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Guo Q, Li J, Wang MR, Zhao M, Zhang G, Tang S, Xiong LB, Gao B, Wang FQ, Wei DZ. Multidimensional engineering of Saccharomyces cerevisiae for the efficient production of heme by exploring the cytotoxicity and tolerance of heme. Metab Eng 2024; 85:46-60. [PMID: 39019249 DOI: 10.1016/j.ymben.2024.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 06/14/2024] [Accepted: 07/14/2024] [Indexed: 07/19/2024]
Abstract
Heme has attracted considerable attention due to its indispensable biological roles and applications in healthcare and artificial foods. The development and utilization of edible microorganisms instead of animals to produce heme is the most promising method to promote the large-scale industrial production and safe application of heme. However, the cytotoxicity of heme severely restricts its efficient synthesis by microorganisms, and the cytotoxic mechanism is not fully understood. In this study, the effect of heme toxicity on Saccharomyces cerevisiae was evaluated by enhancing its synthesis using metabolic engineering. The results showed that the accumulation of heme after the disruption of heme homeostasis caused serious impairments in cell growth and metabolism, as demonstrated by significantly poor growth, mitochondrial damage, cell deformations, and chapped cell surfaces, and these features which were further associated with substantially elevated reactive oxygen species (ROS) levels within the cell (mainly H2O2 and superoxide anion radicals). To improve cellular tolerance to heme, 5 rounds of laboratory evolution were performed, increasing heme production by 7.3-fold and 4.2-fold in terms of the titer (38.9 mg/L) and specific production capacity (1.4 mg/L/OD600), respectively. Based on comparative transcriptomic analyses, 32 genes were identified as candidates that can be modified to enhance heme production by more than 20% in S. cerevisiae. The combined overexpression of 5 genes (SPS22, REE1, PHO84, HEM4 and CLB2) was shown to be an optimal method to enhance heme production. Therefore, a strain with enhanced heme tolerance and ROS quenching ability (R5-M) was developed that could generate 380.5 mg/L heme with a productivity of 4.2 mg/L/h in fed-batch fermentation, with S. cerevisiae strains being the highest producers reported to date. These findings highlight the importance of improving heme tolerance for the microbial production of heme and provide a solution for efficient heme production by engineered yeasts.
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Affiliation(s)
- Qidi Guo
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Jiacun Li
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Ming-Rui Wang
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Ming Zhao
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Gege Zhang
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Shuyan Tang
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Liang-Bin Xiong
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Bei Gao
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China
| | - Feng-Qing Wang
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China.
| | - Dong-Zhi Wei
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China.
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Pi H, Carlin SM, Beavers WN, Hillebrand GH, Krystofiak ES, Stauff DL, Skaar EP. FapR regulates HssRS-mediated heme homeostasis in Bacillus anthracis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.08.602573. [PMID: 39026866 PMCID: PMC11257595 DOI: 10.1101/2024.07.08.602573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Bacillus anthracis, a Gram-positive facultative anaerobe and the causative agent of anthrax, multiplies to extraordinarily high numbers in vertebrate blood, resulting in considerable heme exposure. Heme is an essential nutrient and the preferred iron source for bacteria during vertebrate colonization, but its high redox potential makes it toxic in excess. To regulate heme homeostasis, many Gram-positive bacteria, including B. anthracis, rely on the two-component signaling system HssRS. HssRS comprises the heme sensing histidine kinase HssS, which modulates the activity of the HssR transcription factor to enable bacteria to circumvent heme toxicity. However, the regulation of the HssRS system remains unclear. Here we identify FapR, the transcriptional regulator of fatty acid biosynthesis, as a key factor in HssRS function. FapR plays an important role in maintaining membrane integrity and the localization of the histidine kinase HssS. Specifically, disruption of fapR leads to increased membrane rigidity, which hinders the penetration of HssRS inducers, resulting in the inactivation of HssRS. Furthermore, deletion of fapR affects the loading of HssS onto the cell membrane, compromising its heme sensing function and subsequently reducing endogenous heme biosynthesis. These findings shed light on the molecular mechanisms governing bacterial adaptation to heme stress and provide potential targets for antimicrobial intervention strategies.
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Affiliation(s)
- Hualiang Pi
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN
- Current address: Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT
| | - Sophia M. Carlin
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - William N. Beavers
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN
| | | | - Evan S. Krystofiak
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | | | - Eric P. Skaar
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN
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3
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Saillant V, Morey L, Lipuma D, Boëton P, Siponen M, Arnoux P, Lechardeur D. HssS activation by membrane heme defines a paradigm for two-component system signaling in Staphylococcus aureus. mBio 2024; 15:e0023024. [PMID: 38682935 PMCID: PMC11237747 DOI: 10.1128/mbio.00230-24] [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: 01/26/2024] [Accepted: 04/02/2024] [Indexed: 05/01/2024] Open
Abstract
Strict management of intracellular heme pools, which are both toxic and beneficial, is crucial for bacterial survival during infection. The human pathogen Staphylococcus aureus uses a two-component heme sensing system (HssRS), which counteracts environmental heme toxicity by triggering expression of the efflux transporter HrtBA. The HssS heme sensor is a HisKA-type histidine kinase, characterized as a membrane-bound homodimer containing an extracellular sensor and a cytoplasmic conserved catalytic domain. To elucidate HssS heme-sensing mechanism, a structural simulation of the HssS dimer based on Alphafold2 was docked with heme. In this model, a heme-binding site is present in the HssS dimer between the membrane and extracellular domains. Heme is embedded in the membrane bilayer with its two protruding porphyrin propionates interacting with two conserved Arg94 and Arg163 that are located extracellularly. Single substitutions of these arginines and two highly conserved phenylalanines, Phe25 and Phe128, in the predicted hydrophobic pocket limited the ability of HssS to induce HrtBA synthesis. Combination of the four substitutions abolished HssS activation. Wild-type (WT) HssS copurified with heme from Escherichia coli, whereas heme binding was strongly attenuated in the variants. This study gives evidence that exogenous heme interacts with HssS at the membrane/extracellular interface to initiate HssS activation and induce HrtBA-mediated heme extrusion from the membrane. This "gatekeeper" mechanism could limit intracellular diffusion of exogenous heme in S. aureus and may serve as a paradigm for how efflux transporters control detoxification of exogenous hydrophobic stressors.IMPORTANCEIn the host blood, pathogenic bacteria are exposed to the red pigment heme that concentrates in their lipid membranes, generating cytotoxicity. To overcome heme toxicity, Staphylococcus aureus expresses a membrane sensor protein, HssS. Activation of HssS by heme triggers a phosphotransfer mechanism leading to the expression of a heme efflux system, HrtBA. This detoxification system prevents intracellular accumulation of heme. Our structural and functional data reveal a heme-binding hydrophobic cavity in HssS within the transmembrane domains (TM) helices at the interface with the extracellular domain. This structural pocket is important for the function of HssS as a heme sensor. Our findings provide a new basis for the elucidation of pathogen-sensing mechanisms as a prerequisite to the discovery of inhibitors.
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Affiliation(s)
- Vincent Saillant
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France, Jouy-en-Josas, France
| | - Léo Morey
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France, Jouy-en-Josas, France
| | - Damien Lipuma
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France, Jouy-en-Josas, France
| | - Pierre Boëton
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France, Jouy-en-Josas, France
| | - Marina Siponen
- Aix Marseille Univ., CEA, CNRS, BIAM, Saint Paul-Lez-Durance, France
| | - Pascal Arnoux
- Aix Marseille Univ., CEA, CNRS, BIAM, Saint Paul-Lez-Durance, France
| | - Delphine Lechardeur
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France, Jouy-en-Josas, France
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4
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Ali L, Abdel Aziz MH. Crosstalk involving two-component systems in Staphylococcus aureus signaling networks. J Bacteriol 2024; 206:e0041823. [PMID: 38456702 PMCID: PMC11025333 DOI: 10.1128/jb.00418-23] [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] [Indexed: 03/09/2024] Open
Abstract
Staphylococcus aureus poses a serious global threat to human health due to its pathogenic nature, adaptation to environmental stress, high virulence, and the prevalence of antimicrobial resistance. The signaling network in S. aureus coordinates and integrates various internal and external inputs and stimuli to adapt and formulate a response to the environment. Two-component systems (TCSs) of S. aureus play a central role in this network where surface-expressed histidine kinases (HKs) receive and relay external signals to their cognate response regulators (RRs). Despite the purported high fidelity of signaling, crosstalk within TCSs, between HK and non-cognate RR, and between TCSs and other systems has been detected widely in bacteria. The examples of crosstalk in S. aureus are very limited, and there needs to be more understanding of its molecular recognition mechanisms, although some crosstalk can be inferred from similar bacterial systems that share structural similarities. Understanding the cellular processes mediated by this crosstalk and how it alters signaling, especially under stress conditions, may help decipher the emergence of antibiotic resistance. This review highlights examples of signaling crosstalk in bacteria in general and S. aureus in particular, as well as the effect of TCS mutations on signaling and crosstalk.
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Affiliation(s)
- Liaqat Ali
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - May H. Abdel Aziz
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
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5
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Gangwal A, Kumar N, Sangwan N, Dhasmana N, Dhawan U, Sajid A, Arora G, Singh Y. Giving a signal: how protein phosphorylation helps Bacillus navigate through different life stages. FEMS Microbiol Rev 2023; 47:fuad044. [PMID: 37533212 PMCID: PMC10465088 DOI: 10.1093/femsre/fuad044] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 07/30/2023] [Accepted: 08/01/2023] [Indexed: 08/04/2023] Open
Abstract
Protein phosphorylation is a universal mechanism regulating a wide range of cellular responses across all domains of life. The antagonistic activities of kinases and phosphatases can orchestrate the life cycle of an organism. The availability of bacterial genome sequences, particularly Bacillus species, followed by proteomics and functional studies have aided in the identification of putative protein kinases and protein phosphatases, and their downstream substrates. Several studies have established the role of phosphorylation in different physiological states of Bacillus species as they pass through various life stages such as sporulation, germination, and biofilm formation. The most common phosphorylation sites in Bacillus proteins are histidine, aspartate, tyrosine, serine, threonine, and arginine residues. Protein phosphorylation can alter protein activity, structural conformation, and protein-protein interactions, ultimately affecting the downstream pathways. In this review, we summarize the knowledge available in the field of Bacillus signaling, with a focus on the role of protein phosphorylation in its physiological processes.
