aba5257] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 12/08/2020] [Indexed: 12/16/2022]
Abstract
Single-cell RNA sequencing (scRNA-seq) has become an essential tool for characterizing gene expression in eukaryotes, but current methods are incompatible with bacteria. Here, we introduce microSPLiT (microbial split-pool ligation transcriptomics), a high-throughput scRNA-seq method for Gram-negative and Gram-positive bacteria that can resolve heterogeneous transcriptional states. We applied microSPLiT to >25,000 Bacillus subtilis cells sampled at different growth stages, creating an atlas of changes in metabolism and lifestyle. We retrieved detailed gene expression profiles associated with known, but rare, states such as competence and prophage induction and also identified unexpected gene expression states, including the heterogeneous activation of a niche metabolic pathway in a subpopulation of cells. MicroSPLiT paves the way to high-throughput analysis of gene expression in bacterial communities that are otherwise not amenable to single-cell analysis, such as natural microbiota.
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Affiliation(s)
- Anna Kuchina
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Leandra M Brettner
- Department of Bioengineering, University of Washington, Seattle, WA, USA.,Center for Microbiome Sciences and Therapeutics, School of Medicine, University of Washington, Seattle, WA, USA
| | - Luana Paleologu
- Department of Microbiology, University of Washington, Seattle, WA, USA.,Department of Biology, University of Washington, Seattle, WA, USA
| | - Charles M Roco
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Alexander B Rosenberg
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Alberto Carignano
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Ryan Kibler
- Biological Physics, Structure, and Design, University of Washington, Seattle, WA, USA
| | - Matthew Hirano
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - R William DePaolo
- Center for Microbiome Sciences and Therapeutics, School of Medicine, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Gastroenterology, School of Medicine, University of Washington, Seattle, WA, USA
| | - Georg Seelig
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA. .,Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA.,Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA
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10
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McCall RM, Sievers ME, Fattah R, Ghirlando R, Pomerantsev AP, Leppla SH. Bacillus anthracis Virulence Regulator AtxA Binds Specifically to the pagA Promoter Region. J Bacteriol 2019; 201:e00569-19. [PMID: 31570528 PMCID: PMC6832065 DOI: 10.1128/jb.00569-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 01/12/2023] Open
Abstract
Anthrax toxin activator (AtxA) is the master virulence gene regulator of Bacillus anthracis It regulates genes on the chromosome as well as the pXO1 and pXO2 plasmids. It is not clear how AtxA regulates these genes, and direct binding of AtxA to its targets has not been shown. It has been previously suggested that AtxA and other proteins in the Mga/AtxA global transcriptional regulators family bind to the curvature of their DNA targets, although this has never been experimentally proven. Using electrophoretic mobility shift assays, we demonstrate that AtxA binds directly to the promoter region of pagA upstream of the RNA polymerase binding site. We also demonstrate that in vitro, CO2 appears to have no role in AtxA binding. However, phosphomimetic and phosphoablative substitutions in the phosphotransferase system (PTS) regulation domains (PRDs) do appear to influence AtxA binding and pagA regulation. In silico, in vitro, and in vivo analyses demonstrate that one of two hypothesized stem-loops located upstream of the RNA polymerase binding site in the pagA promoter region is important for AtxA binding in vitro and pagA regulation in vivo Our study clarifies the mechanism by which AtxA interacts with one of its targets.IMPORTANCE Anthrax toxin activator (AtxA) regulates the major virulence genes in Bacillus anthracis The bacterium produces the anthrax toxins, and understanding the mechanism of toxin production may facilitate the development of therapeutics for B. anthracis infection. Since the discovery of AtxA 25 years ago, the mechanism by which it regulates its targets has largely remained a mystery. Here, we provide evidence that AtxA binds to the promoter region of the pagA gene encoding the main central protective antigen (PA) component of the anthrax toxin. These data suggest that AtxA binding plays a direct role in gene regulation. Our work also assists in clarifying the role of CO2 in AtxA's gene regulation and provides more evidence for the role of AtxA phosphorylation in virulence gene regulation.
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Affiliation(s)
- Rita M McCall
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mary E Sievers
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rasem Fattah
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Andrei P Pomerantsev
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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11
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Gannesen AV, Zdorovenko EL, Botchkova EA, Hardouin J, Massier S, Kopitsyn DS, Gorbachevskii MV, Kadykova AA, Shashkov AS, Zhurina MV, Netrusov AI, Knirel YA, Plakunov VK, Feuilloley MGJ. Composition of the Biofilm Matrix of Cutibacterium acnes Acneic Strain RT5. Front Microbiol 2019; 10:1284. [PMID: 31293526 PMCID: PMC6598116 DOI: 10.3389/fmicb.2019.01284] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/23/2019] [Indexed: 12/11/2022] Open
Abstract
In skin, Cutibacterium acnes (former Propionibacterium acnes) can behave as an opportunistic pathogen, depending on the strain and environmental conditions. Acneic strains of C. acnes form biofilms inside skin-gland hollows, inducing inflammation and skin disorders. The essential exogenous products of C. acnes accumulate in the extracellular matrix of the biofilm, conferring essential bacterial functions to this structure. However, little is known about the actual composition of the biofilm matrix of C. acnes. Here, we developed a new technique for the extraction of the biofilm matrix of Gram-positive bacteria without the use of chemical or enzymatic digestion, known to be a source of artifacts. Our method is based on the physical separation of the cells and matrix of sonicated biofilms by ultracentrifugation through a CsCl gradient. Biofilms were grown on the surface of cellulose acetate filters, and the biomass was collected without contamination by the growth medium. The biofilm matrix of the acneic C. acnes RT5 strain appears to consist mainly of polysaccharides. The following is the ratio of the main matrix components: 62.6% polysaccharides, 9.6% proteins, 4.0% DNA, and 23.8% other compounds (porphyrins precursors and other). The chemical structure of the major polysaccharide was determined using a nuclear magnetic resonance technique, the formula being →6)-α-D-Galp-(1→4)-β-D-ManpNAc3NAcA-(1→6)-α-D-Glcp-(1→4)-β-D-ManpNAc3NAcA-(1→3)-β-GalpNAc-(1→. We detected 447 proteins in the matrix, of which the most abundant were the chaperonin GroL, the elongation factors EF-Tu and EF-G, several enzymes of glycolysis, and proteins of unknown function. The matrix also contained more than 20 hydrolases of various substrata, pathogenicity factors, and many intracellular proteins and enzymes. We also performed surface-enhanced Raman spectroscopy analysis of the C. acnes RT5 matrix for the first time, providing the surface-enhanced Raman scattering (SERS) profiles of the C. acnes RT5 biofilm matrix and biofilm biomass. The difference between the matrix and biofilm biomass spectra showed successful matrix extraction rather than simply the presence of cell debris after sonication. These data show the complexity of the biofilm matrix composition and should be essential for the development of new anti-C. acnes biofilms and potential antibiofilm drugs.
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Affiliation(s)
- Andrei V. Gannesen
- Winogradsky Institute of Microbiology, Federal Research Centre «Fundamentals of Biotechnology», Russian Academy of Sciences, Moscow, Russia
| | - Evelina L. Zdorovenko
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Ekaterina A. Botchkova
- Winogradsky Institute of Microbiology, Federal Research Centre «Fundamentals of Biotechnology», Russian Academy of Sciences, Moscow, Russia
- Department of Physical and Colloid Chemistry, Gubkin University, Moscow, Russia
| | - Julie Hardouin
- Laboratory of Polymers, Biopolymers, Surfaces UMR 6270 PBS, Rouen University, Rouen, France
| | - Sebastien Massier
- Laboratory of Polymers, Biopolymers, Surfaces UMR 6270 PBS, Rouen University, Rouen, France
| | - Dmitry S. Kopitsyn
- Department of Physical and Colloid Chemistry, Gubkin University, Moscow, Russia
| | | | - Alexandra A. Kadykova
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Higher Chemical College of the Russian Academy of Sciences, Mendeleyev University of Chemical Technology of Russia, Moscow, Russia
| | - Alexander S. Shashkov
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Marina V. Zhurina
- Winogradsky Institute of Microbiology, Federal Research Centre «Fundamentals of Biotechnology», Russian Academy of Sciences, Moscow, Russia
| | | | - Yuriy A. Knirel
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Vladimir K. Plakunov
- Winogradsky Institute of Microbiology, Federal Research Centre «Fundamentals of Biotechnology», Russian Academy of Sciences, Moscow, Russia
| | - Marc G. J. Feuilloley
- EA4312 Laboratory of Microbiology Signals and Microenvironment, Rouen University, Evreux, France
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12
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Flüchter S, Follonier S, Schiel-Bengelsdorf B, Bengelsdorf FR, Zinn M, Dürre P. Anaerobic Production of Poly(3-hydroxybutyrate) and Its Precursor 3-Hydroxybutyrate from Synthesis Gas by Autotrophic Clostridia. Biomacromolecules 2019; 20:3271-3282. [DOI: 10.1021/acs.biomac.9b00342] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sebastian Flüchter
- Institut für
Mikrobiologie und Biotechnologie, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Stéphanie Follonier
- Institute of Life
Technologies, University of Applied Sciences and Arts Western Switzerland (HES-SO Valais), Route du Rawyl 64, 1950 Sion, Switzerland
| | - Bettina Schiel-Bengelsdorf
- Institut für
Mikrobiologie und Biotechnologie, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Frank R. Bengelsdorf
- Institut für
Mikrobiologie und Biotechnologie, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Manfred Zinn
- Institute of Life
Technologies, University of Applied Sciences and Arts Western Switzerland (HES-SO Valais), Route du Rawyl 64, 1950 Sion, Switzerland
| | - Peter Dürre
- Institut für
Mikrobiologie und Biotechnologie, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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13
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Gyulev IS, Willson BJ, Hennessy RC, Krabben P, Jenkinson ER, Thomas GH. Part by Part: Synthetic Biology Parts Used in Solventogenic Clostridia. ACS Synth Biol 2018; 7:311-327. [PMID: 29186949 DOI: 10.1021/acssynbio.7b00327] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The solventogenic Clostridia are of interest to the chemical industry because of their natural ability to produce chemicals such as butanol, acetone and ethanol from diverse feedstocks. Their use as whole cell factories presents multiple metabolic engineering targets that could lead to improved sustainability and profitability of Clostridium industrial processes. However, engineering efforts have been held back by the scarcity of genetic and synthetic biology tools. Over the past decade, genetic tools to enable transformation and chromosomal modifications have been developed, but the lack of a broad palette of synthetic biology parts remains one of the last obstacles to the rapid engineered improvement of these species for bioproduction. We have systematically reviewed existing parts that have been used in the modification of solventogenic Clostridia, revealing a narrow range of empirically chosen and nonengineered parts that are in current use. The analysis uncovers elements, such as promoters, transcriptional terminators and ribosome binding sites where increased fundamental knowledge is needed for their reliable use in different applications. Together, the review provides the most comprehensive list of parts used and also presents areas where an improved toolbox is needed for full exploitation of these industrially important bacteria.
