1
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An RNA sponge controls quorum sensing dynamics and biofilm formation in Vibrio cholerae. Nat Commun 2022; 13:7585. [PMID: 36482060 PMCID: PMC9732341 DOI: 10.1038/s41467-022-35261-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/24/2022] [Indexed: 12/13/2022] Open
Abstract
Small regulatory RNAs (sRNAs) acting in concert with the RNA chaperone Hfq are prevalent in many bacteria and typically act by base-pairing with multiple target transcripts. In the human pathogen Vibrio cholerae, sRNAs play roles in various processes including antibiotic tolerance, competence, and quorum sensing (QS). Here, we use RIL-seq (RNA-interaction-by-ligation-and-sequencing) to identify Hfq-interacting sRNAs and their targets in V. cholerae. We find hundreds of sRNA-mRNA interactions, as well as RNA duplexes formed between two sRNA regulators. Further analysis of these duplexes identifies an RNA sponge, termed QrrX, that base-pairs with and inactivates the Qrr1-4 sRNAs, which are known to modulate the QS pathway. Transcription of qrrX is activated by QrrT, a previously uncharacterized LysR-type transcriptional regulator. Our results indicate that QrrX and QrrT are required for rapid conversion from individual to community behaviours in V. cholerae.
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2
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The Effect of Heavy Metals on Conjugation Efficiency of an F-Plasmid in Escherichia coli. Antibiotics (Basel) 2022; 11:antibiotics11081123. [PMID: 36009992 PMCID: PMC9404890 DOI: 10.3390/antibiotics11081123] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/11/2022] [Accepted: 08/17/2022] [Indexed: 11/16/2022] Open
Abstract
Conjugation, the process by which conjugative plasmids are transferred between bacteria, is regarded as a major contributor to the spread of antibiotic resistance, in both environmental and clinical settings. Heavy metals are known to co-select for antibiotic resistance, but the impact of the presence of these metals on conjugation itself is not clear. Here, we systematically investigate the impact that five heavy metals (arsenic, cadmium, copper, manganese, and zinc) have on the transfer of an IncF conjugative plasmid in Escherichia coli. Our results show that two of the metals, cadmium and manganese, have no significant impact, while arsenic and zinc both reduce conjugation efficiency by approximately 2-fold. Copper showed the largest impact, with an almost 100-fold decrease in conjugation efficiency. This was not mediated by any change in transcription from the major Py promoter responsible for transcription of the conjugation machinery genes. Further, we show that in order to have this severe impact on the transfer of the plasmid, copper sulfate needs to be present during the mating process, and we suggest explanations for this.
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First insights into a pyruvate sensing and uptake system in Vibrio campbellii and its importance for virulence. J Bacteriol 2021; 203:e0029621. [PMID: 34339295 DOI: 10.1128/jb.00296-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pyruvate is a key metabolite in living cells and has been shown to play a crucial role in the virulence of several bacterial pathogens. The bioluminescent Vibrio campbellii, a severe infectious burden for marine aquaculture, excretes extraordinarily large amounts of pyruvate during growth and rapidly retrieves it by an as-yet unknown mechanism. We have now identified the responsible pyruvate transporter, here named BtsU, and our results show that it is the only pyruvate transporter in V. campbellii. Expression of btsU is tightly regulated by the membrane-integrated LytS-type histidine kinase BtsS, a sensor for extracellular pyruvate, and the LytTR-type response regulator BtsR. Cells lacking either the pyruvate transporter or sensing system show no chemotactic response towards pyruvate, indicating that intracellular pyruvate is required to activate the chemotaxis system. Moreover, pyruvate sensing and uptake were found to be important for the resuscitation of V. campbellii from the viable but nonculturable (VBNC) state and the bacterium's virulence against brine shrimp larvae. IMPORTANCE Bacterial infections are a serious threat to marine aquaculture, one of the fastest growing food sectors on earth. Therefore, it is extremely important to learn more about the pathogens responsible, one of which is Vibrio campbellii. This study sheds light on the importance of pyruvate sensing and uptake for V. campbellii, and reveals that the bacterium possesses only one pyruvate transporter, which is activated by a pyruvate-responsive histidine kinase/response regulator system. Without the ability to sense or take up pyruvate, the virulence of V. campbellii towards gnotobiotic brine shrimp larvae is strongly reduced.
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4
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Krafczyk R, Qi F, Sieber A, Mehler J, Jung K, Frishman D, Lassak J. Proline codon pair selection determines ribosome pausing strength and translation efficiency in bacteria. Commun Biol 2021; 4:589. [PMID: 34002016 PMCID: PMC8129111 DOI: 10.1038/s42003-021-02115-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 04/16/2021] [Indexed: 02/03/2023] Open
Abstract
The speed of mRNA translation depends in part on the amino acid to be incorporated into the nascent chain. Peptide bond formation is especially slow with proline and two adjacent prolines can even cause ribosome stalling. While previous studies focused on how the amino acid context of a Pro-Pro motif determines the stalling strength, we extend this question to the mRNA level. Bioinformatics analysis of the Escherichia coli genome revealed significantly differing codon usage between single and consecutive prolines. We therefore developed a luminescence reporter to detect ribosome pausing in living cells, enabling us to dissect the roles of codon choice and tRNA selection as well as to explain the genome scale observations. Specifically, we found a strong selective pressure against CCC/U-C, a sequon causing ribosomal frameshifting even under wild-type conditions. On the other hand, translation efficiency as positive evolutionary driving force led to an overrepresentation of CCG. This codon is not only translated the fastest, but the corresponding prolyl-tRNA reaches almost saturating levels. By contrast, CCA, for which the cognate prolyl-tRNA amounts are limiting, is used to regulate pausing strength. Thus, codon selection both in discrete positions but especially in proline codon pairs can tune protein copy numbers.