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Affiliation(s)
- Aakriti Gangwal
- Department of Zoology, University of Delhi, Faculty of Science, Delhi- 110007, India
| | - Nishant Kumar
- Department of Zoology, University of Delhi, Faculty of Science, Delhi- 110007, India
| | - Nitika Sangwan
- Department of Zoology, University of Delhi, Faculty of Science, Delhi- 110007, India
- Department of Biomedical Science, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi-110075, India
| | - Neha Dhasmana
- School of Medicine, New York University, 550 First Avenue New York-10016, New York, United States
| | - Uma Dhawan
- Department of Biomedical Science, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi-110075, India
| | - Andaleeb Sajid
- 300 Cedar St, Yale School of Medicine, Yale University, New Haven, Connecticut 06520, New Haven CT, United States
| | - Gunjan Arora
- 300 Cedar St, Yale School of Medicine, Yale University, New Haven, Connecticut 06520, New Haven CT, United States
| | - Yogendra Singh
- Department of Zoology, University of Delhi, Faculty of Science, Delhi- 110007, India
- Delhi School of Public Health, Institution of Eminence, University of Delhi, Delhi-110007, India
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Wang M, Wang Y, Wang M, Liu M, Cheng A. Heme acquisition and tolerance in Gram-positive model bacteria: An orchestrated balance. Heliyon 2023; 9:e18233. [PMID: 37501967 PMCID: PMC10368836 DOI: 10.1016/j.heliyon.2023.e18233] [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: 06/01/2023] [Revised: 06/26/2023] [Accepted: 07/12/2023] [Indexed: 07/29/2023] Open
Abstract
As a nutrient, heme is important for various cellular processes of organism. Bacteria can obtain heme via heme biosynthesis or/and uptake of exogenous heme from the host. On the other side, absorption of excess heme is cytotoxic to bacteria. Thus, bacteria have developed systems to relieve heme toxicity and contribute to the maintenance of heme homeostasis. In the past decades, the mechanisms underlying heme acquisition and tolerance have been well studied in Gram-positive model bacteria, such as Staphylococcus, Streptococcus and other Gram-positive bacteria. Here, we review the elaborate mechanisms by which these bacteria acquire heme and resist heme toxicity. Since both the heme utilization system and the heme tolerance system contribute to bacterial virulence, this review is not only helpful for a comprehensive understanding of the heme homeostasis mechanism in Gram-positive bacteria but also provides a theoretical basis for the development of antimicrobial agents.
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Affiliation(s)
- Mengying Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Yuwei Wang
- Mianyang Academy of Agricultural Sciences, Institute of Livestock Research, Mianyang 621023, China
| | - Mingshu Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Mafeng Liu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Anchun Cheng
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
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7
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Su H, Chen X, Chen S, Guo M, Liu H. Applications of the Whole-Cell System in the Efficient Biosynthesis of Heme. Int J Mol Sci 2023; 24:ijms24098384. [PMID: 37176091 PMCID: PMC10179345 DOI: 10.3390/ijms24098384] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 04/22/2023] [Accepted: 04/30/2023] [Indexed: 05/15/2023] Open
Abstract
Heme has a variety of functions, from electronic reactions to binding gases, which makes it useful in medical treatments, dietary supplements, and food processing. In recent years, whole-cell system-based heme biosynthesis methods have been continuously explored and optimized as an alternative to the low-yield, lasting, and adverse ecological environment of chemical synthesis methods. This method relies on two biosynthetic pathways of microbial precursor 5-aminolevulinic acid (C4, C5) and three known downstream biosynthetic pathways of heme. This paper reviews the genetic and metabolic engineering strategies for heme production in recent years by optimizing culture conditions and techniques from different microorganisms. Specifically, we summarized and analyzed the possibility of using biosensors to explore new strategies for the biosynthesis of heme from the perspective of synthetic biology, providing a new direction for future exploration.
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Affiliation(s)
- Hongfei Su
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Xiaolin Chen
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Shijing Chen
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Mingzhang Guo
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Huilin Liu
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
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8
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Hu B, Yu H, Zhou J, Li J, Chen J, Du G, Lee SY, Zhao X. Whole-Cell P450 Biocatalysis Using Engineered Escherichia coli with Fine-Tuned Heme Biosynthesis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205580. [PMID: 36526588 PMCID: PMC9951570 DOI: 10.1002/advs.202205580] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/05/2022] [Indexed: 05/14/2023]
Abstract
By exploiting versatile P450 enzymes, whole-cell biocatalysis can be performed to synthesize valuable compounds in Escherichia coli. However, the insufficient supply of heme limits the whole-cell P450 biocatalytic activity. Here a strategy for improving intracellular heme biosynthesis to enhance the catalytic efficiencies of P450s is reported. After comparing the effects of improving heme transport and biosynthesis on P450 activities, intracellular heme biosynthesis is optimized through the integrated expression of necessary synthetic genes at proper ratios and the assembly of rate-limiting enzymes using DNA-guided scaffolds. The intracellular heme level is fine-tuned by the combined use of mutated heme-sensitive biosensors and small regulatory RNA systems. The catalytic efficiencies of three different P450s, BM3, sca-2, and CYP105D7, are enhanced through fine-tuning heme biosynthesis for the synthesis of hydroquinone, pravastatin, and 7,3',4'-trihydroxyisoflavone as example products of chemical intermediate, drug, and natural product, respectively. This strategy of fine-tuned heme biosynthesis will be generally useful for developing whole-cell biocatalysts involving hemoproteins.
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Affiliation(s)
- Baodong Hu
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Haibo Yu
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Jingwen Zhou
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Jianghua Li
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Jian Chen
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Guocheng Du
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Key Laboratory of Carbohydrate Chemistry and BiotechnologyMinistry of EducationJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Sang Yup Lee
- Metabolic and Biomolecular Engineering National Research LaboratoryDepartment of Chemical and Biomolecular Engineering (BK21 Plus Program)BioProcess Engineering Research CenterBioinformatics Research Center, and Institute for the BioCenturyKorea Advanced Institute of Science and Technology (KAIST)DaejeonYuseong‐gu34141Republic of Korea
| | - Xinrui Zhao
- Key Laboratory of Industrial BiotechnologyMinistry of EducationSchool of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
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9
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Krüger A, Frunzke J. A pseudokinase version of the histidine kinase ChrS promotes high heme tolerance of Corynebacterium glutamicum. Front Microbiol 2022; 13:997448. [PMID: 36160252 PMCID: PMC9491836 DOI: 10.3389/fmicb.2022.997448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/18/2022] [Indexed: 11/21/2022] Open
Abstract
Heme is an essential cofactor for almost all living cells by acting as prosthetic group for various proteins or serving as alternative iron source. However, elevated levels are highly toxic for cells. Several corynebacterial species employ two paralogous, heme-responsive two-component systems (TCS), ChrSA and HrrSA, to cope with heme stress and to maintain intracellular heme homeostasis. Significant cross-talk at the level of phosphorylation between these systems was previously demonstrated. In this study, we have performed a laboratory evolution experiment to adapt Corynebacterium glutamicum to increasing heme levels. Isolated strains showed a highly increased tolerance to heme growing at concentrations of up to 100 μM. The strain featuring the highest heme tolerance harbored a frameshift mutation in the catalytical and ATPase-domain (CA-domain) of the chrS gene, converting it into a catalytically-inactive pseudokinase (ChrS_CA-fs). Reintroduction of the respective mutation in the parental C. glutamicum strain confirmed high heme tolerance and showed a drastic upregulation of hrtBA encoding a heme export system, conserved in Firmicutes and Actinobacteria. The strain encoding the ChrS pseudokinase variant showed significantly higher heme tolerance than a strain lacking chrS. Mutational analysis revealed that induction of hrtBA in the evolved strain is solely mediated via the cross-phosphorylation of the response regulator (RR) ChrA by the kinase HrrS and BACTH assays revealed the formation of heterodimers between HrrS and ChrS. Overall, our results emphasize an important role of the ChrS pseudokinase in high heme tolerance of the evolved C. glutamicum and demonstrate the promiscuity in heme-dependent signaling of the paralogous two-component systems facilitating fast adaptation to changing environmental conditions.
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10
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Structural basis for heme detoxification by an ATP-binding cassette-type efflux pump in gram-positive pathogenic bacteria. Proc Natl Acad Sci U S A 2022; 119:e2123385119. [PMID: 35767641 PMCID: PMC9271180 DOI: 10.1073/pnas.2123385119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Bacterial pathogens acquire heme from the host hemoglobin as an iron nutrient for their virulence and proliferation in blood. Concurrently, they encounter cytotoxic-free heme that escapes the heme-acquisition process. To overcome this toxicity, many gram-positive bacteria employ an ATP-binding cassette heme-dedicated efflux pump, HrtBA in the cytoplasmic membranes. Although genetic analyses have suggested that HrtBA expels heme from the bacterial membranes, the molecular mechanism of heme efflux remains elusive due to the lack of protein studies. Here, we show the biochemical properties and crystal structures of Corynebacterium diphtheriae HrtBA, alone and in complex with heme or an ATP analog, and we reveal how HrtBA extracts heme from the membrane and releases it. HrtBA consists of two cytoplasmic HrtA ATPase subunits and two transmembrane HrtB permease subunits. A heme-binding site is formed in the HrtB dimer and is laterally accessible to heme in the outer leaflet of the membrane. The heme-binding site captures heme from the membrane using a glutamate residue of either subunit as an axial ligand and sequesters the heme within the rearranged transmembrane helix bundle. By ATP-driven HrtA dimerization, the heme-binding site is squeezed to extrude the bound heme. The mechanism sheds light on the detoxification of membrane-bound heme in this bacterium.
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11
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Michalska K, Rychłowski M, Krupińska M, Szewczyk G, Sarna T, Nakonieczna J. Gallium Mesoporphyrin IX-Mediated Photodestruction: A Pharmacological Trojan Horse Strategy To Eliminate Multidrug-Resistant Staphylococcus aureus. Mol Pharm 2022; 19:1434-1448. [PMID: 35416046 PMCID: PMC9066410 DOI: 10.1021/acs.molpharmaceut.1c00993] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
One of the factors
determining efficient antimicrobial photodynamic
inactivation (aPDI) is the accumulation of a light-activated compound,
namely, a photosensitizer (PS). Targeted PS recognition is the approach
based on the interaction between the membrane receptor on the bacterial
surface and the PS, whereas the compound is efficiently accumulated
by the same mechanism as the natural ligand. In this study, we showed
that gallium mesoporphyrin IX (Ga3+MPIX) provided dual
functionality—iron metabolism disruption and PS properties
in aPDI. Ga3+MPIX induced efficient (>5log10 reduction in CFU/mL) bacterial photodestruction with excitation
in the area of Q band absorption with relatively low eukaryotic cytotoxicity
and phototoxicity. The Ga3+MPIX is recognized by the same
systems as haem by the iron-regulated surface determinant (Isd). However,
the impairment in the ATPase of the haem detoxification efflux pump
was the most sensitive to the Ga3+MPIX-mediated aPDI phenotype.
This indicates that changes within the metalloporphyrin structure
(vinyl vs ethyl groups) did not significantly alter the properties
of recognition of the compound but influenced its biophysical properties.
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Affiliation(s)
- Klaudia Michalska
- Laboratory of Photobiology and Molecular Diagnostics, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, Gdansk 80-307, Poland
| | - Michał Rychłowski
- Laboratory of Virus Molecular Biology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, Gdansk 80-307, Poland
| | - Martyna Krupińska
- Laboratory of Photobiology and Molecular Diagnostics, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, Gdansk 80-307, Poland
| | - Grzegorz Szewczyk
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, Krakow 30-387, Poland
| | - Tadeusz Sarna
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, Krakow 30-387, Poland
| | - Joanna Nakonieczna
- Laboratory of Photobiology and Molecular Diagnostics, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, Gdansk 80-307, Poland
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12
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Pi H, Weiss A, Laut CL, Grunenwald CM, Lin HK, Yi XI, Stauff DL, Skaar EP. An RNA-binding protein acts as a major post-transcriptional modulator in Bacillus anthracis. Nat Commun 2022; 13:1491. [PMID: 35314695 PMCID: PMC8938561 DOI: 10.1038/s41467-022-29209-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 03/01/2022] [Indexed: 12/28/2022] Open
Abstract
HitRS is a two-component system that responds to cell envelope damage in the human pathogen Bacillus anthracis. Here we identify an RNA-binding protein, KrrA, that regulates HitRS function by modulating the stability of the hitRS mRNA. In addition to hitRS, KrrA binds to over 70 RNAs and, directly or indirectly, affects the expression of over 150 genes involved in multiple processes, including genetic competence, sporulation, RNA turnover, DNA repair, transport, and cellular metabolism. KrrA does not exhibit detectable nuclease activity in vitro, and thus the mechanism by which it modulates mRNA stability remains unclear.
