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Fisher DJ, Beare PA. Recent advances in genetic systems in obligate intracellular human-pathogenic bacteria. Front Cell Infect Microbiol 2023; 13:1202245. [PMID: 37404720 PMCID: PMC10315504 DOI: 10.3389/fcimb.2023.1202245] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 07/06/2023] Open
Abstract
The ability to genetically manipulate a pathogen is fundamental to discovering factors governing host-pathogen interactions at the molecular level and is critical for devising treatment and prevention strategies. While the genetic "toolbox" for many important bacterial pathogens is extensive, approaches for modifying obligate intracellular bacterial pathogens were classically limited due in part to the uniqueness of their obligatory lifestyles. Many researchers have confronted these challenges over the past two and a half decades leading to the development of multiple approaches to construct plasmid-bearing recombinant strains and chromosomal gene inactivation and deletion mutants, along with gene-silencing methods enabling the study of essential genes. This review will highlight seminal genetic achievements and recent developments (past 5 years) for Anaplasma spp., Rickettsia spp., Chlamydia spp., and Coxiella burnetii including progress being made for the still intractable Orientia tsutsugamushi. Alongside commentary of the strengths and weaknesses of the various approaches, future research directions will be discussed to include methods for C. burnetii that should have utility in the other obligate intracellular bacteria. Collectively, the future appears bright for unraveling the molecular pathogenic mechanisms of these significant pathogens.
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Affiliation(s)
- Derek J. Fisher
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| | - Paul A. Beare
- Rocky Mountain Laboratory, National Institute of Health, Hamilton, MT, United States
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2
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Kodori M, Amani J, Meshkat Z, Ahmadi A. Coxiella burnetii Pathogenesis: Emphasizing the Role of the Autophagic Pathway. ARCHIVES OF RAZI INSTITUTE 2023; 78:785-796. [PMID: 38028822 PMCID: PMC10657931 DOI: 10.22092/ari.2023.361161.2636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 03/04/2023] [Indexed: 12/01/2023]
Abstract
Coxiella burnetii (C. burnetii), the etiological agent of the Q fever disease, ranks among the most sporadic and persistent global public health concerns. Ruminants are the principal source of human infections and diseases present in both acute and chronic forms. This bacterium is an intracellular pathogen that can survive and reproduce under acidic (pH 4 to 5) and harsh circumstances that contain Coxiella-containing vacuoles. By undermining the autophagy defense system of the host cell, C. burnetii is able to take advantage of the autophagy pathway, which allows it to improve the movement of nutrients and the membrane, thereby extending the vacuole of the reproducing bacteria. For this method to work, it requires the participation of many bacterial effector proteins. In addition, the precise and prompt identification of the causative agent of an acute disease has the potential to delay the onset of its chronic form. Moreover, to make accurate and rapid diagnoses, it is necessary to create diagnostic devices. This review summarizes the most recent research on the epidemiology, pathogenesis, and diagnosis approaches of C. burnetii. This study also explored the complicated relationships between C. burnetii and the autophagic pathway, which are essential for intracellular reproduction and survival in host cells for the infection to be effective.
