1
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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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2
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Hussein M, Allobawi R, Zhao J, Yu H, Neville SL, Wilksch J, Wong LJM, Baker M, McDevitt CA, Rao GG, Li J, Velkov T. Integrated Transcriptomic and Metabolomic Mapping Reveals the Mechanism of Action of Ceftazidime/Avibactam against Pan-Drug-Resistant Klebsiella pneumoniae. ACS Infect Dis 2023; 9:2409-2422. [PMID: 37878861 PMCID: PMC10714405 DOI: 10.1021/acsinfecdis.3c00264] [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: 06/05/2023] [Revised: 10/02/2023] [Accepted: 10/11/2023] [Indexed: 10/27/2023]
Abstract
Here, we employed an integrated metabolomics and transcriptomics approach to investigate the molecular mechanism(s) of action of ceftazidime/avibactam against a pan-drug-resistant K. pneumoniae clinical isolate from a patient with urinary tract infection. Ceftazidime/avibactam induced time-dependent perturbations in the metabolome and transcriptome of the bacterium, mainly at 6 h, with minimal effects at 1 and 3 h. Metabolomics analysis revealed a notable reduction in essential lipids involved in outer membrane glycerolipid biogenesis. This disruption effect extended to peptidoglycan and lipopolysaccharide biosynthetic pathways, including lipid A and O-antigen assembly. Importantly, ceftazidime/avibactam not only affected the final steps of peptidoglycan biosynthesis in the periplasm, a common mechanism of ceftazidime action, but also influenced the synthesis of lipid-linked intermediates and early stages of cytoplasmic peptidoglycan synthesis. Furthermore, ceftazidime/avibactam substantially inhibited central carbon metabolism (e.g., the pentose phosphate pathway and tricarboxylic acid cycle). Consistently, the dysregulation of genes governing these metabolic pathways aligned with the metabolomics findings. Certain metabolomics and transcriptomics signatures associated with ceftazidime resistance were also perturbed. Consistent with the primary target of antibiotic activity, biochemical assays also confirmed the direct impact of ceftazidime/avibactam on peptidoglycan production. This study explored the intricate interactions of ceftazidime and avibactam within bacterial cells, including their impact on cell envelope biogenesis and central carbon metabolism. Our findings revealed the complexities of how ceftazidime/avibactam operates, such as hindering peptidoglycan formation in different cellular compartments. In summary, this study confirms the existing hypotheses about the antibacterial and resistance mechanisms of ceftazidime/avibactam while uncovering novel insights, including its impact on lipopolysaccharide formation.
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Affiliation(s)
- Maytham Hussein
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Rafah Allobawi
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Jinxin Zhao
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Heidi Yu
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Stephanie L. Neville
- Department
of Microbiology and Immunology, The Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Jonathan Wilksch
- Department
of Microbiology and Immunology, The Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Labell J. M. Wong
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Mark Baker
- Discipline
of Biological Sciences, Priority Research Centre in Reproductive Biology,
Faculty of Science and IT, University of
Newcastle, University
Drive, Callaghan, NSW 2308, Australia
| | - Christopher A. McDevitt
- Department
of Microbiology and Immunology, The Peter Doherty Institute for Infection
and Immunity, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Gauri G. Rao
- Division
of Pharmacotherapy and Experimental Therapeutics, Eshelman School
of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599-7355, United
States
| | - Jian Li
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Tony Velkov
- Monash
Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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3
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Salinas AL, Osorio A, Legorreta-Hissner T, Lara-Martinez R, Jimenez-Garcia LF, Camarena L, Poggio S. A new type of phasin characterized by the presence of a helix-hairpin-helix domain is required for normal polyhydroxybutyrate accumulation and granule organization in Caulobacter crescentus. Mol Microbiol 2023; 120:307-323. [PMID: 37487601 DOI: 10.1111/mmi.15124] [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: 10/20/2022] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/26/2023]
Abstract
Bacteria frequently store excess carbon in hydrophobic granules of polyhydroxybutyrate (PHB) that in some growth conditions can occupy most of the cytoplasmic space. Different types of proteins associate to the surface of the granules, mainly enzymes involved in the synthesis and utilization of the reserve polymer and a diverse group of proteins known as phasins. Phasins have different functions, among which are regulating the size and number of the granules, modulating the activity of the granule-associated enzymes and helping in the distribution of the granules inside the cell. Caulobacter crescentus is an oligotrophic bacterium that shows several morphological and regulatory traits that allow it to grow in very nutrient-diluted environments. Under these conditions, storage compounds should be particularly relevant for survival. In this work, we show an initial proteomic characterization of the PHB granules and describe a new type of phasin (PhaH) characterized by the presence of an N-terminal hydrophobic helix followed by a helix-hairpin-helix (HhH) domain. The hydrophobic helix is required for maximal PHB accumulation and maintenance during the stationary phase while the HhH domain is involved in determining the size of the PHB granules and their distribution in the cell.
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Affiliation(s)
- Ana Laura Salinas
- Departamento de Biología Molecular y Biotecnología, Instituto de Ivestigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Aurora Osorio
- Departamento de Biología Molecular y Biotecnología, Instituto de Ivestigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Tonatiuh Legorreta-Hissner
- Departamento de Biología Molecular y Biotecnología, Instituto de Ivestigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Reyna Lara-Martinez
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Luis Felipe Jimenez-Garcia
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Laura Camarena
- Departamento de Biología Molecular y Biotecnología, Instituto de Ivestigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Sebastian Poggio
- Departamento de Biología Molecular y Biotecnología, Instituto de Ivestigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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4
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Keller MR, Dörr T. Bacterial metabolism and susceptibility to cell wall-active antibiotics. Adv Microb Physiol 2023; 83:181-219. [PMID: 37507159 PMCID: PMC11024984 DOI: 10.1016/bs.ampbs.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Bacterial infections are increasingly resistant to antimicrobial therapy. Intense research focus has thus been placed on identifying the mechanisms that bacteria use to resist killing or growth inhibition by antibiotics and the ways in which bacteria share these traits with one another. This work has led to the advancement of new drugs, combination therapy regimens, and a deeper appreciation for the adaptability seen in microorganisms. However, while the primary mechanisms of action of most antibiotics are well understood, the more subtle contributions of bacterial metabolic state to repairing or preventing damage caused by antimicrobials (thereby promoting survival) are still understudied. Here, we review a modern viewpoint on a classical system: examining bacterial metabolism's connection to antibiotic susceptibility. We dive into the relationship between metabolism and antibiotic efficacy through the lens of growth rate, energy state, resource allocation, and the infection environment, focusing on cell wall-active antibiotics.
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Affiliation(s)
- Megan Renee Keller
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States; Department of Microbiology, Cornell University, Ithaca, NY, United States; Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY, United States.
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5
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Sloan R, Surber J, Roy EJ, Hartig E, Morgenstein RM. Enzyme 1 of the phosphoenolpyruvate:sugar phosphotransferase system is involved in resistance to MreB disruption in wild-type and ∆envC cells. Mol Microbiol 2022; 118:588-600. [PMID: 36199205 PMCID: PMC9671846 DOI: 10.1111/mmi.14988] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/27/2022] [Accepted: 09/30/2022] [Indexed: 01/12/2023]
Abstract
Cell wall synthesis in bacteria is determined by two protein complexes: the elongasome and divisome. The elongasome is coordinated by the actin homolog MreB while the divisome is organized by the tubulin homolog FtsZ. While these two systems must coordinate with each other to ensure that elongation and division are coregulated, this cross talk has been understudied. Using the MreB depolymerizing agent, A22, we found that multiple gene deletions result in cells exhibiting increased sensitivity to MreB depolymerization. One of those genes encodes for EnvC, a part of the divisome that is responsible for splitting daughter cells after the completion of cytokinesis through the activation of specific amidases. Here we show this increased sensitivity to A22 works through two known amidase targets of EnvC: AmiA and AmiB. In addition, suppressor analysis revealed that mutations in enzyme 1 of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) can suppress the effects of A22 in both wild-type and envC deletion cells. Together this work helps to link elongation, division, and metabolism.
