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Carrica MDC, Gorgojo JP, Alvarez-Hayes J, Valdez HA, Lamberti YA, Rodriguez ME. BPP0974 is a Bordetella parapertussis adhesin expressed in the avirulent phase, implicated in biofilm formation and intracellular survival. Microb Pathog 2024; 193:106754. [PMID: 38897361 DOI: 10.1016/j.micpath.2024.106754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/28/2024] [Accepted: 06/16/2024] [Indexed: 06/21/2024]
Abstract
B: parapertussis is a bacterium that causes whooping cough, a severe respiratory infection disease, that has shown an increased incidence in the population. Upon transmission through aerosol droplets, the initial steps of host colonization critically depend on the bacterial adhesins. We here described BPP0974, a B. parapertussis protein that exhibits the typical domain architecture of the large repetitive RTX adhesin family. BPP0974 was found to be retained in the bacterial membrane and secreted into the culture medium. This protein was found overexpressed in the avirulent phase of B. parapertussis, the phenotype proposed for initial host colonization. Interestingly, BPP0974 was found relevant for the biofilm formation as well as involved in the bacterial attachment to and survival within the respiratory epithelial cells. Taken together, our results suggest a role for BPP0974 in the early host colonization and pathogenesis of B. parapertussis.
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Affiliation(s)
- Mariela Del Carmen Carrica
- CINDEFI (UNLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
| | - Juan Pablo Gorgojo
- CINDEFI (UNLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Jimena Alvarez-Hayes
- CINDEFI (UNLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Hugo Alberto Valdez
- CINDEFI (UNLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Yanina Andrea Lamberti
- CINDEFI (UNLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Maria Eugenia Rodriguez
- CINDEFI (UNLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
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2
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Vogt LN, Panis G, Schäpers A, Peschek N, Huber M, Papenfort K, Viollier PH, Fröhlich KS. Genome-wide profiling of Hfq-bound RNAs reveals the iron-responsive small RNA RusT in Caulobacter crescentus. mBio 2024; 15:e0315323. [PMID: 38511926 PMCID: PMC11005374 DOI: 10.1128/mbio.03153-23] [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: 11/21/2023] [Accepted: 02/28/2024] [Indexed: 03/22/2024] Open
Abstract
The alphaproteobacterium Caulobacter crescentus thrives in oligotrophic environments and is able to optimally exploit minimal resources by entertaining an intricate network of gene expression control mechanisms. Numerous transcriptional activators and repressors have been reported to contribute to these processes, but only few studies have focused on regulation at the post-transcriptional level in C. crescentus. Small RNAs (sRNAs) are a prominent class of regulators of bacterial gene expression, and most sRNAs characterized today engage in direct base-pairing interactions to modulate the translation and/or stability of target mRNAs. In many cases, the ubiquitous RNA chaperone, Hfq, contributes to the establishment of RNA-RNA interactions. Although the deletion of the hfq gene is associated with a severe loss of fitness in C. crescentus, the RNA ligands of the chaperone have remained largely unexplored. Here we report on the identification of coding and non-coding transcripts associated with Hfq in C. crescentus and demonstrate Hfq-dependent post-transcriptional regulation in this organism. We show that the Hfq-bound sRNA RusT is transcriptionally controlled by the NtrYX two-component system and induced in response to iron starvation. By combining RusT pulse expression with whole-genome transcriptome analysis, we determine 16 candidate target transcripts that are deregulated, many of which encode outer membrane transporters. We hence suggest RusT to support remodeling of the C. crescentus cell surface when iron supplies are limited.IMPORTANCEThe conserved RNA-binding protein Hfq contributes significantly to the adaptation of bacteria to different environmental conditions. Hfq not only stabilizes associated sRNAs but also promotes inter-molecular base-pairing interactions with target transcripts. Hfq plays a pivotal role for growth and survival, controlling central metabolism and cell wall synthesis in the oligotroph Caulobacter crescentus. However, direct evidence for Hfq-dependent post-transcriptional regulation and potential oligotrophy in C. crescentus has been lacking. Here, we identified sRNAs and mRNAs associated with Hfq in vivo, and demonstrated the requirement of Hfq for sRNA-mediated regulation, particularly of outer membrane transporters in C. crescentus.
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Affiliation(s)
- Laura N. Vogt
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Anna Schäpers
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Nikolai Peschek
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Michaela Huber
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kai Papenfort
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University, Jena, Germany
| | - Patrick H. Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Kathrin S. Fröhlich
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University, Jena, Germany
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3
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Freddi L, de la Garza-García JA, Al Dahouk S, Occhialini A, Köhler S. Brucella spp. are facultative anaerobic bacteria under denitrifying conditions. Microbiol Spectr 2023; 11:e0276723. [PMID: 37882559 PMCID: PMC10714718 DOI: 10.1128/spectrum.02767-23] [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: 07/07/2023] [Accepted: 09/06/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE Respiration is a fundamental and complex process that bacteria use to produce energy. Despite aerobic respiration being the most common, some bacteria make use of a mode of respiration in the absence of oxygen, called anaerobic respiration, which can yield advantages in adaptation to various environmental conditions. Denitrification is part of this respiratory process ensuring higher respiratory flexibility under oxygen depletion. Here, we report for the first time the evidence of anaerobic growth of Brucella spp. under denitrifying conditions, which implies that this genus should be reconsidered as facultative anaerobic. Our study further describes that efficient denitrification is not equally found within the Brucella genus, with atypical species showing a greater ability to denitrify, correlated with higher expression of the genes involved, as compared to classical species.
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Affiliation(s)
- Luca Freddi
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University of Montpellier, INSERM, Montpellier, France
| | - Jorge A. de la Garza-García
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University of Montpellier, INSERM, Montpellier, France
| | - Sascha Al Dahouk
- German Federal Institute for Risk Assessment, Berlin, Germany
- German Environment Agency, Berlin, Germany
| | - Alessandra Occhialini
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University of Montpellier, INSERM, Montpellier, France
| | - Stephan Köhler
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, University of Montpellier, INSERM, Montpellier, France
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4
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Ramdass AC, Rampersad SN. Genome features of a novel hydrocarbonoclastic Chryseobacterium oranimense strain and its comparison to bacterial oil-degraders and to other C. oranimense strains. DNA Res 2023; 30:dsad025. [PMID: 37952165 PMCID: PMC10710014 DOI: 10.1093/dnares/dsad025] [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: 07/20/2023] [Revised: 10/29/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023] Open
Abstract
For the first time, we report the whole genome sequence of a hydrocarbonoclastic Chryseobacterium oranimense strain isolated from Trinidad and Tobago (COTT) and its genes involved in the biotransformation of hydrocarbons and xenobiotics through functional annotation. The assembly consisted of 11 contigs with 2,794 predicted protein-coding genes which included a diverse group of gene families involved in aliphatic and polycyclic hydrocarbon degradation. Comparative genomic analyses with 18 crude-oil degrading bacteria in addition to two C. oranimense strains not associated with oil were carried out. The data revealed important differences in terms of annotated genes involved in the hydrocarbon degradation process that may explain the molecular mechanisms of hydrocarbon and xenobiotic biotransformation. Notably, many gene families were expanded to explain COTT's competitive ability to manage habitat-specific stressors. Gene-based evidence of the metabolic potential of COTT supports the application of indigenous microbes for the remediation of polluted terrestrial environments and provides a genomic resource for improving our understanding of how to optimize these characteristics for more effective bioremediation.
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Affiliation(s)
- Amanda Christine Ramdass
- Biochemistry Research Lab (Rm216), Department of Life Sciences, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad and Tobago, West Indies
| | - Sephra Nalini Rampersad
- Biochemistry Research Lab (Rm216), Department of Life Sciences, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad and Tobago, West Indies
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5
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Wiesmann CL, Wang NR, Zhang Y, Liu Z, Haney CH. Origins of symbiosis: shared mechanisms underlying microbial pathogenesis, commensalism and mutualism of plants and animals. FEMS Microbiol Rev 2023; 47:fuac048. [PMID: 36521845 PMCID: PMC10719066 DOI: 10.1093/femsre/fuac048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/07/2022] [Accepted: 12/09/2022] [Indexed: 12/17/2023] Open
Abstract
Regardless of the outcome of symbiosis, whether it is pathogenic, mutualistic or commensal, bacteria must first colonize their hosts. Intriguingly, closely related bacteria that colonize diverse hosts with diverse outcomes of symbiosis have conserved host-association and virulence factors. This review describes commonalities in the process of becoming host associated amongst bacteria with diverse lifestyles. Whether a pathogen, commensal or mutualist, bacteria must sense the presence of and migrate towards a host, compete for space and nutrients with other microbes, evade the host immune system, and change their physiology to enable long-term host association. We primarily focus on well-studied taxa, such as Pseudomonas, that associate with diverse model plant and animal hosts, with far-ranging symbiotic outcomes. Given the importance of opportunistic pathogens and chronic infections in both human health and agriculture, understanding the mechanisms that facilitate symbiotic relationships between bacteria and their hosts will help inform the development of disease treatments for both humans, and the plants we eat.
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Affiliation(s)
- Christina L Wiesmann
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Nicole R Wang
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Yue Zhang
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Zhexian Liu
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Cara H Haney
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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6
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Xing J, Gumerov VM, Zhulin IB. Origin and functional diversification of PAS domain, a ubiquitous intracellular sensor. SCIENCE ADVANCES 2023; 9:eadi4517. [PMID: 37647406 PMCID: PMC10468136 DOI: 10.1126/sciadv.adi4517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
Signal perception is a key function in regulating biological activities and adapting to changing environments. Per-Arnt-Sim (PAS) domains are ubiquitous sensors found in diverse receptors in bacteria, archaea, and eukaryotes, but their origins, distribution across the tree of life, and extent of their functional diversity are not fully characterized. Here, we show that using sequence conservation and structural information, it is possible to propose specific and potential functions for a large portion of nearly 3 million PAS domains. Our analysis suggests that PAS domains originated in bacteria and were horizontally transferred to archaea and eukaryotes. We reveal that gas sensing via a heme cofactor evolved independently in several lineages, whereas redox and light sensing via flavin adenine dinucleotide and flavin mononucleotide cofactors have the same origin. The close relatedness of human PAS domains to those in bacteria provides an opportunity for drug design by exploring potential natural ligands and cofactors for bacterial homologs.
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Affiliation(s)
- Jiawei Xing
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH USA
| | - Vadim M. Gumerov
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH USA
| | - Igor B. Zhulin
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH USA
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7
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Gordon JL, Oliva Chavez AS, Martinez D, Vachiery N, Meyer DF. Possible biased virulence attenuation in the Senegal strain of Ehrlichia ruminantium by ntrX gene conversion from an inverted segmental duplication. PLoS One 2023; 18:e0266234. [PMID: 36800354 PMCID: PMC9937504 DOI: 10.1371/journal.pone.0266234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 03/16/2022] [Indexed: 02/18/2023] Open
Abstract
Ehrlichia ruminantium is a tick-borne intracellular pathogen of ruminants that causes heartwater, a disease present in Sub-saharan Africa, islands in the Indian Ocean and the Caribbean, inducing significant economic losses. At present, three avirulent strains of E. ruminantium (Gardel, Welgevonden and Senegal isolates) have been produced by a process of serial passaging in mammalian cells in vitro, but unfortunately their use as vaccines do not offer a large range of protection against other strains, possibly due to the genetic diversity present within the species. So far no genetic basis for virulence attenuation has been identified in any E. ruminantium strain that could offer targets to facilitate vaccine production. Virulence attenuated Senegal strains have been produced twice independently, and require many fewer passages to attenuate than the other strains. We compared the genomes of a virulent and attenuated Senegal strain and identified a likely attenuator gene, ntrX, a global transcription regulator and member of a two-component system that is linked to environmental sensing. This gene has an inverted partial duplicate close to the parental gene that shows evidence of gene conversion in different E. ruminantium strains. The pseudogenisation of the gene in the avirulent Senegal strain occurred by gene conversion from the duplicate to the parent, transferring a 4 bp deletion which is unique to the Senegal strain partial duplicate amongst the wild isolates. We confirmed that the ntrX gene is not expressed in the avirulent Senegal strain by RT-PCR. The inverted duplicate structure combined with the 4 bp deletion in the Senegal strain can explain both the attenuation and the faster speed of attenuation in the Senegal strain relative to other strains of E. ruminantium. Our results identify nrtX as a promising target for the generation of attenuated strains of E. ruminantium by random or directed mutagenesis that could be used for vaccine production.