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Affiliation(s)
- M Kodori
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University, of Medical Sciences, Tehran, Iran
- Non Communicable Diseases Research Center, Bam University of Medical Sciences, Bam, the Islamic Republic of Iran
| | - J Amani
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University, of Medical Sciences, Tehran, Iran
| | - Z Meshkat
- Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - A Ahmadi
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University, of Medical Sciences, Tehran, Iran
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3
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Wachter S, Larson CL, Virtaneva K, Kanakabandi K, Darwitz B, Crews B, Storrud K, Heinzen RA, Beare PA. A Survey of Two-Component Systems in Coxiella burnetii Reveals Redundant Regulatory Schemes and a Requirement for an Atypical PhoBR System in Mammalian Cell Infection. J Bacteriol 2023; 205:e0041622. [PMID: 36847507 PMCID: PMC10029714 DOI: 10.1128/jb.00416-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 12/20/2022] [Indexed: 03/01/2023] Open
Abstract
Coxiella burnetii is an obligate intracellular bacterium and the etiological agent of Q fever in humans. C. burnetii transitions between a replicative, metabolically active large-cell variant (LCV) and a spore-like, quiescent small-cell variant (SCV) as a likely mechanism to ensure survival between host cells and mammalian hosts. C. burnetii encodes three canonical two-component systems, four orphan hybrid histidine kinases, five orphan response regulators, and a histidine phosphotransfer protein, which have been speculated to play roles in the signaling required for C. burnetii morphogenesis and virulence. However, very few of these systems have been characterized. By employing a CRISPR interference system for genetic manipulation of C. burnetii, we created single- and multigene transcriptional knockdown strains targeting most of these signaling genes. Through this, we revealed a role for the C. burnetii PhoBR canonical two-component system in virulence, regulation of [Pi] maintenance, and Pi transport. We also outline a novel mechanism by which PhoBR function may be regulated by an atypical PhoU-like protein. We also determined that the GacA.2/GacA.3/GacA.4/GacS orphan response regulators coordinately and disparately regulate expression of SCV-associated genes in C. burnetii LCVs. These foundational results will inform future studies on the role of C. burnetii two-component systems in virulence and morphogenesis. IMPORTANCE C. burnetii is an obligate intracellular bacterium with a spore-like stability allowing it to survive long periods of time in the environment. This stability is likely due to its biphasic developmental cycle, whereby it can transition from an environmentally stable small-cell variant (SCV) to a metabolically active large-cell variant (LCV). Here, we define the role of two-component phosphorelay systems (TCS) in C. burnetii's ability to survive within the harsh environment contained in the phagolysosome of host cells. We show that the canonical PhoBR TCS has an important role in C. burnetii virulence and phosphate sensing. Further examination of the regulons controlled by orphan regulators indicated a role in modulating gene expression of SCV-associated genes, including genes essential for cell wall remodeling.
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Affiliation(s)
- Shaun Wachter
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
- Vaccine and Infectious Disease Organization, Saskatoon, Saskatchewan, Canada
| | - Charles L. Larson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Kimmo Virtaneva
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA
| | - Kishore Kanakabandi
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA
| | - Benjamin Darwitz
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Ben Crews
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA
| | - Keelee Storrud
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, USA
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4
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Narra HP, Alsing J, Sahni A, Montini M, Zafar Y, Sahni SK. A Small Non-Coding RNA Mediates Transcript Stability and Expression of Cytochrome bd Ubiquinol Oxidase Subunit I in Rickettsia conorii. Int J Mol Sci 2023; 24:4008. [PMID: 36835430 PMCID: PMC9960880 DOI: 10.3390/ijms24044008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/08/2023] [Accepted: 02/11/2023] [Indexed: 02/19/2023] Open
Abstract
Small regulatory RNAs (sRNAs) are now widely recognized for their role in the post-transcriptional regulation of bacterial virulence and growth. We have previously demonstrated the biogenesis and differential expression of several sRNAs in Rickettsia conorii during interactions with the human host and arthropod vector, as well as the in vitro binding of Rickettsia conorii sRNA Rc_sR42 to bicistronic cytochrome bd ubiquinol oxidase subunits I and II (cydAB) mRNA. However, the mechanism of regulation and the effect of sRNA binding on the stability of the cydAB bicistronic transcript and the expression of the cydA and cydB genes are still unknown. In this study, we determined the expression dynamics of Rc_sR42 and its cognate target genes, cydA and cydB, in mouse lung and brain tissues during R. conorii infection in vivo and employed fluorescent and reporter assays to decode the role of sRNA in regulating cognate gene transcripts. Quantitative RT-PCR revealed significant changes in the expression of sRNA and its cognate target gene transcripts during R. conorii infection in vivo, and a greater abundance of these transcripts was observed in the lungs compared to brain tissue. Interestingly, while Rc_sR42 and cydA exhibited similar patterns of change in their expression, indicating the influence of sRNA on the mRNA target, the expression of cydB was independent of sRNA expression. Further, we constructed reporter plasmids of sRNA and cydAB bicistronic mRNA to decipher the role of sRNA on CydA and CydB expression. We observed increased expression of CydA in the presence of sRNA but detected no change in CydB expression in the presence or absence of sRNA. In sum, our results demonstrate that the binding of Rc_sR42 is required for the regulation of cydA but not cydB. Further studies on understanding the influence of this interaction on the mammalian host and tick vector during R. conorii infection are in progress.