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Affiliation(s)
- Ryan Sloan
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Jacob Surber
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Emma J. Roy
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Ethan Hartig
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Randy M. Morgenstein
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
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6
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Call SN, Andrews LB. CRISPR-Based Approaches for Gene Regulation in Non-Model Bacteria. Front Genome Ed 2022; 4:892304. [PMID: 35813973 PMCID: PMC9260158 DOI: 10.3389/fgeed.2022.892304] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/11/2022] [Indexed: 01/08/2023] Open
Abstract
CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa) have become ubiquitous approaches to control gene expression in bacteria due to their simple design and effectiveness. By regulating transcription of a target gene(s), CRISPRi/a can dynamically engineer cellular metabolism, implement transcriptional regulation circuitry, or elucidate genotype-phenotype relationships from smaller targeted libraries up to whole genome-wide libraries. While CRISPRi/a has been primarily established in the model bacteria Escherichia coli and Bacillus subtilis, a growing numbering of studies have demonstrated the extension of these tools to other species of bacteria (here broadly referred to as non-model bacteria). In this mini-review, we discuss the challenges that contribute to the slower creation of CRISPRi/a tools in diverse, non-model bacteria and summarize the current state of these approaches across bacterial phyla. We find that despite the potential difficulties in establishing novel CRISPRi/a in non-model microbes, over 190 recent examples across eight bacterial phyla have been reported in the literature. Most studies have focused on tool development or used these CRISPRi/a approaches to interrogate gene function, with fewer examples applying CRISPRi/a gene regulation for metabolic engineering or high-throughput screens and selections. To date, most CRISPRi/a reports have been developed for common strains of non-model bacterial species, suggesting barriers remain to establish these genetic tools in undomesticated bacteria. More efficient and generalizable methods will help realize the immense potential of programmable CRISPR-based transcriptional control in diverse bacteria.
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Affiliation(s)
- Stephanie N. Call
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, MA, United States
| | - Lauren B. Andrews
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, MA, United States
- Biotechnology Training Program, University of Massachusetts Amherst, Amherst, MA, United States
- Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst, Amherst, MA, United States
- *Correspondence: Lauren B. Andrews,
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7
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Venzon M, Das R, Luciano DJ, Burnett J, Park HS, Devlin JC, Kool ET, Belasco JG, Hubbard EJA, Cadwell K. Microbial byproducts determine reproductive fitness of free-living and parasitic nematodes. Cell Host Microbe 2022; 30:786-797.e8. [PMID: 35413267 PMCID: PMC9187612 DOI: 10.1016/j.chom.2022.03.015] [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: 09/29/2021] [Revised: 02/09/2022] [Accepted: 03/10/2022] [Indexed: 11/03/2022]
Abstract
Trichuris nematodes reproduce within the microbiota-rich mammalian intestine and lay thousands of eggs daily, facilitating their sustained presence in the environment and hampering eradication efforts. Here, we show that bacterial byproducts facilitate the reproductive development of nematodes. First, we employed a pipeline using the well-characterized, free-living nematode C. elegans to identify microbial factors with conserved roles in nematode reproduction. A screen for E. coli mutants that impair C. elegans fertility identified genes in fatty acid biosynthesis and ethanolamine utilization pathways, including fabH and eutN. Additionally, Trichuris muris eggs displayed defective hatching in the presence of fabH- or eutN-deficient E. coli due to reduced arginine or elevated aldehydes, respectively. T. muris reared in gnotobiotic mice colonized with these E. coli mutants displayed morphological defects and failed to lay viable eggs. These findings indicate that microbial byproducts mediate evolutionarily conserved transkingdom interactions that impact the reproductive fitness of distantly related nematodes.
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Affiliation(s)
- Mericien Venzon
- Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York, NY 10016, USA; Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Ritika Das
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Daniel J Luciano
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Julia Burnett
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Hyun Shin Park
- Seegene Inc., Ogeum-ro, Songpa-Gu, Seoul 05548, Republic of Korea
| | - Joseph Cooper Devlin
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Eric T Kool
- Department of Chemistry, Stanford Cancer Institute, and ChEM-H Institute, Stanford University, Stanford, CA 94305, USA
| | - Joel G Belasco
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - E Jane Albert Hubbard
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA.
| | - Ken Cadwell
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016, USA; Division of Gastroenterology, Department of Medicine, New York University Grossman School of Medicine, New York, NY 10016, USA.
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8
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Martínez-Absalón S, Guadarrama C, Dávalos A, Romero D. RdsA Is a Global Regulator That Controls Cell Shape and Division in Rhizobium etli. Front Microbiol 2022; 13:858440. [PMID: 35464952 PMCID: PMC9022086 DOI: 10.3389/fmicb.2022.858440] [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: 01/20/2022] [Accepted: 03/10/2022] [Indexed: 11/13/2022] Open
Abstract
Unlike other bacteria, cell growth in rhizobiales is unipolar and asymmetric. The regulation of cell division, and its coordination with metabolic processes is an active field of research. In Rhizobium etli, gene RHE_PE00024, located in a secondary chromosome, is essential for growth. This gene encodes a predicted hybrid histidine kinase sensor protein, participating in a, as yet undescribed, two-component signaling system. In this work, we show that a conditional knockdown mutant (cKD24) in RHE_PE00024 (hereby referred as rdsA, after rhizobium division and shape) generates a striking phenotype, where nearly 64% of the cells present a round shape, with stochastic and uncoordinated cell division. For rod-shaped cells, a large fraction (12 to 29%, depending on their origin) present growth from the old pole, a sector that is normally inactive for growth in a wild-type cell. A fraction of the cells (1 to 3%) showed also multiple ectopic polar growths. Homodimerization of RdsA appears to be required for normal function. RNAseq analysis of mutant cKD24 reveals global changes, with downregulated genes in at least five biological processes: cell division, wall biogenesis, respiration, translation, and motility. These modifications may affect proper structuring of the divisome, as well as peptidoglycan synthesis. Together, these results indicate that the hybrid histidine kinase RdsA is an essential global regulator influencing cell division and cell shape in R. etli.
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Affiliation(s)
- Sofía Martínez-Absalón
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Carmen Guadarrama
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Araceli Dávalos
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - David Romero
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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9
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Lemos Rocha LF, Peters K, Biboy J, Depelteau JS, Briegel A, Vollmer W, Blokesch M. The VarA-CsrA regulatory pathway influences cell shape in Vibrio cholerae. PLoS Genet 2022; 18:e1010143. [PMID: 35344548 PMCID: PMC8989286 DOI: 10.1371/journal.pgen.1010143] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/07/2022] [Accepted: 03/11/2022] [Indexed: 12/26/2022] Open
Abstract
Despite extensive studies on the curve-shaped bacterium Vibrio cholerae, the causative agent of the diarrheal disease cholera, its virulence-associated regulatory two-component signal transduction system VarS/VarA is not well understood. This pathway, which mainly signals through the downstream protein CsrA, is highly conserved among gamma-proteobacteria, indicating there is likely a broader function of this system beyond virulence regulation. In this study, we investigated the VarA-CsrA signaling pathway and discovered a previously unrecognized link to the shape of the bacterium. We observed that varA-deficient V. cholerae cells showed an abnormal spherical morphology during late-stage growth. Through peptidoglycan (PG) composition analyses, we discovered that these mutant bacteria contained an increased content of disaccharide dipeptides and reduced peptide crosslinks, consistent with the atypical cellular shape. The spherical shape correlated with the CsrA-dependent overproduction of aspartate ammonia lyase (AspA) in varA mutant cells, which likely depleted the cellular aspartate pool; therefore, the synthesis of the PG precursor amino acid meso-diaminopimelic acid was impaired. Importantly, this phenotype, and the overall cell rounding, could be prevented by means of cell wall recycling. Collectively, our data provide new insights into how V. cholerae use the VarA-CsrA signaling system to adjust its morphology upon unidentified external cues in its environment. Responsible for the diarrheal disease cholera, the bacterium Vibrio cholerae tightly regulates its virulence program according to external stimuli. Here, we discovered that a sensing-response mechanism involved in the regulation of virulence also controls bacterial shape. We show that V. cholerae lacking this system lose their normal comma shape and become spherical due to an abnormal cell wall composition caused by metabolic changes that reduce available cell wall building blocks. Our study therefore sheds new light on how V. cholerae potentially modulates its morphology based on environmental changes.
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Affiliation(s)
- Leonardo F. Lemos Rocha
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Jamie S. Depelteau
- Microbial Sciences, Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Ariane Briegel
- Microbial Sciences, Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- * E-mail:
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10
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Abstract
Metabolomics is a powerful tool that can systematically describe global changes in the metabolome of microbes, thus improving our understanding of the mechanisms of action of antibiotics and facilitating the development of next-generation antibacterial therapies. However, current sample preparation methods are not efficient or reliable for studying the effects of antibiotics on microbes. In the present study, we reported a novel sample preparation approach using cold methanol/ethylene glycol for quenching Escherichia coli, thus overcoming the loss of intracellular metabolites caused by cell membrane damage. After evaluating the extraction efficiency of several extraction methods, we employed the optimized workflow to profile the metabolome of E. coli exposed to cephalexin. In doing so, we proved the utility of the proposed approach and provided insights into the comprehensive metabolic alterations associated with antibiotic treatment. IMPORTANCE The emergence and global spread of multidrug-resistant bacteria and genes are a global problem. It is critical to understand the interactions between antibiotics and bacteria and find alternative treatments for infections when we are moving closer to a postantibiotic era. It has been demonstrated that the bacterial metabolic environment plays an important role in the modulation of antibiotic susceptibility and efficacy. In the present study, we proposed a novel metabolomic approach for intracellular metabolite profiling of E. coli, which can be used to investigate the metabolite alterations of bacteria caused by antibiotic treatment. Further understanding of antibiotic-induced perturbations of bacterial metabolism would facilitate the discovery of new therapeutic targets and pathways.