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Affiliation(s)
- Hualiang Pi
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Andy Weiss
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Clare L Laut
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Caroline M Grunenwald
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Hannah K Lin
- Department of Biology, Grove City College, Grove City, PA, USA
| | - Xinjie I Yi
- Department of Biology, Grove City College, Grove City, PA, USA
| | - Devin L Stauff
- Department of Biology, Grove City College, Grove City, PA, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA.
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13
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Krüger A, Keppel M, Sharma V, Frunzke J. The diversity of heme sensor systems - heme-responsive transcriptional regulation mediated by transient heme protein interactions. FEMS Microbiol Rev 2022; 46:6506450. [PMID: 35026033 DOI: 10.1093/femsre/fuac002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/21/2021] [Accepted: 01/11/2022] [Indexed: 11/13/2022] Open
Abstract
Heme is a versatile molecule that is vital for nearly all cellular life by serving as prosthetic group for various enzymes or as nutritional iron source for diverse microbial species. However, elevated levels of heme molecule are toxic to cells. The complexity of this stimulus has shaped the evolution of diverse heme sensor systems, which are involved in heme-dependent transcriptional regulation in eukaryotes and prokaryotes. The functions of these systems are manifold - ranging from the specific control of heme detoxification or uptake systems to the global integration of heme and iron homeostasis. This review focuses on heme sensor systems, regulating heme homeostasis by transient heme protein interaction. We provide an overview of known heme-binding motifs in prokaryotic and eukaryotic transcription factors. Besides the central ligands, the surrounding amino acid environment was shown to play a pivotal role in heme binding. The diversity of heme-regulatory systems therefore illustrates that prediction based on pure sequence information is hardly possible and requires careful experimental validation. Comprehensive understanding of heme-regulated processes is not only important for our understanding of cellular physiology, but also provides a basis for the development of novel antibacterial drugs and metabolic engineering strategies.
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Affiliation(s)
- Aileen Krüger
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany
| | - Marc Keppel
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany
| | - Vikas Sharma
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany
| | - Julia Frunzke
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany
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14
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DnaJ and ClpX are required for HitRS and HssRS two-component system signaling in Bacillus anthracis. Infect Immun 2021; 90:e0056021. [PMID: 34748369 DOI: 10.1128/iai.00560-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis is the causative agent of anthrax. This Gram-positive bacterium poses a substantial risk to human health due to high mortality rates and the potential for malicious use as a bioterror weapon. To survive within the vertebrate host, B. anthracis relies on two-component system (TCS) signaling to sense host-induced stresses and respond to alterations in the environment through changes in target gene expression. HitRS and HssRS are cross-regulating TCSs in B. anthracis that respond to cell envelope disruptions and high heme levels, respectively. In this study, an unbiased and targeted genetic selection was designed to identify gene products that are involved in HitRS and HssRS signaling. This selection led to the identification of inactivating mutations within dnaJ and clpX that disrupt HitRS- and HssRS-dependent gene expression. DnaJ and ClpX are the substrate-binding subunits of the DnaJK protein chaperone and ClpXP protease, respectively. DnaJ regulates the levels of HitR and HitS to facilitate signal transduction, while ClpX specifically regulates HitS levels. Together these results reveal that the protein homeostasis regulators, DnaJ and ClpX, function to maintain B. anthracis signal transduction activities through TCS regulation. One sentence summary: Use of a genetic selection strategy to identify modulators of two-component system signaling in Bacillus anthracis.
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15
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Herrin BE, Islam S, Rentschler KN, Pert LH, Kopanski SP, Wakeman CA. Haem toxicity provides a competitive advantage to the clinically relevant Staphylococcus aureus small colony variant phenotype. MICROBIOLOGY (READING, ENGLAND) 2021; 167:001044. [PMID: 33749578 PMCID: PMC8289220 DOI: 10.1099/mic.0.001044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Microorganisms encounter toxicities inside the host. Many pathogens exist as subpopulations to maximize survivability. Subpopulations of Staphylococcus aureus include antibiotic-tolerant small colony variants (SCVs). These mutants often emerge following antibiotic treatment but can be present in infections prior to antibiotic exposure. We hypothesize that haem toxicity in the host selects for respiration-deficient S. aureus SCVs in the absence of antibiotics. We demonstrate that some but not all respiration-deficient SCV phenotypes are more protective than the haem detoxification system against transient haem exposure, indicating that haem toxicity in the host may contribute to the dominance of menaquinone-deficient and haem-deficient SCVs prior to antibiotic treatment.
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Affiliation(s)
- Brittany E. Herrin
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
- Present address: Department of Biology, Indiana University, Bloomington, IN, USA
| | - Shariful Islam
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | | | - Lauren H. Pert
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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16
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A Novel Enterococcus faecalis Heme Transport Regulator (FhtR) Senses Host Heme To Control Its Intracellular Homeostasis. mBio 2021; 12:mBio.03392-20. [PMID: 33531389 PMCID: PMC7858072 DOI: 10.1128/mbio.03392-20] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterococcus faecalis, a normal and harmless colonizer of the human intestinal flora can cause severe infectious diseases in immunocompromised patients, particularly those that have been heavily treated with antibiotics. Therefore, it is important to understand the factors that promote its resistance and its virulence. E. faecalis, which cannot synthesize heme, an essential but toxic metabolite, needs to scavenge this molecule from the host to respire and fight stress generated by oxidants. Enterococcus faecalis is a commensal Gram-positive pathogen found in the intestines of mammals and is also a leading cause of severe infections occurring mainly among antibiotic-treated dysbiotic hospitalized patients. Like most intestinal bacteria, E. faecalis does not synthesize heme (in this report, heme refers to iron protoporphyrin IX regardless of the iron redox state). Nevertheless, environmental heme can improve E. faecalis fitness by activating respiration metabolism and a catalase that limits hydrogen peroxide stress. Since free heme also generates toxicity, its intracellular levels need to be strictly controlled. Here, we describe a unique transcriptional regulator, FhtR (named FhtR for faecalis heme transport regulator), which manages heme homeostasis by controlling an HrtBA-like efflux pump (named HrtBAEf for the HrtBA from E. faecalis). We show that FhtR, by managing intracellular heme concentration, regulates the functional expression of the heme-dependent catalase A (KatA), thus participating in heme detoxification. The biochemical features of FhtR binding to DNA, and its interaction with heme that induces efflux, are characterized. The FhtR-HrtBAEf system is shown to be relevant in a mouse intestinal model. We further show that FhtR senses heme from blood and hemoglobin but also from crossfeeding by Escherichia coli. These findings bring to light the central role of heme sensing by FhtR in response to heme fluctuations within the gastrointestinal tract, which allow this pathogen to limit heme toxicity while ensuring expression of an oxidative defense system.
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17
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Pi H, Chu ML, Ivan SJ, Latario CJ, Toth AM, Carlin SM, Hillebrand GH, Lin HK, Reppart JD, Stauff DL, Skaar EP. Directed evolution reveals the mechanism of HitRS signaling transduction in Bacillus anthracis. PLoS Pathog 2020; 16:e1009148. [PMID: 33362282 PMCID: PMC7790381 DOI: 10.1371/journal.ppat.1009148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 01/07/2021] [Accepted: 11/11/2020] [Indexed: 12/03/2022] Open
Abstract
Two component systems (TCSs) are a primary mechanism of signal sensing and response in bacteria. Systematic characterization of an entire TCS could provide a mechanistic understanding of these important signal transduction systems. Here, genetic selections were employed to dissect the molecular basis of signal transduction by the HitRS system that detects cell envelope stress in the pathogen Bacillus anthracis. Numerous point mutations were isolated within HitRS, 17 of which were in a 50-residue HAMP domain. Mutational analysis revealed the importance of hydrophobic interactions within the HAMP domain and highlighted its essentiality in TCS signaling. In addition, these data defined residues critical for activities intrinsic to HitRS, uncovered specific interactions among individual domains and between the two signaling proteins, and revealed that phosphotransfer is the rate-limiting step for signal transduction. Furthermore, this study establishes the use of unbiased genetic selections to study TCS signaling and provides a comprehensive mechanistic understanding of an entire TCS. Bacterial TCSs are a primary strategy for stress sensing and niche adaptation. Although individual domains and proteins of these systems have been extensively studied, systematic characterization of an entire TCS is rare. In this study, through unbiased genetic selections and rigorous biochemical analysis, we provide a detailed characterization and structure-function analysis of an entire TCS and extend our understanding of the molecular basis of signal transduction through TCSs. Moreover, this study provides a comprehensive map of point-mutations in these well-conserved signaling proteins, which will be broadly useful for studying other TCSs. The described genetic selection strategies are applicable to any TCS, providing a powerful tool for researchers interested in microbial signal transduction.
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Affiliation(s)
- Hualiang Pi
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, & Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Michelle L. Chu
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Samuel J. Ivan
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Casey J. Latario
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Allen M. Toth
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Sophia M. Carlin
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Gideon H. Hillebrand
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Hannah K. Lin
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Jared D. Reppart
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Devin L. Stauff
- Department of Biology, Grove City College, Grove City, Pennsylvania, United States of America
| | - Eric P. Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, & Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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18
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Keppel M, Hünnefeld M, Filipchyk A, Viets U, Davoudi CF, Krüger A, Mack C, Pfeifer E, Polen T, Baumgart M, Bott M, Frunzke J. HrrSA orchestrates a systemic response to heme and determines prioritization of terminal cytochrome oxidase expression. Nucleic Acids Res 2020; 48:6547-6562. [PMID: 32453397 PMCID: PMC7337898 DOI: 10.1093/nar/gkaa415] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/26/2020] [Accepted: 05/05/2020] [Indexed: 01/02/2023] Open
Abstract
Heme is a multifaceted molecule. While serving as a prosthetic group for many important proteins, elevated levels are toxic to cells. The complexity of this stimulus has shaped bacterial network evolution. However, only a small number of targets controlled by heme-responsive regulators have been described to date. Here, we performed chromatin affinity purification and sequencing to provide genome-wide insights into in vivo promoter occupancy of HrrA, the response regulator of the heme-regulated two-component system HrrSA of Corynebacterium glutamicum. Time-resolved profiling revealed dynamic binding of HrrA to more than 200 different genomic targets encoding proteins associated with heme biosynthesis, the respiratory chain, oxidative stress response and cell envelope remodeling. By repression of the extracytoplasmic function sigma factor sigC, which activates the cydABCD operon, HrrA prioritizes the expression of genes encoding the cytochrome bc1-aa3 supercomplex. This is also reflected by a significantly decreased activity of the cytochrome aa3 oxidase in the ΔhrrA mutant. Furthermore, our data reveal that HrrA also integrates the response to heme-induced oxidative stress by activating katA encoding the catalase. These data provide detailed insights in the systemic strategy that bacteria have evolved to respond to the versatile signaling molecule heme.