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Affiliation(s)
- Jonathan L. Gordon
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRAe, Univ Montpellier, Montpellier, France
| | - Adela S. Oliva Chavez
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRAe, Univ Montpellier, Montpellier, France
| | | | | | - Damien F. Meyer
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRAe, Univ Montpellier, Montpellier, France
- * E-mail:
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8
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Barr SA, Kennedy EN, McKay LS, Johnson RM, Ohr RJ, Cotter PA, Bourret RB. Phosphorylation chemistry of the Bordetella PlrSR TCS and its contribution to bacterial persistence in the lower respiratory tract. Mol Microbiol 2023; 119:174-190. [PMID: 36577696 PMCID: PMC10313215 DOI: 10.1111/mmi.15019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 12/30/2022]
Abstract
Bordetella species cause lower respiratory tract infections in mammals. B. pertussis and B. bronchiseptica are the causative agents of whooping cough and kennel cough, respectively. The current acellular vaccine for B. pertussis protects against disease but does not prevent transmission or colonization. Cases of pertussis are on the rise even in areas of high vaccination. The PlrSR two-component system, is required for persistence in the mouse lung. A partial plrS deletion strain and a plrS H521Q strain cannot survive past 3 days in the lung, suggesting PlrSR works in a phosphorylation-dependent mechanism. We characterized the biochemistry of B. bronchiseptica PlrSR and found that both proteins function as a canonical two-component system. His521 was essential and Glu522 was critical for PlrS autophosphorylation. Asn525 was essential for phosphatase activity. The PAS domain was critical for both PlrS autophosphorylation and phosphatase activities. PlrS could both phosphotransfer to and exert phosphatase activity toward PlrR. Unexpectedly, PlrR formed a tetramer when unphosphorylated and a dimer upon phosphorylation. Finally, we demonstrated the importance of PlrS phosphatase activity for persistence within the murine lung. By characterizing PlrSR we hope to guide future in vivo investigation for development of new vaccines and therapeutics.
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Affiliation(s)
- Sarah A. Barr
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Emily N. Kennedy
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Liliana S. McKay
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Richard M. Johnson
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Ryan J. Ohr
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Peggy A. Cotter
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Robert B. Bourret
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
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9
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Qi Z, Gao A, Li L, Li Z, Zhang W, Dong S, Liu X. A novel strategy to improving Rhodobacter azotoformans denitrification efficiency: Insight into the role of a two-component system NtrX/Y in denitrification regulation. BIORESOURCE TECHNOLOGY 2023; 368:128349. [PMID: 36400277 DOI: 10.1016/j.biortech.2022.128349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/13/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Transcription factors (TFs) can manage the coordinated expression of genes clusters or multiple genes. TF was used to improve bacterial denitrification ability in this study. During denitrification, the ntrY of R. azotoformans, which encodes the sensor of NtrX/Y system, was significantly upregulated in transcription. Denitrification of the mutant △ntrY was significantly inhibited, and it was recovered after replenishing this gene to the mutant, which indicates the NtrX/Y system plays an important role in regulating bacterial denitrification. According to additional research, the NtrX/Y system regulates bacterial denitrification by directly promoting the expression of the nitrite reductase. ntrY overexpression appears to accelerate bacterial denitrification, and the introduction of a strong promoter tac in conjunction with iron supply optimization increases the rate by 72% further. This study realizes bacterial denitrification enhancement from the perspective of global transcription regulation, which provides a novel strategy for improving microbial ability to degrade pollutants.
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Affiliation(s)
- Zhengliang Qi
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China.
| | - Anxin Gao
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China; State Key Laboratory of Bio-based Material and Green Papermaking (LBMP), Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China
| | - Lu Li
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China; State Key Laboratory of Bio-based Material and Green Papermaking (LBMP), Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China
| | - Zhen Li
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China; State Key Laboratory of Bio-based Material and Green Papermaking (LBMP), Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China
| | - Wenyue Zhang
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China; State Key Laboratory of Bio-based Material and Green Papermaking (LBMP), Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China
| | - Shuhan Dong
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China; State Key Laboratory of Bio-based Material and Green Papermaking (LBMP), Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China
| | - Xinli Liu
- Key Laboratory of Shandong Microbial Engineering, College of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China; State Key Laboratory of Bio-based Material and Green Papermaking (LBMP), Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, PR China
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10
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Spencer-Williams I, Balangoda A, Dabundo R, Elliott E, Haig SJ. Exploring the Impacts of Full-Scale Distribution System Orthophosphate Corrosion Control Implementation on the Microbial Ecology of Hydrologically Connected Urban Streams. Microbiol Spectr 2022; 10:e0215822. [PMID: 36321898 PMCID: PMC9769763 DOI: 10.1128/spectrum.02158-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 10/04/2022] [Indexed: 12/24/2022] Open
Abstract
Many cities across the nation are plagued by lead contamination in drinking water. As such, many drinking water utilities have undertaken lead service line (LSL) replacement to prevent further lead contamination. However, given the urgency of lead mitigation, and the socioeconomic challenges associated with LSL replacement, cities have used phosphate-based corrosion inhibitors (i.e., orthophosphate) alongside LSL replacement. While necessary to ensure public health protection from lead contamination, the addition of orthophosphate into an aging and leaking drinking water system may increase the concentration of phosphate leaching into urban streams characterized by century-old failing water infrastructure. Such increases in phosphate availability may cascade into nutrient and microbial community composition shifts. The purpose of this study was to determine how this occurs and to understand whether full-scale distribution system orthophosphate addition impacts the microbial ecology of urban streams. Through monthly collection of water samples from five urban streams before and after orthophosphate addition, significant changes in microbial community composition (16S rRNA amplicon sequencing) and in the relative abundance of typical freshwater taxa were observed. In addition, key microbial phosphorus and nitrogen metabolism genes (e.g., two component regulatory systems) were predicted to change via BugBase. No significant differences in the absolute abundances of total bacteria, Cyanobacteria, and "Candidatus Accumulibacter" were observed. Overall, the findings from this study provide further evidence that urban streams are compromised by unintentional hydrologic connections with drinking water infrastructure. Moreover, our results suggest that infiltration of phosphate-based corrosion inhibitors can impact urban streams and have important, as-yet-overlooked impacts on urban stream microbial communities. IMPORTANCE Elevated lead levels in drinking water supplies are a public health risk. As such, it is imperative for cities to urgently address lead contamination from aging drinking water supplies by way of lead service line replacements and corrosion control methods. However, when applying corrosion control methods, it is also important to consider the chemical and microbiological effects that can occur in natural settings, given that our water infrastructure is aging and more prone to leaks and breaks. Here, we examine the impacts on the microbial ecology of five urban stream systems before and after full-scale distribution system orthophosphate addition. Overall, the results suggest that infiltration of corrosion inhibitors may impact microbial communities; however, future work should be done to ascertain the true impact to protect both public and environmental health.
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Affiliation(s)
- Isaiah Spencer-Williams
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Anusha Balangoda
- Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Richard Dabundo
- Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Emily Elliott
- Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sarah-Jane Haig
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Environmental and Occupational Health, School of Public Health, University of Pittsburgh, Pennsylvania, USA
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11
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Quintero-Yanes A, Mayard A, Hallez R. The two-component system ChvGI maintains cell envelope homeostasis in Caulobacter crescentus. PLoS Genet 2022; 18:e1010465. [PMID: 36480504 PMCID: PMC9731502 DOI: 10.1371/journal.pgen.1010465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 10/09/2022] [Indexed: 12/13/2022] Open
Abstract
Two-component systems (TCS) are often used by bacteria to rapidly assess and respond to environmental changes. The ChvG/ChvI (ChvGI) TCS conserved in α-proteobacteria is known for regulating expression of genes related to exopolysaccharide production, virulence and growth. The sensor kinase ChvG autophosphorylates upon yet unknown signals and phosphorylates the response regulator ChvI to regulate transcription. Recent studies in Caulobacter crescentus showed that chv mutants are sensitive to vancomycin treatment and fail to grow in synthetic minimal media. In this work, we identified the osmotic imbalance as the main cause of growth impairment in synthetic minimal media. We also determined the ChvI regulon and found that ChvI regulates cell envelope architecture by controlling outer membrane, peptidoglycan assembly/recycling and inner membrane proteins. In addition, we found that ChvI phosphorylation is also activated upon antibiotic treatment with vancomycin. We also challenged chv mutants with other cell envelope related stress and found that treatment with antibiotics targeting transpeptidation of peptidoglycan during cell elongation impairs growth of the mutant. Finally, we observed that the sensor kinase ChvG relocates from a patchy-spotty distribution to distinctive foci after transition from complex to synthetic minimal media. Interestingly, this pattern of (re)location has been described for proteins involved in cell growth control and peptidoglycan synthesis upon osmotic shock. Overall, our data support that the ChvGI TCS is mainly used to monitor and respond to osmotic imbalances and damages in the peptidoglycan layer to maintain cell envelope homeostasis.
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Affiliation(s)
- Alex Quintero-Yanes
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), University of Namur, Namur, Belgium
| | - Aurélie Mayard
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), University of Namur, Namur, Belgium
| | - Régis Hallez
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), University of Namur, Namur, Belgium
- WELBIO, University of Namur, Namur, Belgium
- * E-mail:
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12
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The NtrYX Two-Component System of Paracoccus denitrificans Is Required for the Maintenance of Cellular Iron Homeostasis and for a Complete Denitrification under Iron-Limited Conditions. Int J Mol Sci 2022; 23:ijms23169172. [PMID: 36012437 PMCID: PMC9409073 DOI: 10.3390/ijms23169172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 02/08/2023] Open
Abstract
Denitrification consists of the sequential reduction of nitrate to nitrite, nitric oxide, nitrous oxide, and dinitrogen. Nitrous oxide escapes to the atmosphere, depending on copper availability and other environmental factors. Iron is also a key element because many proteins involved in denitrification contain iron-sulfur or heme centers. The NtrYX two-component regulatory system mediates the responses in a variety of metabolic processes, including denitrification. A quantitative proteomic analysis of a Paracoccus denitrificans NtrY mutant grown under denitrifying conditions revealed the induction of different TonB-dependent siderophore transporters and proteins related to iron homeostasis. This mutant showed lower intracellular iron content than the wild-type strain, and a reduced growth under denitrifying conditions in iron-limited media. Under iron-rich conditions, it releases higher concentrations of siderophores and displayes lower nitrous oxide reductase (NosZ) activity than the wild-type, thus leading to nitrous oxide emission. Bioinformatic and qRT-PCR analyses revealed that NtrYX is a global transcriptional regulatory system that responds to iron starvation and, in turn, controls expression of the iron-responsive regulators fur, rirA, and iscR, the denitrification regulators fnrP and narR, the nitric oxide-responsive regulator nnrS, and a wide set of genes, including the cd1-nitrite reductase NirS, nitrate/nitrite transporters and energy electron transport proteins.