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11
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Barton B, Grinnell A, Morgenstein RM. Disruption of the MreB Elongasome Is Overcome by Mutations in the Tricarboxylic Acid Cycle. Front Microbiol 2021; 12:664281. [PMID: 33968001 PMCID: PMC8102728 DOI: 10.3389/fmicb.2021.664281] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/06/2021] [Indexed: 01/20/2023] Open
Abstract
The bacterial actin homolog, MreB, is highly conserved among rod-shaped bacteria and essential for growth under normal growth conditions. MreB directs the localization of cell wall synthesis and loss of MreB results in round cells and death. Using the MreB depolymerizing drug, A22, we show that changes to central metabolism through deletion of malate dehydrogenase from the tricarboxylic acid (TCA) cycle results in cells with an increased tolerance to A22. We hypothesize that deletion of malate dehydrogenase leads to the upregulation of gluconeogenesis resulting in an increase in cell wall precursors. Consistent with this idea, metabolite analysis revealed that malate dehydrogenase (mdh) deletion cells possess elevated levels of several glycolysis/gluconeogenesis compounds and the cell wall precursor, uridine diphosphate N-acetylglucosamine (UDP-NAG). In agreement with these results, the increased A22 resistance phenotype can be recapitulated through the addition of glucose to the media. Finally, we show that this increase in antibiotic tolerance is not specific to A22 but also applies to the cell wall-targeting antibiotic, mecillinam.
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Affiliation(s)
- Brody Barton
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Addison Grinnell
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Randy M Morgenstein
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
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12
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Sachla AJ, Helmann JD. Resource sharing between central metabolism and cell envelope synthesis. Curr Opin Microbiol 2021; 60:34-43. [PMID: 33581378 DOI: 10.1016/j.mib.2021.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/18/2021] [Accepted: 01/27/2021] [Indexed: 12/14/2022]
Abstract
Synthesis of the bacterial cell envelope requires a regulated partitioning of resources from central metabolism. Here, we consider the key metabolic junctions that provide the precursors needed to assemble the cell envelope. Peptidoglycan synthesis requires redirection of a glycolytic intermediate, fructose-6-phosphate, into aminosugar biosynthesis by the highly regulated branchpoint enzyme GlmS. MurA directs the downstream product, UDP-GlcNAc, specifically into peptidoglycan synthesis. Other shared resources required for cell envelope synthesis include the isoprenoid carrier lipid undecaprenyl phosphate and amino acids required for peptidoglycan cross-bridges. Assembly of the envelope requires a sharing of limited resources between competing cellular pathways and may additionally benefit from scavenging of metabolites released from neighboring cells or the formation of symbiotic relationships with a host.
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Affiliation(s)
- Ankita J Sachla
- Department of Microbiology, Cornell University, 370 Wing Hall, Wing Drive, Ithaca, NY 14853-8101, USA
| | - John D Helmann
- Department of Microbiology, Cornell University, 370 Wing Hall, Wing Drive, Ithaca, NY 14853-8101, USA.
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13
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Sodhi KK, Kumar M, Balan B, Dhaulaniya AS, Shree P, Sharma N, Singh DK. Perspectives on the antibiotic contamination, resistance, metabolomics, and systemic remediation. SN APPLIED SCIENCES 2021. [DOI: 10.1007/s42452-020-04003-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
AbstractAntibiotics have been regarded as the emerging contaminants because of their massive use in humans and veterinary medicines and their persistence in the environment. The global concern of antibiotic contamination to different environmental matrices and the emergence of antibiotic resistance has posed a severe impact on the environment. Different mass-spectrometry-based techniques confirm their presence in the environment. Antibiotics are released into the environment through the wastewater steams and runoff from land application of manure. The microorganisms get exposed to the antibiotics resulting in the development of antimicrobial resistance. Consistent release of the antibiotics, even in trace amount into the soil and water ecosystem, is the major concern because the antibiotics can lead to multi-resistance in bacteria which can cause hazardous effects on agriculture, aquaculture, human, and livestock. A better understanding of the correlation between the antibiotic use and occurrence of antibiotic resistance can help in the development of policies to promote the judicious use of antibiotics. The present review puts a light on the remediation, transportation, uptake, and antibiotic resistance in the environment along with a novel approach of creating a database for systemic remediation, and metabolomics for the cleaner and safer environment.
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14
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Jorgenson MA, Bryant JC. A genetic screen to identify factors affected by undecaprenyl phosphate recycling uncovers novel connections to morphogenesis in Escherichia coli. Mol Microbiol 2021; 115:191-207. [PMID: 32979869 PMCID: PMC10568968 DOI: 10.1111/mmi.14609] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/11/2020] [Indexed: 01/30/2023]
Abstract
Undecaprenyl phosphate (Und-P) is an essential lipid carrier that ferries cell wall intermediates across the cytoplasmic membrane in bacteria. Und-P is generated by dephosphorylating undecaprenyl pyrophosphate (Und-PP). In Escherichia coli, BacA, PgpB, YbjG, and LpxT dephosphorylate Und-PP and are conditionally essential. To identify vulnerabilities that arise when Und-P metabolism is defective, we developed a genetic screen for synthetic interactions which, in combination with ΔybjG ΔlpxT ΔbacA, are lethal or reduce fitness. The screen uncovered novel connections to cell division, DNA replication/repair, signal transduction, and glutathione metabolism. Further analysis revealed several new morphogenes; loss of one of these, qseC, caused cells to enlarge and lyse. QseC is the sensor kinase component of the QseBC two-component system. Loss of QseC causes overactivation of the QseB response regulator by PmrB cross-phosphorylation. Here, we show that deleting qseB completely reverses the shape defect of ΔqseC cells, as does overexpressing rprA (a small RNA). Surprisingly, deleting pmrB only partially suppressed qseC-related shape defects. Thus, QseB is activated by multiple factors in QseC's absence and prior functions ascribed to QseBC may originate from cell wall defects. Altogether, our findings provide a framework for identifying new determinants of cell integrity that could be targeted in future therapies.
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Affiliation(s)
- Matthew A. Jorgenson
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Joseph C. Bryant
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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15
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Fröhlich KS, Velasco Gomariz M. RNA-controlled regulation in Caulobacter crescentus. Curr Opin Microbiol 2021; 60:1-7. [PMID: 33529919 DOI: 10.1016/j.mib.2021.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 01/10/2023]
Abstract
In the past decades, Caulobacter crescentus has been extensively studied, mostly regarding its dimorphic, asymmetric life cycle. Its distinct mode of reproduction and the need to optimally adapt to ever-changing environmental conditions require tight coordination of gene regulation. Post-transcriptional regulation through non-coding RNAs and RNA-binding proteins constitutes an important layer of expression control in bacteria, but its principles and mechanisms in Caulobacter have only recently been explored. RNA-binding proteins including the RNA chaperone Hfq and ribonuclease RNase E contribute to the activity of regulatory RNAs. Riboswitches and RNA thermometers govern expression of downstream open reading frames, while the small regulatory RNAs CrfA, ChvR and GsrN instead control targets encoded in trans by direct base-pairing interactions.
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Affiliation(s)
- Kathrin S Fröhlich
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany; Microverse Cluster, Friedrich Schiller University, Jena, Germany.