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Affiliation(s)
- Ralph Krafczyk
- grid.5252.00000 0004 1936 973XDepartment of Biology I, Microbiology, Ludwig-Maximilians-Universität München, München, Germany
| | - Fei Qi
- grid.411404.40000 0000 8895 903XInstitute of Genomics, School of Biomedical Sciences, Huaqiao University, Xiamen, China ,grid.6936.a0000000123222966Department of Bioinformatics, Wissenschaftzentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Alina Sieber
- grid.5252.00000 0004 1936 973XDepartment of Biology I, Microbiology, Ludwig-Maximilians-Universität München, München, Germany
| | - Judith Mehler
- grid.5252.00000 0004 1936 973XDepartment of Biology I, Microbiology, Ludwig-Maximilians-Universität München, München, Germany
| | - Kirsten Jung
- grid.5252.00000 0004 1936 973XDepartment of Biology I, Microbiology, Ludwig-Maximilians-Universität München, München, Germany
| | - Dmitrij Frishman
- grid.6936.a0000000123222966Department of Bioinformatics, Wissenschaftzentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Jürgen Lassak
- grid.5252.00000 0004 1936 973XDepartment of Biology I, Microbiology, Ludwig-Maximilians-Universität München, München, Germany
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5
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Rova M, Hellberg Lindqvist M, Goetelen T, Blomqvist S, Nilsson T. Heterologous expression of the gene for chlorite dismutase from Ideonella dechloratans is induced by an FNR-type transcription factor. Microbiologyopen 2020; 9:e1049. [PMID: 32319739 PMCID: PMC7349173 DOI: 10.1002/mbo3.1049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 01/30/2023] Open
Abstract
Regulation of the expression of the gene for chlorite dismutase (cld), located on the chlorate reduction composite transposon of the chlorate reducer Ideonella dechloratans, was studied. A 200 bp upstream sequence of the cld gene, and mutated and truncated versions thereof, was used in a reporter system in Escherichia coli. It was found that a sequence within this upstream region, which is nearly identical to the canonical FNR-binding sequence of E. coli, is necessary for anaerobic induction of the reporter gene. Anaerobic induction was regained in an FNR-deficient strain of E. coli when supplemented either with the fnr gene from E. coli or with a candidate fnr gene cloned from I. dechloratans. In vivo transcription of the suggested fnr gene of I. dechloratans was demonstrated by qRT-PCR. Based on these results, the cld promoter of I. dechloratans is suggested to be a class II-activated promoter regulated by an FNR-type protein of I. dechloratans. No fnr-type genes have been found on the chlorate reduction composite transposon of I. dechloratans, making anaerobic upregulation of the cld gene after a gene transfer event dependent on the presence of an fnr-type gene in the recipient.
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Affiliation(s)
- Maria Rova
- Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden
| | | | - Thijs Goetelen
- Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden
| | - Shady Blomqvist
- Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden
| | - Thomas Nilsson
- Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden
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6
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Volkwein W, Krafczyk R, Jagtap PKA, Parr M, Mankina E, Macošek J, Guo Z, Fürst MJLJ, Pfab M, Frishman D, Hennig J, Jung K, Lassak J. Switching the Post-translational Modification of Translation Elongation Factor EF-P. Front Microbiol 2019; 10:1148. [PMID: 31178848 PMCID: PMC6544042 DOI: 10.3389/fmicb.2019.01148] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 05/06/2019] [Indexed: 12/31/2022] Open
Abstract
Tripeptides with two consecutive prolines are the shortest and most frequent sequences causing ribosome stalling. The bacterial translation elongation factor P (EF-P) relieves this arrest, allowing protein biosynthesis to continue. A seven amino acids long loop between beta-strands β3/β4 is crucial for EF-P function and modified at its tip by lysylation of lysine or rhamnosylation of arginine. Phylogenetic analyses unveiled an invariant proline in the -2 position of the modification site in EF-Ps that utilize lysine modifications such as Escherichia coli. Bacteria with the arginine modification like Pseudomonas putida on the contrary have selected against it. Focusing on the EF-Ps from these two model organisms we demonstrate the importance of the β3/β4 loop composition for functionalization by chemically distinct modifications. Ultimately, we show that only two amino acid changes in E. coli EF-P are needed for switching the modification strategy from lysylation to rhamnosylation.