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Affiliation(s)
- Marc Keppel
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Max Hünnefeld
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Andrei Filipchyk
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Ulrike Viets
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Cedric-Farhad Davoudi
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Aileen Krüger
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Christina Mack
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Eugen Pfeifer
- Microbial Evolutionary Genomics, Institute Pasteur, 75015 Paris, France
| | - Tino Polen
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Meike Baumgart
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Michael Bott
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Julia Frunzke
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
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19
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Genetic Regulation of Metal Ion Homeostasis in Staphylococcus aureus. Trends Microbiol 2020; 28:821-831. [PMID: 32381454 DOI: 10.1016/j.tim.2020.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 12/16/2022]
Abstract
The acquisition of metal ions and the proper maturation of holo-metalloproteins are essential processes for all organisms. However, metal ion homeostasis is a double-edged sword. A cytosolic accumulation of metal ions can lead to mismetallation of proteins and cell death. Therefore, maintenance of proper concentrations of intracellular metals is essential for cell fitness and pathogenesis. Staphylococcus aureus, like all bacterial pathogens, uses transcriptional metalloregulatory proteins to aid in the detection and the genetic response to changes in metal ion concentrations. Herein, we review the mechanisms by which S. aureus senses and responds to alterations in the levels of cellular zinc, iron, heme, and copper. The interplay between metal ion sensing and metal-dependent expression of virulence factors is also discussed.
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20
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Laut CL, Perry WJ, Metzger AL, Weiss A, Stauff DL, Walker S, Caprioli RM, Skaar EP. Bacillus anthracis Responds to Targocil-Induced Envelope Damage through EdsRS Activation of Cardiolipin Synthesis. mBio 2020; 11:e03375-19. [PMID: 32234818 PMCID: PMC7157781 DOI: 10.1128/mbio.03375-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/27/2020] [Indexed: 01/08/2023] Open
Abstract
Bacillus anthracis is a spore-forming bacterium that causes devastating infections and has been used as a bioterror agent. This pathogen can survive hostile environments through the signaling activity of two-component systems, which couple environmental sensing with transcriptional activation to initiate a coordinated response to stress. In this work, we describe the identification of a two-component system, EdsRS, which mediates the B. anthracis response to the antimicrobial compound targocil. Targocil is a cell envelope-targeting compound that is toxic to B. anthracis at high concentrations. Exposure to targocil causes damage to the cellular barrier and activates EdsRS to induce expression of a previously uncharacterized cardiolipin synthase, which we have named ClsT. Both EdsRS and ClsT are required for protection against targocil-dependent damage. Induction of clsT by EdsRS during targocil treatment results in an increase in cardiolipin levels, which protects B. anthracis from envelope damage. Together, these results reveal that a two-component system signaling response to an envelope-targeting antimicrobial induces production of a phospholipid associated with stabilization of the membrane. Cardiolipin is then used to repair envelope damage and promote B. anthracis viability.IMPORTANCE Compromising the integrity of the bacterial cell barrier is a common action of antimicrobials. Targocil is an antimicrobial that is active against the bacterial envelope. We hypothesized that Bacillus anthracis, a potential weapon of bioterror, senses and responds to targocil to alleviate targocil-dependent cell damage. Here, we show that targocil treatment increases the permeability of the cellular envelope and is particularly toxic to B. anthracis spores during outgrowth. In vegetative cells, two-component system signaling through EdsRS is activated by targocil. This results in an increase in the production of cardiolipin via a cardiolipin synthase, ClsT, which restores the loss of barrier function, thereby reducing the effectiveness of targocil. By elucidating the B. anthracis response to targocil, we have uncovered an intrinsic mechanism that this pathogen employs to resist toxicity and have revealed therapeutic targets that are important for bacterial defense against structural damage.
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Affiliation(s)
- Clare L Laut
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - William J Perry
- Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee, USA
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Andy Weiss
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Devin L Stauff
- Department of Biology, Grove City College, Grove City, Pennsylvania, USA
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Richard M Caprioli
- Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee, USA
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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21
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Keppel M, Piepenbreier H, Gätgens C, Fritz G, Frunzke J. Toxic but tasty - temporal dynamics and network architecture of heme-responsive two-component signaling in Corynebacterium glutamicum. Mol Microbiol 2019; 111:1367-1381. [PMID: 30767351 PMCID: PMC6850329 DOI: 10.1111/mmi.14226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2019] [Indexed: 01/24/2023]
Abstract
Heme is an essential cofactor and alternative iron source for almost all bacterial species but may cause severe toxicity upon elevated levels and consequently, regulatory mechanisms coordinating heme homeostasis represent an important fitness trait. A remarkable scenario is found in several corynebacterial species, e.g. Corynebacterium glutamicum and Corynebacterium diphtheriae, which dedicate two paralogous, heme-responsive two-component systems, HrrSA and ChrSA, to cope with the Janus nature of heme. Here, we combined experimental reporter profiling with a quantitative mathematical model to understand how this particular regulatory network architecture shapes the dynamic response to heme. Our data revealed an instantaneous activation of the detoxification response (hrtBA) upon stimulus perception and we found that kinase activity of both kinases contribute to this fast onset. Furthermore, instant deactivation of the PhrtBA promoter is achieved by a strong ChrS phosphatase activity upon stimulus decline. While the activation of detoxification response is uncoupled from further factors, heme utilization is additionally governed by the global iron regulator DtxR integrating information on iron availability into the regulatory network. Altogether, our data provide comprehensive insights how TCS cross-regulation and network hierarchy shape the temporal dynamics of detoxification (hrtBA) and utilization (hmuO) as part of a global homeostatic response to heme.
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Affiliation(s)
- Marc Keppel
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Hannah Piepenbreier
- LOEWE-Zentrum für Synthetische Mikrobiologie, Philipps-Universität Marburg, Marburg, 35032, Germany
| | - Cornelia Gätgens
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Georg Fritz
- LOEWE-Zentrum für Synthetische Mikrobiologie, Philipps-Universität Marburg, Marburg, 35032, Germany
| | - Julia Frunzke
- Institute of Bio- und Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, 52425, Germany
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22
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Dos Santos PT, Larsen PT, Menendez-Gil P, Lillebæk EMS, Kallipolitis BH. Listeria monocytogenes Relies on the Heme-Regulated Transporter hrtAB to Resist Heme Toxicity and Uses Heme as a Signal to Induce Transcription of lmo1634, Encoding Listeria Adhesion Protein. Front Microbiol 2018; 9:3090. [PMID: 30619169 PMCID: PMC6305404 DOI: 10.3389/fmicb.2018.03090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/29/2018] [Indexed: 01/29/2023] Open
Abstract
For pathogenic bacteria, host-derived heme represents an important metabolic cofactor and a source for iron. However, high levels of heme are toxic to bacteria. We have previously shown that excess heme has a growth-inhibitory effect on the Gram-positive foodborne pathogen Listeria monocytogenes, and we have learned that the LhrC1-5 family of small RNAs, together with the two-component system (TCS) LisRK, play a role in the adaptation of L. monocytogenes to heme stress conditions. However, a broader knowledge on how this pathogen responds to heme toxicity is still lacking. Here, we analyzed the global transcriptomic response of L. monocytogenes to heme stress. We found that the response of L. monocytogenes to excess heme is multifaceted, involving various strategies acting to minimize the toxic effects of heme. For example, heme exposure triggers the SOS response that deals with DNA damage. In parallel, L. monocytogenes shuts down the transcription of genes involved in heme/iron uptake and utilization. Furthermore, heme stress resulted in a massive increase in the transcription of a putative heme detoxification system, hrtAB, which is highly conserved in Gram-positive bacteria. As expected, we found that the TCS HssRS is required for heme-mediated induction of hrtAB and that a functional heme efflux system is essential for L. monocytogenes to resist heme toxicity. Curiously, the most highly up-regulated gene upon heme stress was lmo1634, encoding the Listeria adhesion protein, LAP, which acts to promote the translocation of L. monocytogenes across the intestinal barrier. Additionally, LAP is predicted to act as a bifunctional acetaldehyde-CoA/alcohol dehydrogenase. Surprisingly, a mutant lacking lmo1634 grows well under heme stress conditions, showing that LAP is not required for L. monocytogenes to resist heme toxicity. Likewise, a functional ResDE TCS, which contributes to heme-mediated expression of lmo1634, is not required for the adaptation of L. monocytogenes to heme stress conditions. Collectively, this study provides novel insights into the strategies employed by L. monocytogenes to resist heme toxicity. Our findings indicate that L. monocytogenes is using heme as a host-derived signaling molecule to control the expression of its virulence genes, as exemplified by lmo1634.
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Affiliation(s)
| | - Pernille Tholund Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Pilar Menendez-Gil
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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Knippel RJ, Zackular JP, Moore JL, Celis AI, Weiss A, Washington MK, DuBois JL, Caprioli RM, Skaar EP. Heme sensing and detoxification by HatRT contributes to pathogenesis during Clostridium difficile infection. PLoS Pathog 2018; 14:e1007486. [PMID: 30576368 PMCID: PMC6303022 DOI: 10.1371/journal.ppat.1007486] [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: 09/18/2018] [Accepted: 11/27/2018] [Indexed: 02/04/2023] Open
Abstract
Clostridium difficile is a Gram-positive, spore-forming anaerobic bacterium that infects the colon, causing symptoms ranging from infectious diarrhea to fulminant colitis. In the last decade, the number of C. difficile infections has dramatically risen, making it the leading cause of reported hospital acquired infection in the United States. Bacterial toxins produced during C. difficile infection (CDI) damage host epithelial cells, releasing erythrocytes and heme into the gastrointestinal lumen. The reactive nature of heme can lead to toxicity through membrane disruption, membrane protein and lipid oxidation, and DNA damage. Here we demonstrate that C. difficile detoxifies excess heme to achieve full virulence within the gastrointestinal lumen during infection, and that this detoxification occurs through the heme-responsive expression of the heme activated transporter system (HatRT). Heme-dependent transcriptional activation of hatRT was discovered through an RNA-sequencing analysis of C. difficile grown in the presence of a sub-toxic concentration of heme. HatRT is comprised of a TetR family transcriptional regulator (hatR) and a major facilitator superfamily transporter (hatT). Strains inactivated for hatR or hatT are more sensitive to heme toxicity than wild-type. HatR binds heme, which relieves the repression of the hatRT operon, whereas HatT functions as a heme efflux pump. In a murine model of CDI, a strain inactivated for hatT displayed lower pathogenicity in a toxin-independent manner. Taken together, these data suggest that HatR senses intracellular heme concentrations leading to increased expression of the hatRT operon and subsequent heme efflux by HatT during infection. These results describe a mechanism employed by C. difficile to relieve heme toxicity within the host, and set the stage for the development of therapeutic interventions to target this bacterial-specific system.