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16
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A CRISPR interference platform for selective downregulation of gene expression in Borrelia burgdorferi. Appl Environ Microbiol 2021; 87:AEM.02519-20. [PMID: 33257311 PMCID: PMC7851697 DOI: 10.1128/aem.02519-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The spirochete Borrelia burgdorferi causes Lyme disease, an increasingly prevalent infection. While previous studies have provided important insight into B. burgdorferi biology, many aspects, including basic cellular processes, remain underexplored. To help speed up the discovery process, we adapted a CRISPR interference (CRISPRi) platform for use in B. burgdorferi For efficiency and flexibility of use, we generated various CRISPRi template constructs that produce different basal and induced levels of dcas9 and carry different antibiotic resistance markers. We characterized the effectiveness of our CRISPRi platform by targeting the motility and cell morphogenesis genes flaB, mreB, rodA, and ftsI, whose native expression levels span two orders of magnitude. For all four genes, we obtained gene repression efficiencies of at least 95%. We showed by darkfield microscopy and cryo-electron tomography that flagellin (FlaB) depletion reduced the length and number of periplasmic flagella, which impaired cellular motility and resulted in cell straightening. Depletion of FtsI caused cell filamentation, implicating this protein in cell division in B. burgdorferi Finally, localized cell bulging in MreB- and RodA-depleted cells matched the locations of new peptidoglycan insertion specific to spirochetes of the Borrelia genus. These results therefore implicate MreB and RodA in the particular mode of cell wall elongation of these bacteria. Collectively, our results demonstrate the efficiency and ease of use of our B. burgdorferi CRISPRi platform, which should facilitate future genetic studies of this important pathogen.IMPORTANCE Gene function studies are facilitated by the availability of rapid and easy-to-use genetic tools. Homologous recombination-based methods traditionally used to genetically investigate gene function remain cumbersome to perform in B. burgdorferi, as they often are relatively inefficient. In comparison, our CRISPRi platform offers an easy and fast method to implement as it only requires a single plasmid transformation step and IPTG addition to obtain potent (>95%) downregulation of gene expression. To facilitate studies of various genes in wild-type and genetically modified strains, we provide over 30 CRISPRi plasmids that produce distinct levels of dcas9 expression and carry different antibiotic resistance markers. Our CRISPRi platform represents a useful and efficient complement to traditional genetic and chemical methods to study gene function in B. burgdorferi.
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17
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c-di-AMP Accumulation Impairs Muropeptide Synthesis in Listeria monocytogenes. J Bacteriol 2020; 202:JB.00307-20. [PMID: 33020220 DOI: 10.1128/jb.00307-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/17/2020] [Indexed: 12/14/2022] Open
Abstract
Cyclic di-AMP (c-di-AMP) is an essential and ubiquitous second messenger among bacteria. c-di-AMP regulates many cellular pathways through direct binding to several molecular targets in bacterial cells. c-di-AMP depletion is well known to destabilize the bacterial cell wall, resulting in increased bacteriolysis and enhanced susceptibility to cell wall targeting antibiotics. Using the human pathogen Listeria monocytogenes as a model, we found that c-di-AMP accumulation also impaired cell envelope integrity. An L. monocytogenes mutant deleted for c-di-AMP phosphodiesterases (pdeA pgpH mutant) exhibited a 4-fold increase in c-di-AMP levels and several cell wall defects. For instance, the pdeA pgpH mutant was defective for the synthesis of peptidoglycan muropeptides and was susceptible to cell wall-targeting antimicrobials. Among different muropeptide precursors, we found that the pdeA pgpH strain was particularly impaired in the synthesis of d-Ala-d-Ala, which is required to complete the pentapeptide stem associated with UDP-N-acetylmuramic acid (MurNAc). This was consistent with an increased sensitivity to d-cycloserine, which inhibits the d-alanine branch of peptidoglycan synthesis. Finally, upon examining d-Ala:d-Ala ligase (Ddl), which catalyzes the conversion of d-Ala to d-Ala-d-Ala, we found that its activity was activated by K+ Based on previous reports that c-di-AMP inhibits K+ uptake, we propose that c-di-AMP accumulation impairs peptidoglycan synthesis, partially through the deprivation of cytoplasmic K+ levels, which are required for cell wall-synthetic enzymes.IMPORTANCE The bacterial second messenger c-di-AMP is produced by a large number of bacteria and conditionally essential to many species. Conversely, c-di-AMP accumulation is also toxic to bacterial physiology and pathogenesis, but its mechanisms are largely undefined. We found that in Listeria monocytogenes, elevated c-di-AMP levels diminished muropeptide synthesis and increased susceptibility to cell wall-targeting antimicrobials. Cell wall defects might be an important mechanism for attenuated virulence in bacteria with high c-di-AMP levels.
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18
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Bancroft PJ, Turapov O, Jagatia H, Arnvig KB, Mukamolova GV, Green J. Coupling of Peptidoglycan Synthesis to Central Metabolism in Mycobacteria: Post-transcriptional Control of CwlM by Aconitase. Cell Rep 2020; 32:108209. [PMID: 32997986 PMCID: PMC7527780 DOI: 10.1016/j.celrep.2020.108209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 06/18/2020] [Accepted: 09/09/2020] [Indexed: 10/25/2022] Open
Abstract
Mycobacterium tuberculosis causes human tuberculosis, and a better understanding of its biology is required to identify vulnerabilities that might be exploited in developing new therapeutics. The iron-sulfur cluster of the essential M. tuberculosis central metabolic enzyme, aconitase (AcnA), disassembles when exposed to oxidative/nitrosative stress or iron chelators. The catalytically inactive apo-AcnA interacts with a sequence resembling an iron-responsive element (IRE) located within the transcript of another essential protein, CwlM, a regulator of peptidoglycan synthesis. A Mycobacterium smegmatis cwlM conditional mutant complemented with M. tuberculosis cwlM with a disrupted IRE is unable to recover from combinations of oxidative, nitrosative, and iron starvation stresses. An equivalent M. tuberculosis cwlM conditional mutant complemented with the cwlM gene lacking a functional IRE exhibits a growth defect in THP-1 macrophages. It appears that AcnA acts to couple peptidoglycan synthesis and central metabolism, and disruption of this coupling potentially leaves mycobacteria vulnerable to attack by macrophages.
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Affiliation(s)
- Peter J Bancroft
- Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Obolbek Turapov
- Leicester Tuberculosis Research Group, Department of Respiratory Sciences, University of Leicester, Maurice Shock Medical Sciences Building, University Road, Leicester, LE1 9HN, UK
| | - Heena Jagatia
- Leicester Tuberculosis Research Group, Department of Respiratory Sciences, University of Leicester, Maurice Shock Medical Sciences Building, University Road, Leicester, LE1 9HN, UK
| | - Kristine B Arnvig
- Institute for Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Galina V Mukamolova
- Leicester Tuberculosis Research Group, Department of Respiratory Sciences, University of Leicester, Maurice Shock Medical Sciences Building, University Road, Leicester, LE1 9HN, UK.
| | - Jeffrey Green
- Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK.
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19
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AimB Is a Small Protein Regulator of Cell Size and MreB Assembly. Biophys J 2020; 119:593-604. [PMID: 32416080 DOI: 10.1016/j.bpj.2020.04.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/17/2020] [Accepted: 04/27/2020] [Indexed: 12/27/2022] Open
Abstract
The MreB actin-like cytoskeleton assembles into dynamic polymers that coordinate cell shape in many bacteria. In contrast to most other cytoskeleton systems, few MreB-interacting proteins have been well characterized. Here, we identify a small protein from Caulobacter crescentus, an assembly inhibitor of MreB (AimB). AimB overexpression mimics inhibition of MreB polymerization, leading to increased cell width and MreB delocalization. Furthermore, aimB appears to be essential, and its depletion results in decreased cell width and increased resistance to A22, a small-molecule inhibitor of MreB assembly. Molecular dynamics simulations suggest that AimB binds MreB at its monomer-monomer protofilament interaction cleft and that this interaction is favored for C. crescentus MreB over Escherichia coli MreB because of a closer match in the degree of opening with AimB size, suggesting coevolution of AimB with MreB conformational dynamics in C. crescentus. We support this model through functional analysis of point mutants in both AimB and MreB, photo-cross-linking studies with site-specific unnatural amino acids, and species-specific activity of AimB. Together, our findings are consistent with AimB promoting MreB dynamics by inhibiting monomer-monomer assembly interactions, representing a new mechanism for regulating actin-like polymers and the first identification of a non-toxin MreB assembly inhibitor. Because AimB has only 104 amino acids and small proteins are often poorly characterized, our work suggests the possibility of more bacterial cytoskeletal regulators to be found in this class. Thus, like FtsZ and eukaryotic actin, MreB may have a rich repertoire of regulators to tune its precise assembly and dynamics.
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20
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The Lon Protease Links Nucleotide Metabolism with Proteotoxic Stress. Mol Cell 2020; 79:758-767.e6. [PMID: 32755596 DOI: 10.1016/j.molcel.2020.07.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 04/29/2020] [Accepted: 07/07/2020] [Indexed: 12/24/2022]
Abstract
During proteotoxic stress, bacteria maintain critical processes like DNA replication while removing misfolded proteins, which are degraded by the Lon protease. Here, we show that in Caulobacter crescentus Lon controls deoxyribonucleoside triphosphate (dNTP) pools during stress through degradation of the transcription factor CcrM. Elevated dNTP/nucleotide triphosphate (NTP) ratios in Δlon cells protects them from deletion of otherwise essential deoxythymidine triphosphate (dTTP)-producing pathways and shields them from hydroxyurea-induced loss of dNTPs. Increased dNTP production in Δlon results from higher expression of ribonucleotide reductase driven by increased CcrM. We show that misfolded proteins can stabilize CcrM by competing for limited protease and that Lon-dependent control of dNTPs improves fitness during protein misfolding conditions. We propose that linking dNTP production with availability of Lon allows Caulobacter to maintain replication capacity when misfolded protein burden increases, such as during rapid growth. Because Lon recognizes misfolded proteins regardless of the stress, this mechanism allows for response to a variety of unanticipated conditions.