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13
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Transcription Regulation of Cell Cycle Regulatory Genes Mediated by NtrX to Affect Sinorhizobium meliloti Cell Division. Genes (Basel) 2022; 13:genes13061066. [PMID: 35741828 PMCID: PMC9223101 DOI: 10.3390/genes13061066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/25/2022] [Accepted: 04/26/2022] [Indexed: 12/10/2022] Open
Abstract
The cell division of the alfalfa symbiont, Sinorhizobium meliloti, is dictated by a cell cycle regulatory pathway containing the key transcription factors CtrA, GcrA, and DnaA. In this study, we found that NtrX, one of the regulators of nitrogen metabolism, can directly regulate the expression of ctrA, gcrA, and dnaA from the cell cycle pathway. Three sets of S. meliloti ntrX mutants showed similar cell division defects, such as slow growth, abnormal morphology of some cells, and delayed DNA synthesis. Transcription of ctrA and gcrA was upregulated, whereas the transcription of dnaA and ftsZ1 was downregulated in the insertion mutant and the strain of Sm1021 expressing ntrXD53E. Correspondingly, the inducible transcription of ntrX activates the expression of dnaA and ftsZ1, but represses ctrA and gcrA in the depletion strain. The expression levels of CtrA and GcrA were confirmed by Western blotting. The transcription regulation of these genes requires phosphorylation of the conserved 53rd aspartate in the NtrX protein that binds directly to the promoter regions of ctrA, gcrA, dnaA, and ftsZ1 by recognizing the characteristic sequence CAAN2-5TTG. Our findings suggest that NtrX affects S. meliloti cell division by regulating the transcription of the key cell cycle regulatory genes.
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Lakey BD, Myers KS, Alberge F, Mettert EL, Kiley PJ, Noguera DR, Donohue TJ. The essential Rhodobacter sphaeroides CenKR two-component system regulates cell division and envelope biosynthesis. PLoS Genet 2022; 18:e1010270. [PMID: 35767559 PMCID: PMC9275681 DOI: 10.1371/journal.pgen.1010270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 07/12/2022] [Accepted: 05/20/2022] [Indexed: 12/13/2022] Open
Abstract
Bacterial two-component systems (TCSs) often function through the detection of an extracytoplasmic stimulus and the transduction of a signal by a transmembrane sensory histidine kinase. This kinase then initiates a series of reversible phosphorylation modifications to regulate the activity of a cognate, cytoplasmic response regulator as a transcription factor. Several TCSs have been implicated in the regulation of cell cycle dynamics, cell envelope integrity, or cell wall development in Escherichia coli and other well-studied Gram-negative model organisms. However, many α-proteobacteria lack homologs to these regulators, so an understanding of how α-proteobacteria orchestrate extracytoplasmic events is lacking. In this work we identify an essential TCS, CenKR (Cell envelope Kinase and Regulator), in the α-proteobacterium Rhodobacter sphaeroides and show that modulation of its activity results in major morphological changes. Using genetic and biochemical approaches, we dissect the requirements for the phosphotransfer event between CenK and CenR, use this information to manipulate the activity of this TCS in vivo, and identify genes that are directly and indirectly controlled by CenKR in Rb. sphaeroides. Combining ChIP-seq and RNA-seq, we show that the CenKR TCS plays a direct role in maintenance of the cell envelope, regulates the expression of subunits of the Tol-Pal outer membrane division complex, and indirectly modulates the expression of peptidoglycan biosynthetic genes. CenKR represents the first TCS reported to directly control the expression of Tol-Pal machinery genes in Gram-negative bacteria, and we predict that homologs of this TCS serve a similar function in other closely related organisms. We propose that Rb. sphaeroides genes of unknown function that are directly regulated by CenKR play unknown roles in cell envelope biosynthesis, assembly, and/or remodeling in this and other α-proteobacteria. The bacterial cell envelope is home to an array of important functions including energy conservation, motility, influx/efflux of nutrients and toxins, modulation of cell morphology and division, cell-cell interaction, and biofilm formation. Consequently, it is a major target of antibiotics and antimicrobial agents that inhibit these essential processes. Key to the recognition of environmental stressors or stimuli are bacterial TCSs, however systems that monitor or directly regulate cell envelope assembly and homeostasis are not widely conserved amongst bacteria. Here, we use Rhodobacter sphaeroides as a model to investigate the function of the CenKR TCS in this and other α-proteobacteria. We show that this essential TCS plays a key role in maintenance of the cell envelope through the regulation of outer membrane integrity and division, cell wall remodeling and homeostasis, and an alternate sigma factor that controls global cellular stress response. We provide evidence that this TCS and its function is widely conserved in α-proteobacteria and identify genes of unknown function as candidates for the study of cell envelope assembly in this and related bacteria.
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Affiliation(s)
- Bryan D. Lakey
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kevin S. Myers
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - François Alberge
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Erin L. Mettert
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Patricia J. Kiley
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Daniel R. Noguera
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Timothy J. Donohue
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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15
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An F, Zhang L, Zheng W, Shan D, Wang Y, Yu L, Luo L. Molecular oxygen levels regulate Sinorhizobium meliloti cell division through a FixJ-dependent transcription control mechanism. Biochem Biophys Res Commun 2022; 614:132-137. [PMID: 35588563 DOI: 10.1016/j.bbrc.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 05/02/2022] [Indexed: 11/18/2022]
Abstract
Rhizobia infect the roots of host legumes and induce formation of nitrogen-fixing nodules, where nitrogenase genes are inducibly expressed by micro-aerobic signals. FixL/FixJ is an oxygen signal sensing system that is unique to rhizobia. FixL monitors molecular oxygen levels and phosphorylates the response regulator FixJ, thereby regulating downstream gene expression. The cell division of rhizobia is regulated by a phosphorylation relaying cascade that includes the transcription factors CtrA, GcrA, and DnaA. In Sinorhizobium meliloti the expression of these proteins is regulated by NtrX, which affects cell division. In the present work, by analyzing the cell division phenotypes and gene expression patterns of S. meliloti fixJ and ntrX mutants, we found that S. meliloti cell division is regulated by oxygen gas levels. Under normal conditions, FixJ induced NtrX and DnaA expression, but repressed CtrA and GcrA expression. In contrast, under hypoxic conditions, phosphorylated FixJ specifically bound to gene promoter regions to directly induce CtrA and GcrA expression, but to repress DnaA expression. Our findings reveal that molecular oxygen levels regulate S. meliloti cell division by a FixJ-dependent transcription control mechanism.
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Affiliation(s)
- Fang An
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Lanya Zhang
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Wenjia Zheng
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Dandan Shan
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Yawen Wang
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Liangliang Yu
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Li Luo
- Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China.
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16
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Yan J, Liang Q, Chai Z, Duan N, Li X, Liu Y, Yang N, Li M, Jin Y, Bai F, Wu W, Cheng Z. Glutathione Synthesis Regulated by CtrA Protects Ehrlichia chaffeensis From Host Cell Oxidative Stress. Front Microbiol 2022; 13:846488. [PMID: 35432225 PMCID: PMC9005958 DOI: 10.3389/fmicb.2022.846488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
Ehrlichia chaffeensis, a small Gram-negative obligatory intracellular bacterium, infects human monocytes or macrophages, and causes human monocytic ehrlichiosis, one of the most prevalent, life-threatening emerging zoonoses. Reactive oxygen species are produced by the host immune cells in response to bacterial infections. The mechanisms exploited by E. chaffeensis to resist oxidative stress have not been comprehensively demonstrated. Here, we found that E. chaffeensis encodes two functional enzymes, GshA and GshB, to synthesize glutathione that confers E. chaffeensis the oxidative stress resistance, and that the expression of gshA and gshB is upregulated by CtrA, a global transcriptional regulator, upon oxidative stress. We found that in E. chaffeensis, the expression of gshA and gshB was upregulated upon oxidative stress using quantitative RT-PCR. Ehrlichia chaffeensis GshA or GshB restored the ability of Pseudomonas aeruginosa GshA or GshB mutant to cope with oxidative stress, respectively. Recombinant E. chaffeensis CtrA directly bound to the promoters of gshA and gshB, determined with electrophoretic mobility shift assay, and activated the expression of gshA and gshB determined with reporter assay. Peptide nucleic acid transfection of E. chaffeensis, which reduced the CtrA protein level, inhibited the oxidative stress-induced upregulation of gshA and gshB. Our findings provide insights into the function and regulation of the two enzymes critical for E. chaffeensis resistance to oxidative stress and may deepen our understanding of E. chaffeensis pathogenesis and adaptation in hosts.
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Affiliation(s)
- Jiaqi Yan
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Qi'an Liang
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhouyi Chai
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Nan Duan
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiaoxiao Li
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yajing Liu
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Nan Yang
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Meifang Li
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yongxin Jin
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Fang Bai
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Weihui Wu
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhihui Cheng
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
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17
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Li Q, Zhou Y, Lu R, Zheng P, Wang Y. Phylogeny, distribution and potential metabolism of candidate bacterial phylum KSB1. PeerJ 2022; 10:e13241. [PMID: 35433121 PMCID: PMC9012183 DOI: 10.7717/peerj.13241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 03/18/2022] [Indexed: 01/13/2023] Open
Abstract
Candidate phylum KSB1 is composed of uncultured bacteria and has been reported across various environments. However, the phylogeny and metabolic potential of KSB1 have not been studied comprehensively. In this study, phylogenomic analysis of KSB1 genomes from public databases and eleven metagenome-assembled genomes (MAGs) from marine and hydrothermal sediments revealed that those genomes were clustered into four clades. Isolation source and relative abundance of KSB1 genomes showed that clade I was particularly abundant in bioreactor sludge. Genes related to dissimilatory reduction of nitrate to ammonia (DNRA), the last step of denitrification converting nitrous oxide to nitrogen and assimilatory sulfur reduction were observed in the expanded genomes of clade I, which may due to horizontal gene transfer that frequently occurred in bioreactor. Annotation and metabolic reconstruction of clades II and IV showed flagellum assembly and chemotaxis genes in the genomes, which may indicate that exploration and sensing for nutrients and chemical gradients are critical for the two clades in deep-sea and hydrothermal sediment. Metabolic potentials of fatty acids and short-chain hydrocarbons utilization were predicted in clades I and IV of KSB1. Collectively, phylogenomic and metabolic analyses of KSB1 clades provide insight into their anaerobic heterotrophic lifestyle and differentiation in potential ecological roles.