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Affiliation(s)
- Hema P. Narra
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
| | | | | | | | | | - Sanjeev K. Sahni
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
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Sun H, Wang M, Liu Y, Wu P, Yao T, Yang W, Yang Q, Yan J, Yang B. Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7. Gut Microbes 2022; 14:2110822. [PMID: 35971812 PMCID: PMC9387321 DOI: 10.1080/19490976.2022.2110822] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
ABSTARCTEnterohemorrhagic Escherichia coli (EHEC) O157:H7 is a human pathogen that causes a variety of diseases, such as hemorrhagic colitis and lethal hemolytic uremic syndrome. Flagellum-dependent motility plays diverse roles in the pathogenesis of EHEC O157:H7, including its migration to an optimal host site, adherence and colonization, survival at the infection site, and post-infection dispersal. However, it is very expensive for cellular economy in terms of the number of genes and the energy required for flagellar biosynthesis and functioning. Furthermore, the flagellar filament bears strong antigenic properties that induce a strong host immune response. Consequently, the flagellar gene expression and biosynthesis are highly regulated to occur at the appropriate time and place by different regulatory influences. The present review focuses on the regulatory mechanisms of EHEC O157:H7 motility and flagellar biosynthesis, especially in terms of flagellar gene regulation by environmental factors, regulatory proteins, and small regulatory RNAs.
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Affiliation(s)
- Hongmin Sun
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Min Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Yutao Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Pan Wu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Ting Yao
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Wen Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Qian Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Jun Yan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Bin Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China,CONTACT Bin Yang TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin300457, P. R. China
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6
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Krieger MC, Merritt J, Raghavan R. Genome-Wide Identification of Novel sRNAs in Streptococcus mutans. J Bacteriol 2022; 204:e0057721. [PMID: 35285723 PMCID: PMC9017351 DOI: 10.1128/jb.00577-21] [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: 11/16/2021] [Accepted: 02/10/2022] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans is a major pathobiont involved in the development of dental caries. Its ability to utilize numerous sugars and to effectively respond to environmental stress promotes S. mutans proliferation in oral biofilms. Because of their quick action and low energetic cost, noncoding small RNAs (sRNAs) represent an ideal mode of gene regulation in stress response networks, yet their roles in oral pathogens have remained largely unexplored. We identified 15 novel sRNAs in S. mutans and show that they respond to four stress-inducing conditions commonly encountered by the pathogen in human mouth: sugar-phosphate stress, hydrogen peroxide exposure, high temperature, and low pH. To better understand the role of sRNAs in S. mutans, we further explored the function of the novel sRNA SmsR4. Our data demonstrate that SmsR4 regulates the enzyme IIA (EIIA) component of the sorbitol phosphotransferase system, which transports and phosphorylates the sugar alcohol sorbitol. The fine-tuning of EIIA availability by SmsR4 likely promotes S. mutans growth while using sorbitol as the main carbon source. Our work lays a foundation for understanding the role of sRNAs in regulating gene expression in stress response networks in S. mutans and highlights the importance of the underexplored phenomenon of posttranscriptional gene regulation in oral bacteria. IMPORTANCE Small RNAs (sRNAs) are important gene regulators in bacteria, but the identities and functions of sRNAs in Streptococcus mutans, the principal bacterium involved in the formation of dental caries, are unknown. In this study, we identified 15 putative sRNAs in S. mutans and show that they respond to four common stress-inducing conditions present in human mouth: sugar-phosphate stress, hydrogen peroxide exposure, high temperature, and low pH. We further show that the novel sRNA SmsR4 likely modulates sorbitol transport into the cell by regulating SMU_313 mRNA, which encodes the EIIA subunit of the sorbitol phosphotransferase system. Gaining a better understanding of sRNA-based gene regulation may provide new opportunities to develop specific inhibitors of S. mutans growth, thereby improving oral health.