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21
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Gray WT, Govers SK, Xiang Y, Parry BR, Campos M, Kim S, Jacobs-Wagner C. Nucleoid Size Scaling and Intracellular Organization of Translation across Bacteria. Cell 2020; 177:1632-1648.e20. [PMID: 31150626 DOI: 10.1016/j.cell.2019.05.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/01/2019] [Accepted: 05/08/2019] [Indexed: 01/10/2023]
Abstract
The scaling of organelles with cell size is thought to be exclusive to eukaryotes. Here, we demonstrate that similar scaling relationships hold for the bacterial nucleoid. Despite the absence of a nuclear membrane, nucleoid size strongly correlates with cell size, independent of changes in DNA amount and across various nutrient conditions. This correlation is observed in diverse bacteria, revealing a near-constant ratio between nucleoid and cell size for a given species. As in eukaryotes, the nucleocytoplasmic ratio in bacteria varies greatly among species. This spectrum of nucleocytoplasmic ratios is independent of genome size, and instead it appears linked to the average population cell size. Bacteria with different nucleocytoplasmic ratios have a cytoplasm with different biophysical properties, impacting ribosome mobility and localization. Together, our findings identify new organizational principles and biophysical features of bacterial cells, implicating the nucleocytoplasmic ratio and cell size as determinants of the intracellular organization of translation.
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Affiliation(s)
- William T Gray
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Pharmacology, Yale University, New Haven, CT, USA
| | - Sander K Govers
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Yingjie Xiang
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Bradley R Parry
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Manuel Campos
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Sangjin Kim
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Christine Jacobs-Wagner
- Microbial Sciences Institute, Yale University, West Haven, CT, USA; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT, USA; Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, USA.
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22
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Hartl J, Kiefer P, Kaczmarczyk A, Mittelviefhaus M, Meyer F, Vonderach T, Hattendorf B, Jenal U, Vorholt JA. Untargeted metabolomics links glutathione to bacterial cell cycle progression. Nat Metab 2020; 2:153-166. [PMID: 32090198 PMCID: PMC7035108 DOI: 10.1038/s42255-019-0166-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/17/2019] [Indexed: 12/21/2022]
Abstract
Cell cycle progression requires the coordination of cell growth, chromosome replication, and division. Consequently, a functional cell cycle must be coupled with metabolism. However, direct measurements of metabolome dynamics remained scarce, in particular in bacteria. Here, we describe an untargeted metabolomics approach with synchronized Caulobacter crescentus cells to monitor the relative abundance changes of ~400 putative metabolites as a function of the cell cycle. While the majority of metabolite pools remains homeostatic, ~14% respond to cell cycle progression. In particular, sulfur metabolism is redirected during the G1-S transition, and glutathione levels periodically change over the cell cycle with a peak in late S phase. A lack of glutathione perturbs cell size by uncoupling cell growth and division through dysregulation of KefB, a K+/H+ antiporter. Overall, we here describe the impact of the C. crescentus cell cycle progression on metabolism, and in turn relate glutathione and potassium homeostasis to timely cell division.
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Affiliation(s)
- Johannes Hartl
- ETH Zurich, Institute of Microbiology, Zurich, Switzerland.
| | - Patrick Kiefer
- ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | | | | | - Fabian Meyer
- ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | - Thomas Vonderach
- ETH Zurich, Laboratory of Inorganic Chemistry, Zurich, Switzerland
| | - Bodo Hattendorf
- ETH Zurich, Laboratory of Inorganic Chemistry, Zurich, Switzerland
| | - Urs Jenal
- Biozentrum of the University of Basel, Basel, Switzerland
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23
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Abstract
Caulobacter crescentus is a major model organism for understanding cell cycle regulation and cellular asymmetry. The current genetic tools for deleting or silencing the expression of individual genes, particularly those essential for viability, are time-consuming and labor-intensive, which limits global genetic studies. Here, we optimized CRISPR interference (CRISPRi) for use in Caulobacter. Using Streptococcus thermophilus CRISPR3 or Streptococcus pasteurianus CRISPR systems, we show that the coexpression of a catalytically dead form of Cas9 (dCas9) with a single guide RNA (sgRNA) containing a seed region that targets the promoter region of a gene of interest efficiently downregulates the expression of the targeted gene. We also demonstrate that multiple sgRNAs can be produced in parallel to enable the facile silencing of multiple genes, opening the door to systematic genetic interaction studies. In sum, our work now provides a rapid, specific, and powerful new tool for silencing gene expression in C. crescentus and possibly other alphaproteobacteria. CRISPR interference (CRISPRi) is a powerful new tool used in different organisms that provides a fast, specific, and reliable way to knock down gene expression. Caulobacter crescentus is a well-studied model bacterium, and although a variety of genetic tools have been developed, it currently takes several weeks to delete or deplete individual genes, which significantly limits genetic studies. Here, we optimized a CRISPRi approach to specifically downregulate the expression of genes in C. crescentus. Although the Streptococcus pyogenes CRISPRi system commonly used in other organisms does not work efficiently in Caulobacter, we demonstrate that a catalytically dead version of Cas9 (dCas9) derived from the type II CRISPR3 module of Streptococcus thermophilus or from Streptococcus pasteurianus can each be effectively used in Caulobacter. We show that these CRISPRi systems can be used to rapidly and inducibly deplete ctrA or gcrA, two essential well-studied genes in Caulobacter, in either asynchronous or synchronized populations of cells. Additionally, we demonstrate the ability to multiplex CRISPRi-based gene knockdowns, opening new possibilities for systematic genetic interaction studies in Caulobacter.
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24
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Woldemeskel SA, Daitch AK, Alvarez L, Panis G, Zeinert R, Gonzalez D, Smith E, Collier J, Chien P, Cava F, Viollier PH, Goley ED. The conserved transcriptional regulator CdnL is required for metabolic homeostasis and morphogenesis in Caulobacter. PLoS Genet 2020; 16:e1008591. [PMID: 31961855 PMCID: PMC6994171 DOI: 10.1371/journal.pgen.1008591] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 01/31/2020] [Accepted: 01/01/2020] [Indexed: 12/23/2022] Open
Abstract
Bacterial growth and division require regulated synthesis of the macromolecules used to expand and replicate components of the cell. Transcription of housekeeping genes required for metabolic homeostasis and cell proliferation is guided by the sigma factor σ70. The conserved CarD-like transcriptional regulator, CdnL, associates with promoter regions where σ70 localizes and stabilizes the open promoter complex. However, the contributions of CdnL to metabolic homeostasis and bacterial physiology are not well understood. Here, we show that Caulobacter crescentus cells lacking CdnL have severe morphological and growth defects. Specifically, ΔcdnL cells grow slowly in both rich and defined media, and are wider, more curved, and have shorter stalks than WT cells. These defects arise from transcriptional downregulation of most major classes of biosynthetic genes, leading to significant decreases in the levels of critical metabolites, including pyruvate, α-ketoglutarate, ATP, NAD+, UDP-N-acetyl-glucosamine, lipid II, and purine and pyrimidine precursors. Notably, we find that ΔcdnL cells are glutamate auxotrophs, and ΔcdnL is synthetic lethal with other genetic perturbations that limit glutamate synthesis and lipid II production. Our findings implicate CdnL as a direct and indirect regulator of genes required for metabolic homeostasis that impacts morphogenesis through availability of lipid II and other metabolites.