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Affiliation(s)
- Wolfram Volkwein
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ralph Krafczyk
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Marina Parr
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany.,St. Petersburg State Polytechnic University, Saint Petersburg, Russia
| | - Elena Mankina
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany
| | - Jakub Macošek
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Faculty of Biosciences, Collaboration for Joint PhD Degree Between EMBL and Heidelberg University, Heidelberg, Germany
| | - Zhenghuan Guo
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Maximilian Josef Ludwig Johannes Fürst
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany.,Molecular Enzymology Group, University of Groningen, Groningen, Netherlands
| | - Miriam Pfab
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Dmitrij Frishman
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany.,St. Petersburg State Polytechnic University, Saint Petersburg, Russia
| | - Janosch Hennig
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Kirsten Jung
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jürgen Lassak
- Center for Integrated Protein Science Munich, Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Munich, Germany
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7
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Jung K, Fabiani F, Hoyer E, Lassak J. Bacterial transmembrane signalling systems and their engineering for biosensing. Open Biol 2019; 8:rsob.180023. [PMID: 29695618 PMCID: PMC5936718 DOI: 10.1098/rsob.180023] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/03/2018] [Indexed: 12/27/2022] Open
Abstract
Every living cell possesses numerous transmembrane signalling systems that receive chemical and physical stimuli from the environment and transduce this information into an intracellular signal that triggers some form of cellular response. As unicellular organisms, bacteria require these systems for survival in rapidly changing environments. The receptors themselves act as ‘sensory organs’, while subsequent signalling circuits can be regarded as forming a ‘neural network’ that is involved in decision making, adaptation and ultimately in ensuring survival. Bacteria serve as useful biosensors in industry and clinical diagnostics, in addition to producing drugs for therapeutic purposes. Therefore, there is a great demand for engineered bacterial strains that contain transmembrane signalling systems with high molecular specificity, sensitivity and dose dependency. In this review, we address the complexity of transmembrane signalling systems and discuss principles to rewire receptors and their signalling outputs.
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Affiliation(s)
- Kirsten Jung
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Florian Fabiani
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Elisabeth Hoyer
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Jürgen Lassak
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
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8
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Measures of single- versus multiple-round translation argue against a mechanism to ensure coupling of transcription and translation. Proc Natl Acad Sci U S A 2018; 115:10774-10779. [PMID: 30275301 DOI: 10.1073/pnas.1812940115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In prokaryotes, the synthesis of RNA and protein occurs simultaneously in the cytoplasm. A number of studies indicate that translation can strongly impact transcription, a phenomenon often attributed to physical coupling between RNA polymerase (RNAP) and the lead ribosome on the nascent mRNA. Whether there generally exists a mechanism to ensure or promote RNAP-ribosome coupling remains unclear. Here, we used an efficient hammerhead ribozyme and developed a reporter system to measure single- versus multiple-round translation in Escherichia coli Six pairs of cotranscribed and differentially translated genes were analyzed. For five of them, the stoichiometry of the two protein products came no closer to unity (1:1) when the rounds of translation were severely reduced in wild-type cells. Introduction of mutation rpoB(I572N), which slows RNAP elongation, could promote coupling, as indicated by stoichiometric SspA and SspB products in the single-round assay. These data are consistent with models of stochastic coupling in which the probability of coupling depends on the relative rates of transcription and translation and suggest that RNAP often transcribes without a linked ribosome.
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9
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A Single-Cell View of the BtsSR/YpdAB Pyruvate Sensing Network in Escherichia coli and Its Biological Relevance. J Bacteriol 2017; 200:JB.00536-17. [PMID: 29038258 DOI: 10.1128/jb.00536-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/09/2017] [Indexed: 12/16/2022] Open
Abstract
Fluctuating environments and individual physiological diversity force bacteria to constantly adapt and optimize the uptake of substrates. We focus here on two very similar two-component systems (TCSs) of Escherichia coli belonging to the LytS/LytTR family: BtsS/BtsR (formerly YehU/YehT) and YpdA/YpdB. Both TCSs respond to extracellular pyruvate, albeit with different affinities, typically during postexponential growth, and each system regulates expression of a single transporter gene, yjiY and yhjX, respectively. To obtain insights into the biological significance of these TCSs, we analyzed the activation of the target promoters at the single-cell level. We found unimodal cell-to-cell variability; however, the degree of variance was strongly influenced by the available nutrients and differed between the two TCSs. We hypothesized that activation of either of the TCSs helps individual cells to replenish carbon resources. To test this hypothesis, we compared wild-type cells with the btsSR ypdAB mutant under two metabolically modulated conditions: protein overproduction and persister formation. Although all wild-type cells were able to overproduce green fluorescent protein (GFP), about half of the btsSR ypdAB population was unable to overexpress GFP. Moreover, the percentage of persister cells, which tolerate antibiotic stress, was significantly lower in the wild-type cells than in the btsSR ypdAB population. Hence, we suggest that the BtsS/BtsR and YpdA/YpdB network contributes to a balancing of the physiological state of all cells within a population.IMPORTANCE Histidine kinase/response regulator (HK/RR) systems enable bacteria to respond to environmental and physiological fluctuations. Escherichia coli and other members of the Enterobacteriaceae possess two similar LytS/LytTR-type HK/RRs, BtsS/BtsR (formerly YehU/YehT) and YpdA/YpdB, which form a functional network. Both systems are activated in response to external pyruvate, typically when cells face overflow metabolism during post-exponential growth. Single-cell analysis of the activation of their respective target genes yjiY and yhjX revealed cell-to-cell variability, and the range of variation was strongly influenced by externally available nutrients. Based on the phenotypic characterization of a btsSR ypdAB mutant compared to the parental strain, we suggest that this TCS network supports an optimization of the physiological state of the individuals within the population.