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Affiliation(s)
- Ivan S. Gyulev
- Department
of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
| | - Benjamin J. Willson
- Department
of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
| | - Rosanna C. Hennessy
- Department
of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, 1871, Denmark
| | - Preben Krabben
- Green Biologics Limited, Milton Park, Abingdon, Oxfordshire OX14 4RU, United Kingdom
| | | | - Gavin H. Thomas
- Department
of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
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14
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Impact of Cell Surface Molecules on Conjugative Transfer of the Integrative and Conjugative Element ICE St3 of Streptococcus thermophilus. Appl Environ Microbiol 2018; 84:AEM.02109-17. [PMID: 29247061 DOI: 10.1128/aem.02109-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 12/13/2017] [Indexed: 12/30/2022] Open
Abstract
Integrative conjugative elements (ICEs) are chromosomal elements that are widely distributed in bacterial genomes, hence contributing to genome plasticity, adaptation, and evolution of bacteria. Conjugation requires a contact between both the donor and the recipient cells and thus likely depends on the composition of the cell surface envelope. In this work, we investigated the impact of different cell surface molecules, including cell surface proteins, wall teichoic acids, lipoteichoic acids, and exopolysaccharides, on the transfer and acquisition of ICESt3 from Streptococcus thermophilus The transfer of ICESt3 from wild-type (WT) donor cells to mutated recipient cells increased 5- to 400-fold when recipient cells were affected in lipoproteins, teichoic acids, or exopolysaccharides compared to when the recipient cells were WT. These mutants displayed an increased biofilm-forming ability compared to the WT, suggesting better cell interactions that could contribute to the increase of ICESt3 acquisition. Microscopic observations of S. thermophilus cell surface mutants showed different phenotypes (aggregation in particular) that can also have an impact on conjugation. In contrast, the same mutations did not have the same impact when the donor cells, instead of recipient cells, were mutated. In that case, the transfer frequency of ICESt3 decreased compared to that with the WT. The same observation was made when both donor and recipient cells were mutated. The dominant effect of mutations in donor cells suggests that modifications of the cell envelope could impair the establishment or activity of the conjugation machinery required for DNA transport.IMPORTANCE ICEs contribute to horizontal gene transfer of adaptive traits (for example, virulence, antibiotic resistance, or biofilm formation) and play a considerable role in bacterial genome evolution, thus underlining the need of a better understanding of their conjugative mechanism of transfer. While most studies focus on the different functions encoded by ICEs, little is known about the effect of host factors on their conjugative transfer. Using ICESt3 of S. thermophilus as a model, we demonstrated the impact of lipoproteins, teichoic acids, and exopolysaccharides on ICE transfer and acquisition. This opens up new avenues to control gene transfer mediated by ICEs.
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15
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Yi Y, Frenzel E, Spoelder J, Elzenga JTM, van Elsas JD, Kuipers OP. Optimized fluorescent proteins for the rhizosphere-associated bacterium Bacillus mycoides with endophytic and biocontrol agent potential. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:57-74. [PMID: 29195004 DOI: 10.1111/1758-2229.12607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/23/2017] [Indexed: 06/07/2023]
Abstract
Tracking of fluorescent protein (FP)-labelled rhizobacteria is a key prerequisite to gain insights into plant-bacteria interaction mechanisms. However, the performance of FPs mostly has to be optimized for the bacterial host and for the environment of intended application. We report on the construction of mutational libraries of the superfolder green fluorescent protein sfGFP and the red fluorescent protein mKate2 in the bacterium B. mycoides, which next to its potential as plant-biocontrol agent occasionally enters an endophytic lifestyle. By fluorescence-activated cell sorting and comparison of signal intensities at the colony and single-cell level, the variants sfGFP(SPS6) and mKate (KPS12) with significantly increased brightness were isolated. Their high applicability for plant-bacteria interaction studies was shown by confocal laser scanning microscopy tracking of FP-tagged B. mycoides strains after inoculation to Chinese cabbage plants in a hydroponic system. During the process of colonization, strain EC18 rapidly attached to plant roots and formed a multicellular matrix, especially at the branching regions of the root hair, which probably constitute entrance sites to establish an endophytic lifestyle. The universal applicability of the novels FPs was proven by expression from a weak promoter, dual-labelling of B. mycoides, and by excellent expression and detectability in additional soil- and rhizosphere-associated Bacillus species.
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Affiliation(s)
- Yanglei Yi
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Elrike Frenzel
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Jan Spoelder
- Plant Physiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - J Theo M Elzenga
- Plant Physiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Jan Dirk van Elsas
- Microbial Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Oscar P Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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16
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Schelkle B, Choi Y, Baillie LW, Richter W, Buyuk F, Celik E, Wendling M, Sahin M, Gallagher T. Caenorhabditis elegans Predation on Bacillus anthracis: Decontamination of Spore Contaminated Soil with Germinants and Nematodes. Front Microbiol 2018; 8:2601. [PMID: 29379472 PMCID: PMC5770795 DOI: 10.3389/fmicb.2017.02601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 12/13/2017] [Indexed: 11/16/2022] Open
Abstract
Remediation of Bacillus anthracis-contaminated soil is challenging and approaches to reduce overall spore levels in environmentally contaminated soil or after intentional release of the infectious disease agent in a safe, low-cost manner are needed. B. anthracis spores are highly resistant to biocides, but once germinated they become susceptible to traditional biocides or potentially even natural predators such as nematodes in the soil environment. Here, we describe a two-step approach to reducing B. anthracis spore load in soil during laboratory trials, whereby germinants and Caenorhabditis elegans nematodes are applied concurrently. While the application of germinants reduced B. anthracis spore load by up to four logs depending on soil type, the addition of nematodes achieved a further log reduction in spore count. These laboratory based results suggest that the combined use of nematodes and germinants could represent a promising approach for the remediation of B. anthracis spore contaminated soil. Originality-Significance Statement: This study demonstrates for the first time the successful use of environmentally friendly decontamination methods to inactivate Bacillus anthracis spores in soil using natural predators of the bacterium, nematode worms.
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Affiliation(s)
- Bettina Schelkle
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Young Choi
- Battelle Biomedical Research Center, Columbus, OH, United States
| | - Leslie W Baillie
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - William Richter
- Battelle Biomedical Research Center, Columbus, OH, United States
| | - Fatih Buyuk
- Faculty of Veterinary Medicine, Department of Microbiology, University of Kafkas, Kars, Turkey
| | - Elif Celik
- Faculty of Veterinary Medicine, Department of Microbiology, University of Kafkas, Kars, Turkey
| | - Morgan Wendling
- Battelle Biomedical Research Center, Columbus, OH, United States
| | - Mitat Sahin
- Faculty of Veterinary Medicine, Department of Microbiology, University of Kafkas, Kars, Turkey
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17
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Frenzel E, Legebeke J, van Stralen A, van Kranenburg R, Kuipers OP. In vivo selection of sfGFP variants with improved and reliable functionality in industrially important thermophilic bacteria. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:8. [PMID: 29371884 PMCID: PMC5771013 DOI: 10.1186/s13068-017-1008-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/29/2017] [Indexed: 05/03/2023]
Abstract
BACKGROUND Fluorescent reporter proteins (FP) have become an indispensable tool for the optimization of microbial cell factories and in synthetic biology per se. The applicability of the currently available FPs is, however, constrained by species-dependent performance and misfolding at elevated temperatures. To obtain functional reporters for thermophilic, biotechnologically important bacteria such as Parageobacillus thermoglucosidasius, an in vivo screening approach based on a mutational library of superfolder GFP was applied. RESULTS Flow cytometry-based benchmarking of a set of GFPs, sfGFPs and species-specific codon-optimized variants revealed that none of the proteins was satisfyingly detectable in P. thermoglucosidasius at its optimal growth temperature of 60 °C. An undirected mutagenesis approach coupled to fluorescence-activated cell sorting allowed the isolation of sfGFP variants that were extremely well expressed in the chassis background at 60 °C. Notably, a few nucleotide substitutions, including silent mutations, significantly improved the functionality and brightness. The best mutant sfGFP(N39D/A179A) showed an 885-fold enhanced mean fluorescence intensity (MFI) at 60 °C and is the most reliable reporter protein with respect to cell-to-cell variation and signal intensity reported so far. The in vitro spectral and thermostability properties were unaltered as compared to the parental sfGFP protein, strongly indicating that the combination of the amino acid exchange and an altered translation or folding speed, or protection from degradation, contribute to the strongly improved in vivo performance. Furthermore, sfGFP(N39D/A179A) and the newly developed cyan and yellow derivatives were successfully used for labeling several industrially relevant thermophilic bacilli, thus proving their broad applicability. CONCLUSIONS This study illustrates the power of in vivo isolation of thermostable proteins to obtain reporters for highly efficient fluorescence labeling. Successful expression in a variety of thermophilic bacteria proved that the novel FPs are highly suitable for imaging and flow cytometry-based studies. This enables a reliable cell tracking and single-cell-based real-time monitoring of biological processes that are of industrial and biotechnological interest.