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Affiliation(s)
- Qingmei Li
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China,University of Chinese Academy of Sciences, Beijing, China
| | - Yingli Zhou
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China,University of Chinese Academy of Sciences, Beijing, China
| | - Rui Lu
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China,University of Chinese Academy of Sciences, Beijing, China
| | - Pengfei Zheng
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Yong Wang
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China,Institute for Marine Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
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18
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Wang Y, Ma F, Yang J, Guo H, Su D, Yu L. Adaption and Degradation Strategies of Methylotrophic 1,4-Dioxane Degrading Strain Xanthobacter sp. YN2 Revealed by Transcriptome-Scale Analysis. Int J Mol Sci 2021; 22:ijms221910435. [PMID: 34638775 PMCID: PMC8508750 DOI: 10.3390/ijms221910435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 09/17/2021] [Accepted: 09/23/2021] [Indexed: 12/21/2022] Open
Abstract
Biodegradation of 1,4-dioxane (dioxane) contamination has gained much attention for decades. In our previous work, we isolated a highly efficient dioxane degrader, Xanthobacter sp. YN2, but the underlying mechanisms of its extraordinary degradation performance remained unresolved. In this study, we performed a comparative transcriptome analysis of YN2 grown on dioxane and citrate to elucidate its genetic degradation mechanism and investigated the transcriptomes of different dioxane degradation stages (T0, T24, T48). We also analyzed the transcriptional response of YN2 over time during which the carbon source switched from citrate to dioxane. The results indicate that strain YN2 was a methylotroph, which provides YN2 a major advantage as a pollutant degrader. A large number of genes involved in dioxane metabolism were constitutively expressed prior to dioxane exposure. Multiple genes related to the catabolism of each intermediate were upregulated by treatment in response to dioxane. Glyoxylate metabolism was essential during dioxane degradation by YN2, and the key intermediate glyoxylate was metabolized through three routes: glyoxylate carboligase pathway, malate synthase pathway, and anaplerotic ethylmalonyl-CoA pathway. Genes related to quorum sensing and transporters were significantly upregulated during the early stages of degradation (T0, T24) prior to dioxane depletion, while the expression of genes encoding two-component systems was significantly increased at late degradation stages (T48) when total organic carbon in the culture was exhausted. This study is the first to report the participation of genes encoding glyoxalase, as well as methylotrophic genes xoxF and mox, in dioxane metabolism. The present study reveals multiple genetic and transcriptional strategies used by YN2 to rapidly increase biomass during growth on dioxane, achieve high degradation efficiency and tolerance, and adapt to dioxane exposure quickly, which provides useful information regarding the molecular basis for efficient dioxane biodegradation.
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Affiliation(s)
- Yingning Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Y.W.); (J.Y.); (D.S.); (L.Y.)
| | - Fang Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Y.W.); (J.Y.); (D.S.); (L.Y.)
- Correspondence:
| | - Jixian Yang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Y.W.); (J.Y.); (D.S.); (L.Y.)
| | - Haijuan Guo
- College of Energy and Environmental Engineering, Hebei University of Engineering, Handan 056107, China;
| | - Delin Su
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Y.W.); (J.Y.); (D.S.); (L.Y.)
| | - Lan Yu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Y.W.); (J.Y.); (D.S.); (L.Y.)
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19
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The ChvG-ChvI and NtrY-NtrX Two-Component Systems Coordinately Regulate Growth of Caulobacter crescentus. J Bacteriol 2021; 203:e0019921. [PMID: 34124942 DOI: 10.1128/jb.00199-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Two-component signaling systems (TCSs) are comprised of a sensory histidine kinase and a response regulator protein. In response to environmental changes, sensor kinases directly phosphorylate their cognate response regulator to affect gene expression. Bacteria typically express multiple TCSs that are insulated from one another and regulate distinct physiological processes. There are examples of cross-regulation between TCSs, but this phenomenon remains relatively unexplored. We have identified regulatory links between the ChvG-ChvI (ChvGI) and NtrY-NtrX (NtrYX) TCSs, which control important and often overlapping processes in alphaproteobacteria, including maintenance of the cell envelope. Deletion of chvG and chvI in Caulobacter crescentus limited growth in defined medium, and a selection for genetic suppressors of this growth phenotype uncovered interactions among chvGI, ntrYX, and ntrZ, which encodes a previously uncharacterized periplasmic protein. Significant overlap in the experimentally defined ChvI and NtrX transcriptional regulons provided support for the observed genetic connections between ntrYX and chvGI. Moreover, we present evidence that the growth defect of strains lacking chvGI is influenced by the phosphorylation state of NtrX and, to some extent, by levels of the TonB-dependent receptor ChvT. Measurements of NtrX phosphorylation in vivo indicated that NtrZ is an upstream regulator of NtrY and that NtrY primarily functions as an NtrX phosphatase. We propose a model in which NtrZ functions in the periplasm to inhibit NtrY phosphatase activity; regulation of phosphorylated NtrX levels by NtrZ and NtrY provides a mechanism to modulate and balance expression of the NtrX and ChvI regulons under different growth conditions. IMPORTANCE TCSs enable bacteria to regulate gene expression in response to physiochemical changes in their environment. The ChvGI and NtrYX TCSs regulate diverse pathways associated with pathogenesis, growth, and cell envelope function in many alphaproteobacteria. We used Caulobacter crescentus as a model to investigate regulatory connections between ChvGI and NtrYX. Our work defined the ChvI transcriptional regulon in C. crescentus and revealed a genetic interaction between ChvGI and NtrYX, whereby modulation of NtrYX signaling affects the survival of cells lacking ChvGI. In addition, we identified NtrZ as a periplasmic inhibitor of NtrY phosphatase activity in vivo. Our work establishes C. crescentus as an excellent model to investigate multilevel regulatory connections between ChvGI and NtrYX in alphaproteobacteria.
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20
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Roop RM, Barton IS, Hopersberger D, Martin DW. Uncovering the Hidden Credentials of Brucella Virulence. Microbiol Mol Biol Rev 2021; 85:e00021-19. [PMID: 33568459 PMCID: PMC8549849 DOI: 10.1128/mmbr.00021-19] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.
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Affiliation(s)
- R Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ian S Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Dariel Hopersberger
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Daniel W Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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21
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Zeng S, Xing S, An F, Yang X, Yan J, Yu L, Luo L. Sinorhizobium meliloti NtrX interacts with different regions of the visN promoter. Acta Biochim Biophys Sin (Shanghai) 2020; 52:910-913. [PMID: 32510129 DOI: 10.1093/abbs/gmaa057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 10/17/2019] [Accepted: 12/26/2019] [Indexed: 11/12/2022] Open
Affiliation(s)
- Shuang Zeng
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Shenghui Xing
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Fang An
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Xinwei Yang
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Junhui Yan
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Liangliang Yu
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Li Luo
- Shanghai Key Laboratory of Bio-energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai 200444, China
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22
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Abstract
The bacterial cell envelope provides many important functions. It protects cells from harsh environments, serves as a selective permeability barrier, houses bioenergetic functions, defines sensitivity to antibacterial agents, and plays a crucial role in biofilm formation, symbiosis, and virulence. Despite the important roles of this cellular compartment, we lack a detailed understanding of the biosynthesis and remodeling of the cell envelope. Here, we report that the R. sphaeroides two-component signaling system NtrYX is a previously undescribed regulator of cell envelope processes, providing evidence that it is directly involved in controlling transcription of genes involved in cell envelope assembly, structure, and function in this and possibly other bacteria. Thus, our data report on a newly discovered process used by bacteria to assemble and remodel the cell envelope. Activity of the NtrYX two-component system has been associated with important processes in diverse bacteria, ranging from symbiosis to nitrogen and energy metabolism. In the facultative alphaproteobacterium Rhodobacter sphaeroides, loss of the two-component system NtrYX results in increased lipid production and sensitivity to some known cell envelope-active compounds. In this study, we show that NtrYX directly controls multiple properties of the cell envelope. We find that the response regulator NtrX binds upstream of cell envelope genes, including those involved in peptidoglycan biosynthesis and modification and in cell division. We show that loss of NtrYX impacts the cellular levels of peptidoglycan precursors and lipopolysaccharide and alters cell envelope structure, increasing cell length and the thickness of the periplasm. Cell envelope function is also disrupted in the absence of NtrYX, resulting in increased outer membrane permeability. Based on the properties of R. sphaeroides cells lacking NtrYX and the target genes under direct control of this two-component system, we propose that NtrYX plays a previously undescribed, and potentially conserved, role in the assembly, structure, and function of the cell envelope in a variety of bacteria.
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23
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Lobão JBDS, Gondim ACS, Guimarães WG, Gilles‐Gonzalez M, Lopes LGDF, Sousa EHS. Oxygen triggers signal transduction in the DevS (DosS) sensor of
Mycobacterium tuberculosis
by modulating the quaternary structure. FEBS J 2019; 286:479-494. [DOI: 10.1111/febs.14734] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 11/05/2018] [Accepted: 12/14/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Josiane Bezerra da Silva Lobão
- Laboratory of Bioinorganic Chemistry Department of Organic and Inorganic Chemistry Federal University of Ceara Center for Sciences Fortaleza Brazil
| | - Ana C. S. Gondim
- Laboratory of Bioinorganic Chemistry Department of Organic and Inorganic Chemistry Federal University of Ceara Center for Sciences Fortaleza Brazil
| | - Wellinson G. Guimarães
- Laboratory of Bioinorganic Chemistry Department of Organic and Inorganic Chemistry Federal University of Ceara Center for Sciences Fortaleza Brazil
| | | | - Luiz Gonzaga de França Lopes
- Laboratory of Bioinorganic Chemistry Department of Organic and Inorganic Chemistry Federal University of Ceara Center for Sciences Fortaleza Brazil
| | - Eduardo H. S. Sousa
- Laboratory of Bioinorganic Chemistry Department of Organic and Inorganic Chemistry Federal University of Ceara Center for Sciences Fortaleza Brazil
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24
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Shimizu T, Lengalova A, Martínek V, Martínková M. Heme: emergent roles of heme in signal transduction, functional regulation and as catalytic centres. Chem Soc Rev 2019; 48:5624-5657. [DOI: 10.1039/c9cs00268e] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Molecular mechanisms of unprecedented functions of exchangeable/labile heme and heme proteins including transcription, DNA binding, protein kinase activity, K+ channel functions, cis–trans isomerization, N–N bond formation, and other functions are described.
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Affiliation(s)
- Toru Shimizu
- Department of Biochemistry
- Faculty of Science
- Charles University
- Prague 2
- Czech Republic
| | - Alzbeta Lengalova
- Department of Biochemistry
- Faculty of Science
- Charles University
- Prague 2
- Czech Republic
| | - Václav Martínek
- Department of Biochemistry
- Faculty of Science
- Charles University
- Prague 2
- Czech Republic
| | - Markéta Martínková
- Department of Biochemistry
- Faculty of Science
- Charles University
- Prague 2
- Czech Republic
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25
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Kang JG, Lee HW, Ko S, Chae JS. Comparative proteomic analysis of outer membrane protein 43 ( omp43)-deficient Bartonella henselae. J Vet Sci 2018; 19:59-70. [PMID: 28693313 PMCID: PMC5799401 DOI: 10.4142/jvs.2018.19.1.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/09/2017] [Accepted: 06/08/2017] [Indexed: 12/17/2022] Open
Abstract
Outer membrane proteins (OMPs) of Gram-negative bacteria constitute the first line of defense protecting cells against environmental stresses including chemical, biophysical, and biological attacks. Although the 43-kDa OMP (OMP43) is major porin protein among Bartonella henselae-derived OMPs, its function remains unreported. In this study, OMP43-deficient mutant B. henselae (Δomp43) was generated to investigate OMP43 function. Interestingly, Δomp43 exhibited weaker proliferative ability than that of wild-type (WT) B. henselae. To study the differences in proteomic expression between WT and Δomp43, two-dimensional gel electrophoresis-based proteomic analysis was performed. Based on Clusters of Orthologus Groups functional assignments, 12 proteins were associated with metabolism, 7 proteins associated with information storage and processing, and 3 proteins associated with cellular processing and signaling. By semi-quantitative reverse transcriptase polymerase chain reaction, increases in tldD, efp, ntrX, pdhA, purB, and ATPA mRNA expression and decreases in Rho and yfeA mRNA expression were confirmed in Δomp43. In conclusion, this is the first report showing that a loss of OMP43 expression in B. henselae leads to retarded proliferation. Furthermore, our proteomic data provide useful information for the further investigation of mechanisms related to the growth of B. henselae.