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10
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Volkwein W, Maier C, Krafczyk R, Jung K, Lassak J. A Versatile Toolbox for the Control of Protein Levels Using N ε-Acetyl-l-lysine Dependent Amber Suppression. ACS Synth Biol 2017; 6:1892-1902. [PMID: 28594177 DOI: 10.1021/acssynbio.7b00048] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The analysis of the function of essential genes in vivo depends on the ability to experimentally modulate levels of their protein products. Current methods to address this are based on transcriptional or post-transcriptional regulation of mRNAs, but approaches based on the exploitation of translation regulation have so far been neglected. Here we describe a toolbox, based on amber suppression in the presence of Nε-acetyl-l-lysine (AcK), for translational tuning of protein output. We chose the highly sensitive luminescence system LuxCDABE as a reporter and incorporated a UAG stop codon into the gene for the reductase subunit LuxC. The system was used to measure and compare the effects of AcK- and Nε-(tert-butoxycarbonyl)-l-lysine (BocK) dependent amber suppression in Escherichia coli. We also demonstrate here that, in combination with transcriptional regulation, the system allows protein production to be either totally repressed or gradually adjusted. To identify sequence motifs that provide improved translational regulation, we varied the sequence context of the amber codon and found that insertion of two preceding prolines drastically decreases luminescence. In addition, using LacZ as a reporter, we demonstrated that a strain encoding a variant with a Pro-Pro amber motif can only grow on lactose when AcK is supplied, thus confirming the tight translational regulation of protein output. In parallel, we constructed an E. coli strain that carries an isopropyl β-d-1-thiogalactopyranoside (IPTG)-inducible version of the AcK-tRNA synthetase (AcKRS) gene on the chromosome, thus preventing mischarging of noncognate substrates. Subsequently, a diaminopimelic acid auxotrophic mutant (ΔdapA) was generated demonstrating the potential of this strain in regulating essential gene products. Furthermore, we assembled a set of vectors based on the broad-host-range pBBR ori that enable the AcK-dependent amber suppression system to control protein output not only in E. coli, but also in Salmonella enterica and Vibrio cholerae.
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Affiliation(s)
- Wolfram Volkwein
- Center for integrated Protein
Science Munich (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, 82152 Martinsried, Germany
| | - Christopher Maier
- Center for integrated Protein
Science Munich (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, 82152 Martinsried, Germany
| | - Ralph Krafczyk
- Center for integrated Protein
Science Munich (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, 82152 Martinsried, Germany
| | - Kirsten Jung
- Center for integrated Protein
Science Munich (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, 82152 Martinsried, Germany
| | - Jürgen Lassak
- Center for integrated Protein
Science Munich (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, 82152 Martinsried, Germany
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11
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Identification and Characterization of Differentially-Regulated Type IVb Pilin Genes Necessary for Predation in Obligate Bacterial Predators. Sci Rep 2017; 7:1013. [PMID: 28432347 PMCID: PMC5430801 DOI: 10.1038/s41598-017-00951-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/17/2017] [Indexed: 11/08/2022] Open
Abstract
Bdellovibrio bacteriovorus is an obligate predator of bacteria that grows and divides within the periplasm of its prey. Functions involved in the early steps of predation have been identified and characterized, but mediators of prey invasion are still poorly detailed. By combining omics data available for Bdellovibrio and like organisms (BALO’s), we identified 43 genes expressed in B. bacteriovorus during the early interaction with prey. These included genes in a tight adherence (TAD) operon encoding for two type IVb fimbriae-like pilin proteins (flp1 and flp2), and their processing and export machinery. Two additional flp genes (flp3 and flp4) were computationally identified at other locations along the chromosome, defining the largest and most diverse type IVb complement known in bacteria to date. Only flp1, flp2 and flp4 were expressed; their respective gene knock-outs resulted in a complete loss of the predatory ability without losing the ability to adhere to prey cells. Additionally, we further demonstrate differential regulation of the flp genes as the TAD operon of BALOs with different predatory strategies is controlled by a flagellar sigma factor FliA, while flp4 is not. Finally, we show that FliA, a known flagellar transcriptional regulator in other bacteria, is an essential Bdellovibrio gene.
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12
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Lorenz N, Shin JY, Jung K. Activity, Abundance, and Localization of Quorum Sensing Receptors in Vibrio harveyi. Front Microbiol 2017; 8:634. [PMID: 28458660 PMCID: PMC5394107 DOI: 10.3389/fmicb.2017.00634] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 03/28/2017] [Indexed: 12/20/2022] Open
Abstract
Quorum sensing (QS) is a process enabling a bacterial population to communicate via small molecules called autoinducers (AIs). This intercellular communication process allows single cells to synchronize their behavior within a population. The marine bacterium Vibrio harveyi ATCC BAA-1116 channels the information of three AI signals into one QS cascade. Three receptors perceive these AIs, the hybrid histidine kinases LuxN, Lux(P)Q and CqsS, to transduce the information to the histidine phosphotransfer (HPt) protein LuxU via phosphorelay, and finally to the response regulator LuxO. Hence, the level of phosphorylated LuxO depends on the AI concentrations. The phosphorylated LuxO (P-LuxO) controls the expression of small regulatory RNAs (sRNAs), which together with the RNA chaperon Hfq, destabilize the transcript of the master regulator luxR. LuxR is responsible for the induction and repression of several genes (e.g., for bioluminescence, exoprotease and siderophore production). In vivo studies with various mutants have demonstrated that the ratio between kinase and phosphatase activities of the individual QS receptors and therefore the P-LuxO/LuxO ratio is crucial not only for the output strength but also for the degree of noise. This study was undertaken to better understand the inherent design principles of this complex signaling cascade, which allows sensing and integration of different signals, but also the differentiated output in individual cells. Therefore, we quantitatively analyzed not only the enzymatic activities, but also the abundance and localization of the three QS receptors. We found that LuxN presents the highest capacity to phosphorylate LuxU, while the phosphatase activity was comparable to LuxQ and CqsS in vitro. In whole cells the copy number of LuxN was higher than that of LuxQ and CqsS, and further increased in the late exponential growth phase. Microscopy experiments indicate that LuxN and LuxQ form independent clusters. Altogether, these results suggest, that the three QS receptors act in parallel, and V. harveyi has developed with LuxN the most dynamic sensing range for HAI-1, the species-specific AI.