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Affiliation(s)
- Madeline C Krieger
- Department of Biology, Portland State University, Portland, Oregon, USA
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, Oregon, USA
| | - Justin Merritt
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, Oregon, USA
| | - Rahul Raghavan
- Department of Biology, Portland State University, Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, The University of Texas at San Antoniogrid.215352.2, San Antonio, Texas, USA
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7
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Osbron CA, Goodman AG. To die or not to die: Programmed cell death responses and their interactions with Coxiella burnetii infection. Mol Microbiol 2022; 117:717-736. [PMID: 35020241 PMCID: PMC9018580 DOI: 10.1111/mmi.14878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 01/04/2022] [Accepted: 01/09/2022] [Indexed: 12/01/2022]
Abstract
Coxiella burnetii is a Gram-negative, obligate intracellular, macrophage-tropic bacterium and the causative agent of the zoonotic disease Q fever. The epidemiology of Q fever is associated with the presence of infected animals; sheep, goats, cattle, and humans primarily become infected by inhalation of contaminated aerosols. In humans, the acute phase of the disease is characterized primarily by influenza-like symptoms, and approximately 3-5% of the infected individuals develop chronic infection. C. burnetii infection activates many types of immune responses, and the bacteria's genome encodes for numerous effector proteins that interact with host immune signaling mechanisms. Here, we will discuss two forms of programmed cell death, apoptosis and pyroptosis. Apoptosis is a form of non-inflammatory cell death that leads to phagocytosis of small membrane-bound bodies. Conversely, pyroptosis results in lytic cell death accompanied by the release of proinflammatory cytokines. Both apoptosis and pyroptosis have been implicated in the clearance of intracellular bacterial pathogens, including C. burnetii. Finally, we will discuss the role of autophagy, the degradation of unwanted cellular components, during C. burnetii infection. Together, the review of these forms of programmed cell death will open new research questions aimed at combating this highly infectious pathogen for which treatment options are limited.
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Affiliation(s)
- Chelsea A Osbron
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164
| | - Alan G Goodman
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164.,Paul G. Allen School of Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164
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8
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Lai YJ, Yakhnin H, Pannuri A, Pourciau C, Babitzke P, Romeo T. CsrA regulation via binding to the base-pairing small RNA Spot 42. Mol Microbiol 2022; 117:32-53. [PMID: 34107125 PMCID: PMC10000020 DOI: 10.1111/mmi.14769] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/26/2021] [Accepted: 06/08/2021] [Indexed: 02/03/2023]
Abstract
The carbon storage regulator system and base-pairing small RNAs (sRNAs) represent two predominant modes of bacterial post-transcriptional regulation, which globally influence gene expression. Binding of CsrA protein to the 5' UTR or initial mRNA coding sequences can affect translation, RNA stability, and/or transcript elongation. Base-pairing sRNAs also regulate these processes, often requiring assistance from the RNA chaperone Hfq. Transcriptomics studies in Escherichia coli have identified many new CsrA targets, including Spot 42 and other base-pairing sRNAs. Spot 42 synthesis is repressed by cAMP-CRP, induced by the presence of glucose, and Spot 42 post-transcriptionally represses operons that facilitate metabolism of nonpreferred carbon sources. CsrA activity is also increased by glucose via effects on CsrA sRNA antagonists, CsrB/C. Here, we elucidate a mechanism wherein CsrA binds to and protects Spot 42 sRNA from RNase E-mediated cleavage. This protection leads to enhanced repression of srlA by Spot 42, a gene required for sorbitol uptake. A second, independent mechanism by which CsrA represses srlA is by binding to and inhibiting translation of srlM mRNA, encoding a transcriptional activator of srlA. Our findings demonstrate a novel means of regulation, by CsrA binding to a sRNA, and indicate that such interactions can help to shape complex bacterial regulatory circuitry.