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Affiliation(s)
- Elrike Frenzel
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Jelmer Legebeke
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Atze van Stralen
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Richard van Kranenburg
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Corbion, Arkselsedijk 46, 4206 AC Gorinchem, The Netherlands
| | - Oscar P. Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
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18
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Gregory DJ, Kramnik I, Kobzik L. Protection of macrophages from intracellular pathogens by miR-182-5p mimic-a gene expression meta-analysis approach. FEBS J 2017; 285:244-260. [PMID: 29197182 DOI: 10.1111/febs.14348] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 09/29/2017] [Accepted: 11/28/2017] [Indexed: 12/25/2022]
Abstract
The goals of this study were to (a) define which host genes are of particular importance during the interactions between macrophages and intracellular pathogens, and (b) use this knowledge to gain fresh, experimental understanding of how macrophage activities may be manipulated during host defense. We designed an in silico method for meta-analysis of microarray gene expression data, and used this to combine data from 16 different studies of cells in the monocyte-macrophage lineage infected with seven different pathogens. Three thousand four hundred ninety-eight genes were identified, which we call the macrophage intracellular pathogen response (macIPR) gene set. As expected, the macIPR gene set showed a strong bias toward genes previously associated with the immune response. Predicted target sites for miR-182-5p (miR-182) were strongly over-represented among macIPR genes, indicating an unexpected role for miR-182-regulatable genes during intracellular pathogenesis. We therefore transfected primary human alveolar macrophage-like monocyte-derived macrophages from multiple different donors with synthetic miR-182, and found that miR-182 overexpression (a) increases proinflammatory gene induction during infection with Francisella tularensis live vaccine strain (LVS), (b) primes macrophages for increased autophagy, and (c) enhances macrophage control of both gram negative F. tularensisLVS and gram positive Bacillus anthracisANR-1 spores. These data therefore suggest a new application for miR-182 in promoting resistance to intracellular pathogens.
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Affiliation(s)
- David J Gregory
- Molecular and Physiological Sciences Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Igor Kramnik
- Pulmonary Center, Department of Medicine, National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, MA, USA
| | - Lester Kobzik
- Molecular and Physiological Sciences Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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19
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Ben Rejeb S, Lereclus D, Slamti L. Analysis of abrB Expression during the Infectious Cycle of Bacillus thuringiensis Reveals Population Heterogeneity. Front Microbiol 2017; 8:2471. [PMID: 29312181 PMCID: PMC5732988 DOI: 10.3389/fmicb.2017.02471] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/28/2017] [Indexed: 11/19/2022] Open
Abstract
Using the model host/pathogen pair Galleria mellonella/Bacillus thuringiensis, we have shown that these bacteria could kill their insect host, survive in its cadaver and form spores by sequentially activating virulence, necrotrophism and sporulation genes. However, the population isolated from the cadavers was heterogeneous, including non-sporulating cells in an unknown physiological state. To characterize these bacteria, we used a transcriptional fusion between the promoter of a gene expressed during early exponential growth (abrB) and a reporter gene encoding a destabilized version of GFP, in combination with a fluorescent reporter of the necrotrophic state. The composition of the bacterial population during infection was then analyzed by flow cytometry. We showed that the PabrB promoter was activated in the population that had turned on the necrotrophic reporter, suggesting a re-entry into vegetative growth. Strikingly, the cells that did not go through the necrotrophic state did not activate the PabrB promoter and appear as a dormant subpopulation. We propose a new model describing the B. thuringiensis cell types during infection.
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Affiliation(s)
- Samia Ben Rejeb
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Didier Lereclus
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Leyla Slamti
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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20
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Cyclic Di-GMP Binding by an Assembly ATPase (PilB2) and Control of Type IV Pilin Polymerization in the Gram-Positive Pathogen Clostridium perfringens. J Bacteriol 2017; 199:JB.00034-17. [PMID: 28242722 DOI: 10.1128/jb.00034-17] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 02/18/2017] [Indexed: 11/20/2022] Open
Abstract
The Gram-positive pathogen Clostridium perfringens possesses type IV pili (TFP), which are extracellular fibers that are polymerized from a pool of pilin monomers in the cytoplasmic membrane. Two proteins that are essential for pilus functions are an assembly ATPase (PilB) and an inner membrane core protein (PilC). Two homologues each of PilB and PilC are present in C. perfringens, called PilB1/PilB2 and PilC1/PilC2, respectively, along with four pilin proteins, PilA1 to PilA4. The gene encoding PilA2, which is considered the major pilin based on previous studies, is immediately downstream of the pilB2 and pilC2 genes. Purified PilB2 had ATPase activity, bound zinc, formed hexamers even in the absence of ATP, and bound the second messenger molecule cyclic di-GMP (c-di-GMP). Circular dichroism spectroscopy of purified PilC2 indicated that it retained its predicted degree of alpha-helical secondary structure. Even though no direct interactions between PilB2 and PilC2 could be detected in vivo or in vitro even in the presence of c-di-GMP, high levels of expression of a diguanylate cyclase from C. perfringens (CPE1788) stimulated polymerization of PilA2 in a PilB2- and PilC2-dependent manner. These results suggest that PilB2 activity is controlled by c-di-GMP levels in vivo but that PilB2-PilC2 interactions are either transitory or of low affinity, in contrast to results reported previously from in vivo studies of the PilB1/PilC1 pair in which PilC1 was needed for polar localization of PilB1. This is the first biochemical characterization of a c-di-GMP-dependent assembly ATPase from a Gram-positive bacterium.IMPORTANCE Type IV pili (TFP) are protein fibers involved in important bacterial functions, including motility, adherence to surfaces and host cells, and natural transformation. All clostridia whose genomes have been sequenced show evidence of the presence of TFP. The genetically tractable species Clostridium perfringens was used to study proteins involved in polymerizing the pilin, PilA2, into a pilus. The assembly ATPase PilB2 and its cognate membrane protein partner, PilC2, were purified. PilB2 bound the intracellular signal molecule c-di-GMP. Increased levels of intracellular c-di-GMP led to increased polymerization of PilA2, indicating that Gram-positive bacteria use this molecule to regulate pilus synthesis. These findings provide valuable information for understanding how pathogenic clostridia regulate TFP to cause human diseases.
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Bertram R. Complementation Plasmids, Inducible Gene-Expression Systems, and Reporters for Staphylococci. Methods Mol Biol 2016; 1373:25-32. [PMID: 25646605 DOI: 10.1007/7651_2014_181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
A cornucopia of methods and molecular tools is available for genetic modification of staphylococci, as shown for at least ten different species to date (Prax et al. Microbiology 159:421-435, 2013). This chapter reviews a number of frequently used vectors for complementation purposes that usually replicate in E. coli and staphylococci and differ in parameters including copy number, mode of replication, and sequence length. Systems for the artificial control of gene expression are described that are modulated by low-molecular-weight effectors such as metal cations, carbohydrates, and antibiotics. Finally, the usefulness of reporter proteins that exhibit enzymatic or autofluorescent characteristics in staphylococci is highlighted.
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Affiliation(s)
- Ralph Bertram
- Department of Microbial Genetics, Faculty of Science, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Waldhäuser Str. 70/8, 72076, Tübingen, Germany. .,, Ernst-Simon-Str. 2-4, 72072, Tübingen, Germany.
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22
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N'Diaye A, Mijouin L, Hillion M, Diaz S, Konto-Ghiorghi Y, Percoco G, Chevalier S, Lefeuvre L, Harmer NJ, Lesouhaitier O, Feuilloley MGJ. Effect of Substance P in Staphylococcus aureus and Staphylococcus epidermidis Virulence: Implication for Skin Homeostasis. Front Microbiol 2016; 7:506. [PMID: 27148195 PMCID: PMC4832252 DOI: 10.3389/fmicb.2016.00506] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/29/2016] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus and Staphylococcus epidermidis are two major skin associated bacteria, and Substance P (SP) is a major skin neuropeptide. Since bacteria are known to sense and response to many human hormones, we investigated the effects of SP on Staphylococci virulence in reconstructed human epidermis model and HaCaT keratinocytes. We show that SP is stimulating the virulence of S. aureus and S. epidermidis in a reconstructed human epidermis model. qRT-PCR array analysis of 64 genes expressed by keratinocytes in the response to bacterial infection revealed a potential link between the action of SP on Staphylococci and skin physiopathology. qRT-PCR and direct assay of cathelicidin and human β-defensin 2 secretion also provided that demonstration that the action of SP on bacteria is independent of antimicrobial peptide expression by keratinocytes. Considering an effect of SP on S. aureus and S. epidermidis, we observed that SP increases the adhesion potential of both bacteria on keratinocytes. However, SP modulates the virulence of S. aureus and S. epidermidis through different mechanisms. The response of S. aureus is associated with an increase in Staphylococcal Enterotoxin C2 (SEC2) production and a reduction of exolipase processing whereas in S. epidermidis the effect of SP appears mediated by a rise in biofilm formation activity. The Thermo unstable ribosomal Elongation factor Ef-Tu was identified as the SP-interacting protein in S. aureus and S. epidermidis. SP appears as an inter-kingdom communication factor involved in the regulation of bacterial virulence and essential for skin microflora homeostasis.