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Affiliation(s)
- Nicola Lorenz
- Microbiology, Munich Center for Integrated Protein Science (CIPSM) at the Department of Biology I, Ludwig-Maximilians-Universität MünchenMartinsried, Germany
| | - Jae Yen Shin
- Microbiology, Munich Center for Integrated Protein Science (CIPSM) at the Department of Biology I, Ludwig-Maximilians-Universität MünchenMartinsried, Germany
| | - Kirsten Jung
- Microbiology, Munich Center for Integrated Protein Science (CIPSM) at the Department of Biology I, Ludwig-Maximilians-Universität MünchenMartinsried, Germany
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13
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Schramke H, Laermann V, Tegetmeyer HE, Brachmann A, Jung K, Altendorf K. Revisiting regulation of potassium homeostasis in Escherichia coli: the connection to phosphate limitation. Microbiologyopen 2017; 6. [PMID: 28097817 PMCID: PMC5458449 DOI: 10.1002/mbo3.438] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/29/2016] [Accepted: 12/06/2016] [Indexed: 11/10/2022] Open
Abstract
Two-component signal transduction constitutes the predominant strategy used by bacteria to adapt to fluctuating environments. The KdpD/KdpE system is one of the most widespread, and is crucial for K+ homeostasis. In Escherichia coli, the histidine kinase KdpD senses K+ availability, whereas the response regulator KdpE activates synthesis of the high-affinity K+ uptake system KdpFABC. Here we show that, in the absence of KdpD, kdpFABC expression can be activated via phosphorylation of KdpE by the histidine kinase PhoR. PhoR and its cognate response regulator PhoB comprise a phosphate-responsive two-component system, which senses phosphate limitation indirectly through the phosphate transporter PstCAB and its accessory protein PhoU. In vivo two-hybrid interaction studies based on the bacterial adenylate cyclase reveal pairwise interactions between KdpD, PhoR, and PhoU. Finally, we demonstrate that cross-regulation between the kdpFABC and pstSCAB operons occurs in both directions under simultaneous K+ and phosphate limitation, both in vitro and in vivo. This study for the first time demonstrates direct coupling between intracellular K+ and phosphate homeostasis and provides a mechanism for fine-tuning of the balance between positively and negatively charged ions in the bacterial cell.
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Affiliation(s)
- Hannah Schramke
- Department of Biology I, Microbiology, Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Vera Laermann
- Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
| | - Halina E Tegetmeyer
- Centrum für Biotechnologie, Universität Bielefeld, Bielefeld, Germany.,Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Andreas Brachmann
- Department of Biology I, Genetics, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Kirsten Jung
- Department of Biology I, Microbiology, Center for integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Martinsried, Germany
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14
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Müller KMH, Berghoff BA, Eisenhardt BD, Remes B, Klug G. Characteristics of Pos19 - A Small Coding RNA in the Oxidative Stress Response of Rhodobacter sphaeroides. PLoS One 2016; 11:e0163425. [PMID: 27669425 PMCID: PMC5036791 DOI: 10.1371/journal.pone.0163425] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/08/2016] [Indexed: 02/07/2023] Open
Abstract
The phototrophic bacterium Rhodobacter sphaeroides induces several small RNAs (sRNAs) when singlet oxygen (1O2) levels are elevated, a situation also referred to as photo-oxidative stress. An RNA-seq study identified the RSs0019 sRNA, which is renamed Pos19 (photo-oxidative stress induced sRNA 19). Pos19 is part of the RpoE regulon and consequently induced upon 1O2 and peroxide stress. The 219 nt long Pos19 transcript contains a small open reading frame (sORF) of 150 nt, which is translated in vivo. Over-expression of Pos19 results in reduced mRNA levels for several genes, of which numerous are involved in sulfur metabolism. The negative effect on the potential targets is maintained even when translation of the sORF is abolished, arguing that regulation is entailed by the sRNA itself. Reporter studies further revealed that regulation of the most affected mRNA, namely RSP_0557, by Pos19 is Hfq-dependent. Direct binding of Pos19 to Hfq was shown by co-immunoprecipitation. Physiological experiments indicated Pos19 to be involved in the balance of glutathione biosynthesis. Moreover, a lack of Pos19 leads to elevated reactive oxygen species levels. Taken together our data identify the sRNA Pos19 as a coding sRNA with a distinct expression pattern and potential role under oxidative stress in the phototrophic bacterium R. sphaeroides.