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Affiliation(s)
- Ying-Jung Lai
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Helen Yakhnin
- Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Archana Pannuri
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Christine Pourciau
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Paul Babitzke
- Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Tony Romeo
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
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9
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Legüe M, Aguila B, Calixto A. Interspecies RNA Interactome of Pathogen and Host in a Heritable Defensive Strategy. Front Microbiol 2021; 12:649858. [PMID: 34367078 PMCID: PMC8334366 DOI: 10.3389/fmicb.2021.649858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 06/17/2021] [Indexed: 12/13/2022] Open
Abstract
Communication with bacteria deeply impacts the life history traits of their hosts. Through specific molecules and metabolites, bacteria can promote short- and long-term phenotypic and behavioral changes in the nematode Caenorhabditis elegans. The chronic exposure of C. elegans to pathogens promotes the adaptive behavior in the host’s progeny called pathogen-induced diapause formation (PIDF). PIDF is a pathogen avoidance strategy induced in the second generation of animals infected and can be recalled transgenerationally. This behavior requires the RNA interference machinery and specific nematode and bacteria small RNAs (sRNAs). In this work, we assume that RNAs from both species co-exist and can interact with each other. Under this principle, we explore the potential interspecies RNA interactions during PIDF-triggering conditions, using transcriptomic data from the holobiont. We study two transcriptomics datasets: first, the dual sRNA expression of Pseudomonas aeruginosa PAO1 and C. elegans in a transgenerational paradigm for six generations and second, the simultaneous expression of sRNAs and mRNA in intergenerational PIDF. We focus on those bacterial sRNAs that are systematically overexpressed in the intestines of animals compared with sRNAs expressed in host-naïve bacteria. We selected diverse in silico methods that represent putative mechanisms of RNA-mediated interspecies interaction. These interactions are as follows: heterologous perfect and incomplete pairing between bacterial RNA and host mRNA; sRNAs of similar sequence expressed in both species that could mimic each other; and known or predicted eukaryotic motifs present in bacterial transcripts. We conclude that a broad spectrum of tools can be applied for the identification of potential sRNA and mRNA targets of the interspecies RNA interaction that can be subsequently tested experimentally.
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Affiliation(s)
- Marcela Legüe
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile
| | - Blanca Aguila
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile.,Programa de Doctorado en Microbiología, Universidad de Chile, Santiago, Chile
| | - Andrea Calixto
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile
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10
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Brenner AE, Muñoz-Leal S, Sachan M, Labruna MB, Raghavan R. Coxiella burnetii and Related Tick Endosymbionts Evolved from Pathogenic Ancestors. Genome Biol Evol 2021; 13:6278299. [PMID: 34009306 PMCID: PMC8290121 DOI: 10.1093/gbe/evab108] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2021] [Indexed: 12/11/2022] Open
Abstract
Both symbiotic and pathogenic bacteria in the family Coxiellaceae cause morbidity and mortality in humans and animals. For instance, Coxiella-like endosymbionts (CLEs) improve the reproductive success of ticks—a major disease vector, while Coxiella burnetii causes human Q fever, and uncharacterized coxiellae infect both animals and humans. To better understand the evolution of pathogenesis and symbiosis in this group of intracellular bacteria, we sequenced the genome of a CLE present in the soft tick Ornithodoros amblus (CLEOA) and compared it to the genomes of other bacteria in the order Legionellales. Our analyses confirmed that CLEOA is more closely related to C. burnetii, the human pathogen, than to CLEs in hard ticks, and showed that most clades of CLEs contain both endosymbionts and pathogens, indicating that several CLE lineages have evolved independently from pathogenic Coxiella. We also determined that the last common ancestorof CLEOA and C. burnetii was equipped to infect macrophages and that even though horizontal gene transfer (HGT) contributed significantly to the evolution of C. burnetii, most acquisition events occurred primarily in ancestors predating the CLEOA–C. burnetii divergence. These discoveries clarify the evolution of C. burnetii, which previously was assumed to have emerged when an avirulent tick endosymbiont recently gained virulence factors via HGT. Finally, we identified several metabolic pathways, including heme biosynthesis, that are likely critical to the intracellular growth of the human pathogen but not the tick symbiont, and show that the use of heme analog is a promising approach to controlling C. burnetii infections.