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Affiliation(s)
- Reece J. Knippel
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Joseph P. Zackular
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Jessica L. Moore
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States of America
| | - Arianna I. Celis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States of America
| | - Andy Weiss
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - M. Kay Washington
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Jennifer L. DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States of America
| | - Richard M. Caprioli
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
| | - Eric P. Skaar
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America
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24
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Dos Santos PT, Menendez-Gil P, Sabharwal D, Christensen JH, Brunhede MZ, Lillebæk EMS, Kallipolitis BH. The Small Regulatory RNAs LhrC1-5 Contribute to the Response of Listeria monocytogenes to Heme Toxicity. Front Microbiol 2018; 9:599. [PMID: 29636750 PMCID: PMC5880928 DOI: 10.3389/fmicb.2018.00599] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/15/2018] [Indexed: 11/29/2022] Open
Abstract
The LhrC family of small regulatory RNAs (sRNAs) is known to be induced when the foodborne pathogen Listeria monocytogenes is exposed to infection-relevant conditions, such as human blood. Here we demonstrate that excess heme, the core component of hemoglobin in blood, leads to a strong induction of the LhrC family members LhrC1–5. The heme-dependent activation of lhrC1–5 relies on the response regulator LisR, which is known to play a role in virulence and stress tolerance. Importantly, our studies revealed that LhrC1–5 and LisR contribute to the adaptation of L. monocytogenes to excess heme. Regarding the regulatory function of the sRNAs, we demonstrate that LhrC1–5 act to down-regulate the expression of known LhrC target genes under heme-rich conditions: oppA, tcsA, and lapB, encoding surface exposed proteins with virulence functions. These genes were originally identified as targets for LhrC-mediated control under cell envelope stress conditions, suggesting a link between the response to heme toxicity and cell envelope stress in L. monocytogenes. We also investigated the role of LhrC1–5 in controlling the expression of genes involved in heme uptake and utilization: lmo2186 and lmo2185, encoding the heme-binding proteins Hbp1 and Hbp2, respectively, and lmo0484, encoding a heme oxygenase-like protein. Using in vitro binding assays, we demonstrated that the LhrC family member LhrC4 interacts with mRNAs encoded from lmo2186, lmo2185, and lmo0484. For lmo0484, we furthermore show that LhrC4 uses a CU-rich loop for basepairing to the AG-rich Shine–Dalgarno region of the mRNA. The presence of a link between the response to heme toxicity and cell envelope stress was further underlined by the observation that LhrC1–5 down-regulate the expression of lmo0484 in response to the cell wall-acting antibiotic cefuroxime. Collectively, this study suggests a role for the LisR-regulated sRNAs LhrC1–5 in a coordinated response to excess heme and cell envelope stress in L. monocytogenes.
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Affiliation(s)
- Patrícia T Dos Santos
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Pilar Menendez-Gil
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Dharmesh Sabharwal
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jens-Henrik Christensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Maja Z Brunhede
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Eva M S Lillebæk
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Birgitte H Kallipolitis
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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25
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Keppel M, Davoudi E, Gätgens C, Frunzke J. Membrane Topology and Heme Binding of the Histidine Kinases HrrS and ChrS in Corynebacterium glutamicum. Front Microbiol 2018; 9:183. [PMID: 29479345 PMCID: PMC5812335 DOI: 10.3389/fmicb.2018.00183] [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] [Received: 12/11/2017] [Accepted: 01/26/2018] [Indexed: 01/11/2023] Open
Abstract
The HrrSA and the ChrSA two-component systems play a central role in the coordination of heme homeostasis in the Gram-positive soil bacterium Corynebacterium glutamicum and the prominent pathogen Corynebacterium diphtheriae, both members of the Corynebacteriaceae. In this study, we have performed a comparative analysis of the membrane topology and heme-binding characteristics of the histidine kinases HrrS and ChrS of C. glutamicum. While the cytoplasmic catalytic domains are highly conserved between HrrS and ChrS, the N-terminal sensing parts share only minor sequence similarity. PhoA and LacZ fusions of the N-terminal sensor domains of HrrS and ChrS revealed that both proteins are embedded into the cytoplasmic membrane via six α-helices. Although the overall membrane topology appeared to be conserved, target gene profiling indicated a higher sensitivity of the ChrS system to low heme levels (< 1 μM). In vitro, solubilized and purified full-length proteins bound heme in a 1:1 stoichiometry per monomer. Alanine-scanning of conserved amino acid residues in the N-terminal sensor domain revealed three aromatic residues (Y112, F115, and F118), which apparently contribute to heme binding of HrrS. Exchange of either one or all three residues resulted in an almost abolished heme binding of HrrS in vitro. In contrast, ChrS mutants only displayed a red shift of the soret band from 406 to 418 nm suggesting an altered set of ligands in the triple mutant. In line with target gene profiling, these in vitro studies suggest distinct differences in the heme-protein interface of HrrS and ChrS. Since the membrane topology mapping displayed no extensive loop regions and alanine-scanning revealed potential heme-binding residues in α-helix number four, we propose an intramembrane sensing mechanism for both proteins. Overall, we present a first comparative analysis of the ChrS and HrrS kinases functioning as transient heme sensors in the Corynebacteriaceae.
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Affiliation(s)
- Marc Keppel
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
| | - Eva Davoudi
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
| | - Cornelia Gätgens
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
| | - Julia Frunzke
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
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26
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Choby JE, Grunenwald CM, Celis AI, Gerdes SY, DuBois JL, Skaar EP. Staphylococcus aureus HemX Modulates Glutamyl-tRNA Reductase Abundance To Regulate Heme Biosynthesis. mBio 2018; 9:e02287-17. [PMID: 29437922 PMCID: PMC5801465 DOI: 10.1128/mbio.02287-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 01/08/2018] [Indexed: 12/30/2022] Open
Abstract
Staphylococcus aureus is responsible for a significant amount of devastating disease. Its ability to colonize the host and cause infection is supported by a variety of proteins that are dependent on the cofactor heme. Heme is a porphyrin used broadly across kingdoms and is synthesized de novo from common cellular precursors and iron. While heme is critical to bacterial physiology, it is also toxic in high concentrations, requiring that organisms encode regulatory processes to control heme homeostasis. In this work, we describe a posttranscriptional regulatory strategy in S. aureus heme biosynthesis. The first committed enzyme in the S. aureus heme biosynthetic pathway, glutamyl-tRNA reductase (GtrR), is regulated by heme abundance and the integral membrane protein HemX. GtrR abundance increases dramatically in response to heme deficiency, suggesting a mechanism by which S. aureus responds to the need to increase heme synthesis. Additionally, HemX is required to maintain low levels of GtrR in heme-proficient cells, and inactivation of hemX leads to increased heme synthesis. Excess heme synthesis in a ΔhemX mutant activates the staphylococcal heme stress response, suggesting that regulation of heme synthesis is critical to reduce self-imposed heme toxicity. Analysis of diverse organisms indicates that HemX is widely conserved among heme-synthesizing bacteria, suggesting that HemX is a common factor involved in the regulation of GtrR abundance. Together, this work demonstrates that S. aureus regulates heme synthesis by modulating GtrR abundance in response to heme deficiency and through the activity of the broadly conserved HemX.IMPORTANCEStaphylococcus aureus is a leading cause of skin and soft tissue infections, endocarditis, bacteremia, and osteomyelitis, making it a critical health care concern. Development of new antimicrobials against S. aureus requires knowledge of the physiology that supports this organism's pathogenesis. One component of staphylococcal physiology that contributes to growth and virulence is heme. Heme is a widely utilized cofactor that enables diverse chemical reactions across many enzyme families. S. aureus relies on many critical heme-dependent proteins and is sensitive to excess heme toxicity, suggesting S. aureus must maintain proper intracellular heme homeostasis. Because S. aureus provides heme for heme-dependent enzymes via synthesis from common precursors, we hypothesized that regulation of heme synthesis is one mechanism to maintain heme homeostasis. In this study, we identify that S. aureus posttranscriptionally regulates heme synthesis by restraining abundance of the first heme biosynthetic enzyme, GtrR, via heme and the broadly conserved membrane protein HemX.
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Affiliation(s)
- Jacob E Choby
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Graduate Program in Microbiology & Immunology, Vanderbilt University, Nashville, Tennessee, USA
| | - Caroline M Grunenwald
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Arianna I Celis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | | | - Jennifer L DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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27
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Antibacterial photosensitization through activation of coproporphyrinogen oxidase. Proc Natl Acad Sci U S A 2017; 114:E6652-E6659. [PMID: 28739897 DOI: 10.1073/pnas.1700469114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Gram-positive bacteria cause the majority of skin and soft tissue infections (SSTIs), resulting in the most common reason for clinic visits in the United States. Recently, it was discovered that Gram-positive pathogens use a unique heme biosynthesis pathway, which implicates this pathway as a target for development of antibacterial therapies. We report here the identification of a small-molecule activator of coproporphyrinogen oxidase (CgoX) from Gram-positive bacteria, an enzyme essential for heme biosynthesis. Activation of CgoX induces accumulation of coproporphyrin III and leads to photosensitization of Gram-positive pathogens. In combination with light, CgoX activation reduces bacterial burden in murine models of SSTI. Thus, small-molecule activation of CgoX represents an effective strategy for the development of light-based antimicrobial therapies.
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28
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Gupta V, Chaudhary N, Aggarwal S, Adlakha N, Gulati P, Bhatnagar R. Functional analysis of BAS2108-2109 two component system: Evidence for protease regulation in Bacillus anthracis. Int J Biochem Cell Biol 2017; 89:71-84. [PMID: 28602714 DOI: 10.1016/j.biocel.2017.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/01/2017] [Accepted: 06/03/2017] [Indexed: 01/18/2023]
Abstract
BACKGROUND Bacillus anthracis (BA) is a major bioterrorism concern which has evolved complex regulatory mechanisms for its virulence factors. Secreted proteases play an imperative role in the pathogenesis of BA, however their regulation remains elusive. Two component systems (TCS) are often employed by bacteria to sense and adapt to the environmental perturbations. In several pathogens, TCS are commonly associated with the regulation of virulence factors including proteases. The genome of BA encodes 41 TCS pairs, however, the role of any TCS in regulation of its proteases is not known. PRINCIPAL FINDINGS The study established BAS2108-2109 as a prototypical TCS where BAS2108 functions as a histidine kinase and BAS2109 as the response regulator. The expression of BAS2109 was found to be elevated under host simulated conditions and in pellicle forming cells. Electrophoretic mobility shift assay (EMSA) and lacZ reporter assay revealed positive autoregulation of the BAS2108-2109 operon by BAS2109. Collective analysis of ANS assay and EMSA demonstrated Lys167, Thr179 and Thr182 residues are crucial for the DNA binding activity of BAS2109. EMSA analysis further highlighted BAS2109 as the transcriptional regulator for different genes of BA, particularly proteases. Upregulation of proteases in BA overexpressing BAS2109 further strengthen its role in protease regulation. SIGNIFICANCE This is the first report to identify a TCS pair for its role in the regulation of proteases of BA. Importance of proteases in the pathogenesis of BA is well documented, therefore, studying the regulatory networks governing their expression will help in identification of new drug targets.
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Affiliation(s)
- Vatika Gupta
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India; Medical Microbiology and Bioprocess Technology Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Neha Chaudhary
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Somya Aggarwal
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Nidhi Adlakha
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Pooja Gulati
- Medical Microbiology and Bioprocess Technology Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India.
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29
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Visualization of the role of host heme on the virulence of the heme auxotroph Streptococcus agalactiae. Sci Rep 2017; 7:40435. [PMID: 28091535 PMCID: PMC5238366 DOI: 10.1038/srep40435] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 12/06/2016] [Indexed: 12/21/2022] Open
Abstract
Heme is essential for several cellular key functions but is also toxic. Whereas most bacterial pathogens utilize heme as a metabolic cofactor and iron source, the impact of host heme during bacterial infection remains elusive. The opportunist pathogen Streptococcus agalactiae does not synthesize heme but still uses it to activate a respiration metabolism. Concomitantly, heme toxicity is mainly controlled by the HrtBA efflux transporter. Here we investigate how S. agalactiae manages heme toxicity versus benefits in the living host. Using bioluminescent bacteria and heme-responsive reporters for in vivo imaging, we show that the capacity of S. agalactiae to overcome heme toxicity is required for successful infection, particularly in blood-rich organs. Host heme is simultaneously required, as visualized by a generalized infection defect of a respiration-negative mutant. In S. agalactiae, HrtBA expression responds to an intracellular heme signal via activation of the two-component system HssRS. A hssRS promoter-driven intracellular luminescent heme sensor was designed to identify host compartments that supply S. agalactiae with heme. S. agalactiae acquires heme in heart, kidneys, and liver, but not in the brain. We conclude that S. agalactiae response to heme is organ-dependent, and its efflux may be particularly relevant in late stages of infection.