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Affiliation(s)
- Awa N'Diaye
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
| | - Lily Mijouin
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
| | - Mélanie Hillion
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
| | - Suraya Diaz
- Department of Biosciences, University of Exeter Exeter, UK
| | - Yoan Konto-Ghiorghi
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
| | - Giuseppe Percoco
- GlycoMev EA 4358, Normandie Université, Université de RouenMont-Saint-Aignan, France; Bio-EC LaboratoryLongjumeau, France
| | - Sylvie Chevalier
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
| | - Luc Lefeuvre
- Dermatologic Laboratories Uriage Neuilly-Sur-Seine, France
| | | | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
| | - Marc G J Feuilloley
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université de Rouen Evreux, France
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Kondakova T, Catovic C, Barreau M, Nusser M, Brenner-Weiss G, Chevalier S, Dionnet F, Orange N, Poc CD. Response to Gaseous NO2 Air Pollutant of P. fluorescens Airborne Strain MFAF76a and Clinical Strain MFN1032. Front Microbiol 2016; 7:379. [PMID: 27065229 PMCID: PMC4814523 DOI: 10.3389/fmicb.2016.00379] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 03/09/2016] [Indexed: 01/22/2023] Open
Abstract
Human exposure to nitrogen dioxide (NO2), an air pollutant of increasing interest in biology, results in several toxic effects to human health and also to the air microbiota. The aim of this study was to investigate the bacterial response to gaseous NO2. Two Pseudomonas fluorescens strains, namely the airborne strain MFAF76a and the clinical strain MFN1032 were exposed to 0.1, 5, or 45 ppm concentrations of NO2, and their effects on bacteria were evaluated in terms of motility, biofilm formation, antibiotic resistance, as well as expression of several chosen target genes. While 0.1 and 5 ppm of NO2did not lead to any detectable modification in the studied phenotypes of the two bacteria, several alterations were observed when the bacteria were exposed to 45 ppm of gaseous NO2. We thus chose to focus on this high concentration. NO2-exposed P. fluorescens strains showed reduced swimming motility, and decreased swarming in case of the strain MFN1032. Biofilm formed by NO2-treated airborne strain MFAF76a showed increased maximum thickness compared to non-treated cells, while NO2 had no apparent effect on the clinical MFN1032 biofilm structure. It is well known that biofilm and motility are inversely regulated by intracellular c-di-GMP level. The c-di-GMP level was however not affected in response to NO2 treatment. Finally, NO2-exposed P. fluorescens strains were found to be more resistant to ciprofloxacin and chloramphenicol. Accordingly, the resistance nodulation cell division (RND) MexEF-OprN efflux pump encoding genes were highly upregulated in the two P. fluorescens strains. Noticeably, similar phenotypes had been previously observed following a NO treatment. Interestingly, an hmp-homolog gene in P. fluorescens strains MFAF76a and MFN1032 encodes a NO dioxygenase that is involved in NO detoxification into nitrites. Its expression was upregulated in response to NO2, suggesting a possible common pathway between NO and NO2 detoxification. Taken together, our study provides evidences for the bacterial response to NO2 toxicity.
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Affiliation(s)
- Tatiana Kondakova
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIBEvreux, France; Aerothermic and Internal Combustion Engine Technological Research CentreSaint Etienne du Rouvray, France
| | - Chloé Catovic
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIB Evreux, France
| | - Magalie Barreau
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIB Evreux, France
| | - Michael Nusser
- Institute of Functional Interfaces, Karlsruhe Institute of Technology Karlsruhe, Germany
| | - Gerald Brenner-Weiss
- Institute of Functional Interfaces, Karlsruhe Institute of Technology Karlsruhe, Germany
| | - Sylvie Chevalier
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIB Evreux, France
| | - Frédéric Dionnet
- Aerothermic and Internal Combustion Engine Technological Research Centre Saint Etienne du Rouvray, France
| | - Nicole Orange
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIB Evreux, France
| | - Cécile Duclairoir Poc
- Laboratory of Microbiology Signals and Microenvironment EA 4312, Normandy University, University of Rouen, SéSa, IRIB Evreux, France
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Poupel O, Moyat M, Groizeleau J, Antunes LCS, Gribaldo S, Msadek T, Dubrac S. Transcriptional Analysis and Subcellular Protein Localization Reveal Specific Features of the Essential WalKR System in Staphylococcus aureus. PLoS One 2016; 11:e0151449. [PMID: 26999783 PMCID: PMC4801191 DOI: 10.1371/journal.pone.0151449] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 02/29/2016] [Indexed: 11/21/2022] Open
Abstract
The WalKR two-component system, controlling cell wall metabolism, is highly conserved among Bacilli and essential for cell viability. In Staphylococcus aureus, walR and walK are followed by three genes of unknown function: walH, walI and walJ. Sequence analysis and transcript mapping revealed a unique genetic structure for this locus in S. aureus: the last gene of the locus, walJ, is transcribed independently, whereas transcription of the tetra-cistronic walRKHI operon occurred from two independent promoters located upstream from walR. Protein topology analysis and protein-protein interactions in E. coli as well as subcellular localization in S. aureus allowed us to show that WalH and WalI are membrane-bound proteins, which associate with WalK to form a complex at the cell division septum. While these interactions suggest that WalH and WalI play a role in activity of the WalKR regulatory pathway, deletion of walH and/or walI did not have a major effect on genes whose expression is strongly dependent on WalKR or on associated phenotypes. No effect of WalH or WalI was seen on tightly controlled WalKR regulon genes such as sle1 or saouhsc_00773, which encodes a CHAP-domain amidase. Of the genes encoding the two major S. aureus autolysins, AtlA and Sle1, only transcription of atlA was increased in the ΔwalH or ΔwalI mutants. Likewise, bacterial autolysis was not increased in the absence of WalH and/or WalI and biofilm formation was lowered rather than increased. Our results suggest that contrary to their major role as WalK inhibitors in B. subtilis, the WalH and WalI proteins have evolved a different function in S. aureus, where they are more accessory. A phylogenomic analysis shows a striking conservation of the 5 gene wal cluster along the evolutionary history of Bacilli, supporting the key importance of this signal transduction system, and indicating that the walH and walI genes were lost in the ancestor of Streptococcaceae, leading to their atypical 3 wal gene cluster, walRKJ.
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Affiliation(s)
- Olivier Poupel
- Institut Pasteur, Biology of Gram-Positive Pathogens, Department of Microbiology, Paris, France
- CNRS, ERL3526, Paris, France
| | - Mati Moyat
- Institut Pasteur, Biology of Gram-Positive Pathogens, Department of Microbiology, Paris, France
- CNRS, ERL3526, Paris, France
| | - Julie Groizeleau
- Institut Pasteur, Biology of Gram-Positive Pathogens, Department of Microbiology, Paris, France
- CNRS, ERL3526, Paris, France
| | - Luísa C. S. Antunes
- Institut Pasteur, Molecular Biology of Gene in Extremophiles, Department of Microbiology, Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Molecular Biology of Gene in Extremophiles, Department of Microbiology, Paris, France
| | - Tarek Msadek
- Institut Pasteur, Biology of Gram-Positive Pathogens, Department of Microbiology, Paris, France
- CNRS, ERL3526, Paris, France
- * E-mail: (TM); (SD)
| | - Sarah Dubrac
- Institut Pasteur, Biology of Gram-Positive Pathogens, Department of Microbiology, Paris, France
- CNRS, ERL3526, Paris, France
- * E-mail: (TM); (SD)
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25
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Abstract
Here we describe protocols for using the red fluorescent protein mCherryOpt in Clostridium difficile. The protocols can be readily adapted to similar fluorescent proteins (FPs), such as green fluorescent protein (GFP) and cyan fluorescent protein (CFP). There are three critical considerations for using FPs in C. difficile. (1) Choosing the right color: Blue and (especially) red are preferred because C. difficile exhibits considerable yellow-green autofluorescence. (2) Codon optimization: Most FP genes in general circulation have a GC content of ~60 %, so they are not well expressed in low-GC bacteria. (3) Fixing anaerobically grown cells prior to exposure to O2: The FPs under consideration here are non-fluorescent when produced anaerobically because O2 is required to introduce double bonds into the chromophore. Fixation prevents C. difficile cells from becoming degraded during the several hours required for chromophore maturation after cells are exposed to air. Fixation can probably be omitted for studies in which maintaining cellular architecture is not important, such as using mCherryOpt to monitor gene expression.
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Affiliation(s)
- Eric M Ransom
- Department of Microbiology, University of Iowa, 51 Newton Rd, 3-372 Bowen Science Building, Iowa City, IA, 52242, USA
- Johne's Testing Center, School of Veterinary Medicine, Madison, WI, USA
| | - David S Weiss
- Department of Microbiology, University of Iowa, 51 Newton Rd, 3-372 Bowen Science Building, Iowa City, IA, 52242, USA
| | - Craig D Ellermeier
- Department of Microbiology, University of Iowa, 51 Newton Rd, 3-372 Bowen Science Building, Iowa City, IA, 52242, USA.
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26
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Vickerman MM, Mansfield JM, Zhu M, Walters KS, Banas JA. Codon-optimized fluorescent mTFP and mCherry for microscopic visualization and genetic counterselection of streptococci and enterococci. J Microbiol Methods 2015; 116:15-22. [PMID: 26122309 PMCID: PMC4522221 DOI: 10.1016/j.mimet.2015.06.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 06/19/2015] [Accepted: 06/19/2015] [Indexed: 01/20/2023]
Abstract
Despite the powerful potential of fluorescent proteins for labeling bacteria, their use has been limited in multi-species oral biofilm models. Fermentative metabolism by streptococcal species that initiate biofilm colonization results in an acidic, reduced microenvironment that may limit the activities of some fluorescent proteins which are influenced by pH and oxygen availability. The need to reliably distinguish morphologically similar strains within biofilms was the impetus for this work. Teal fluorescent protein (mTFP1) and red fluorescent protein (mCherry) were chosen because their fluorescent properties made them promising candidates. Since tRNA availability has been implicated in efficient translation of sufficient quantities of protein for maximum fluorescence, a streptococcal codon optimization approach was used. DNA was synthesized to encode either protein using codons most frequently used in streptococci; each coding region was preceded by an engineered ribosomal binding site and restriction sites for cloning a promoter. Plasmids carrying this synthesized DNA under control of the Streptococcus mutans lactate dehydrogenase promoter conferred fluorescence to nine representative streptococcal and two Enterococcus faecalis strains. Further characterization in Streptococcus gordonii showed that mTFP1 and mCherry expressions could be detected in cells grown planktonically, in biofilms, or in colonies on agar when expressed on an extrachromosomal plasmid or in single copy integrated into the chromosome. This latter property facilitated counterselection of chromosomal mutations demonstrating value for bacterial strain construction. Fluorescent and non-fluorescent bacteria were distinguishable at acidic pH. These codon-optimized versions of mTFP1 and mCherry have promising potential for use in multiple experimental applications.