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Affiliation(s)
- Katrin M. H. Müller
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Bork A. Berghoff
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Benjamin D. Eisenhardt
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Bernhard Remes
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Gabriele Klug
- Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
- * E-mail:
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15
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Trachtmann N, Alvarez Fong KF, Guitart Font E, Sprenger GA. Construction of chromosomally encoded lacZ
and gfp
reporter strains of Escherichia coli
for the study of global regulation of metabolism. Eng Life Sci 2016. [DOI: 10.1002/elsc.201600056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
| | | | - Emma Guitart Font
- Institut für Mikrobiologie; Universität Stuttgart; Stuttgart Germany
| | - Georg A. Sprenger
- Institut für Mikrobiologie; Universität Stuttgart; Stuttgart Germany
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16
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Lorenz N, Reiger M, Toro-Nahuelpan M, Brachmann A, Poettinger L, Plener L, Lassak J, Jung K. Identification and Initial Characterization of Prophages in Vibrio campbellii. PLoS One 2016; 11:e0156010. [PMID: 27214518 PMCID: PMC4877103 DOI: 10.1371/journal.pone.0156010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/06/2016] [Indexed: 12/21/2022] Open
Abstract
Phages are bacteria targeting viruses and represent the most abundant biological entities on earth. Marine environments are exceptionally rich in bacteriophages, harboring a total of 4x1030 viruses. Nevertheless, marine phages remain poorly characterized. Here we describe the identification of intact prophage sequences in the genome of the marine γ-proteobacterium Vibrio campbellii ATCC BAA-1116 (formerly known as V. harveyi ATCC BAA-1116), which presumably belong to the family of Myoviridae. One prophage was found on chromosome I and shows significant similarities to the previously identified phage ΦHAP-1. The second prophage region is located on chromosome II and is related to Vibrio phage kappa. Exposure of V. campbellii to mitomycin C induced the lytic cycle of two morphologically distinct phages and, as expected, extracellular DNA from induced cultures was found to be specifically enriched for the sequences previously identified as prophage regions. Heat stress (50°C, 30 min) was also found to induce phage release in V. campbellii. Notably, promoter activity of two representative phage genes indicated heterogeneous phage induction within the population.
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Affiliation(s)
- Nicola Lorenz
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Matthias Reiger
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Mauricio Toro-Nahuelpan
- Department of Microbiology, University of Bayreuth, Bayreuth, Germany
- Department of Molecular Structural Biology, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Andreas Brachmann
- Department of Biology I, Genetics, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Lisa Poettinger
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Laure Plener
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Jürgen Lassak
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Kirsten Jung
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
- * E-mail:
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17
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Moreau PL, Loiseau L. Characterization of acetic acid-detoxifying Escherichia coli evolved under phosphate starvation conditions. Microb Cell Fact 2016; 15:42. [PMID: 26895825 PMCID: PMC4759930 DOI: 10.1186/s12934-016-0441-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/07/2016] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND During prolonged incubation of Escherichia coli K-12 in batch culture under aerobic, phosphate (Pi) starvation conditions, excess glucose is converted into acetic acid, which may trigger cell death. Following serial cultures, we isolated five evolved strains in two populations that survived prolonged incubation. METHODS We sequenced the genomes of the ancestral and evolved strains, and determined the effects of the genetic changes, tested alone and in combination, on characteristic phenotypes in pure and in mixed cultures. RESULTS Evolved strains used two main strategies: (1) the constitutive expression of the Trk- and Kdp-dependent K(+) transport systems, and (2) the inactivation of the ArcA global regulator. Both processes helped to maintain a residual activity of the tricarboxylic acid cycle, which decreased the production of acetic acid and eventually allowed its re-consumption. Evolved strains acquired a few additional genetic changes besides the trkH, kdpD and arcA mutations, which might increase the scavenging of organophosphates (phnE (+), lapB, and rseP) and the resistance to oxidative (rsxC) and acetic acid stresses (e14(-)/icd (+)). CONCLUSIONS Evolved strains rapidly acquired mutations (phnE (+) lapB rpoS trkH and phnE (+) rseP kdpD) that were globally beneficial to growth on glucose and organophosphates, but detrimental to long-term viability. The spread of these mutant strains might give the ancestral strain time to accumulate up to five genetic changes (phnE (+) arcA rsxC crfC e14(-)/icd (+)), which allowed growth on glucose and organophosphates, and provided a long-term survival. The latter strain, which expressed several mechanisms of protection against endogenous and exogenous stresses, might provide a platform for producing toxic recombinant proteins and chemicals during prolonged incubation under aerobic, Pi starvation conditions.
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Affiliation(s)
- Patrice L Moreau
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université, Marseille, France.
- Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France.
| | - Laurent Loiseau
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université, Marseille, France.
- Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France.
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18
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Geng S, Tian Q, An S, Pan Z, Chen X, Jiao X. High-Efficiency, Two-Step Scarless-Markerless Genome Genetic Modification in Salmonella enterica. Curr Microbiol 2016; 72:700-6. [PMID: 26883127 PMCID: PMC4853454 DOI: 10.1007/s00284-016-1002-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 12/26/2015] [Indexed: 11/23/2022]
Abstract
We present a two-step method for scarless–markerless genome genetic modification in Salmonella enterica based on the improved suicide plasmid pGMB152. The whole LacZYA gene can provide a lacZ-based blue/white screening strategy for fast selection of double-crossover mutants by allelic exchange. The high efficiency of this genetic engineering strategy permits the study of gene function by gene knockin, site-directed mutagenesis, and gene knockout to construct live attenuated vaccines.
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Affiliation(s)
- Shizhong Geng
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China
| | - Qin Tian
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China
| | - Shuming An
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China
| | - Zhiming Pan
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China
| | - Xiang Chen
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China.