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Affiliation(s)
- Selamawit Abi Woldemeskel
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Allison K. Daitch
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Laura Alvarez
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Rilee Zeinert
- Department of Biochemistry and Molecular Biology, University of Massachusetts-Amherst, MA, United States of America
| | - Diego Gonzalez
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Erika Smith
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Justine Collier
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Peter Chien
- Department of Biochemistry and Molecular Biology, University of Massachusetts-Amherst, MA, United States of America
| | - Felipe Cava
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Patrick H. Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Erin D. Goley
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
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25
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Growth Dynamics and Survival of Liberibacter crescens BT-1, an Important Model Organism for the Citrus Huanglongbing Pathogen " Candidatus Liberibacter asiaticus". Appl Environ Microbiol 2019; 85:AEM.01656-19. [PMID: 31420343 PMCID: PMC6803310 DOI: 10.1128/aem.01656-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 08/12/2019] [Indexed: 11/20/2022] Open
Abstract
Liberibacter crescens is a bacterium that is closely related to plant pathogens that have caused billions of dollars in crop losses in recent years. Particularly devastating are citrus losses due to citrus greening disease, also known as Huanglongbing, which is caused by “Candidatus Liberibacter asiaticus” and carried by the Asian citrus psyllid. L. crescens is the only close relative of “Ca. Liberibacter asiaticus” that can currently be grown in culture, and it therefore serves as an important model organism for the growth, genetic manipulation, and biological control of the pathogenic species. Here, we show that one of the greatest limitations to L. crescens growth is the sharp increase in alkaline conditions it produces as a consequence of consumption of its preferred nutrient source. In addition to new information about L. crescens growth and metabolism, we provide new guidelines for culture conditions that improve the survival and yield of L. crescens. Liberibacter crescens is the only cultured member of its genus, which includes the devastating plant pathogen “Candidatus Liberibacter asiaticus,” associated with citrus greening/Huanglongbing (HLB). L. crescens has a larger genome and greater metabolic flexibility than “Ca. Liberibacter asiaticus” and the other uncultured plant-pathogenic Liberibacter species, and it is currently the best model organism available for these pathogens. L. crescens grows slowly and dies rapidly under current culture protocols and this extreme fastidiousness makes it challenging to study. We have determined that a major cause of rapid death of L. crescens in batch culture is its alkalinization of the medium (to pH 8.5 by the end of logarithmic phase). The majority of this alkalinization is due to consumption of alpha-ketoglutaric acid as its primary carbon source, with a smaller proportion of the pH rise due to NH3 production. Controlling the pH rise with higher buffering capacity and lower starting pH improved recoverability of cells from 10-day cultures by >1,000-fold. We have also performed a detailed analysis of L. crescens growth with total cell numbers calibrated to the optical density and the percentage of live and recoverable bacteria determined over 10-day time courses. We modified L. crescens culture conditions to greatly enhance survival and increase maximum culture density. The similarities between L. crescens and the pathogenic liberibacters make this work relevant to efforts to culture the latter organisms. Our results also suggest that growth-dependent pH alteration that overcomes medium buffering should always be considered when growing fastidious bacteria. IMPORTANCELiberibacter crescens is a bacterium that is closely related to plant pathogens that have caused billions of dollars in crop losses in recent years. Particularly devastating are citrus losses due to citrus greening disease, also known as Huanglongbing, which is caused by “Candidatus Liberibacter asiaticus” and carried by the Asian citrus psyllid. L. crescens is the only close relative of “Ca. Liberibacter asiaticus” that can currently be grown in culture, and it therefore serves as an important model organism for the growth, genetic manipulation, and biological control of the pathogenic species. Here, we show that one of the greatest limitations to L. crescens growth is the sharp increase in alkaline conditions it produces as a consequence of consumption of its preferred nutrient source. In addition to new information about L. crescens growth and metabolism, we provide new guidelines for culture conditions that improve the survival and yield of L. crescens.
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Hill IT, Tallo T, Dorman MJ, Dove SL. Loss of RNA Chaperone Hfq Unveils a Toxic Pathway in Pseudomonas aeruginosa. J Bacteriol 2019; 201:e00232-19. [PMID: 31358608 PMCID: PMC6755729 DOI: 10.1128/jb.00232-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/22/2019] [Indexed: 12/17/2022] Open
Abstract
Hfq is an RNA chaperone that serves as a master regulator of bacterial physiology. Here we show that in the opportunistic pathogen Pseudomonas aeruginosa, the loss of Hfq can result in a dramatic reduction in growth in a manner that is dependent upon MexT, a transcription regulator that governs antibiotic resistance in this organism. Using a combination of chromatin immunoprecipitation with high-throughput sequencing and transposon insertion sequencing, we identify the MexT-activated genes responsible for mediating the growth defect of hfq mutant cells. These include a newly identified MexT-controlled gene that we call hilR We demonstrate that hilR encodes a small protein that is acutely toxic to wild-type cells when produced ectopically. Furthermore, we show that hilR expression is negatively regulated by Hfq, offering a possible explanation for the growth defect of hfq mutant cells. Finally, we present evidence that the expression of MexT-activated genes is dependent upon GshA, an enzyme involved in the synthesis of glutathione. Our findings suggest that Hfq can influence the growth of P. aeruginosa by limiting the toxic effects of specific MexT-regulated genes. Moreover, our results identify glutathione to be a factor important for the in vivo activity of MexT.IMPORTANCE Here we show that the conserved RNA chaperone Hfq is important for the growth of the opportunistic pathogen Pseudomonas aeruginosa We found that the growth defect of hfq mutant cells is dependent upon the expression of genes that are under the control of the transcription regulator MexT. These include a gene that we refer to as hilR, which we show is negatively regulated by Hfq and encodes a small protein that can be toxic when ectopically produced in wild-type cells. Thus, Hfq can influence the growth of P. aeruginosa by limiting the toxic effects of MexT-regulated genes, including one encoding a previously unrecognized small protein. We also show that MexT activity depends on an enzyme that synthesizes glutathione.
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Affiliation(s)
- Ian T Hill
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas Tallo
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew J Dorman
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Simon L Dove
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Choosing an Optimal Sample Preparation in Caulobacter crescentus for Untargeted Metabolomics Approaches. Metabolites 2019; 9:metabo9100193. [PMID: 31547088 PMCID: PMC6836107 DOI: 10.3390/metabo9100193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 09/13/2019] [Accepted: 09/17/2019] [Indexed: 11/16/2022] Open
Abstract
Untargeted metabolomics aims to provide a global picture of the metabolites present in the system under study. To this end, making a careful choice of sample preparation is mandatory to obtain reliable and reproducible biological information. In this study, eight different sample preparation techniques were evaluated using Caulobacter crescentus as a model for Gram-negative bacteria. Two cell retrieval systems, two quenching and extraction solvents, and two cell disruption procedures were combined in a full factorial experimental design. To fully exploit the multivariate structure of the generated data, the ANOVA multiblock orthogonal partial least squares (AMOPLS) algorithm was employed to decompose the contribution of each factor studied and their potential interactions for a set of annotated metabolites. All main effects of the factors studied were found to have a significant contribution on the total observed variability. Cell retrieval, quenching and extraction solvent, and cell disrupting mechanism accounted respectively for 27.6%, 8.4%, and 7.0% of the total variability. The reproducibility and metabolome coverage of the sample preparation procedures were then compared and evaluated in terms of relative standard deviation (RSD) on the area for the detected metabolites. The protocol showing the best performance in terms of recovery, versatility, and variability was centrifugation for cell retrieval, using MeOH:H2O (8:2) as quenching and extraction solvent, and freeze-thaw cycles as the cell disrupting mechanism.
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Fröhlich KS, Förstner KU, Gitai Z. Post-transcriptional gene regulation by an Hfq-independent small RNA in Caulobacter crescentus. Nucleic Acids Res 2019; 46:10969-10982. [PMID: 30165530 PMCID: PMC6237742 DOI: 10.1093/nar/gky765] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 08/21/2018] [Indexed: 12/15/2022] Open
Abstract
Bacterial small RNAs (sRNAs) are a heterogeneous group of post-transcriptional regulators that often act at the heart of large networks. Hundreds of sRNAs have been discovered by genome-wide screens and most of these sRNAs exert their functions by base-pairing with target mRNAs. However, studies addressing the molecular roles of sRNAs have been largely confined to gamma-proteobacteria, such as Escherichia coli. Here we identify and characterize a novel sRNA, ChvR, from the alpha-proteobacterium Caulobacter crescentus. Transcription of chvR is controlled by the conserved two-component system ChvI-ChvG and it is expressed in response to DNA damage, low pH, and growth in minimal medium. Transient over-expression of ChvR in combination with genome-wide transcriptome profiling identified the mRNA of the TonB-dependent receptor ChvT as the sole target of ChvR. Genetic and biochemical analyses showed that ChvR represses ChvT at the post-transcriptional level through direct base-pairing. Fine-mapping of the ChvR-chvT interaction revealed the requirement of two distinct base-pairing sites for full target regulation. Finally, we show that ChvR-controlled repression of chvT is independent of the ubiquitous RNA-chaperone Hfq, and therefore distinct from previously reported mechanisms employed by prototypical bacterial sRNAs. These findings have implications for the mechanism and evolution of sRNA function across bacterial species.