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Affiliation(s)
- Jun-Gu Kang
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Hee-Woo Lee
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Sungjin Ko
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Joon-Seok Chae
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
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26
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Fernández I, Sycz G, Goldbaum FA, Carrica MDC. Acidic pH triggers the phosphorylation of the response regulator NtrX in alphaproteobacteria. PLoS One 2018; 13:e0194486. [PMID: 29634773 PMCID: PMC5892882 DOI: 10.1371/journal.pone.0194486] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 03/05/2018] [Indexed: 11/19/2022] Open
Abstract
Many signaling pathways that control cellular development, cell-cycle progression and nutritional versatility have been studied in Caulobacter crescentus. For example, it was suggested that the response regulator NtrX is conditionally essential for this bacterium and that it might be necessary for responding to a signal produced in phosphate-replete minimal medium. However, such signal has not been identified yet and the role of NtrX in C. crescentus biology remains elusive. Here, using wild-type C. crescentus and a strain with a chromosomally myc-tagged ntrX gene, we demonstrate that high concentrations of phosphate (10 mM) regulate ntrX transcription and the abundance of the protein. We also show that the pH of the medium acts as a switch able to regulate the phosphorylation status of NtrX, promoting its phosphorylation under mildly acidic conditions and its dephosphorylation at neutral pH. Moreover, we demonstrate that the ntrX gene is required for survival in environments with low pH and under acidic stress. Finally, we prove that NtrX phosphorylation is also triggered by low pH in Brucella abortus, a pathogenic alphaproteobacterium. Overall, our work contributes to deepen the general knowledge of this system and provides tools to elucidate the NtrX regulon.
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Affiliation(s)
- Ignacio Fernández
- Fundación Instituto Leloir, IIBBA-CONICET, Patricias Argentinas, Buenos Aires, Argentina
| | - Gabriela Sycz
- Fundación Instituto Leloir, IIBBA-CONICET, Patricias Argentinas, Buenos Aires, Argentina
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27
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Zheng R, Feng X, Wei X, Pan X, Liu C, Song R, Jin Y, Bai F, Jin S, Wu W, Cheng Z. PutA Is Required for Virulence and Regulated by PruR in Pseudomonas aeruginosa. Front Microbiol 2018; 9:548. [PMID: 29632523 PMCID: PMC5879082 DOI: 10.3389/fmicb.2018.00548] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/09/2018] [Indexed: 01/08/2023] Open
Abstract
Pseudomonas aeruginosa, a Gram-negative opportunistic pathogenic bacterium, causes acute and chronic infections. Upon entering the host, P. aeruginosa alters global gene expression to adapt to host environment and avoid clearance by the host immune system. Proline utilization A (PutA) is a bifunctional enzyme, which converts proline to glutamate. Here we report that PutA was required for the virulence of P. aeruginosa in a murine acute pneumonia model. A putA mutant was more susceptible to oxidative stress compared to the wild type strain. An AraC/XylS family protein, PruR, directly bound to the upstream of −35 box in the putA promoter and activated putA expression. High concentration of proline in bacteria up-regulated pruR expression, which led to the activation of putA expression. As a feedback regulation, glutamate produced by PutA released PruR from the putA promoter and turned off the putA expression. PruR affected bacterial virulence through the regulation of the putA expression. Altogether, these data are the first to reveal that PutA plays an important role in the pathogenesis of P. aeruginosa, as well as to describe the genetic regulation of PutA in P. aeruginosa.
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Affiliation(s)
- Ruiping Zheng
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xuemei Feng
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xueying Wei
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiaolei Pan
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Chang Liu
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Ruopu Song
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yongxin Jin
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Fang Bai
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Shouguang Jin
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China.,Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Weihui Wu
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhihui Cheng
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
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28
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Schulz A, Hermann L, Freibert SA, Bönig T, Hoffmann T, Riclea R, Dickschat JS, Heider J, Bremer E. Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues. Environ Microbiol 2017; 19:4599-4619. [PMID: 28892254 DOI: 10.1111/1462-2920.13924] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/29/2017] [Accepted: 08/31/2017] [Indexed: 01/04/2023]
Abstract
Ectoine and hydroxyectoine are effective microbial osmostress protectants, but can also serve as versatile nutrients for bacteria. We have studied the genetic regulation of ectoine and hydroxyectoine import and catabolism in the marine Roseobacter species Ruegeria pomeroyi and identified three transcriptional regulators involved in these processes: the GabR/MocR-type repressor EnuR, the feast and famine-type regulator AsnC and the two-component system NtrYX. The corresponding genes are widely associated with ectoine and hydroxyectoine uptake and catabolic gene clusters (enuR, asnC), and with microorganisms predicted to consume ectoines (ntrYX). EnuR contains a covalently bound pyridoxal-5'-phosphate as a co-factor and the chemistry underlying the functioning of MocR/GabR-type regulators typically requires a system-specific low molecular mass effector molecule. Through ligand binding studies with purified EnuR, we identified N-(alpha)-L-acetyl-2,4-diaminobutyric acid and L-2,4-diaminobutyric acid as inducers for EnuR that are generated through ectoine catabolism. AsnC/Lrp-type proteins can wrap DNA into nucleosome-like structures, and we found that the asnC gene was essential for use of ectoines as nutrients. Furthermore, we discovered through transposon mutagenesis that the NtrYX two-component system is required for their catabolism. Database searches suggest that our findings have important ramifications for an understanding of the molecular biology of most microbial consumers of ectoines.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, Philipps-University Marburg, Robert-Koch Str. 6, D-35032 Marburg, Germany
| | - Tobias Bönig
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Ramona Riclea
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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29
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Rossetti CA, Drake KL, Lawhon SD, Nunes JS, Gull T, Khare S, Adams LG. Systems Biology Analysis of Temporal In vivo Brucella melitensis and Bovine Transcriptomes Predicts host:Pathogen Protein-Protein Interactions. Front Microbiol 2017; 8:1275. [PMID: 28798726 PMCID: PMC5529337 DOI: 10.3389/fmicb.2017.01275] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/26/2017] [Indexed: 01/13/2023] Open
Abstract
To date, fewer than 200 gene-products have been identified as Brucella virulence factors, and most were characterized individually without considering how they are temporally and coordinately expressed or secreted during the infection process. Here, we describe and analyze the in vivo temporal transcriptional profile of Brucella melitensis during the initial 4 h interaction with cattle. Pathway analysis revealed an activation of the "Two component system" providing evidence that the in vivo Brucella sense and actively regulate their metabolism through the transition to an intracellular lifestyle. Contrarily, other Brucella pathways involved in virulence such as "ABC transporters" and "T4SS system" were repressed suggesting a silencing strategy to avoid stimulation of the host innate immune response very early in the infection process. Also, three flagellum-encoded loci (BMEII0150-0168, BMEII1080-1089, and BMEII1105-1114), the "flagellar assembly" pathway and the cell components "bacterial-type flagellum hook" and "bacterial-type flagellum" were repressed in the tissue-associated B. melitensis, while RopE1 sigma factor, a flagellar repressor, was activated throughout the experiment. These results support the idea that Brucella employ a stealthy strategy at the onset of the infection of susceptible hosts. Further, through systems-level in silico host:pathogen protein-protein interactions simulation and correlation of pathogen gene expression with the host gene perturbations, we identified unanticipated interactions such as VirB11::MAPK8IP1; BtaE::NFKBIA, and 22 kDa OMP precursor::BAD and MAP2K3. These findings are suggestive of new virulence factors and mechanisms responsible for Brucella evasion of the host's protective immune response and the capability to maintain a dormant state. The predicted protein-protein interactions and the points of disruption provide novel insights that will stimulate advanced hypothesis-driven approaches toward revealing a clearer understanding of new virulence factors and mechanisms influencing the pathogenesis of brucellosis.
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Affiliation(s)
- Carlos A Rossetti
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | | | - Sara D Lawhon
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Jairo S Nunes
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Tamara Gull
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Sangeeta Khare
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Leslie G Adams
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
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30
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Caudill MT, Budnick JA, Sheehan LM, Lehman CR, Purwantini E, Mukhopadhyay B, Caswell CC. Proline utilization system is required for infection by the pathogenic α-proteobacterium Brucella abortus. MICROBIOLOGY-SGM 2017; 163:970-979. [PMID: 28691659 DOI: 10.1099/mic.0.000490] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Proline utilization (Put) systems have been described in a number of bacteria; however, the importance and functionality of the Put system in the intracellular pathogen Brucellaabortus has not been explored. Generally, bacterial Put systems are composed of the bifunctional enzyme proline dehydrogenase PutA and its transcriptional activator PutR. Here, we demonstrate that the genes putA (bab2_0518) and putR (bab2_0517) are critical for the chronic infection of mice by B. abortus, but putA and putR are not required for the survival and replication of the bacteria in naive macrophages. Additionally, in vitro experiments revealed that putR is necessary for the ability of the bacteria to withstand oxidative stress, as a ΔputR deletion strain is hypersensitive to hydrogen peroxide exposure. Quantitative reverse transcription-PCR and putA-lacZ transcriptional reporter studies revealed that PutR acts as a transcriptional activator of putA in Brucella, and electrophoretic mobility shift assays confirmed that PutR binds directly to the putA promoter region. Biochemical analyses demonstrated that a purified recombinant B. abortus PutA protein possesses quintessential proline dehydrogenase activity, as PutA is capable of catalysing the conversion of proline to glutamate. Altogether, these data are the first to reveal that the Put system plays a significant role in the ability of B. abortus to replicate and survive within its host, as well as to describe the genetic regulation and biochemical activity of the Put system in Brucella.
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Affiliation(s)
- Mitchell T Caudill
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24060, USA
| | - James A Budnick
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24060, USA
| | - Lauren M Sheehan
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24060, USA
| | - Christian R Lehman
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24060, USA
| | - Endang Purwantini
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | | | - Clayton C Caswell
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24060, USA
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31
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Calatrava-Morales N, Nogales J, Ameztoy K, van Steenbergen B, Soto MJ. The NtrY/NtrX System of Sinorhizobium meliloti GR4 Regulates Motility, EPS I Production, and Nitrogen Metabolism but Is Dispensable for Symbiotic Nitrogen Fixation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:566-577. [PMID: 28398840 DOI: 10.1094/mpmi-01-17-0021-r] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Sinorhizobium meliloti can translocate over surfaces. However, little is known about the regulatory mechanisms that control this trait and its relevance for establishing symbiosis with alfalfa plants. To gain insights into this field, we isolated Tn5 mutants of S. meliloti GR4 with impaired surface motility. In mutant strain GRS577, the transposon interrupted the ntrY gene encoding the sensor kinase of the NtrY/NtrX two-component regulatory system. GRS577 is impaired in flagella synthesis and overproduces succinoglycan, which is responsible for increased biofilm formation. The mutant also shows altered cell morphology and higher susceptibility to salt stress. GRS577 induces nitrogen-fixing nodules in alfalfa but exhibits decreased competitive nodulation. Complementation experiments indicate that both ntrY and ntrX account for all the phenotypes displayed by the ntrY::Tn5 mutant. Ectopic overexpression of VisNR, the motility master regulator, was sufficient to rescue motility and competitive nodulation of the transposant. A transcriptome profiling of GRS577 confirmed differential expression of exo and flagellar genes, and led to the demonstration that NtrY/NtrX allows for optimal expression of denitrification and nifA genes under microoxic conditions in response to nitrogen compounds. This study extends our knowledge of the complex role played by NtrY/NtrX in S. meliloti.