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30
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Guckes KR, Breland EJ, Zhang EW, Hanks SC, Gill NK, Algood HMS, Schmitz JE, Stratton CW, Hadjifrangiskou M. Signaling by two-component system noncognate partners promotes intrinsic tolerance to polymyxin B in uropathogenic Escherichia coli. Sci Signal 2017; 10:10/461/eaag1775. [PMID: 28074004 PMCID: PMC5677524 DOI: 10.1126/scisignal.aag1775] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bacteria use two-component systems (TCSs) to react appropriately to environmental stimuli. Typical TCSs comprise a sensor histidine kinase that acts as a receptor coupled to a partner response regulator that coordinates changes in bacterial behavior, often through its activity as a transcriptional regulator. TCS interactions are typically confined to cognate pairs of histidine kinases and response regulators. We describe two distinct TCSs in uropathogenic Escherichia coli (UPEC) that interact to mediate a response to ferric iron. The PmrAB and QseBC TCSs were both required for proper transcriptional response to ferric iron. Ferric iron induced the histidine kinase PmrB to phosphotransfer to both its cognate response regulator PmrA and the noncognate response regulator QseB, leading to transcriptional responses coordinated by both regulators. Pretreatment of the UPEC strain UTI89 with ferric iron led to increased resistance to polymyxin B that required both PmrA and QseB. Similarly, pretreatment of several UPEC isolates with ferric iron increased tolerance to polymyxin B. This study defines physiologically relevant cross talk between TCSs in a bacterial pathogen and provides a potential mechanism for antibiotic resistance of some strains of UPEC.
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Affiliation(s)
- Kirsten R Guckes
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Erin J Breland
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ellisa W Zhang
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | | | - Holly M S Algood
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Veterans Affairs Tennessee Valley Healthcare Services, Nashville, TN 37212, USA
| | - Jonathan E Schmitz
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Charles W Stratton
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Maria Hadjifrangiskou
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA. .,Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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31
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Abstract
Transition metals are required trace elements for all forms of life. Due to their unique inorganic and redox properties, transition metals serve as cofactors for enzymes and other proteins. In bacterial pathogenesis, the vertebrate host represents a rich source of nutrient metals, and bacteria have evolved diverse metal acquisition strategies. Host metal homeostasis changes dramatically in response to bacterial infections, including production of metal sequestering proteins and the bombardment of bacteria with toxic levels of metals. In response, bacteria have evolved systems to subvert metal sequestration and toxicity. The coevolution of hosts and their bacterial pathogens in the battle for metals has uncovered emerging paradigms in social microbiology, rapid evolution, host specificity, and metal homeostasis across domains. This review focuses on recent advances and open questions in our understanding of the complex role of transition metals at the host-pathogen interface.
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Affiliation(s)
- Lauren D Palmer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37212;
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37212;
- Tennessee Valley Healthcare System, US Department of Veterans Affairs, Nashville, Tennessee 37212
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32
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Choby JE, Skaar EP. Heme Synthesis and Acquisition in Bacterial Pathogens. J Mol Biol 2016; 428:3408-28. [PMID: 27019298 PMCID: PMC5125930 DOI: 10.1016/j.jmb.2016.03.018] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis.
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Affiliation(s)
- Jacob E Choby
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA; Tennessee Valley Healthcare System, U.S. Department of Veterans Affairs, Nashville, TN, USA.
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33
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Surdel MC, Dutter BF, Sulikowski GA, Skaar EP. Bacterial Nitric Oxide Synthase Is Required for the Staphylococcus aureus Response to Heme Stress. ACS Infect Dis 2016; 2:572-8. [PMID: 27626297 DOI: 10.1021/acsinfecdis.6b00081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Staphylococcus aureus is a pathogen that causes significant morbidity and mortality worldwide. Within the vertebrate host, S. aureus requires heme as a nutrient iron source and as a cofactor for multiple cellular processes. Although required for pathogenesis, excess heme is toxic. S. aureus employs a two-component system, the heme sensor system (HssRS), to sense and protect against heme toxicity. Upon activation, HssRS induces the expression of the heme-regulated transporter (HrtAB), an efflux pump that alleviates heme toxicity. The ability to sense and respond to heme is critical for the pathogenesis of numerous Gram-positive organisms, yet the mechanism of heme sensing remains unknown. Compound '3981 was identified in a high-throughput screen as an activator of staphylococcal HssRS that triggers HssRS independently of heme accumulation. '3981 is toxic to S. aureus; however, derivatives of '3981 were synthesized that lack toxicity while retaining HssRS activation, enabling the interrogation of the heme stress response without confounding toxic effects of the parent molecule. Using '3981 derivatives as probes of the heme stress response, numerous genes required for '3981-induced activation of HssRS were uncovered. Specifically, multiple genes involved in the production of nitric oxide were identified, including the gene encoding bacterial nitric oxide synthase (bNOS). bNOS protects S. aureus from oxidative stress imposed by heme. Taken together, this work identifies bNOS as crucial for the S. aureus heme stress response, providing evidence that nitric oxide synthesis and heme sensing are intertwined.
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Affiliation(s)
- Matthew C. Surdel
- Department of Pathology, Microbiology,
and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Brendan F. Dutter
- Department of Chemistry, Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Gary A. Sulikowski
- Department of Chemistry, Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Eric P. Skaar
- Department of Pathology, Microbiology,
and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
- Tennessee
Valley Healthcare Systems, U.S. Department of Veterans Affairs, Nashville, Tennessee 37212, United States
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Hayrapetyan H, Siezen R, Abee T, Nierop Groot M. Comparative Genomics of Iron-Transporting Systems in Bacillus cereus Strains and Impact of Iron Sources on Growth and Biofilm Formation. Front Microbiol 2016; 7:842. [PMID: 27375568 PMCID: PMC4896950 DOI: 10.3389/fmicb.2016.00842] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/20/2016] [Indexed: 12/18/2022] Open
Abstract
Iron is an important element for bacterial viability, however it is not readily available in most environments. We studied the ability of 20 undomesticated food isolates of Bacillus cereus and two reference strains for capacity to use different (complex) iron sources for growth and biofilm formation. Studies were performed in media containing the iron scavenger 2,2-Bipyridine. Transcriptome analysis using B. cereus ATCC 10987 indeed showed upregulation of predicted iron transporters in the presence of 2,2-Bipyridine, confirming that iron was depleted upon its addition. Next, the impact of iron sources on growth performance of the 22 strains was assessed and correlations between growth stimulation and presence of putative iron transporter systems in the genome sequences were analyzed. All 22 strains effectively used Fe citrate and FeCl3 for growth, and possessed genes for biosynthesis of the siderophore bacillibactin, whereas seven strains lacked genes for synthesis of petrobactin. Hemoglobin could be used by all strains with the exception of one strain that lacked functional petrobactin and IlsA systems. Hemin could be used by the majority of the tested strains (19 of 22). Notably, transferrin, ferritin, and lactoferrin were not commonly used by B. cereus for growth, as these iron sources could be used by 6, 3, and 2 strains, respectively. Furthermore, biofilm formation was found to be affected by the type of iron source used, including stimulation of biofilms at liquid-air interphase (FeCl3 and Fe citrate) and formation of submerged type biofilms (hemin and lactoferrin). Our results show strain variability in the genome-encoded repertoire of iron-transporting systems and differences in efficacy to use complex iron sources for growth and biofilm formation. These features may affect B. cereus survival and persistence in specific niches.
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Affiliation(s)
- Hasmik Hayrapetyan
- Laboratory of Food Microbiology, Wageningen UniversityWageningen, Netherlands; Top Institute of Food and NutritionWageningen, Netherlands
| | - Roland Siezen
- Top Institute of Food and NutritionWageningen, Netherlands; Microbial Bioinformatics, NIZOEde, Netherlands; Center for Molecular and Biomolecular Informatics, Radboud University Medical CentreNijmegen, Netherlands
| | - Tjakko Abee
- Laboratory of Food Microbiology, Wageningen UniversityWageningen, Netherlands; Top Institute of Food and NutritionWageningen, Netherlands
| | - Masja Nierop Groot
- Top Institute of Food and NutritionWageningen, Netherlands; Wageningen UR Food and Biobased ResearchWageningen, Netherlands
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Sachla AJ, Eichenbaum Z. The GAS PefCD exporter is a MDR system that confers resistance to heme and structurally diverse compounds. BMC Microbiol 2016; 16:68. [PMID: 27095127 PMCID: PMC4837585 DOI: 10.1186/s12866-016-0687-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 04/13/2016] [Indexed: 11/13/2022] Open
Abstract
Background Group A streptococcus (GAS) is the etiological agent of a variety of local and invasive infections as well as post-infection complications in humans. This β-hemolytic bacterium encounters environmental heme in vivo in a concentration that depends on the infection type and stage. While heme is a noxious molecule, the regulation of cellular heme levels and toxicity is underappreciated in GAS. We previously reported that heme induces three GAS genes that are similar to the pefRCD (porphyrin regulated efflux) genes from group B streptococcus. Here, we investigate the contributions of the GAS pef genes to heme management and physiology. Results In silico analysis revealed that the PefCD proteins entail a Class-1 ABC-type transporter with homology to selected MDR systems from Gram-positive bacteria. RT-PCR experiments confirmed that the pefRCD genes are transcribed to polycistronic mRNA and that a pefC insertion inactivation mutant lost the expression of both pefC and pefD genes. This mutant was hypersensitive to heme, exhibiting significant growth inhibition already in the presence of 1 μM heme. In addition, the pefC mutant was more sensitive to several drugs and nucleic acid dyes and demonstrated higher cellular accumulation of heme in comparison with the wild type and the complemented strains. Finally, the absence of the PefCD transporter potentiated the damaging effects of heme on GAS building blocks including lipids and DNA. Conclusion We show here that in GAS, the pefCD genes encode a multi-drug efflux system that allows the bacterium to circumvent the challenges imposed by labile heme. This is the first heme resistance machinery described in GAS.
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Affiliation(s)
- Ankita J Sachla
- Department of Biology, College of Arts and Sciences, Georgia State University, P.O. Box 4010, Atlanta, GA, 30302-4010, USA
| | - Zehava Eichenbaum
- Department of Biology, College of Arts and Sciences, Georgia State University, P.O. Box 4010, Atlanta, GA, 30302-4010, USA.