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19
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Drees B, Reiger M, Jung K, Bischofs IB. A modular view of the diversity of cell-density-encoding schemes in bacterial quorum-sensing systems. Biophys J 2015; 107:266-77. [PMID: 24988360 PMCID: PMC4119280 DOI: 10.1016/j.bpj.2014.05.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 05/20/2014] [Accepted: 05/23/2014] [Indexed: 11/29/2022] Open
Abstract
Certain environmental parameters are accessible to cells only indirectly and require an encoding step for cells to retrieve the relevant information. A prominent example is the phenomenon of quorum sensing by microorganisms, where information about cell density is encoded by means of secreted signaling molecules. The mapping of cell density to signal molecule concentration and the corresponding network modules involved have been at least partially characterized in many bacteria, and vary markedly between different systems. In this study, we investigate theoretically how differences in signal transport, signal modification, and site of signal detection shape the encoding function and affect the sensitivity and the noise characteristics of the cell-density-encoding process. We find that different modules are capable of implementing both fairly basic as well as more complex encoding schemes, whose qualitative characteristics vary with cell density and are linked to network architecture, providing the basis for a hierarchical classification scheme. We exploit the tight relationship between encoding behavior and network architecture to constrain the network topology of partially characterized natural systems, and verify one such prediction by showing experimentally that Vibrio harveyi is capable of importing Autoinducer 2. The framework developed in this research can serve not only to guide reverse engineering of natural systems but also to stimulate the design of synthetic systems and generally facilitate a better understanding of the complexities arising in the quorum-sensing process because of variations in the physical organization of the encoder network module.
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Affiliation(s)
- Bastian Drees
- Center for Molecular Biology (ZMBH), University of Heidelberg, Germany; BioQuant, University of Heidelberg, Germany
| | - Matthias Reiger
- Munich Center for Integrated Protein Science (CIPSM) at the Department of Microbiology, Ludwig-Maximilians-Universität München, Germany
| | - Kirsten Jung
- Munich Center for Integrated Protein Science (CIPSM) at the Department of Microbiology, Ludwig-Maximilians-Universität München, Germany.
| | - Ilka B Bischofs
- Center for Molecular Biology (ZMBH), University of Heidelberg, Germany; BioQuant, University of Heidelberg, Germany.
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20
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Martínez P, Huedo P, Martinez-Servat S, Planell R, Ferrer-Navarro M, Daura X, Yero D, Gibert I. Stenotrophomonas maltophilia responds to exogenous AHL signals through the LuxR solo SmoR (Smlt1839). Front Cell Infect Microbiol 2015; 5:41. [PMID: 26029670 PMCID: PMC4432800 DOI: 10.3389/fcimb.2015.00041] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/28/2015] [Indexed: 11/22/2022] Open
Abstract
Quorum Sensing (QS) mediated by Acyl Homoserine Lactone (AHL) molecules are probably the most widespread and studied among Gram-negative bacteria. Canonical AHL systems are composed by a synthase (LuxI family) and a regulator element (LuxR family), whose genes are usually adjacent in the genome. However, incomplete AHL-QS machinery lacking the synthase LuxI is frequently observed in Proteobacteria, and the regulator element is then referred as LuxR solo. It has been shown that certain LuxR solos participate in interspecific communication by detecting signals produced by different organisms. In the case of Stenotrophomonas maltophilia, a preliminary genome sequence analysis revealed numerous putative luxR genes, none of them associated to a luxI gene. From these, the hypothetical LuxR solo Smlt1839, here designated SmoR, presents a conserved AHL binding domain and a helix-turn-helix DNA binding motif. Its genomic organization—adjacent to hchA gene—indicate that SmoR belongs to the new family “LuxR regulator chaperone HchA-associated.” AHL-binding assays revealed that SmoR binds to AHLs in-vitro, at least to oxo-C8-homoserine lactone, and it regulates operon transcription, likely by recognizing a conserved palindromic regulatory box in the hchA upstream region. Supplementation with concentrated supernatants from Pseudomonas aeruginosa, which contain significant amounts of AHLs, promoted swarming motility in S. maltophilia. Contrarily, no swarming stimulation was observed when the P. aeruginosa supernatant was treated with the lactonase AiiA from Bacillus subtilis, confirming that AHL contributes to enhance the swarming ability of S. maltophilia. Finally, mutation of smoR resulted in a swarming alteration and an apparent insensitivity to the exogenous AHLs provided by P. aeruginosa. In conclusion, our results demonstrate that S. maltophilia senses AHLs produced by neighboring bacteria through the LuxR solo SmoR, regulating population behaviors such as swarming motility.
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Affiliation(s)
- Paula Martínez
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Pol Huedo
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Sònia Martinez-Servat
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Raquel Planell
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Mario Ferrer-Navarro
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Xavier Daura
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Catalan Institution for Research and Advanced Studies Barcelona, Spain
| | - Daniel Yero
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Isidre Gibert
- Grup de Genètica Molecular i Patogènesi Bacteriana, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
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21
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Effect of the Min system on timing of cell division in Escherichia coli. PLoS One 2014; 9:e103863. [PMID: 25090009 PMCID: PMC4121188 DOI: 10.1371/journal.pone.0103863] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 07/03/2014] [Indexed: 11/19/2022] Open
Abstract
In Escherichia coli the Min protein system plays an important role in positioning the division site. We show that this system also has an effect on timing of cell division. We do this in a quantitative way by measuring the cell division waiting time (defined as time difference between appearance of a division site and the division event) and the Z-ring existence time. Both quantities are found to be different in WT and cells without functional Min system. We develop a series of theoretical models whose predictions are compared with the experimental findings. Continuous improvement leads to a final model that is able to explain all relevant experimental observations. In particular, it shows that the chromosome segregation defect caused by the absence of Min proteins has an important influence on timing of cell division. Our results indicate that the Min system affects the septum formation rate. In the absence of the Min proteins this rate is reduced, leading to the observed strongly randomized cell division events and the longer division waiting times.