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Affiliation(s)
- Nieves Calatrava-Morales
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Joaquina Nogales
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Kinia Ameztoy
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Bart van Steenbergen
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - María J Soto
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
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32
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Abstract
Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation in Rhodobacter sphaeroides. By screening an R. sphaeroides Tn5 mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. This paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these alterations can be enhanced by growing cells in bioreactor configurations that can be used industrially. We propose that our findings can inform current and future efforts to increase production of microbial lipids, other fuels, or chemicals that are currently derived from petroleum.
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33
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Abdou E, Jiménez de Bagüés MP, Martínez-Abadía I, Ouahrani-Bettache S, Pantesco V, Occhialini A, Al Dahouk S, Köhler S, Jubier-Maurin V. RegA Plays a Key Role in Oxygen-Dependent Establishment of Persistence and in Isocitrate Lyase Activity, a Critical Determinant of In vivo Brucella suis Pathogenicity. Front Cell Infect Microbiol 2017; 7:186. [PMID: 28573107 PMCID: PMC5435760 DOI: 10.3389/fcimb.2017.00186] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 04/28/2017] [Indexed: 12/25/2022] Open
Abstract
For aerobic human pathogens, adaptation to hypoxia is a critical factor for the establishment of persistent infections, as oxygen availability is low inside the host. The two-component system RegB/A of Brucella suis plays a central role in the control of respiratory systems adapted to oxygen deficiency, and in persistence in vivo. Using an original "in vitro model of persistence" consisting in gradual oxygen depletion, we compared transcriptomes and proteomes of wild-type and ΔregA strains to identify the RegA-regulon potentially involved in the set-up of persistence. Consecutive to oxygen consumption resulting in growth arrest, 12% of the genes in B. suis were potentially controlled directly or indirectly by RegA, among which numerous transcriptional regulators were up-regulated. In contrast, genes or proteins involved in envelope biogenesis and in cellular division were repressed, suggesting a possible role for RegA in the set-up of a non-proliferative persistence state. Importantly, the greatest number of the RegA-repressed genes and proteins, including aceA encoding the functional IsoCitrate Lyase (ICL), were involved in energy production. A potential consequence of this RegA impact may be the slowing-down of the central metabolism as B. suis progressively enters into persistence. Moreover, ICL is an essential determinant of pathogenesis and long-term interactions with the host, as demonstrated by the strict dependence of B. suis on ICL activity for multiplication and persistence during in vivo infection. RegA regulates gene or protein expression of all functional groups, which is why RegA is a key regulator of B. suis in adaptation to oxygen depletion. This function may contribute to the constraint of bacterial growth, typical of chronic infection. Oxygen-dependent activation of two-component systems that control persistence regulons, shared by several aerobic human pathogens, has not been studied in Brucella sp. before. This work therefore contributes significantly to the unraveling of persistence mechanisms in this important zoonotic pathogen.
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Affiliation(s)
- Elias Abdou
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - María P. Jiménez de Bagüés
- Unidad de Tecnología en Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria, Instituto Agroalimentario de Aragón (CITA-Universidad de Zaragoza)Zaragoza, Spain
| | - Ignacio Martínez-Abadía
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Safia Ouahrani-Bettache
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Véronique Pantesco
- Institut de Médecine Régénératrice et Biothérapie—U1183 Institut National de la Santé et de la Recherche MédicaleMontpellier, France
| | - Alessandra Occhialini
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Sascha Al Dahouk
- Department of Biological Safety, German Federal Institute for Risk AssessmentBerlin, Germany
| | - Stephan Köhler
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Véronique Jubier-Maurin
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
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Transcriptional and translational adaptation to aerobic nitrate anabolism in the denitrifier Paracoccus denitrificans. Biochem J 2017; 474:1769-1787. [PMID: 28385879 PMCID: PMC5424462 DOI: 10.1042/bcj20170115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/04/2017] [Accepted: 04/06/2017] [Indexed: 01/05/2023]
Abstract
Transcriptional adaptation to nitrate-dependent anabolism by Paracoccus denitrificans PD1222 was studied. A total of 74 genes were induced in cells grown with nitrate as N-source compared with ammonium, including nasTSABGHC and ntrBC genes. The nasT and nasS genes were cotranscribed, although nasT was more strongly induced by nitrate than nasS. The nasABGHC genes constituted a transcriptional unit, which is preceded by a non-coding region containing hairpin structures involved in transcription termination. The nasTS and nasABGHC transcripts were detected at similar levels with nitrate or glutamate as N-source, but nasABGHC transcript was undetectable in ammonium-grown cells. The nitrite reductase NasG subunit was detected by two-dimensional polyacrylamide gel electrophoresis in cytoplasmic fractions from nitrate-grown cells, but it was not observed when either ammonium or glutamate was used as the N-source. The nasT mutant lacked both nasABGHC transcript and nicotinamide adenine dinucleotide (NADH)-dependent nitrate reductase activity. On the contrary, the nasS mutant showed similar levels of the nasABGHC transcript to the wild-type strain and displayed NasG protein and NADH–nitrate reductase activity with all N-sources tested, except with ammonium. Ammonium repression of nasABGHC was dependent on the Ntr system. The ntrBC and ntrYX genes were expressed at low levels regardless of the nitrogen source supporting growth. Mutational analysis of the ntrBCYX genes indicated that while ntrBC genes are required for nitrate assimilation, ntrYX genes can only partially restore growth on nitrate in the absence of ntrBC genes. The existence of a regulation mechanism for nitrate assimilation in P. denitrificans, by which nitrate induction operates at both transcriptional and translational levels, is proposed.
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Bordetella PlrSR regulatory system controls BvgAS activity and virulence in the lower respiratory tract. Proc Natl Acad Sci U S A 2017; 114:E1519-E1527. [PMID: 28167784 DOI: 10.1073/pnas.1609565114] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial pathogens coordinate virulence using two-component regulatory systems (TCS). The Bordetella virulence gene (BvgAS) phosphorelay-type TCS controls expression of all known protein virulence factor-encoding genes and is considered the "master virulence regulator" in Bordetella pertussis, the causal agent of pertussis, and related organisms, including the broad host range pathogen Bordetella bronchiseptica We recently discovered an additional sensor kinase, PlrS [for persistence in the lower respiratory tract (LRT) sensor], which is required for B. bronchiseptica persistence in the LRT. Here, we show that PlrS is required for BvgAS to become and remain fully active in mouse lungs but not the nasal cavity, demonstrating that PlrS coordinates virulence specifically in the LRT. PlrS is required for LRT persistence even when BvgAS is rendered constitutively active, suggesting the presence of BvgAS-independent, PlrS-dependent virulence factors that are critical for bacterial survival in the LRT. We show that PlrS is also required for persistence of the human pathogen B. pertussis in the murine LRT and we provide evidence that PlrS most likely functions via the putative cognate response regulator PlrR. These data support a model in which PlrS senses conditions present in the LRT and activates PlrR, which controls expression of genes required for the maintenance of BvgAS activity and for essential BvgAS-independent functions. In addition to providing a major advance in our understanding of virulence regulation in Bordetella, which has served as a paradigm for several decades, these results indicate the existence of previously unknown virulence factors that may serve as new vaccine components and therapeutic or diagnostic targets.
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Fernández I, Cornaciu I, Carrica MDC, Uchikawa E, Hoffmann G, Sieira R, Márquez JA, Goldbaum FA. Three-Dimensional Structure of Full-Length NtrX, an Unusual Member of the NtrC Family of Response Regulators. J Mol Biol 2017; 429:1192-1212. [PMID: 28088479 DOI: 10.1016/j.jmb.2016.12.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/21/2016] [Accepted: 12/29/2016] [Indexed: 12/15/2022]
Abstract
Bacteria sense and adapt to environmental changes using two-component systems. These signaling pathways are formed by a histidine kinase that phosphorylates a response regulator (RR), which finally modulates the transcription of target genes. The bacterium Brucella abortus codes for a two-component system formed by the histidine kinase NtrY and the RR NtrX that participates in sensing low oxygen tension and generating an adaptive response. NtrX is a modular protein with REC, AAA+, and DNA-binding domains, an architecture that classifies it among the NtrC subfamily of RRs. However, it lacks the signature GAFTGA motif that is essential for activating transcription by the mechanism proposed for canonical members of this subfamily. In this article, we present the first crystal structure of full-length NtrX, which is also the first structure of a full-length NtrC-like RR with all the domains solved, showing that the protein is structurally similar to other members of the subfamily. We also report that NtrX binds nucleotides and the structures of the protein bound to ATP and ADP. Despite binding ATP, NtrX does not have ATPase activity and does not form oligomers in response to phosphorylation or nucleotide binding. We also identify a nucleotide sequence recognized by NtrX that allows it to bind to a promoter region that regulates its own transcription and to establish a negative feedback mechanism to modulate its expression. Overall, this article provides a detailed description of the NtrX RR and supports that it functions by a mechanism different to classical NtrC-like RRs.
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Affiliation(s)
- Ignacio Fernández
- Fundación Instituto Leloir, IIBBA-CONICET, Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Irina Cornaciu
- European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | | | - Emiko Uchikawa
- European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Guillaume Hoffmann
- European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Rodrigo Sieira
- Fundación Instituto Leloir, IIBBA-CONICET, Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - José Antonio Márquez
- European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Fernando A Goldbaum
- Fundación Instituto Leloir, IIBBA-CONICET, Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina.
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Genome-wide screen identifies host colonization determinants in a bacterial gut symbiont. Proc Natl Acad Sci U S A 2016; 113:13887-13892. [PMID: 27849596 DOI: 10.1073/pnas.1610856113] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Animal guts are often colonized by host-specialized bacterial species to the exclusion of other transient microorganisms, but the genetic basis of colonization ability is largely unknown. The bacterium Snodgrassella alvi is a dominant gut symbiont in honey bees, specialized in colonizing the hindgut epithelium. We developed methods for transposon-based mutagenesis in S. alvi and, using high-throughput DNA sequencing, screened genome-wide transposon insertion (Tn-seq) and transcriptome (RNA-seq) libraries to characterize both the essential genome and the genes facilitating host colonization. Comparison of Tn-seq results from laboratory cultures and from monoinoculated worker bees reveal that 519 of 2,226 protein-coding genes in S. alvi are essential in culture, whereas 399 are not essential but are beneficial for gut colonization. Genes facilitating colonization fall into three broad functional categories: extracellular interactions, metabolism, and stress responses. Extracellular components with strong fitness benefits in vivo include trimeric autotransporter adhesins, O antigens, and type IV pili (T4P). Experiments with T4P mutants establish that T4P in S. alvi likely function in attachment and biofilm formation, with knockouts experiencing a competitive disadvantage in vivo. Metabolic processes promoting colonization include essential amino acid biosynthesis and iron acquisition pathways, implying nutrient scarcity within the hindgut environment. Mechanisms to deal with various stressors, such as for the repair of double-stranded DNA breaks and protein quality control, are also critical in vivo. This genome-wide study identifies numerous genetic networks underlying colonization by a gut commensal in its native host environment, including some known from more targeted studies in other host-microbe symbioses.