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Affiliation(s)
- Amanda E Brenner
- Department of Biology and Center for Life in Extreme Environments, Portland State University, Portland, OR, USA
| | - Sebastián Muñoz-Leal
- Departamento de Patología y Medicina Preventiva, Facultad de Ciencias Veterinarias, Universidad de Concepción, Chillán, Ñuble, Chile
| | - Madhur Sachan
- Department of Biology and Center for Life in Extreme Environments, Portland State University, Portland, OR, USA
| | - Marcelo B Labruna
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil
| | - Rahul Raghavan
- Department of Biology and Center for Life in Extreme Environments, Portland State University, Portland, OR, USA.,Department of Biology and South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, USA
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11
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Wachter S, Hicks LD, Raghavan R, Minnick MF. Novel small RNAs expressed by Bartonella bacilliformis under multiple conditions reveal potential mechanisms for persistence in the sand fly vector and human host. PLoS Negl Trop Dis 2020; 14:e0008671. [PMID: 33216745 PMCID: PMC7717549 DOI: 10.1371/journal.pntd.0008671] [Citation(s) in RCA: 6] [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: 07/28/2020] [Revised: 12/04/2020] [Accepted: 10/06/2020] [Indexed: 11/30/2022] Open
Abstract
Bartonella bacilliformis, the etiological agent of Carrión’s disease, is a Gram-negative, facultative intracellular alphaproteobacterium. Carrión’s disease is an emerging but neglected tropical illness endemic to Peru, Colombia, and Ecuador. B. bacilliformis is spread between humans through the bite of female phlebotomine sand flies. As a result, the pathogen encounters significant and repeated environmental shifts during its life cycle, including changes in pH and temperature. In most bacteria, small non-coding RNAs (sRNAs) serve as effectors that may post-transcriptionally regulate the stress response to such changes. However, sRNAs have not been characterized in B. bacilliformis, to date. We therefore performed total RNA-sequencing analyses on B. bacilliformis grown in vitro then shifted to one of ten distinct conditions that simulate various environments encountered by the pathogen during its life cycle. From this, we identified 160 sRNAs significantly expressed under at least one of the conditions tested. sRNAs included the highly-conserved tmRNA, 6S RNA, RNase P RNA component, SRP RNA component, ffH leader RNA, and the alphaproteobacterial sRNAs αr45 and speF leader RNA. In addition, 153 other potential sRNAs of unknown function were discovered. Northern blot analysis was used to confirm the expression of eight novel sRNAs. We also characterized a Bartonellabacilliformisgroup I intron (BbgpI) that disrupts an un-annotated tRNACCUArg gene and determined that the intron splices in vivo and self-splices in vitro. Furthermore, we demonstrated the molecular targeting of Bartonellabacilliformissmall RNA 9 (BbsR9) to transcripts of the ftsH, nuoF, and gcvT genes, in vitro. B. bacilliformis is a bacterial pathogen that is transmitted between humans by phlebotomine sand flies. Bacteria often express sRNAs to fine-tune the production of proteins involved in a wide array of biological processes. We cultured B. bacilliformis in vitro under standard conditions then shifted the pathogen for a period of time to ten distinct environments, including multiple temperatures, pH levels, and infections of human blood and human vascular endothelial cells. After RNA-sequencing, a manual transcriptome search identified 160 putative sRNAs, including seven highly-conserved sRNAs and 153 novel potential sRNAs. We then characterized two of the novel sRNAs, BbgpI and BbsR9. BbgpI is a group I intron (ribozyme) that self-splices and disrupts an unannotated gene coding for a transfer RNA (tRNACCUArg). BbsR9 is an intergenic sRNA expressed under conditions that simulate the sand fly. We found that BbsR9 targets transcripts of the ftsH, nuoF, and gcvT genes. Furthermore, we determined the specific sRNA-mRNA interactions responsible for BbsR9 binding to its target mRNAs through in vitro mutagenesis and binding assays.