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Affiliation(s)
- Kathrin S Fröhlich
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratories, Princeton, NJ 08544, USA.,Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, D-82152 Martinsried, Germany
| | - Konrad U Förstner
- Core Unit Systems Medicine, University of Würzburg, D-97080 Würzburg, Germany
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratories, Princeton, NJ 08544, USA
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Taylor JA, Sichel SR, Salama NR. Bent Bacteria: A Comparison of Cell Shape Mechanisms in Proteobacteria. Annu Rev Microbiol 2019; 73:457-480. [PMID: 31206344 DOI: 10.1146/annurev-micro-020518-115919] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Helical cell shape appears throughout the bacterial phylogenetic tree. Recent exciting work characterizing cell shape mutants in a number of curved and helical Proteobacteria is beginning to suggest possible mechanisms and provide tools to assess functional significance. We focus here on Caulobacter crescentus, Vibrio cholerae, Helicobacter pylori, and Campylobacter jejuni, organisms from three classes of Proteobacteria that live in diverse environments, from freshwater and saltwater to distinct compartments within the gastrointestinal tract of humans and birds. Comparisons among these bacteria reveal common themes as well as unique solutions to the task of maintaining cell curvature. While motility appears to be influenced in all these bacteria when cell shape is perturbed, consequences on niche colonization are diverse, suggesting the need to consider additional selective pressures.
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Affiliation(s)
- Jennifer A Taylor
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA; .,Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Sophie R Sichel
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.,Molecular Medicine and Mechanisms of Disease Graduate Program, University of Washington, Seattle, Washington 98195, USA
| | - Nina R Salama
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA; .,Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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30
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Caulobacter crescentus Hfq structure reveals a conserved mechanism of RNA annealing regulation. Proc Natl Acad Sci U S A 2019; 116:10978-10987. [PMID: 31076551 PMCID: PMC6561178 DOI: 10.1073/pnas.1814428116] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In many bacteria, the RNA chaperone protein Hfq binds to hundreds of small noncoding RNAs and improves their efficacy by aiding base pairing to target mRNAs. Hfq proteins contain a variable C-terminal domain (CTD), usually structurally disordered, which was recently demonstrated to inhibit Hfq from mediating nonspecific RNA annealing. We obtained a new structure that shows how this inhibition is achieved in Caulobacter crescentus Hfq. The structural data and chaperone assays provide an initial view of the little-known mechanism of small RNA regulation in Caulobacter. In addition, this work demonstrates how the Hfq CTD has evolved to meet the needs for species-specific selectivity in RNA binding and pairing of regulatory RNAs with cognate targets. We have solved the X-ray crystal structure of the RNA chaperone protein Hfq from the alpha-proteobacterium Caulobacter crescentus to 2.15-Å resolution, resolving the conserved core of the protein and the entire C-terminal domain (CTD). The structure reveals that the CTD of neighboring hexamers pack in crystal contacts, and that the acidic residues at the C-terminal tip of the protein interact with positive residues on the rim of Hfq, as has been recently proposed for a mechanism of modulating RNA binding. De novo computational models predict a similar docking of the acidic tip residues against the core of Hfq. We also show that C. crescentus Hfq has sRNA binding and RNA annealing activities and is capable of facilitating the annealing of certain Escherichia coli sRNA:mRNA pairs in vivo. Finally, we describe how the Hfq CTD and its acidic tip residues provide a mechanism to modulate annealing activity and substrate specificity in various bacteria.
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Assis NG, Ribeiro RA, da Silva LG, Vicente AM, Hug I, Marques MV. Identification of Hfq-binding RNAs in Caulobacter crescentus. RNA Biol 2019; 16:719-726. [PMID: 30870072 DOI: 10.1080/15476286.2019.1593091] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Small RNAs are important for post-transcriptional regulation of gene expression, affecting stability and activity of their target mRNAs. The bacterial Sm-like protein Hfq is required to promote pairing between both RNAs when their sequence complementarity is limited. To provide a first global view on the post-transcriptional landscape of the α-proteobacterium Caulobacter crescentus, we have identified the Hfq-binding RNAs employing High-throughput sequencing of RNA isolated by cross-linking immunoprecipitation (HITS-CLIP). A total of 261 RNAs, including 3 unannotated RNAs, were successfully identified and classified according to putative function. Moreover, possible interactions between the identified sRNAs with mRNA targets were postulated through computational target predictions.
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Affiliation(s)
- Nadine G Assis
- a Departamento de Microbiologia, Instituto de Ciências Biomédicas , Universidade de São Paulo , São Paulo , Brazil
| | - Rodolfo A Ribeiro
- a Departamento de Microbiologia, Instituto de Ciências Biomédicas , Universidade de São Paulo , São Paulo , Brazil
| | - Larissa G da Silva
- a Departamento de Microbiologia, Instituto de Ciências Biomédicas , Universidade de São Paulo , São Paulo , Brazil
| | - Alexandre M Vicente
- a Departamento de Microbiologia, Instituto de Ciências Biomédicas , Universidade de São Paulo , São Paulo , Brazil
| | - Isabelle Hug
- b Biozentrum , University of Basel , Basel , Switzerland
| | - Marilis V Marques
- a Departamento de Microbiologia, Instituto de Ciências Biomédicas , Universidade de São Paulo , São Paulo , Brazil
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Multilayered control of chromosome replication in Caulobacter crescentus. Biochem Soc Trans 2019; 47:187-196. [PMID: 30626709 PMCID: PMC6393856 DOI: 10.1042/bst20180460] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/24/2022]
Abstract
The environmental Alphaproteobacterium Caulobacter crescentus is a classical model to study the regulation of the bacterial cell cycle. It divides asymmetrically, giving a stalked cell that immediately enters S phase and a swarmer cell that stays in the G1 phase until it differentiates into a stalked cell. Its genome consists in a single circular chromosome whose replication is tightly regulated so that it happens only in stalked cells and only once per cell cycle. Imbalances in chromosomal copy numbers are the most often highly deleterious, if not lethal. This review highlights recent discoveries on pathways that control chromosome replication when Caulobacter is exposed to optimal or less optimal growth conditions. Most of these pathways target two proteins that bind directly onto the chromosomal origin: the highly conserved DnaA initiator of DNA replication and the CtrA response regulator that is found in most Alphaproteobacteria The concerted inactivation and proteolysis of CtrA during the swarmer-to-stalked cell transition license cells to enter S phase, while a replisome-associated Regulated Inactivation and proteolysis of DnaA (RIDA) process ensures that initiation starts only once per cell cycle. When Caulobacter is stressed, it turns on control systems that delay the G1-to-S phase transition or the elongation of DNA replication, most probably increasing its fitness and adaptation capacities.
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Mouammine A, Eich K, Frandi A, Collier J. Control of proline utilization by the Lrp-like regulator PutR in Caulobacter crescentus. Sci Rep 2018; 8:14677. [PMID: 30279528 PMCID: PMC6168545 DOI: 10.1038/s41598-018-32660-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 09/11/2018] [Indexed: 11/09/2022] Open
Abstract
Cellular metabolism recently emerged as a central player modulating the bacterial cell cycle. The Alphaproteobacterium Caulobacter crescentus appears as one of the best models to study these connections, but its metabolism is still poorly characterized. Considering that it lives in oligotrophic environments, its capacity to use amino-acids is often critical for its growth. Here, we characterized the C. crescentus PutA bi-functional enzyme and showed that it is required for the utilization of proline as a carbon source. We also found that putA transcription and proline utilization by PutA are strictly dependent on the Lrp-like PutR activator. The activation of putA by PutR needs proline, which most likely acts as an effector molecule for PutR. Surprisingly, we also observed that an over-production of PutR leads to cell elongation in liquid medium containing proline, while it inhibits colony formation even in the absence of proline on solid medium. These cell division and growth defects were equally pronounced in a ΔputA mutant background, indicating that PutR can play other roles beyond the control of proline catabolism. Altogether, these findings suggest that PutR might connect central metabolism with cell cycle processes.
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Affiliation(s)
- Annabelle Mouammine
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH, 1015, Switzerland
| | - Katharina Eich
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH, 1015, Switzerland
| | - Antonio Frandi
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH, 1015, Switzerland
| | - Justine Collier
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH, 1015, Switzerland.
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Zhao H, Roistacher DM, Helmann JD. Aspartate deficiency limits peptidoglycan synthesis and sensitizes cells to antibiotics targeting cell wall synthesis in Bacillus subtilis. Mol Microbiol 2018; 109:826-844. [PMID: 29995990 DOI: 10.1111/mmi.14078] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 07/02/2018] [Accepted: 07/05/2018] [Indexed: 12/31/2022]
Abstract
Peptidoglycan synthesis is an important target for antibiotics and relies on intermediates derived from central metabolism. As a result, alterations of metabolism may affect antibiotic sensitivity. An aspB mutant is auxotrophic for aspartate (Asp) and asparagine (Asn) and lyses when grown in Difco sporulation medium (DSM), but not in LB medium. Genetic and physiological studies, supported by amino acid analysis, reveal that cell lysis in DSM results from Asp limitation due to a relatively low Asp and high glutamate (Glu) concentrations, with Glu functioning as a competitive inhibitor of Asp uptake by the major Glu/Asp transporter GltT. Lysis can be specifically suppressed by supplementation with 2,6-diaminopimelate (DAP), which is imported by two different cystine uptake systems. These studies suggest that aspartate limitation depletes the peptidoglycan precursor meso-2,6-diaminopimelate (mDAP), inhibits peptidoglycan synthesis, upregulates the cell envelope stress response mediated by σM and eventually leads to cell lysis. Aspartate limitation sensitizes cells to antibiotics targeting late steps of PG synthesis, but not steps prior to the addition of mDAP into the pentapeptide sidechain. This work highlights the ability of perturbations of central metabolism to sensitize cells to peptidoglycan synthesis inhibitors.