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Bonato P, Alves LR, Osaki JH, Rigo LU, Pedrosa FO, Souza EM, Zhang N, Schumacher J, Buck M, Wassem R, Chubatsu LS. The NtrY-NtrX two-component system is involved in controlling nitrate assimilation in Herbaspirillum seropedicae strain SmR1. FEBS J 2016; 283:3919-3930. [PMID: 27634462 DOI: 10.1111/febs.13897] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/15/2016] [Accepted: 09/13/2016] [Indexed: 10/21/2022]
Abstract
Herbaspirillum seropedicae is a diazotrophic β-Proteobacterium found endophytically associated with gramineae (Poaceae or graminaceous plants) such as rice, sorghum and sugar cane. In this work we show that nitrate-dependent growth in this organism is regulated by the master nitrogen regulatory two-component system NtrB-NtrC, and by NtrY-NtrX, which functions to specifically regulate nitrate metabolism. NtrY is a histidine kinase sensor protein predicted to be associated with the membrane and NtrX is the response regulator partner. The ntrYntrX genes are widely distributed in Proteobacteria. In α-Proteobacteria they are frequently located downstream from ntrBC, whereas in β-Proteobacteria these genes are located downstream from genes encoding an RNA methyltransferase and a proline-rich protein with unknown function. The NtrX protein of α-Proteobacteria has an AAA+ domain, absent in those from β-Proteobacteria. An ntrY mutant of H. seropedicae showed the wild-type nitrogen fixation phenotype, but the nitrate-dependent growth was abolished. Gene fusion assays indicated that NtrY is involved in the expression of genes coding for the assimilatory nitrate reductase as well as the nitrate-responsive two-component system NarX-NarL (narK and narX promoters, respectively). The purified NtrX protein was capable of binding the narK and narX promoters, and the binding site at the narX promoter for the NtrX protein was determined by DNA footprinting. In silico analyses revealed similar sequences in other promoter regions of H. seropedicae that are related to nitrate assimilation, supporting the role of the NtrY-NtrX system in regulating nitrate metabolism in H. seropedicae.
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Affiliation(s)
- Paloma Bonato
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
| | - Lysangela R Alves
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
| | - Juliana H Osaki
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
| | - Liu U Rigo
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
| | - Fabio O Pedrosa
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
| | - Emanuel M Souza
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
| | - Nan Zhang
- Department of Life Sciences, Imperial College London, UK
| | | | - Martin Buck
- Department of Life Sciences, Imperial College London, UK
| | - Roseli Wassem
- Department of Genetics, Universidade Federal do Paraná, Curitiba, Brazil
| | - Leda S Chubatsu
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil
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Nishikawa S, Shinzawa N, Nakamura K, Ishigaki K, Abe H, Horiguchi Y. Thebvg-repressed genebrtA, encoding biofilm-associated surface adhesin, is expressed during host infection byBordetella bronchiseptica. Microbiol Immunol 2016; 60:93-105. [DOI: 10.1111/1348-0421.12356] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 12/24/2015] [Accepted: 01/07/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Sayaka Nishikawa
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases; Osaka University; 3-1 Yamada-oka Suita Osaka 565-0871 Japan
| | - Naoaki Shinzawa
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases; Osaka University; 3-1 Yamada-oka Suita Osaka 565-0871 Japan
| | - Keiji Nakamura
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases; Osaka University; 3-1 Yamada-oka Suita Osaka 565-0871 Japan
| | - Keisuke Ishigaki
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases; Osaka University; 3-1 Yamada-oka Suita Osaka 565-0871 Japan
| | - Hiroyuki Abe
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases; Osaka University; 3-1 Yamada-oka Suita Osaka 565-0871 Japan
| | - Yasuhiko Horiguchi
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases; Osaka University; 3-1 Yamada-oka Suita Osaka 565-0871 Japan
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Liu Q, Liu X, Yan F, He Y, Wei J, Zhang Y, Liu L, Sun Y. Comparative transcriptome analysis of Brucella melitensis in an acidic environment: Identification of the two-component response regulator involved in the acid resistance and virulence of Brucella. Microb Pathog 2015; 91:92-8. [PMID: 26691825 DOI: 10.1016/j.micpath.2015.11.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 11/06/2015] [Accepted: 11/09/2015] [Indexed: 01/01/2023]
Abstract
Brucella melitensis, encounters a very stressful environment in phagosomes, especially low pH levels. So identifying the genes that contribute to the replication and survival within an acidic environment is critical in understanding the pathogenesis of the Brucella bacteria. In our research, comparative transcriptome with RNA-seq were used to analyze the changes of genes in normal-medium culture and in pH4.4-medium culture. The results reveal that 113 genes expressed with significant differences (|log2Ratio| ≥ 3); about 44% genes expressed as up-regulated. With GO term analysis, structural constituent of the ribosome, rRNA binding, structural molecule activity, and cation-transporting ATPase activity were significantly enriched (p-value ≤ 0.05). These genes distributed in 51 pathways, in which ribosome and photosynthesis pathways were significantly enriched. Six pathways (oxidative phosphorylation, iron-transporting, bacterial secretion system, transcriptional regulation, two-component system, and ABC transporters pathways) tightly related to the intracellular survival and virulence of Brucella were analyzed. A two-component response regulator gene in the transcriptional regulation pathway, identified through gene deletion and complementary technologies, played an important role in the resistance to the acid-resistance and virulence of Brucella.
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Affiliation(s)
- Qianhong Liu
- Jilin Agricultural Science and Technology University, Jilin 132101, China.
| | - Xingyu Liu
- Guangzhou Airport Entry-Exit Inspection and Quarantine Brueau of P.R.C, Guangzhou 510470, China
| | - Feng Yan
- Jilin Agricultural Science and Technology University, Jilin 132101, China
| | - Yuhua He
- Jilin Agricultural Science and Technology University, Jilin 132101, China
| | - Jie Wei
- Jilin Agricultural Science and Technology University, Jilin 132101, China
| | - Yuanyuan Zhang
- Jilin Agricultural Science and Technology University, Jilin 132101, China
| | - Lu Liu
- Jilin Agricultural Science and Technology University, Jilin 132101, China
| | - Youpeng Sun
- Jilin Agricultural Science and Technology University, Jilin 132101, China
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Fernández I, Otero LH, Klinke S, Carrica MDC, Goldbaum FA. Snapshots of Conformational Changes Shed Light into the NtrX Receiver Domain Signal Transduction Mechanism. J Mol Biol 2015; 427:3258-3272. [DOI: 10.1016/j.jmb.2015.06.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 05/11/2015] [Accepted: 06/17/2015] [Indexed: 11/29/2022]
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Shimizu T, Huang D, Yan F, Stranava M, Bartosova M, Fojtíková V, Martínková M. Gaseous O2, NO, and CO in signal transduction: structure and function relationships of heme-based gas sensors and heme-redox sensors. Chem Rev 2015; 115:6491-533. [PMID: 26021768 DOI: 10.1021/acs.chemrev.5b00018] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Toru Shimizu
- †Department of Cell Biology and Genetics and Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, Guangdong 515041, China
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
- §Research Center for Compact Chemical System, National Institute of Advanced Industrial Science and Technology (AIST), Sendai 983-8551, Japan
| | - Dongyang Huang
- †Department of Cell Biology and Genetics and Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Fang Yan
- †Department of Cell Biology and Genetics and Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Martin Stranava
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
| | - Martina Bartosova
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
| | - Veronika Fojtíková
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
| | - Markéta Martínková
- ‡Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2 128 43, Czech Republic
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Comparative analysis of wolbachia genomes reveals streamlining and divergence of minimalist two-component systems. G3-GENES GENOMES GENETICS 2015; 5:983-96. [PMID: 25809075 PMCID: PMC4426382 DOI: 10.1534/g3.115.017137] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Two-component regulatory systems are commonly used by bacteria to coordinate intracellular responses with environmental cues. These systems are composed of functional protein pairs consisting of a sensor histidine kinase and cognate response regulator. In contrast to the well-studied Caulobacter crescentus system, which carries dozens of these pairs, the streamlined bacterial endosymbiont Wolbachia pipientis encodes only two pairs: CckA/CtrA and PleC/PleD. Here, we used bioinformatic tools to compare characterized two-component system relays from C. crescentus, the related Anaplasmataceae species Anaplasma phagocytophilum and Ehrlichia chaffeensis, and 12 sequenced Wolbachia strains. We found the core protein pairs and a subset of interacting partners to be highly conserved within Wolbachia and these other Anaplasmataceae. Genes involved in two-component signaling were positioned differently within the various Wolbachia genomes, whereas the local context of each gene was conserved. Unlike Anaplasma and Ehrlichia, Wolbachia two-component genes were more consistently found clustered with metabolic genes. The domain architecture and key functional residues standard for two-component system proteins were well-conserved in Wolbachia, although residues that specify cognate pairing diverged substantially from other Anaplasmataceae. These findings indicate that Wolbachia two-component signaling pairs share considerable functional overlap with other α-proteobacterial systems, whereas their divergence suggests the potential for regulatory differences and cross-talk.
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44
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Sycz G, Carrica MC, Tseng TS, Bogomolni RA, Briggs WR, Goldbaum FA, Paris G. LOV Histidine Kinase Modulates the General Stress Response System and Affects the virB Operon Expression in Brucella abortus. PLoS One 2015; 10:e0124058. [PMID: 25993430 PMCID: PMC4438053 DOI: 10.1371/journal.pone.0124058] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 03/05/2015] [Indexed: 12/31/2022] Open
Abstract
Brucella is the causative agent of the zoonotic disease brucellosis, and its success as an intracellular pathogen relies on its ability to adapt to the harsh environmental conditions that it encounters inside the host. The Brucella genome encodes a sensor histidine kinase containing a LOV domain upstream from the kinase, LOVHK, which plays an important role in light-regulated Brucella virulence. In this report we study the intracellular signaling pathway initiated by the light sensor LOVHK using an integrated biochemical and genetic approach. From results of bacterial two-hybrid assays and phosphotransfer experiments we demonstrate that LOVHK functionally interacts with two response regulators: PhyR and LovR, constituting a functional two-component signal-transduction system. LOVHK contributes to the activation of the General Stress Response (GSR) system in Brucella via PhyR, while LovR is proposed to be a phosphate-sink for LOVHK, decreasing its phosphorylation state. We also show that in the absence of LOVHK the expression of the virB operon is down-regulated. In conclusion, our results suggest that LOVHK positively regulates the GSR system in vivo, and has an effect on the expression of the virB operon. The proposed regulatory network suggests a similar role for LOVHK in other microorganisms.
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Affiliation(s)
- Gabriela Sycz
- Laboratorio de Inmunología y Microbiología Molecular, Fundación Instituto Leloir (IIBBA-CONICET), Buenos Aires, Argentina
| | - Mariela Carmen Carrica
- Laboratorio de Inmunología y Microbiología Molecular, Fundación Instituto Leloir (IIBBA-CONICET), Buenos Aires, Argentina
| | - Tong-Seung Tseng
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California, United States of America
| | - Roberto A. Bogomolni
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Winslow R. Briggs
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California, United States of America
| | - Fernando A. Goldbaum
- Laboratorio de Inmunología y Microbiología Molecular, Fundación Instituto Leloir (IIBBA-CONICET), Buenos Aires, Argentina
| | - Gastón Paris
- Laboratorio de Inmunología y Microbiología Molecular, Fundación Instituto Leloir (IIBBA-CONICET), Buenos Aires, Argentina
- * E-mail:
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Ronneau S, Moussa S, Barbier T, Conde-Álvarez R, Zuniga-Ripa A, Moriyon I, Letesson JJ. Brucella, nitrogen and virulence. Crit Rev Microbiol 2014; 42:507-25. [PMID: 25471320 DOI: 10.3109/1040841x.2014.962480] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The brucellae are α-Proteobacteria causing brucellosis, an important zoonosis. Although multiplying in endoplasmic reticulum-derived vacuoles, they cause no cell death, suggesting subtle but efficient use of host resources. Brucellae are amino-acid prototrophs able to grow with ammonium or use glutamate as the sole carbon-nitrogen source in vitro. They contain more than twice amino acid/peptide/polyamine uptake genes than the amino-acid auxotroph Legionella pneumophila, which multiplies in a similar vacuole, suggesting a different nutritional strategy. During these two last decades, many mutants of key actors in nitrogen metabolism (transporters, enzymes, regulators, etc.) have been described to be essential for full virulence of brucellae. Here, we review the genomic and experimental data on Brucella nitrogen metabolism and its connection with virulence. An analysis of various aspects of this metabolism (transport, assimilation, biosynthesis, catabolism, respiration and regulation) has highlighted differences and similarities in nitrogen metabolism with other α-Proteobacteria. Together, these data suggest that, during their intracellular life cycle, the brucellae use various nitrogen sources for biosynthesis, catabolism and respiration following a strategy that requires prototrophy and a tight regulation of nitrogen use.