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Schmidt RM, Carter MM, Chu ML, Latario CJ, Stadler SK, Stauff DL. Heme sensing in Bacillus thuringiensis: a supplementary HssRS-regulated heme resistance system. FEMS Microbiol Lett 2016; 363:fnw076. [PMID: 27030728 DOI: 10.1093/femsle/fnw076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2016] [Indexed: 12/16/2022] Open
Abstract
Several Gram-positive pathogens scavenge host-derived heme to satisfy their nutritional iron requirement. However, heme is a toxic molecule capable of damaging the bacterial cell. Gram-positive pathogens within the phylum Firmicutes overcome heme toxicity by sensing heme through HssRS, a two-component system that regulates the heme detoxification transporter HrtAB. Here we show that heme sensing by HssRS and heme detoxification by HrtAB occur in the insect pathogen Bacillus thuringiensis We find that in B. thuringiensis, HssRS directly regulates an operon, hrmXY, encoding hypothetical membrane proteins that are not found in other Firmicutes with characterized HssRS and HrtAB systems. This novel HssRS-regulated operon or its orthologs BMB171_c3178 and BMB171_c3330 are required for maximal heme resistance. Furthermore, the activity of HrmXY is not dependent on expression of HrtAB. These results suggest that B. thuringiensis senses heme through HssRS and induces expression of separate membrane-localized systems capable of overcoming different aspects of heme toxicity.
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Affiliation(s)
- Rachel M Schmidt
- Department of Biology, Grove City College, 100 Campus Drive, Grove City, PA 16127, USA
| | - Micaela M Carter
- Department of Biology, Grove City College, 100 Campus Drive, Grove City, PA 16127, USA
| | - Michelle L Chu
- Department of Biology, Grove City College, 100 Campus Drive, Grove City, PA 16127, USA
| | - Casey J Latario
- Department of Biology, Grove City College, 100 Campus Drive, Grove City, PA 16127, USA
| | - Sarah K Stadler
- Department of Biology, Grove City College, 100 Campus Drive, Grove City, PA 16127, USA
| | - Devin L Stauff
- Department of Biology, Grove City College, 100 Campus Drive, Grove City, PA 16127, USA
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Mullins EA, Shi R, Parsons ZD, Yuen PK, David SS, Igarashi Y, Eichman BF. The DNA glycosylase AlkD uses a non-base-flipping mechanism to excise bulky lesions. Nature 2015; 527:254-8. [PMID: 26524531 DOI: 10.1038/nature15728] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/18/2015] [Indexed: 01/10/2023]
Abstract
Threats to genomic integrity arising from DNA damage are mitigated by DNA glycosylases, which initiate the base excision repair pathway by locating and excising aberrant nucleobases. How these enzymes find small modifications within the genome is a current area of intensive research. A hallmark of these and other DNA repair enzymes is their use of base flipping to sequester modified nucleotides from the DNA helix and into an active site pocket. Consequently, base flipping is generally regarded as an essential aspect of lesion recognition and a necessary precursor to base excision. Here we present the first, to our knowledge, DNA glycosylase mechanism that does not require base flipping for either binding or catalysis. Using the DNA glycosylase AlkD from Bacillus cereus, we crystallographically monitored excision of an alkylpurine substrate as a function of time, and reconstructed the steps along the reaction coordinate through structures representing substrate, intermediate and product complexes. Instead of directly interacting with the damaged nucleobase, AlkD recognizes aberrant base pairs through interactions with the phosphoribose backbone, while the lesion remains stacked in the DNA duplex. Quantum mechanical calculations revealed that these contacts include catalytic charge-dipole and CH-π interactions that preferentially stabilize the transition state. We show in vitro and in vivo how this unique means of recognition and catalysis enables AlkD to repair large adducts formed by yatakemycin, a member of the duocarmycin family of antimicrobial natural products exploited in bacterial warfare and chemotherapeutic trials. Bulky adducts of this or any type are not excised by DNA glycosylases that use a traditional base-flipping mechanism. Hence, these findings represent a new model for DNA repair and provide insights into catalysis of base excision.
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Affiliation(s)
- Elwood A Mullins
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Rongxin Shi
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Zachary D Parsons
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Philip K Yuen
- Department of Chemistry, University of California, Davis, California 95616, USA
| | - Sheila S David
- Department of Chemistry, University of California, Davis, California 95616, USA
| | - Yasuhiro Igarashi
- Biotechnology Research Center, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan
| | - Brandt F Eichman
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
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Nobles CL, Clark JR, Green SI, Maresso AW. A dual component heme biosensor that integrates heme transport and synthesis in bacteria. J Microbiol Methods 2015; 118:7-17. [PMID: 26253803 DOI: 10.1016/j.mimet.2015.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/09/2015] [Accepted: 07/09/2015] [Indexed: 01/28/2023]
Abstract
Bacterial pathogens acquire host iron to power cellular processes and replication. Heme, an iron-containing cofactor bound to hemoglobin, is scavenged by bacterial proteins to attain iron. Methods to measure intracellular heme are laborious, involve complex chemistry, or require radioactivity. Such drawbacks limit the study of the mechanistic steps of heme transport and breakdown. Hypothesizing heme homeostasis could be measured with fluorescent methods, we coupled the conversion of heme to biliverdin IXα (a product of heme catabolism) by heme oxygenase 1 (HO1) with the production of near-infrared light upon binding this verdin by infrared fluorescent protein (IFP1.4). The resultant heme sensor, IFP-HO1, was fluorescent in pathogenic E. coli exposed to heme but not in the absence of the heme transporter ChuA and membrane coupling protein TonB, thereby validating their long-standing proposed role in heme uptake. Fluorescence was abolished in a strain lacking hemE, the central gene in the heme biosynthetic pathway, but stimulated by iron, signifying the sensor reports on intracellular heme production. Finally, an invasive strain of E. coli harboring the sensor was fluorescent during an active infection. This work will allow researchers to expand the molecular toolbox used to study heme and iron acquisition in culture and during infection.
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Affiliation(s)
- Christopher L Nobles
- Molecular Virology and Microbiology Department, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Justin R Clark
- Molecular Virology and Microbiology Department, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Sabrina I Green
- Molecular Virology and Microbiology Department, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Anthony W Maresso
- Molecular Virology and Microbiology Department, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
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Bacillus anthracis Overcomes an Amino Acid Auxotrophy by Cleaving Host Serum Proteins. J Bacteriol 2015; 197:2400-11. [PMID: 25962917 DOI: 10.1128/jb.00073-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/21/2015] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Bacteria sustain an infection by acquiring nutrients from the host to support replication. The host sequesters these nutrients as a growth-restricting strategy, a concept termed "nutritional immunity." Historically, the study of nutritional immunity has centered on iron uptake because many bacteria target hemoglobin, an abundant circulating protein, as an iron source. Left unresolved are the mechanisms that bacteria use to attain other nutrients from host sources, including amino acids. We employed a novel medium designed to mimic the chemical composition of human serum, and we show here that Bacillus anthracis, the causative agent of anthrax disease, proteolyzes human hemoglobin to liberate essential amino acids which enhance its growth. This property can be traced to the actions of InhA1, a secreted metalloprotease, and extends to at least three other serum proteins, including serum albumin. The results suggest that we must also consider proteolysis of key host proteins to be a way for bacterial pathogens to attain essential nutrients, and we provide an experimental framework to determine the host and bacterial factors involved in this process. IMPORTANCE The mechanisms by which bacterial pathogens acquire nutrients during infection are poorly understood. Here we used a novel defined medium that approximates the chemical composition of human blood serum, blood serum mimic (BSM), to better model the nutritional environment that pathogens encounter during bacteremia. Removing essential amino acids from BSM revealed that two of the most abundant proteins in blood-hemoglobin and serum albumin-can satiate the amino acid requirement for Bacillus anthracis, the causative agent of anthrax. We further demonstrate that hemoglobin is proteolyzed by the secreted protease InhA1. These studies highlight that common blood proteins can be a nutrient source for bacteria. They also challenge the historical view that hemoglobin is solely an iron source for bacterial pathogens.
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40
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Muraki N, Kitatsuji C, Aono S. A new biological function of heme as a signaling molecule. J PORPHYR PHTHALOCYA 2015. [DOI: 10.1142/s1088424614501090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This mini-review presents a recent development of a new function of heme as a signaling molecule especially in the regulation of gene expression. Heme is biosynthesized as a prosthetic group for heme proteins, which play crucial roles for respiration, photosynthesis, and many other metabolic reactions. In some bacteria, exogenous heme molecules are used as a heme or an iron sources to be uptaken into cytoplasm. As free heme molecules are cytotoxic, the intracellular concentrations of biosynthesized or uptaken heme should be strictly controlled. In this mini-review, we summarize the biochemical and biophysical properties of the transcriptional regulators and heme-sensor proteins responsible for these regulatory systems to maintain heme homeostasis.
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Affiliation(s)
- Norifumi Muraki
- Okazaki Institute for Integrative Bioscience & Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Chihiro Kitatsuji
- Okazaki Institute for Integrative Bioscience & Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Shigetoshi Aono
- Okazaki Institute for Integrative Bioscience & Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
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Sachla AJ, Le Breton Y, Akhter F, McIver KS, Eichenbaum Z. The crimson conundrum: heme toxicity and tolerance in GAS. Front Cell Infect Microbiol 2014; 4:159. [PMID: 25414836 PMCID: PMC4220732 DOI: 10.3389/fcimb.2014.00159] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 10/17/2014] [Indexed: 01/16/2023] Open
Abstract
The massive erythrocyte lysis caused by the Group A Streptococcus (GAS) suggests that the β-hemolytic pathogen is likely to encounter free heme during the course of infection. In this study, we investigated GAS mechanisms for heme sensing and tolerance. We compared the minimal inhibitory concentration of heme among several isolates and established that excess heme is bacteriostatic and exposure to sub-lethal concentrations of heme resulted in noticeable damage to membrane lipids and proteins. Pre-exposure of the bacteria to 0.1 μM heme shortened the extended lag period that is otherwise observed when naive cells are inoculated into heme-containing medium, implying that GAS is able to adapt. The global response to heme exposure was determined using microarray analysis revealing a significant transcriptome shift that included 79 up regulated and 84 down regulated genes. Among other changes, the induction of stress-related chaperones and proteases, including groEL/ES (8x), the stress regulators spxA2 (5x) and ctsR (3x), as well as redox active enzymes were prominent. The heme stimulon also encompassed a number of regulatory proteins and two-component systems that are important for virulence. A three-gene cluster that is homologous to the pefRCD system of the Group B Streptococcus was also induced by heme. PefR, a MarR-like regulator, specifically binds heme with stoichiometry of 1:2 and protoporphyrin IX (PPIX) with stoichiometry of 1:1, implicating it is one of the GAS mediators to heme response. In summary, here we provide evidence that heme induces a broad stress response in GAS, and that its success as a pathogen relies on mechanisms for heme sensing, detoxification, and repair.