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Affiliation(s)
- M Margaret Vickerman
- Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine, Buffalo, NY, USA; Department of Oral Biology, University at Buffalo School of Dental Medicine, Buffalo, NY, USA.
| | - Jillian M Mansfield
- Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine, Buffalo, NY, USA; Department of Oral Biology, University at Buffalo School of Dental Medicine, Buffalo, NY, USA
| | - Min Zhu
- Dows Institute for Research, University of Iowa College of Dentistry, Iowa City, IA, USA
| | - Katherine S Walters
- Central Microscopy Research Facility, University of Iowa, Iowa City, IA, USA
| | - Jeffrey A Banas
- Dows Institute for Research, University of Iowa College of Dentistry, Iowa City, IA, USA
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27
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Cho H, Jeong DW, Liu Q, Yeo WS, Vogl T, Skaar EP, Chazin WJ, Bae T. Calprotectin Increases the Activity of the SaeRS Two Component System and Murine Mortality during Staphylococcus aureus Infections. PLoS Pathog 2015; 11:e1005026. [PMID: 26147796 PMCID: PMC4492782 DOI: 10.1371/journal.ppat.1005026] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 06/16/2015] [Indexed: 11/19/2022] Open
Abstract
Calprotectin, the most abundant cytoplasmic protein in neutrophils, suppresses the growth of Staphylococcus aureus by sequestering the nutrient metal ions Zn and Mn. Here we show that calprotectin can also enhance the activity of the SaeRS two component system (TCS), a signaling system essential for production of over 20 virulence factors in S. aureus. The activity of the SaeRS TCS is repressed by certain divalent ions found in blood or neutrophil granules; however, the Zn bound-form of calprotectin relieves this repression. During staphylococcal encounter with murine neutrophils or staphylococcal infection of the murine peritoneal cavity, calprotectin increases the activity of the SaeRS TCS as well as the production of proinflammatory cytokines such as IL-1β and TNF-α, resulting in higher murine mortality. These results suggest that, under certain conditions, calprotectin can be exploited by S. aureus to increase bacterial virulence and host mortality. Staphylococcus aureus is an important human pathogen causing skin infections and a variety of life-threatening diseases such as pneumonia, sepsis, and toxic shock syndrome. Previous study showed that the growth of S. aureus in abscesses is suppressed by the host antimicrobial protein calprotectin, which sequesters Zn and Mn from bacterial usage. During bacterial infection, calprotectin also plays an important role in the production of proinflammatory cytokines. Although the antimicrobial activity of calprotectin has been well defined, it is not known how the proinflammatory property of calprotectin affects staphylococcal infection. In this study, we found that the Zn-binding property of calprotectin increases the pathogenic potential of S. aureus by enhancing the activity of the SaeRS two component system in S. aureus. We also found that, under certain infection conditions, the proinflammatory property of calprotectin is rather detrimental to host survival. Our study illustrates that the important antimicrobial protein can be exploited by S. aureus to render the bacterium a more effective pathogen, and provides an example of the intricate tug-of-war between host and a bacterial pathogen.
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Affiliation(s)
- Hoonsik Cho
- Indiana University School of Medicine-Northwest, Gary, Indiana, United States of America
| | - Do-Won Jeong
- Indiana University School of Medicine-Northwest, Gary, Indiana, United States of America
| | - Qian Liu
- Indiana University School of Medicine-Northwest, Gary, Indiana, United States of America
| | - Won-Sik Yeo
- Indiana University School of Medicine-Northwest, Gary, Indiana, United States of America
| | - Thomas Vogl
- Institute of Immunology, University of Muenster, Muenster, Germany
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Walter J. Chazin
- Department of Biochemistry and Chemistry, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Taeok Bae
- Indiana University School of Medicine-Northwest, Gary, Indiana, United States of America
- * E-mail:
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28
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Streptococcus thermophilus, an emerging and promising tool for heterologous expression: Advantages and future trends. Food Microbiol 2015; 53:2-9. [PMID: 26611164 DOI: 10.1016/j.fm.2015.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 05/07/2015] [Accepted: 05/09/2015] [Indexed: 11/19/2022]
Abstract
Streptococcus thermophilus is the second most used bacterium in dairy industry. It is daily consumed by millions of people through the worldwide consumption of yogurts, cheeses and fermented milks. S. thermophilus presents many features that make it a good candidate for the production of heterologous proteins. First, its ability to be naturally transformable allows obtaining swiftly and easily recombinant strains using various genetic tools available. Second, its Generally Recognised As Safe status and its ability to produce beneficial molecules or to liberate bioactive peptides from milk proteins open up the way for the development of new functional foods to maintain health and well-being of consumers. Finally, its ability to survive the intestinal passage and to be metabolically active in gastrointestinal tract allows considering S. thermophilus as a potential tool for delivering various biological molecules to the gastrointestinal tract. The aim of this review is therefore to take stock of various genetic tools which can be employed in S. thermophilus to produce heterologous proteins and to highlight the advantages and future trends of use of this bacterium as a heterologous expression host.
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29
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Kamenyeva O, Boularan C, Kabat J, Cheung GYC, Cicala C, Yeh AJ, Chan JL, Periasamy S, Otto M, Kehrl JH. Neutrophil recruitment to lymph nodes limits local humoral response to Staphylococcus aureus. PLoS Pathog 2015; 11:e1004827. [PMID: 25884622 PMCID: PMC4401519 DOI: 10.1371/journal.ppat.1004827] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 03/23/2015] [Indexed: 12/25/2022] Open
Abstract
Neutrophils form the first line of host defense against bacterial pathogens. They are rapidly mobilized to sites of infection where they help marshal host defenses and remove bacteria by phagocytosis. While splenic neutrophils promote marginal zone B cell antibody production in response to administered T cell independent antigens, whether neutrophils shape humoral immunity in other lymphoid organs is controversial. Here we investigate the neutrophil influx following the local injection of Staphylococcus aureus adjacent to the inguinal lymph node and determine neutrophil impact on the lymph node humoral response. Using intravital microscopy we show that local immunization or infection recruits neutrophils from the blood to lymph nodes in waves. The second wave occurs temporally with neutrophils mobilized from the bone marrow. Within lymph nodes neutrophils infiltrate the medulla and interfollicular areas, but avoid crossing follicle borders. In vivo neutrophils form transient and long-lived interactions with B cells and plasma cells, and their depletion augments production of antigen-specific IgG and IgM in the lymph node. In vitro activated neutrophils establish synapse- and nanotube-like interactions with B cells and reduce B cell IgM production in a TGF- β1 dependent manner. Our data reveal that neutrophils mobilized from the bone marrow in response to a local bacterial challenge dampen the early humoral response in the lymph node. Highly antibiotic resistant Staphylococcus aureus (S. aureus) are an important human pathogen and major cause of hospital acquired infections. An early host defense mechanism against bacterial infection is neutrophil recruitment, which helps eliminate the bacteria at the site of invasion. However, unless quickly neutralized, pathogens such as S. aureus can gain access to nearby lymph nodes via draining lymphatics. Lymph nodes protect the host by mobilizing additional resources that limit further pathogen dissemination. These include recruitment of neutrophils to the lymph node to directly target pathogens and the initiation of adaptive immune mechanisms, such as the humoral immune response, which transforms B lymphocytes capable of making pathogen specific antibodies into antibody producing plasma cells. Using a mouse model that allows direct visualization of lymphocytes, neutrophils, and fluorescently-labeled S. aureus in lymph nodes, we document the rapid appearance of bacteria in the lymph node following local S. aureus infection. We characterize the dynamic influx of neutrophils that occurs as a consequence and reveal direct B cell-neutrophil interactions within the lymph node parenchyma. We find that while lymph node neutrophils rapidly engage bacteria, they limit the subsequent humoral immune response likely by producing Transforming Growth Factor-β1, a factor known to limit B cell responses. These finding have important implication for our understanding of B cell responses against potent pathogens such as S. aureus and for the design of effective vaccines.
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Affiliation(s)
- Olena Kamenyeva
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Cedric Boularan
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Juraj Kabat
- Biological Imaging Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Claudia Cicala
- Immunopathogenesis Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Anthony J Yeh
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - June L Chan
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Saravanan Periasamy
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John H Kehrl
- B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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30
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Liu Q, Cho H, Yeo WS, Bae T. The extracytoplasmic linker peptide of the sensor protein SaeS tunes the kinase activity required for staphylococcal virulence in response to host signals. PLoS Pathog 2015; 11:e1004799. [PMID: 25849574 PMCID: PMC4388633 DOI: 10.1371/journal.ppat.1004799] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 03/11/2015] [Indexed: 11/26/2022] Open
Abstract
Bacterial pathogens often employ two-component systems (TCSs), typically consisting of a sensor kinase and a response regulator, to control expression of a set of virulence genes in response to changing host environments. In Staphylococcus aureus, the SaeRS TCS is essential for in vivo survival of the bacterium. The intramembrane-sensing histidine kinase SaeS contains, along with a C-terminal kinase domain, a simple N-terminal domain composed of two transmembrane helices and a nine amino acid-long extracytoplasmic linker peptide. As a molecular switch, SaeS maintains low but significant basal kinase activity and increases its kinase activity in response to inducing signals such as human neutrophil peptide 1 (HNP1). Here we show that the linker peptide of SaeS controls SaeS’s basal kinase activity and that the amino acid sequence of the linker peptide is highly optimized for its function. Without the linker peptide, SaeS displays aberrantly elevated kinase activity even in the absence of the inducing signal, and does not respond to HNP1. Moreover, SaeS variants with alanine substitution of the linker peptide amino acids exhibit altered basal kinase activity and/or irresponsiveness to HNP1. Biochemical assays reveal that those SaeS variants have altered autokinase and phosphotransferase activities. Finally, animal experiments demonstrate that the linker peptide-mediated fine tuning of SaeS kinase activity is critical for survival of the pathogen. Our results indicate that the function of the linker peptide in SaeS is a highly evolved feature with very optimized amino acid sequences, and we propose that, in other SaeS-like intramembrane sensing histidine kinases, the extracytoplasmic linker peptides actively fine-control their kinases. A bacterial pathogen Staphylococcus aureus uses the SaeRS two-component system to control the production of multiple toxins, resulting in a wide range of diseases in human. The sensor kinase SaeS is a member of the intramembrane-sensing histidine kinases (IM-HKs) that lacks a sensory domain and harbors a simple N-terminal domain with two transmembrane helices and a short linker peptide. It’s been considered that the linker peptide of IM-HKs transmits the external signals into the cytoplasmic catalytic domain to control the HK’s kinase activity. However, it is unclear how the external signal input propagates through the linker to modulate the kinase activity of HKs. Here we show that the linker peptide of SaeS is critical in maintaining the basal kinase activity and functions as a part of a “tripwire” to jumpstart the activation of the SaeRS system upon exposure to the specific host signals. We establish that a single amino acid substitution of the linker peptide alters SaeS’s kinase activity, resulting in different expression levels of the SaeR-activated genes and alteration of the bacterial virulence in mice. Our study provides new molecular insights into how the pathogenic bacterium utilizes the simple protein domain to control its disease-causing potentials in response to host immune signals.