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Affiliation(s)
| | - Simon Moussa
- a UNamur, URBM 61 rue de Bruxelles , Namur , Belgium and
| | | | - Raquel Conde-Álvarez
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
| | - Amaia Zuniga-Ripa
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
| | - Ignacio Moriyon
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
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Ehrlichia chaffeensis proliferation begins with NtrY/NtrX and PutA/GlnA upregulation and CtrA degradation induced by proline and glutamine uptake. mBio 2014; 5:e02141. [PMID: 25425236 PMCID: PMC4251998 DOI: 10.1128/mbio.02141-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
How the obligatory intracellular bacterium Ehrlichia chaffeensis begins to replicate upon entry into human monocytes is poorly understood. Here, we examined the potential role of amino acids in initiating intracellular replication. PutA converts proline to glutamate, and GlnA converts glutamate to glutamine. E. chaffeensis PutA and GlnA complemented Escherichia coli putA and glnA mutants. Methionine sulfoximine, a glutamine synthetase inhibitor, inhibited E. chaffeensis GlnA activity and E. chaffeensis infection of human cells. Incubation of E. chaffeensis with human cells rapidly induced putA and glnA expression that peaked at 24 h postincubation. E. chaffeensis took up proline and glutamine but not glutamate. Pretreatment of E. chaffeensis with a proline transporter inhibitor (protamine), a glutamine transporter inhibitor (histidine), or proline analogs inhibited E. chaffeensis infection, whereas pretreatment with proline or glutamine enhanced infection and upregulated putA and glnA faster than no treatment or glutamate pretreatment. The temporal response of putA and glnA expression was similar to that of NtrY and NtrX, a two-component system, and electrophoretic mobility shift assays showed specific binding of recombinant E. chaffeensis NtrX (rNtrX) to the promoter regions of E. chaffeensis putA and glnA. Furthermore, rNtrX transactivated E. chaffeensis putA and glnA promoter-lacZ fusions in E. coli. Growth-promoting activities of proline and glutamine were also accompanied by rapid degradation of the DNA-binding protein CtrA. Our results suggest that proline and glutamine uptake regulates putA and glnA expression through NtrY/NtrX and facilitates degradation of CtrA to initiate a new cycle of E. chaffeensis growth. Human monocytic ehrlichiosis (HME) is one of the most prevalent, life-threatening emerging infectious zoonoses in the United States. HME is caused by infection with E. chaffeensis, an obligatory intracellular bacterium in the order Rickettsiales, which includes several category B/C pathogens, such as those causing Rocky Mountain spotted fever and epidemic typhus. The limited understanding of the mechanisms that control bacterial growth within eukaryotic cells continues to impede the identification of new therapeutic targets against rickettsial diseases. Extracellular rickettsia cannot replicate, but rickettsial replication ensues upon entry into eukaryotic host cells. Our findings will provide insights into a novel mechanism of the two-component system that regulates E. chaffeensis growth initiation in human monocytes. The result is also important because little is known about the NtrY/NtrX two-component system in any bacteria, let alone obligatory intracellular bacteria. Our findings will advance the field’s current conceptual paradigm on regulation of obligatory intracellular nutrition, metabolism, and growth.
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Prol García MJ, D'Alvise PW, Rygaard AM, Gram L. Biofilm formation is not a prerequisite for production of the antibacterial compound tropodithietic acid in Phaeobacter inhibens DSM17395. J Appl Microbiol 2014; 117:1592-600. [PMID: 25284322 DOI: 10.1111/jam.12659] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 09/18/2014] [Accepted: 09/30/2014] [Indexed: 01/06/2023]
Abstract
AIMS The goal of this study was to investigate if biofilm formation on population level is a physiological requirement for antagonism in Phaeobacter inhibens DSM17395, since the antibiotic compound tropodithietic acid (TDA) is produced by several Roseobacter clade species during growth as multicellular aggregates or biofilms at the air-liquid interface and is induced on single cell level upon attachment. METHODS AND RESULTS A mutant library was created by Tn5 transposon insertion and 22 TDA-positive (brown) mutants with decreased biofilm formation or adhesion, and eight TDA-negative (white) mutants with increased biofilm formation or adhesion were selected. None of the selected biofilm-overproducing white mutants showed any antibiotic activity, while all brown mutants with reduced or disabled biofilm formation produced the antibacterial compound. Sequencing analysis indicated that genes that are likely involved in EPS/LPS production, motility and chemotaxis, and redox regulation play a role in biofilm formation and/or adhesion in P. inhibens DSM17395. CONCLUSIONS Cell aggregation and biofilm formation are not physiological prerequisites for TDA production. SIGNIFICANCE AND IMPACT OF THE STUDY This study contributes to the understanding of TDA production in P. inhibens, which has great potential as a probiotic in marine larviculture.
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Affiliation(s)
- M J Prol García
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
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Agrobacterium tumefaciens exoR controls acid response genes and impacts exopolysaccharide synthesis, horizontal gene transfer, and virulence gene expression. J Bacteriol 2014; 196:3221-33. [PMID: 24982308 DOI: 10.1128/jb.01751-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Agrobacterium tumefaciens is a facultative plant pathogen and the causative agent of crown gall disease. The initial stage of infection involves attachment to plant tissues, and subsequently, biofilms may form at these sites. This study focuses on the periplasmic ExoR regulator, which was identified based on the severe biofilm deficiency of A. tumefaciens exoR mutants. Genome-wide expression analysis was performed to elucidate the complete ExoR regulon. Overproduction of the exopolysaccharide succinoglycan is a dramatic phenotype of exoR mutants. Comparative expression analyses revealed that the core ExoR regulon is unaffected by succinoglycan synthesis. Several findings are consistent with previous observations: genes involved in succinoglycan biosynthesis, motility, and type VI secretion are differentially expressed in the ΔexoR mutant. In addition, these studies revealed new functional categories regulated by ExoR, including genes related to virulence, conjugation of the pAtC58 megaplasmid, ABC transporters, and cell envelope architecture. To address how ExoR exerts a broad impact on gene expression from its periplasmic location, a genetic screen was performed to isolate suppressor mutants that mitigate the exoR motility phenotype and identify downstream components of the ExoR regulatory pathway. This suppression analysis identified the acid-sensing two-component system ChvG-ChvI, and the suppressor mutant phenotypes suggest that all or most of the characteristic exoR properties are mediated through ChvG-ChvI. Subsequent analysis indicates that exoR mutants are simulating a response to acidic conditions, even in neutral media. This work expands the model for ExoR regulation in A. tumefaciens and underscores the global role that this regulator plays on gene expression.
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Torres MJ, Argandoña M, Vargas C, Bedmar EJ, Fischer HM, Mesa S, Delgado MJ. The global response regulator RegR controls expression of denitrification genes in Bradyrhizobium japonicum. PLoS One 2014; 9:e99011. [PMID: 24949739 PMCID: PMC4064962 DOI: 10.1371/journal.pone.0099011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 04/24/2014] [Indexed: 12/03/2022] Open
Abstract
Bradyrhizobium japonicum RegSR regulatory proteins belong to the family of two-component regulatory systems, and orthologs are present in many Proteobacteria where they globally control gene expression mostly in a redox-responsive manner. In this work, we have performed a transcriptional profiling of wild-type and regR mutant cells grown under anoxic denitrifying conditions. The comparative analyses of wild-type and regR strains revealed that almost 620 genes induced in the wild type under denitrifying conditions were regulated (directly or indirectly) by RegR, pointing out the important role of this protein as a global regulator of denitrification. Genes controlled by RegR included nor and nos structural genes encoding nitric oxide and nitrous oxide reductase, respectively, genes encoding electron transport proteins such as cycA (blr7544) or cy2 (bll2388), and genes involved in nitric oxide detoxification (blr2806-09) and copper homeostasis (copCAB), as well as two regulatory genes (bll3466, bll4130). Purified RegR interacted with the promoters of norC (blr3214), nosR (blr0314), a fixK-like gene (bll3466), and bll4130, which encodes a LysR-type regulator. By using fluorescently labeled oligonucleotide extension (FLOE), we were able to identify two transcriptional start sites located at about 35 (P1) and 22 (P2) bp upstream of the putative translational start codon of norC. P1 matched with the previously mapped 5′end of norC mRNA which we demonstrate in this work to be under FixK2 control. P2 is a start site modulated by RegR and specific for anoxic conditions. Moreover, qRT-PCR experiments, expression studies with a norC-lacZ fusion, and heme c-staining analyses revealed that anoxia and nitrate are required for RegR-dependent induction of nor genes, and that this control is independent of the sensor protein RegS.
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Affiliation(s)
- Maria J. Torres
- Estación Experimental del Zaidin, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Montserrat Argandoña
- Departamento de Microbiología y Parasitología, Universidad de Sevilla, Sevilla, Spain
| | - Carmen Vargas
- Departamento de Microbiología y Parasitología, Universidad de Sevilla, Sevilla, Spain
| | - Eulogio J. Bedmar
- Estación Experimental del Zaidin, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | | | - Socorro Mesa
- Estación Experimental del Zaidin, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - María J. Delgado
- Estación Experimental del Zaidin, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
- * E-mail:
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The Sinorhizobium meliloti ntrX gene is involved in succinoglycan production, motility, and symbiotic nodulation on alfalfa. Appl Environ Microbiol 2013; 79:7150-9. [PMID: 24038694 DOI: 10.1128/aem.02225-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Rhizobia establish a symbiotic relationship with their host legumes to induce the formation of nitrogen-fixing nodules. This process is regulated by many rhizobium regulators, including some two-component regulatory systems (TCSs). NtrY/NtrX, a TCS that was first identified in Azorhizobium caulinodans, is required for free-living nitrogen metabolism and symbiotic nodulation on Sesbania rostrata. However, its functions in a typical rhizobium such as Sinorhizobium meliloti remain unclear. Here we found that the S. meliloti response regulator NtrX but not the histidine kinase NtrY is involved in the regulation of exopolysaccharide production, motility, and symbiosis with alfalfa. A plasmid insertion mutant of ntrX formed mucous colonies, which overproduced succinoglycan, an exopolysaccharide, by upregulating its biosynthesis genes. This mutant also exhibited motility defects due to reduced flagella and decreased expression of flagellins and regulatory genes. The regulation is independent of the known regulatory systems of ExoR/ExoS/ChvI, EmmABC, and ExpR. Alfalfa plants inoculated with the ntrX mutant were small and displayed symptoms of nitrogen starvation. Interestingly, the deletion mutant of ntrY showed a phenotype similar to that of the parent strain. These findings demonstrate that the S. meliloti NtrX is a new regulator of succinoglycan production and motility that is not genetically coupled with NtrY.
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