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Affiliation(s)
- Shaun Wachter
- Program in Cellular, Molecular & Microbial Biology, Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Linda D. Hicks
- Program in Cellular, Molecular & Microbial Biology, Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Rahul Raghavan
- Department of Biology and Center for Life in Extreme Environments, Portland State University, Portland, Oregon, United States of America
| | - Michael F. Minnick
- Program in Cellular, Molecular & Microbial Biology, Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
- * E-mail:
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12
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Thomas DR, Newton P, Lau N, Newton HJ. Interfering with Autophagy: The Opposing Strategies Deployed by Legionella pneumophila and Coxiella burnetii Effector Proteins. Front Cell Infect Microbiol 2020; 10:599762. [PMID: 33251162 PMCID: PMC7676224 DOI: 10.3389/fcimb.2020.599762] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/13/2020] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a fundamental and highly conserved eukaryotic process, responsible for maintaining cellular homeostasis and releasing nutrients during times of starvation. An increasingly important function of autophagy is its role in the cell autonomous immune response; a process known as xenophagy. Intracellular pathogens are engulfed by autophagosomes and targeted to lysosomes to eliminate the threat to the host cell. To counteract this, many intracellular bacterial pathogens have developed unique approaches to overcome, evade, or co-opt host autophagy to facilitate a successful infection. The intracellular bacteria Legionella pneumophila and Coxiella burnetii are able to avoid destruction by the cell, causing Legionnaires' disease and Q fever, respectively. Despite being related and employing homologous Dot/Icm type 4 secretion systems (T4SS) to translocate effector proteins into the host cell, these pathogens have developed their own unique intracellular niches. L. pneumophila evades the host endocytic pathway and instead forms an ER-derived vacuole, while C. burnetii requires delivery to mature, acidified endosomes which it remodels into a large, replicative vacuole. Throughout infection, L. pneumophila effectors act at multiple points to inhibit recognition by xenophagy receptors and disrupt host autophagy, ensuring it avoids fusion with destructive lysosomes. In contrast, C. burnetii employs its effector cohort to control autophagy, hypothesized to facilitate the delivery of nutrients and membrane to support the growing vacuole and replicating bacteria. In this review we explore the effector proteins that these two organisms utilize to modulate the host autophagy pathway in order to survive and replicate. By better understanding how these pathogens manipulate this highly conserved pathway, we can not only develop better treatments for these important human diseases, but also better understand and control autophagy in the context of human health and disease.
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Affiliation(s)
| | | | | | - Hayley J. Newton
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia
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13
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Diallo I, Provost P. RNA-Sequencing Analyses of Small Bacterial RNAs and their Emergence as Virulence Factors in Host-Pathogen Interactions. Int J Mol Sci 2020; 21:E1627. [PMID: 32120885 PMCID: PMC7084465 DOI: 10.3390/ijms21051627] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 02/22/2020] [Accepted: 02/25/2020] [Indexed: 12/14/2022] Open
Abstract
Proteins have long been considered to be the most prominent factors regulating so-called invasive genes involved in host-pathogen interactions. The possible role of small non-coding RNAs (sRNAs), either intracellular, secreted or packaged in outer membrane vesicles (OMVs), remained unclear until recently. The advent of high-throughput RNA-sequencing (RNA-seq) techniques has accelerated sRNA discovery. RNA-seq radically changed the paradigm on bacterial virulence and pathogenicity to the point that sRNAs are emerging as an important, distinct class of virulence factors in both gram-positive and gram-negative bacteria. The potential of OMVs, as protectors and carriers of these functional, gene regulatory sRNAs between cells, has also provided an additional layer of complexity to the dynamic host-pathogen relationship. Using a non-exhaustive approach and through examples, this review aims to discuss the involvement of sRNAs, either free or loaded in OMVs, in the mechanisms of virulence and pathogenicity during bacterial infection. We provide a brief overview of sRNA origin and importance, and describe the classical and more recent methods of identification that have enabled their discovery, with an emphasis on the theoretical lower limit of RNA sizes considered for RNA sequencing and bioinformatics analyses.
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Affiliation(s)
| | - Patrick Provost
- CHUQ Research Center/CHUL, Department of Microbiology-Infectious Disease and Immunity, Faculty of Medicine, Université Laval, Quebec, QC G1V 0A6, Canada;
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