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Affiliation(s)
- Qian Liu
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest,Gary, Indiana, United States of America
| | - Hoonsik Cho
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest,Gary, Indiana, United States of America
| | - Won-Sik Yeo
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest,Gary, Indiana, United States of America
| | - Taeok Bae
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest,Gary, Indiana, United States of America
- * E-mail:
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Ransom EM, Ellermeier CD, Weiss DS. Use of mCherry Red fluorescent protein for studies of protein localization and gene expression in Clostridium difficile. Appl Environ Microbiol 2015; 81:1652-60. [PMID: 25527559 PMCID: PMC4325159 DOI: 10.1128/aem.03446-14] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/17/2014] [Indexed: 01/05/2023] Open
Abstract
Fluorescent proteins are powerful reporters in biology, but most require O2 for chromophore maturation, making them inherently difficult to use in anaerobic bacteria. Clostridium difficile, a strict anaerobe with a genomic GC content of only 29%, is the leading cause of hospital-acquired diarrhea in developed countries, and new methods for studying this pathogen are sorely needed. We recently demonstrated that a cyan fluorescent protein called CFPopt that has been codon optimized for production in low-GC bacteria can be used to study protein localization in C. difficile provided the cells are fixed prior to exposure to air. We describe here a codon-optimized variant of mCherry (mCherryOpt) that exhibits faster acquisition of fluorescence and a better signal-to-noise ratio than CFPopt. We utilized mCherryOpt to construct plasmids for studying protein localization (pRAN473) and gene expression (pDSW1728) in C. difficile. Plasmid pRAN473 is an mCherryOpt fusion vector with a tetracycline-inducible promoter. To document its biological utility, we demonstrated septal localization of two cell division proteins, MldA and ZapA. Plasmid pDSW1728 is designed for cloning a promoter of interest upstream of mCherryOpt. As proof of principle, we studied the expression of the pdaV operon, which is required for lysozyme resistance. In confirmation and extension of previous reports, we found that expression of the pdaV operon requires the alternative sigma factor σ(v) and that induction by lysozyme is dose dependent and uniform across the population of lysozyme-treated cells.
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Affiliation(s)
- Eric M Ransom
- Department of Microbiology, University of Iowa, Iowa City, Iowa, USA
| | | | - David S Weiss
- Department of Microbiology, University of Iowa, Iowa City, Iowa, USA
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Hoang PM, Cho S, Kim KE, Byun SJ, Lee TK, Lee S. Development of Lactobacillus paracasei harboring nucleic acid-hydrolyzing 3D8 scFv as a preventive probiotic against murine norovirus infection. Appl Microbiol Biotechnol 2014; 99:2793-803. [PMID: 25487889 DOI: 10.1007/s00253-014-6257-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 11/18/2014] [Accepted: 11/20/2014] [Indexed: 01/15/2023]
Abstract
The protein 3D8 single-chain variable fragment (3D8 scFv) has potential anti-viral activity due to its ability to penetrate into cells and hydrolyze nucleic acids. Probiotic Lactobacillus paracasei engineered to secrete 3D8 scFv for oral administration was used to test the anti-viral effects of 3D8 scFv against gastrointestinal virus infections. We found that injection of 3D8 scFv into the intestinal lumen resulted in the penetration of 3D8 scFv into the intestinal villi and lamina propria. 3D8 scFv secreted from engineered L. paracasei retained its cell-penetrating and nucleic acid-hydrolyzing activities, which were previously shown with 3D8 scFv expressed in Escherichia coli. Pretreatment of RAW264.7 cells with 3D8 scFv purified from L. paracasei prevented apoptosis induction by murine norovirus infection and decreased messenger RNA (mRNA) expression of the viral capsid protein VP1. In a mouse model, oral administration of the engineered L. paracasei prior to murine norovirus infection reduced the expression level of mRNA encoding viral polymerase. Taken together, these results suggest that L. paracasei secreting 3D8 scFv provides a basis for the development of ingestible anti-viral probiotics active against gastrointestinal viral infection.
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Affiliation(s)
- Phuong Mai Hoang
- Department of Genetic Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, 440-746, Korea
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Trauth S, Bischofs IB. Ectopic integration vectors for generating fluorescent promoter fusions in Bacillus subtilis with minimal dark noise. PLoS One 2014; 9:e98360. [PMID: 24874808 PMCID: PMC4038550 DOI: 10.1371/journal.pone.0098360] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/01/2014] [Indexed: 11/19/2022] Open
Abstract
Fluorescent protein promoter reporters are important tools that are widely used for diverse purposes in microbiology, systems biology and synthetic biology and considerable engineering efforts are still geared at improving the sensitivity of the reporter systems. Here we focus on dark noise, i.e. the signal that is generated by the empty vector control. We quantitatively characterize the dark noise of a few common bacterial reporter systems by single cell microscopy. All benchmarked reporter systems generated significant amounts of dark noise that exceed the cellular autofluorescence to different extents. We then reengineered a multicolor set of fluorescent ectopic integration vectors for Bacillus subtilis by introducing a terminator immediately upstream of the promoter insertion site, resulting in an up to 2.7-fold reduction of noise levels. The sensitivity and dynamic range of the new high-performance pXFP_Star reporter system is only limited by cellular autofluorescence. Moreover, based on studies of the rapE promoter of B. subtilis we show that the new pXFP_Star reporter system reliably reports on the weak activity of the rapE promoter whereas the original reporter system fails because of transcriptional interference. Since the pXFP_Star reporter system properly isolates the promoter from spurious transcripts, it is a particularly suitable tool for quantitative characterization of weak promoters in B. subtilis.
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Affiliation(s)
- Stephanie Trauth
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
- Center for Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Heidelberg, Germany
| | - Ilka B. Bischofs
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
- Center for Quantitative Analysis of Molecular and Cellular Biosystems (BioQuant), University of Heidelberg, Heidelberg, Germany
- * E-mail:
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Identification and characterization of a gene cluster required for proper rod shape, cell division, and pathogenesis in Clostridium difficile. J Bacteriol 2014; 196:2290-300. [PMID: 24727226 DOI: 10.1128/jb.00038-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Little is known about cell division in Clostridium difficile, a strict anaerobe that causes serious diarrheal diseases in people whose normal intestinal microbiome has been perturbed by treatment with broad-spectrum antibiotics. Here we identify and characterize a gene cluster encoding three cell division proteins found only in C. difficile and a small number of closely related bacteria. These proteins were named MldA, MldB, and MldC, for midcell localizing division proteins. MldA is predicted to be a membrane protein with coiled-coil domains and a peptidoglycan-binding SPOR domain. MldB and MldC are predicted to be cytoplasmic proteins; MldB has two predicted coiled-coil domains, but MldC lacks obvious conserved domains or sequence motifs. Mutants of mldA or mldB had morphological defects, including loss of rod shape (a curved cell phenotype) and inefficient separation of daughter cells (a chaining phenotype). Fusions of cyan fluorescent protein (CFP) to MldA, MldB, and MldC revealed that all three proteins localize sharply to the division site. This application of CFP was possible because we discovered that O2-dependent fluorescent proteins produced anaerobically can acquire fluorescence after cells are fixed with cross-linkers to preserve native patterns of protein localization. Mutants lacking the Mld proteins are severely attenuated for pathogenesis in a hamster model of C. difficile infection. Because all three Mld proteins are essentially unique to C. difficile, they might be exploited as targets for antibiotics that combat C. difficile without disrupting the intestinal microbiome.
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Abstract
Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species.
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McKenzie AT, Pomerantsev AP, Sastalla I, Martens C, Ricklefs SM, Virtaneva K, Anzick S, Porcella SF, Leppla SH. Transcriptome analysis identifies Bacillus anthracis genes that respond to CO2 through an AtxA-dependent mechanism. BMC Genomics 2014; 15:229. [PMID: 24661624 PMCID: PMC3987803 DOI: 10.1186/1471-2164-15-229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 03/12/2014] [Indexed: 11/30/2022] Open
Abstract
Background Upon infection of a mammalian host, Bacillus anthracis responds to host cues, and particularly to elevated temperature (37°C) and bicarbonate/CO2 concentrations, with increased expression of virulence factors that include the anthrax toxins and extracellular capsular layer. This response requires the presence of the pXO1 virulence plasmid-encoded pleiotropic regulator AtxA. To better understand the genetic basis of this response, we utilized a controlled in vitro system and Next Generation sequencing to determine and compare RNA expression profiles of the parental strain and an isogenic AtxA-deficient strain in a 2 × 2 factorial design with growth environments containing or lacking carbon dioxide. Results We found 15 pXO1-encoded genes and 3 chromosomal genes that were strongly regulated by the separate or synergistic actions of AtxA and carbon dioxide. The majority of the regulated genes responded to both AtxA and carbon dioxide rather than to just one of these factors. Interestingly, we identified two previously unrecognized small RNAs that are highly expressed under physiological carbon dioxide concentrations in an AtxA-dependent manner. Expression levels of the two small RNAs were found to be higher than that of any other gene differentially expressed in response to these conditions. Secondary structure and small RNA-mRNA binding predictions for the two small RNAs suggest that they may perform important functions in regulating B. anthracis virulence. Conclusions A majority of genes on the virulence plasmid pXO1 that are regulated by the presence of either CO2 or AtxA separately are also regulated synergistically in the presence of both. These results also elucidate novel pXO1-encoded small RNAs that are associated with virulence conditions.