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22
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To be or not to be a poly(3-hydroxybutyrate) (PHB) depolymerase: PhaZd1 (PhaZ6) and PhaZd2 (PhaZ7) of Ralstonia eutropha, highly active PHB depolymerases with no detectable role in mobilization of accumulated PHB. Appl Environ Microbiol 2014; 80:4936-46. [PMID: 24907326 DOI: 10.1128/aem.01056-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The putative physiological functions of two related intracellular poly(3-hydroxybutyrate) (PHB) depolymerases, PhaZd1 and PhaZd2, of Ralstonia eutropha H16 were investigated. Purified PhaZd1 and PhaZd2 were active with native PHB granules in vitro. Partial removal of the proteinaceous surface layer of native PHB granules by trypsin treatment or the use of PHB granules isolated from ΔphaP1 or ΔphaP1-phaP5 mutant strains resulted in increased specific PHB depolymerase activity, especially for PhaZd2. Constitutive expression of PhaZd1 or PhaZd2 reduced or even prevented the accumulation of PHB under PHB-permissive conditions in vivo. Expression of translational fusions of enhanced yellow fluorescent protein (EYFP) with PhaZd1 and PhaZd2 in which the active-site serines (S190 and Ser193) were replaced with alanine resulted in the colocalization of only PhaZd1 fusions with PHB granules. C-terminal fusions of inactive PhaZd2(S193A) with EYFP revealed the presence of spindle-like structures, and no colocalization with PHB granules was observed. Chromosomal deletion of phaZd1, phaZd2, or both depolymerase genes had no significant effect on PHB accumulation and mobilization during growth in nutrient broth (NB) or NB-gluconate medium. Moreover, neither proteome analysis of purified native PHB granules nor lacZ fusion studies gave any indication that PhaZd1 or PhaZd2 was detectably present in the PHB granule fraction or expressed at all during growth on NB-gluconate medium. In conclusion, PhaZd1 and PhaZd2 are two PHB depolymerases with a high capacity to degrade PHB when artificially expressed but are apparently not involved in PHB mobilization in the wild type. The true in vivo functions of PhaZd1 and PhaZd2 remain obscure.
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23
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Loenen WAM, Dryden DTF, Raleigh EA, Wilson GG, Murray NE. Highlights of the DNA cutters: a short history of the restriction enzymes. Nucleic Acids Res 2014; 42:3-19. [PMID: 24141096 PMCID: PMC3874209 DOI: 10.1093/nar/gkt990] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/24/2013] [Accepted: 10/02/2013] [Indexed: 11/16/2022] Open
Abstract
In the early 1950's, 'host-controlled variation in bacterial viruses' was reported as a non-hereditary phenomenon: one cycle of viral growth on certain bacterial hosts affected the ability of progeny virus to grow on other hosts by either restricting or enlarging their host range. Unlike mutation, this change was reversible, and one cycle of growth in the previous host returned the virus to its original form. These simple observations heralded the discovery of the endonuclease and methyltransferase activities of what are now termed Type I, II, III and IV DNA restriction-modification systems. The Type II restriction enzymes (e.g. EcoRI) gave rise to recombinant DNA technology that has transformed molecular biology and medicine. This review traces the discovery of restriction enzymes and their continuing impact on molecular biology and medicine.
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Affiliation(s)
- Wil A. M. Loenen
- Leiden University Medical Center, Leiden, the Netherlands, EaStChemSchool of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, Scotland, UK and New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, USA
| | - David T. F. Dryden
- Leiden University Medical Center, Leiden, the Netherlands, EaStChemSchool of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, Scotland, UK and New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, USA
| | - Elisabeth A. Raleigh
- Leiden University Medical Center, Leiden, the Netherlands, EaStChemSchool of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, Scotland, UK and New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, USA
| | - Geoffrey G. Wilson
- Leiden University Medical Center, Leiden, the Netherlands, EaStChemSchool of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, Scotland, UK and New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, USA
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24
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Ude S, Lassak J, Starosta AL, Kraxenberger T, Wilson DN, Jung K. Translation elongation factor EF-P alleviates ribosome stalling at polyproline stretches. Science 2012; 339:82-5. [PMID: 23239623 DOI: 10.1126/science.1228985] [Citation(s) in RCA: 332] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Translation elongation factor P (EF-P) is critical for virulence in bacteria. EF-P is present in all bacteria and orthologous to archaeal and eukaryotic initiation factor 5A, yet the biological function has so far remained enigmatic. Here, we demonstrate that EF-P is an elongation factor that enhances translation of polyproline-containing proteins: In the absence of EF-P, ribosomes stall at polyproline stretches, whereas the presence of EF-P alleviates the translational stalling. Moreover, we demonstrate the physiological relevance of EF-P to fine-tune the expression of the polyproline-containing pH receptor CadC to levels necessary for an appropriate stress response. Bacterial, archaeal, and eukaryotic cells have hundreds to thousands of polyproline-containing proteins of diverse function, suggesting that EF-P and a/eIF-5A are critical for copy-number adjustment of multiple pathways across all kingdoms of life.
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Affiliation(s)
- Susanne Ude
- Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-Universität München, Munich, Germany
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