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Affiliation(s)
- Heng Zhao
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | | | - John D Helmann
- Department of Microbiology, Cornell University, Ithaca, NY, USA
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35
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Schofield WB, Zimmermann-Kogadeeva M, Zimmermann M, Barry NA, Goodman AL. The Stringent Response Determines the Ability of a Commensal Bacterium to Survive Starvation and to Persist in the Gut. Cell Host Microbe 2018; 24:120-132.e6. [PMID: 30008292 PMCID: PMC6086485 DOI: 10.1016/j.chom.2018.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/21/2018] [Accepted: 06/05/2018] [Indexed: 01/16/2023]
Abstract
In the mammalian gut, bacteria compete for resources to maintain their populations, but the factors determining their success are poorly understood. We report that the human gut bacterium Bacteroides thetaiotaomicron relies on the stringent response, an intracellular signaling pathway that allocates resources away from growth, to survive carbon starvation and persist in the gut. Genome-scale transcriptomics, 13C-labeling, and metabolomics analyses reveal that B. thetaiotaomicron uses the alarmone (p)ppGpp to repress multiple biosynthetic pathways and upregulate tricarboxylic acid (TCA) cycle genes in these conditions. During carbon starvation, (p)ppGpp triggers accumulation of the metabolite alpha-ketoglutarate, which itself acts as a metabolic regulator; alpha-ketoglutarate supplementation restores viability to a (p)ppGpp-deficient strain. These studies uncover how commensal bacteria adapt to the gut by modulating central metabolism and reveal that halting rather than accelerating growth can be a determining factor for membership in the gut microbiome.
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Affiliation(s)
- Whitman B Schofield
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Maria Zimmermann-Kogadeeva
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Michael Zimmermann
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Natasha A Barry
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Andrew L Goodman
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536, USA.
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36
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Collier J. Cell division control in Caulobacter crescentus. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:685-690. [PMID: 29715525 DOI: 10.1016/j.bbagrm.2018.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/31/2022]
Abstract
Caulobacter crescentus is a free-living Alphaproteobacterium that thrives in oligotrophic environments. This review focuses on the regulatory network used by this bacterium to control the levels of cell division proteins, their organization inside the cell and their activity as a function of the cell cycle. Strikingly, C. crescentus makes frequent use of master transcriptional regulators and epigenetic signals, most likely to synchronize cell division with other events of the cell cycle. In addition, cellular metabolism and DNA damage sensors emerge as central players regulating cell division in response to changing environmental conditions.
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Affiliation(s)
- Justine Collier
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH 1015, Switzerland.
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37
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Tien M, Fiebig A, Crosson S. Gene network analysis identifies a central post-transcriptional regulator of cellular stress survival. eLife 2018. [PMID: 29537368 PMCID: PMC5869019 DOI: 10.7554/elife.33684] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells adapt to shifts in their environment by remodeling transcription. Measuring changes in transcription at the genome scale is now routine, but defining the functional significance of individual genes within large gene expression datasets remains a major challenge. We applied a network-based algorithm to interrogate publicly available gene expression data to predict genes that serve major functional roles in Caulobacter crescentus stress survival. This approach identified GsrN, a conserved small RNA that is directly activated by the general stress sigma factor, σT, and functions as a potent post-transcriptional regulator of survival across distinct conditions including osmotic and oxidative stress. Under hydrogen peroxide stress, GsrN protects cells by base pairing with the leader of katG mRNA and activating expression of KatG catalase/peroxidase protein. We conclude that GsrN convenes a post-transcriptional layer of gene expression that serves a central functional role in Caulobacter stress physiology.
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Affiliation(s)
- Matthew Tien
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Aretha Fiebig
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Sean Crosson
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States.,Department of Microbiology, University of Chicago, Chicago, United States
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Mack SG, Turner RL, Dwyer DJ. Achieving a Predictive Understanding of Antimicrobial Stress Physiology through Systems Biology. Trends Microbiol 2018. [PMID: 29530606 DOI: 10.1016/j.tim.2018.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The dramatic spread and diversity of antibiotic-resistant pathogens has significantly reduced the efficacy of essentially all antibiotic classes, bringing us ever closer to a postantibiotic era. Exacerbating this issue, our understanding of the multiscale physiological impact of antimicrobial challenge on bacterial pathogens remains incomplete. Concerns over resistance and the need for new antibiotics have motivated the collection of omics measurements to provide systems-level insights into antimicrobial stress responses for nearly 20 years. Although technological advances have markedly improved the types and resolution of such measurements, continued development of mathematical frameworks aimed at providing a predictive understanding of complex antimicrobial-associated phenotypes is critical to maximize the utility of multiscale data. Here we highlight recent efforts utilizing systems biology to enhance our knowledge of antimicrobial stress physiology. We provide a brief historical perspective of antibiotic-focused omics measurements, highlight new measurement discoveries and trends, discuss examples and opportunities for integrating measurements with mathematical models, and describe future challenges for the field.
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Affiliation(s)
- Sean G Mack
- Department of Chemical & Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA
| | - Randi L Turner
- Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Daniel J Dwyer
- Department of Chemical & Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA; Department of Cell Biology & Molecular Genetics, University of Maryland, College Park, MD 20742, USA; Institute for Physical Sciences & Technology, University of Maryland, College Park, MD 20742, USA; Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; Maryland Pathogen Research Institute, University of Maryland, College Park, MD 20742, USA.
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39
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Westfall CS, Levin PA. Comprehensive analysis of central carbon metabolism illuminates connections between nutrient availability, growth rate, and cell morphology in Escherichia coli. PLoS Genet 2018; 14:e1007205. [PMID: 29432413 PMCID: PMC5825171 DOI: 10.1371/journal.pgen.1007205] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/23/2018] [Accepted: 01/17/2018] [Indexed: 01/23/2023] Open
Abstract
Bacterial morphology is a complex trait that is highly sensitive to changes in the environment. For heterotrophic organisms, such as Escherichia coli, increases in nutrient levels are frequently accompanied by several-fold increases in both size and growth rate. Despite the dramatic nature of these changes, how alterations in nutrient availability translate into changes in growth and morphology remains a largely open question. To understand the signaling networks coupling nutrient availability with size and shape, we examined the impact of deletions in the entirety of non-essential central carbon metabolic genes on E. coli growth rate and cell size. Our data reveal the presence of multiple metabolic nodes that play important yet distinctive roles in dictating biosynthetic capacity and shaping cell morphology. Specifically, perturbations of acetyl-CoA metabolism impact cell size and division through changes in fatty acid synthesis. Additionally, we identify a genetic pathway linking glucose levels to cell width through the signaling molecule cyclic-AMP. Together our findings highlight a surprising diversity of factors and mechanisms contributing to growth potential and cell morphology, providing a foundation for further studies. Often taken for granted, the shape of bacterial cells is a complex trait that is highly sensitive to environmental perturbations. Nutrients in particular, strongly impact bacterial morphology together with growth rate. The ubiquitous, rod-shaped bacteria Escherichia coli increases both length and width several fold upon a shift from nutrient poor to nutrient rich medium, a change accompanied by an equally dramatic increase in growth rate. Central carbon metabolism is an obvious site for the integration of nutrient dependent signals that dictate cell size and shape. To develop a clearer picture of the molecular mechanisms coupling nutrient assimilation with cell growth and morphology, we screened the entirety of non-essential carbon metabolic genes for their contribution to growth rate and cell shape. Our data reveal the presence of multiple regulatory circuits coordinating different metabolic pathways with specific aspects of cell growth and morphology. Together, these data firmly establish a role for central carbon metabolism as an environmentally sensitive sculptor of bacterial cells.
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Affiliation(s)
- Corey S. Westfall
- Department of Biology, Washington University, St. Louis, Missouri, United States of America
| | - Petra Anne Levin
- Department of Biology, Washington University, St. Louis, Missouri, United States of America
- * E-mail:
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Abstract
An innovative approach to harness cellular dimensions reveals fundamental links between cell size and other cellular processes in the bacterium Escherichia coli.
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Affiliation(s)
- Matthew A Jorgenson
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock AR 72205, USA.
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