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Affiliation(s)
| | - Andrei P Pomerantsev
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA.
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Mijouin L, Hillion M, Ramdani Y, Jaouen T, Duclairoir-Poc C, Follet-Gueye ML, Lati E, Yvergnaux F, Driouich A, Lefeuvre L, Farmer C, Misery L, Feuilloley MGJ. Effects of a skin neuropeptide (substance p) on cutaneous microflora. PLoS One 2013; 8:e78773. [PMID: 24250813 PMCID: PMC3826737 DOI: 10.1371/journal.pone.0078773] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 09/16/2013] [Indexed: 01/01/2023] Open
Abstract
Background Skin is the largest human neuroendocrine organ and hosts the second most numerous microbial population but the interaction of skin neuropeptides with the microflora has never been investigated. We studied the effect of Substance P (SP), a peptide released by nerve endings in the skin on bacterial virulence. Methodology/Principal Findings Bacillus cereus, a member of the skin transient microflora, was used as a model. Exposure to SP strongly stimulated the cytotoxicity of B. cereus (+553±3% with SP 10−6 M) and this effect was rapid (<5 min). Infection of keratinocytes with SP treated B. cereus led to a rise in caspase1 and morphological alterations of the actin cytoskeleton. Secretome analysis revealed that SP stimulated the release of collagenase and superoxide dismutase. Moreover, we also noted a shift in the surface polarity of the bacteria linked to a peel-off of the S-layer and the release of S-layer proteins. Meanwhile, the biofilm formation activity of B. cereus was increased. The Thermo unstable ribosomal Elongation factor (Ef-Tu) was identified as the SP binding site in B. cereus. Other Gram positive skin bacteria, namely Staphylococcus aureus and Staphylococcus epidermidis also reacted to SP by an increase of virulence. Thermal water from Uriage-les-Bains and an artificial polysaccharide (Teflose®) were capable to antagonize the effect of SP on bacterial virulence. Conclusions/Significance SP is released in sweat during stress and is known to be involved in the pathogenesis of numerous skin diseases through neurogenic inflammation. Our study suggests that a direct effect of SP on the skin microbiote should be another mechanism.
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Affiliation(s)
- Lily Mijouin
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université Rouen, Evreux, France
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Sastalla I, Fattah R, Coppage N, Nandy P, Crown D, Pomerantsev AP, Leppla SH. The Bacillus cereus Hbl and Nhe tripartite enterotoxin components assemble sequentially on the surface of target cells and are not interchangeable. PLoS One 2013; 8:e76955. [PMID: 24204713 PMCID: PMC3799921 DOI: 10.1371/journal.pone.0076955] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/28/2013] [Indexed: 02/06/2023] Open
Abstract
Bacillus cereus is a spore-forming, Gram-positive bacterium commonly associated with outbreaks of food poisoning. It is also known as an opportunistic pathogen causing clinical infections such as bacteremia, meningitis, pneumonia, and gas gangrene-like cutaneous infections, mostly in immunocompromised patients. B. cereus secretes a plethora of toxins of which four are associated with the symptoms of food poisoning. Two of these, the non-hemolytic enterotoxin Nhe and the hemolysin BL (Hbl) toxin, are predicted to be structurally similar and are unique in that they require the combined action of three toxin proteins to induce cell lysis. Despite their dominant role in disease, the molecular mechanism of their toxic function is still poorly understood. We report here that B. cereus strain ATCC 10876 harbors not only genes encoding Nhe, but also two copies of the hbl genes. We identified Hbl as the major secreted toxin responsible for inducing rapid cell lysis both in cultured cells and in an intraperitoneal mouse toxicity model. Antibody neutralization and deletion of Hbl-encoding genes resulted in significant reductions of cytotoxic activity. Microscopy studies with Chinese Hamster Ovary cells furthermore showed that pore formation by both Hbl and Nhe occurs through a stepwise, sequential binding of toxin components to the cell surface and to each other. This begins with binding of Hbl-B or NheC to the eukaryotic membrane, and is followed by the recruitment of Hbl-L1 or NheB, respectively, followed by the corresponding third protein. Lastly, toxin component complementation studies indicate that although Hbl and Nhe can be expressed simultaneously and are predicted to be structurally similar, they are incompatible and cannot complement each other.
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Affiliation(s)
- Inka Sastalla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| | - Rasem Fattah
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicole Coppage
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Poulomi Nandy
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Andrei P. Pomerantsev
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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Live-cell imaging tool optimization to study gene expression levels and dynamics in single cells of Bacillus cereus. Appl Environ Microbiol 2013; 79:5643-51. [PMID: 23851094 DOI: 10.1128/aem.01347-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Single-cell methods are a powerful application in microbial research to study the molecular mechanism underlying phenotypic heterogeneity and cell-to-cell variability. Here, we describe the optimization and application of single-cell time-lapse fluorescence microscopy for the food spoilage bacterium Bacillus cereus specifically. This technique is useful to study cellular development and adaptation, gene expression, protein localization, protein mobility, and cell-to-cell communication over time at the single-cell level. By adjusting existing protocols, we have enabled the visualization of growth and development of single B. cereus cells within a microcolony over time. Additionally, several different fluorescent reporter proteins were tested in order to select the most suitable green fluorescent protein (GFP) and red fluorescent protein (RFP) candidates for visualization of growth stage- and cell compartment-specific gene expression in B. cereus. With a case study concerning cotD expression during sporulation, we demonstrate the applicability of time-lapse fluorescence microscopy. It enables the assessment of gene expression levels, dynamics, and heterogeneity at the single-cell level. We show that cotD is not heterogeneously expressed among cells of a subpopulation. Furthermore, we discourage using plasmid-based reporter fusions for such studies, due to an introduced heterogeneity through copy number differences. This stresses the importance of using single-copy integrated reporter fusions for single-cell studies.
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Brzoska AJ, Firth N. Two-plasmid vector system for independently controlled expression of green and red fluorescent fusion proteins in Staphylococcus aureus. Appl Environ Microbiol 2013; 79:3133-6. [PMID: 23455338 PMCID: PMC3623144 DOI: 10.1128/aem.00144-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 02/21/2013] [Indexed: 02/07/2023] Open
Abstract
We have constructed a system for the regulated coexpression of green fluorescent protein (GFP) and red fluorescent protein (RFP) fusions in Staphylococcus aureus. It was validated by simultaneous localization of cell division proteins FtsZ and Noc and used to detect filament formation by an actin-like ParM plasmid partitioning protein in its native coccoid host.
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Affiliation(s)
- Anthony J Brzoska
- School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia
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Kaito C, Saito Y, Ikuo M, Omae Y, Mao H, Nagano G, Fujiyuki T, Numata S, Han X, Obata K, Hasegawa S, Yamaguchi H, Inokuchi K, Ito T, Hiramatsu K, Sekimizu K. Mobile genetic element SCCmec-encoded psm-mec RNA suppresses translation of agrA and attenuates MRSA virulence. PLoS Pathog 2013; 9:e1003269. [PMID: 23592990 PMCID: PMC3617227 DOI: 10.1371/journal.ppat.1003269] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 02/08/2013] [Indexed: 01/02/2023] Open
Abstract
Community acquired-methicillin resistant Staphylococcus aureus (CA-MRSA) is a socially problematic pathogen that infects healthy individuals, causing severe disease. CA-MRSA is more virulent than hospital associated-MRSA (HA-MRSA). The underlying mechanism for the high virulence of CA-MRSA is not known. The transcription product of the psm-mec gene, located in the mobile genetic element SCCmec of HA-MRSA, but not CA-MRSA, suppresses the expression of phenol-soluble modulin α (PSMα), a cytolytic toxin of S. aureus. Here we report that psm-mec RNA inhibits translation of the agrA gene encoding a positive transcription factor for the PSMα gene via specific binding to agrA mRNA. Furthermore, 25% of 325 clinical MRSA isolates had a mutation in the psm-mec promoter that attenuated transcription, and 9% of the strains had no psm-mec. In most of these psm-mec-mutated or psm-mec-deleted HA-MRSAs, PSMα expression was increased compared with strains carrying intact psm-mec, and some mutated strains produced high amounts of PSMα comparable with that of CA-MRSA. Deletion of psm-mec from HA-MRSA strains carrying intact psm-mec increased the expression of AgrA protein and PSMα, and virulence in mice. Thus, psm-mec RNA suppresses MRSA virulence via inhibition of agrA translation and the absence of psm-mec function in CA-MRSA causes its high virulence property. Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to various antibiotics, including β-lactams, thus causing serious clinical problems. Hospital-associated (HA)-MRSA infects immunocompromised patients in hospitals. Community-acquired (CA)-MRSA causes serious diseases in healthy people who have not had contact with hospitals in the United States, Canada, or Europe. CA-MRSA produces higher amounts of extracellular toxins and has higher virulence than HA-MRSA, although the reason for this is unclear. SCCmec is a foreign DNA integrated into the MRSA chromosome that contains several genes including the mecA gene that confers resistance against methicillin. The SCCmec of CA-MRSA does not contain the psm-mec gene that exists in the HA-MRSA SCCmec. In the present study, we found that the transcription product of psm-mec inhibits translation of the agrA gene encoding a positive transcription factor for many extracellular toxins by direct binding to the agrA mRNA, resulting in decreased extracellular toxin production. Furthermore, some HA-MRSA strains carry mutated psm-mec or no psm-mec and produce higher amounts of extracellular toxins than HA-MRSA strains carrying intact psm-mec. These findings suggest that psm-mec RNA negatively regulates agrA and mutation or absence of psm-mec leads to a high virulence capacity of MRSA.
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Affiliation(s)
- Chikara Kaito
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
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Prax M, Lee CY, Bertram R. An update on the molecular genetics toolbox for staphylococci. MICROBIOLOGY-SGM 2013; 159:421-435. [PMID: 23378573 PMCID: PMC3709823 DOI: 10.1099/mic.0.061705-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Staphylococci are Gram-positive spherical bacteria of enormous clinical and biotechnological relevance. Staphylococcus aureus has been extensively studied as a model pathogen. A plethora of methods and molecular tools has been developed for genetic modification of at least ten different staphylococcal species to date. Here we review recent developments of various genetic tools and molecular methods for staphylococcal research, which include reporter systems and vectors for controllable gene expression, gene inactivation, gene essentiality testing, chromosomal integration and transposon delivery. It is furthermore illustrated how mutant strain construction by homologous or site-specific recombination benefits from sophisticated counterselection methods. The underlying genetic components have been shown to operate in wild-type staphylococci or modified chassis strains. Finally, possible future developments in the field of applied Staphylococcus genetics are highlighted.
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Affiliation(s)
- Marcel Prax
- Department of Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Faculty of Science, University of Tübingen, Waldhäuser Str. 70/8, 72076 Tübingen, Germany
| | - Chia Y Lee
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 511, Little Rock, AR 72205, USA
| | - Ralph Bertram
- Department of Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Faculty of Science, University of Tübingen, Waldhäuser Str. 70/8, 72076 Tübingen, Germany
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Ceuppens S, Timmery S, Mahillon J, Uyttendaele M, Boon N. Small Bacillus cereus
ATCC 14579 subpopulations are responsible for cytotoxin K production. J Appl Microbiol 2013; 114:899-906. [DOI: 10.1111/jam.12096] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 11/22/2012] [Accepted: 11/27/2012] [Indexed: 11/30/2022]
Affiliation(s)
- S. Ceuppens
- Laboratory of Food Microbiology and Food Preservation (LFMFP), Faculty of Bioscience Engineering; Ghent University; Gent Belgium
- Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering; Ghent University; Gent Belgium
| | - S. Timmery
- Laboratory of Food and Environmental Microbiology, Faculty of Bioscience Engineering; Université catholique de Louvain; Louvain-la-Neuve Belgium
| | - J. Mahillon
- Laboratory of Food and Environmental Microbiology, Faculty of Bioscience Engineering; Université catholique de Louvain; Louvain-la-Neuve Belgium
| | - M. Uyttendaele
- Laboratory of Food Microbiology and Food Preservation (LFMFP), Faculty of Bioscience Engineering; Ghent University; Gent Belgium
| | - N. Boon
- Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering; Ghent University; Gent Belgium
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Distinct roles of phenol-soluble modulins in spreading of Staphylococcus aureus on wet surfaces. Appl Environ Microbiol 2012. [PMID: 23183971 DOI: 10.1128/aem.03157-12] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The human pathogen Staphylococcus aureus is renowned for the rapid colonization of contaminated wounds, medical implants, and food products. Nevertheless, little is known about the mechanisms that allow S. aureus to colonize the respective wet surfaces. The present studies were therefore aimed at identifying factors used by S. aureus cells to spread over wet surfaces, starting either from planktonic or biofilm-associated states. Through proteomics analyses we pinpoint phenol-soluble modulins (PSMs) as prime facilitators of the spreading process. To dissect the roles of the eight PSMs produced by S. aureus, these peptides were chemically synthesized and tested in spreading assays with different psm mutant strains. The results show that PSMα3 and PSMγ are the strongest facilitators of spreading both for planktonic cells and cells in catheter-associated biofilms. Compared to the six other PSMs of S. aureus, PSMα3 and PSMγ combine strong surfactant activities with a relatively low overall hydropathicity. Importantly, we show that PSM-mediated motility of S. aureus facilitates the rapid colonization of wet surfaces next to catheters and the colonization of fresh meat.
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45
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Loh LN, Ward TH. Escherichia coli K1 invasion of human brain microvascular endothelial cells. Methods Enzymol 2012; 506:93-113. [PMID: 22341221 DOI: 10.1016/b978-0-12-391856-7.00030-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The pathogenic Escherichia coli strain E. coli K1 is a primary causative agent of neonatal meningitis. Understanding how these bacteria cross the blood-brain barrier is vital to develop therapeutics. Here, we describe the use of live-cell imaging techniques to study E. coli K1 interactions with cellular markers following infection of human brain microvascular endothelial cells, a model system of the blood-brain barrier. We also discuss optimization of endothelial cell transfection conditions using nonviral transfection technique, bacterial labeling techniques, and in vitro assays to screen for fluorescent bacteria that retain their ability to invade host cells.
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Affiliation(s)
- Lip Nam Loh
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Okugawa S, Moayeri M, Pomerantsev AP, Sastalla I, Crown D, Gupta PK, Leppla SH. Lipoprotein biosynthesis by prolipoprotein diacylglyceryl transferase is required for efficient spore germination and full virulence of Bacillus anthracis. Mol Microbiol 2012; 83:96-109. [PMID: 22103323 PMCID: PMC3245379 DOI: 10.1111/j.1365-2958.2011.07915.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacterial lipoproteins play a crucial role in virulence in some gram-positive bacteria. However, the role of lipoprotein biosynthesis in Bacillus anthracis is unknown. We created a B. anthracis mutant strain altered in lipoproteins by deleting the lgt gene encoding the enzyme prolipoprotein diacylglyceryl transferase, which attaches the lipid anchor to prolipoproteins. (14)C-palmitate labelling confirmed that the mutant strain lacked lipoproteins, and hydrocarbon partitioning showed it to have decreased surface hydrophobicity. The anthrax toxin proteins were secreted from the mutant strain at nearly the same levels as from the wild-type strain. The TLR2-dependent TNF-α response of macrophages to heat-killed lgt mutant bacteria was reduced. Spores of the lgt mutant germinated inefficiently in vitro and in mouse skin. As a result, in a murine subcutaneous infection model, lgt mutant spores had markedly attenuated virulence. In contrast, vegetative cells of the lgt mutant were as virulent as those of the wild-type strain. Thus, lipoprotein biosynthesis in B. anthracis is required for full virulence in a murine infection model.
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Affiliation(s)
- Shu Okugawa
- Laboratory of Bacterial Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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47
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Gauger T, Weihs F, Mayer S, Krismer B, Liese J, Kull M, Bertram R. Intracellular monitoring of target protein production in Staphylococcus aureus by peptide tag-induced reporter fluorescence. Microb Biotechnol 2011; 5:129-34. [PMID: 21958360 PMCID: PMC3815279 DOI: 10.1111/j.1751-7915.2011.00304.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
An intracellular approach for monitoring protein production in Staphylococcus aureus is described. mCherry, fused to the dodecapeptide Tip, was capable of inducing tetracycline repressor (TetR). Time‐ and concentration‐dependent production of mCherry could be correlated to TetR‐controlled GFPmut2 activity. This approach can potentially be extended to native S. aureus proteins.
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Affiliation(s)
- Tina Gauger
- Lehrbereich Mikrobielle Genetik, Waldhäuser Str. 70/8, Eberhard Karls Universität Tübingen, Germany
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48
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Leroch M, Mernke D, Koppenhoefer D, Schneider P, Mosbach A, Doehlemann G, Hahn M. Living colors in the gray mold pathogen Botrytis cinerea: codon-optimized genes encoding green fluorescent protein and mCherry, which exhibit bright fluorescence. Appl Environ Microbiol 2011; 77:2887-97. [PMID: 21378036 PMCID: PMC3126427 DOI: 10.1128/aem.02644-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Accepted: 02/25/2011] [Indexed: 12/18/2022] Open
Abstract
The green fluorescent protein (GFP) and its variants have been widely used in modern biology as reporters that allow a variety of live-cell imaging techniques. So far, GFP has rarely been used in the gray mold fungus Botrytis cinerea because of low fluorescence intensity. The codon usage of B. cinerea genes strongly deviates from that of commonly used GFP-encoding genes and reveals a lower GC content than other fungi. In this study, we report the development and use of a codon-optimized version of the B. cinerea enhanced GFP (eGFP)-encoding gene (Bcgfp) for improved expression in B. cinerea. Both the codon optimization and, to a smaller extent, the insertion of an intron resulted in higher mRNA levels and increased fluorescence. Bcgfp was used for localization of nuclei in germinating spores and for visualizing host penetration. We further demonstrate the use of promoter-Bcgfp fusions for quantitative evaluation of various toxic compounds as inducers of the atrB gene encoding an ABC-type drug efflux transporter of B. cinerea. In addition, a codon-optimized mCherry-encoding gene was constructed which yielded bright red fluorescence in B. cinerea.
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Affiliation(s)
- Michaela Leroch
- Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany.
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50
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Construction and characterization of a lactose-inducible promoter system for controlled gene expression in Clostridium perfringens. Appl Environ Microbiol 2010; 77:471-8. [PMID: 21097603 DOI: 10.1128/aem.01536-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium perfringens is a Gram-positive anaerobic pathogen which causes many diseases in humans and animals. While some genetic tools exist for working with C. perfringens, a tightly regulated, inducible promoter system is currently lacking. Therefore, we constructed a plasmid-based promoter system that provided regulated expression when lactose was added. This plasmid (pKRAH1) is an Escherichia coli-C. perfringens shuttle vector containing the gene encoding a transcriptional regulator, BgaR, and a divergent promoter upstream of gene bgaL (bgaR-P(bgaL)). To measure transcription at the bgaL promoter in pKRAH1, the E. coli reporter gene gusA, encoding β-glucuronidase, was placed downstream of the P(bgaL) promoter to make plasmid pAH2. When transformed into three strains of C. perfringens, pAH2 exhibited lactose-inducible expression. C. perfringens strain 13, a commonly studied strain, has endogenous β-glucuronidase activity. We mutated gene bglR, encoding a putative β-glucuronidase, and observed an 89% decrease in endogenous activity with no lactose. This combination of a system for regulated gene expression and a mutant of strain 13 with low β-glucuronidase activity are useful tools for studying gene regulation and protein expression in an important pathogenic bacterium. We used this system to express the yfp-pilB gene, comprised of a yellow fluorescent protein (YFP)-encoding gene fused to an assembly ATPase gene involved in type IV pilus-dependent gliding motility in C. perfringens. Expression in the wild-type strain showed that YFP-PilB localized mostly to the poles of cells, but in a pilC mutant it localized throughout the cell, demonstrating that the membrane protein PilC is required for polar localization of PilB.
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