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Affiliation(s)
- Ankita J Sachla
- Department of Biology, College of Arts and Sciences, Georgia State University Atlanta, GA, USA
| | - Yoann Le Breton
- Department of Cell Biology and Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland College Park, MD, USA
| | - Fahmina Akhter
- Department of Biology, College of Arts and Sciences, Georgia State University Atlanta, GA, USA
| | - Kevin S McIver
- Department of Cell Biology and Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland College Park, MD, USA
| | - Zehava Eichenbaum
- Department of Biology, College of Arts and Sciences, Georgia State University Atlanta, GA, USA
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Joubert L, Derré-Bobillot A, Gaudu P, Gruss A, Lechardeur D. HrtBA and menaquinones control haem homeostasis inLactococcus lactis. Mol Microbiol 2014; 93:823-33. [DOI: 10.1111/mmi.12705] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Laetitia Joubert
- INRA; UMR1319 Micalis; F-78350 Jouy-en-Josas France
- AgroParisTech; UMR Micalis; F-78350 Jouy-en-Josas France
| | - Aurélie Derré-Bobillot
- INRA; UMR1319 Micalis; F-78350 Jouy-en-Josas France
- AgroParisTech; UMR Micalis; F-78350 Jouy-en-Josas France
| | - Philippe Gaudu
- INRA; UMR1319 Micalis; F-78350 Jouy-en-Josas France
- AgroParisTech; UMR Micalis; F-78350 Jouy-en-Josas France
| | - Alexandra Gruss
- INRA; UMR1319 Micalis; F-78350 Jouy-en-Josas France
- AgroParisTech; UMR Micalis; F-78350 Jouy-en-Josas France
| | - Delphine Lechardeur
- INRA; UMR1319 Micalis; F-78350 Jouy-en-Josas France
- AgroParisTech; UMR Micalis; F-78350 Jouy-en-Josas France
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Two-component system cross-regulation integrates Bacillus anthracis response to heme and cell envelope stress. PLoS Pathog 2014; 10:e1004044. [PMID: 24675902 PMCID: PMC3968170 DOI: 10.1371/journal.ppat.1004044] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 02/06/2014] [Indexed: 11/30/2022] Open
Abstract
Two-component signaling systems (TCSs) are one of the mechanisms that bacteria employ to sense and adapt to changes in the environment. A prototypical TCS functions as a phosphorelay from a membrane-bound sensor histidine kinase (HK) to a cytoplasmic response regulator (RR) that controls target gene expression. Despite significant homology in the signaling domains of HKs and RRs, TCSs are thought to typically function as linear systems with little to no cross-talk between non-cognate HK-RR pairs. Here we have identified several cell envelope acting compounds that stimulate a previously uncharacterized Bacillus anthracis TCS. Furthermore, this TCS cross-signals with the heme sensing TCS HssRS; therefore, we have named it HssRS interfacing TCS (HitRS). HssRS reciprocates cross-talk to HitRS, suggesting a link between heme toxicity and cell envelope stress. The signaling between HssRS and HitRS occurs in the parental B. anthracis strain; therefore, we classify HssRS-HitRS interactions as cross-regulation. Cross-talk between HssRS and HitRS occurs at both HK-RR and post-RR signaling junctions. Finally, HitRS also regulates a previously unstudied ABC transporter implicating this transporter in the response to cell envelope stress. This chemical biology approach to probing TCS signaling provides a new model for understanding how bacterial signaling networks are integrated to enable adaptation to complex environments such as those encountered during colonization of the vertebrate host. The vertebrate host is a hostile environment to microbes, where large variations in temperature, oxygen, and nutrient availability challenge microbial replication. In order to successfully infect vertebrates, pathogens must sense that they have entered their host and alter gene expression accordingly. One way bacteria adapt to their environment is by using two-component signaling systems (TCS), which are comprised of a signal sensor and a transcriptional regulator. The core signaling components of TCSs are conserved across the bacterial Kingdom; however, examples of interactions between two distinct TCS are extremely rare. Here we have probed how Bacillus anthracis, the causative agent of anthrax, adapts to life in the vertebrate host. The B. anthracis heme sensing TCS, HssRS, senses heme as a component of vertebrate blood and protects the bacteria from heme toxicity. We have identified a new TCS (HitRS), which is activated by compounds that alter the integrity of the cell envelope, and interacts with HssRS to coordinate a simultaneous response to both heme and cell envelope stress. This reciprocal HssRS-HitRS signaling is an unusual demonstration of bacterial signal cross-regulation and suggests that coordinating the response to heme and cell envelope stress is important for B. anthracis adaptation to the vertebrate host.
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Differential activation of Staphylococcus aureus heme detoxification machinery by heme analogues. J Bacteriol 2014; 196:1335-42. [PMID: 24443529 DOI: 10.1128/jb.01067-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The reactive nature of heme enables its use as an enzymatic cofactor while rendering excess heme toxic. The importance of heme detoxification machinery is highlighted by the presence of various types of these homeostatic systems in Gram-positive and Gram-negative microorganisms. A number of pathogens possess orthologs of the HssRS/HrtAB heme detoxification system, underscoring a potential role this system plays in the survival of bacteria in heme-rich environments such as the vertebrate host. In this work, we sought to determine the role of this system in protection against metalloporphyrin heme analogues identified by previous studies as antimicrobial agents. Our findings demonstrate that only toxic metalloporphyrins maximally activate expression of the Staphylococcus aureus heme detoxification system, suggesting that the sensing mechanism of HssRS might require a component of the associated toxicity rather than or in addition to the metalloporphyrin itself. We further establish that only a subset of toxic metalloporphyrins elicit the oxidative damage previously shown to be a significant component of heme toxicity whereas all toxic noniron metalloporphyrins inhibit bacterial respiration. Finally, we demonstrate that, despite the fact that toxic metalloporphyrin treatment induces expression of S. aureus heme detoxification machinery, the HrtAB heme export pump is unable to detoxify most of these molecules. The ineffectiveness of HrtAB against toxic heme analogues provides an explanation for their increased antimicrobial activity relative to heme. Additionally, these studies define the specificity of HssRS/HrtAB, which may provide future insight into the biochemical mechanisms of these systems.
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Dhiman A, Bhatnagar S, Kulshreshtha P, Bhatnagar R. Functional characterization of WalRK: A two-component signal transduction system from Bacillus anthracis. FEBS Open Bio 2014; 4:65-76. [PMID: 24490131 PMCID: PMC3907690 DOI: 10.1016/j.fob.2013.12.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/24/2013] [Accepted: 12/24/2013] [Indexed: 12/20/2022] Open
Abstract
Two-component signal transduction systems (TCS), consisting of a sensor histidine protein kinase and its cognate response regulator, are an important mode of environmental sensing in bacteria. Additionally, they have been found to regulate virulence determinants in several pathogens. Bacillus anthracis, the causative agent of anthrax and a bioterrorism agent, harbours 41 pairs of TCS. However, their role in its pathogenicity has remained largely unexplored. Here, we show that WalRK of B. anthracis forms a functional TCS which exhibits some species-specific functions. Biochemical studies showed that domain variants of WalK, the histidine kinase, exhibit classical properties of autophosphorylation and phosphotransfer to its cognate response regulator WalR. Interestingly, these domain variants also show phosphatase activity towards phosphorylated WalR, thereby making WalK a bifunctional histidine kinase/phosphatase. An in silico regulon determination approach, using a consensus binding sequence from Bacillus subtilis, provided a list of 30 genes that could form a putative WalR regulon in B. anthracis. Further, electrophoretic mobility shift assay was used to show direct binding of purified WalR to the upstream regions of three putative regulon candidates, an S-layer protein EA1, a cell division ABC transporter FtsE and a sporulation histidine kinase KinB3. Our work lends insight into the species-specific functions and mode of action of B. anthracis WalRK. WalRK forms a functional TCS in B. anthracis, expressed throughout the growth phase. WalK variants exhibit autophosphorylation and phosphotransfer to WalR. WalKc variants also show phosphatase activity towards phosphorylated WalR. A potential WalR regulon in B. anthracis was predicted in silico. DNA binding ability was demonstrated for WalR.
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Affiliation(s)
- Alisha Dhiman
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sonika Bhatnagar
- Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology, Dwarka, New Delhi 110078, India
| | - Parul Kulshreshtha
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
- Corresponding author. Tel.: +91 1126704079/1126742040; fax: +91 1126742040.
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Activation of heme biosynthesis by a small molecule that is toxic to fermenting Staphylococcus aureus. Proc Natl Acad Sci U S A 2013; 110:8206-11. [PMID: 23630262 DOI: 10.1073/pnas.1303674110] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus is a significant infectious threat to global public health. Acquisition or synthesis of heme is required for S. aureus to capture energy through respiration, but an excess of this critical cofactor is toxic to bacteria. S. aureus employs the heme sensor system (HssRS) to overcome heme toxicity; however, the mechanism of heme sensing is not defined. Here, we describe the identification of a small molecule activator of HssRS that induces endogenous heme biosynthesis by perturbing central metabolism. This molecule is toxic to fermenting S. aureus, including clinically relevant small colony variants. The utility of targeting fermenting bacteria is exemplified by the fact that this compound prevents the emergence of antibiotic resistance, enhances phagocyte killing, and reduces S. aureus pathogenesis. Not only is this small molecule a powerful tool for studying bacterial heme biosynthesis and central metabolism; it also establishes targeting of fermentation as a viable antibacterial strategy.
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Gruss A, Borezée-Durant E, Lechardeur D. Environmental heme utilization by heme-auxotrophic bacteria. Adv Microb Physiol 2013; 61:69-124. [PMID: 23046952 DOI: 10.1016/b978-0-12-394423-8.00003-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Heme, an iron-containing porphyrin, is the prosthetic group for numerous key cellular enzymatic and regulatory processes. Many bacteria encode the biosynthetic enzymes needed for autonomous heme production. Remarkably, however, numerous other bacteria lack a complete heme biosynthesis pathway, yet encode heme-requiring functions. For such heme-auxotrophic bacteria (HAB), heme or porphyrins must be captured from the environment. Functional studies, aided by genomic analyses, provide insight into the HAB lifestyle, how they acquire and manage heme, and the uses of heme that make it worthwhile, and sometimes necessary, to capture this bioactive molecule.
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Affiliation(s)
- Alexandra Gruss
- INRA, UMR1319 Micalis and AgroParisTech, UMR Micalis, Jouy-en-Josas, France
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Wakeman CA, Hammer ND, Stauff DL, Attia AS, Anzaldi LL, Dikalov SI, Calcutt MW, Skaar EP. Menaquinone biosynthesis potentiates haem toxicity in Staphylococcus aureus. Mol Microbiol 2012; 86:1376-92. [PMID: 23043465 DOI: 10.1111/mmi.12063] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2012] [Indexed: 02/06/2023]
Abstract
Staphylococcus aureus is a pathogen that infects multiple anatomical sites leading to a diverse array of diseases. Although vertebrates can restrict the growth of invading pathogens by sequestering iron within haem, S. aureus surmounts this challenge by employing high-affinity haem uptake systems. However, the presence of excess haem is highly toxic, necessitating tight regulation of haem levels. To overcome haem stress, S. aureus expresses the detoxification system HrtAB. In this work, a transposon screen was performed in the background of a haem-susceptible, HrtAB-deficient S. aureus strain to identify the substrate transported by this putative pump and the source of haem toxicity. While a recent report indicates that HrtAB exports haem itself, the haem-resistant mutants uncovered by the transposon selection enabled us to elucidate the cellular factors contributing to haem toxicity. All mutants identified in this screen inactivated the menaquinone (MK) biosynthesis pathway. Deletion of the final steps of this pathway revealed that quinone molecules localizing to the cell membrane potentiate haem-associated superoxide production and subsequent oxidative damage. These data suggest a model in which membrane-associated haem and quinone molecules form a redox cycle that continuously generates semiquinones and reduced haem, both of which react with atmospheric oxygen to produce superoxide.
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Affiliation(s)
- Catherine A Wakeman
- Department of Pathology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Heyer A, Gätgens C, Hentschel E, Kalinowski J, Bott M, Frunzke J. The two-component system ChrSA is crucial for haem tolerance and interferes with HrrSA in haem-dependent gene regulation in Corynebacterium glutamicum. MICROBIOLOGY-SGM 2012; 158:3020-3031. [PMID: 23038807 DOI: 10.1099/mic.0.062638-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We recently showed that the two-component system (TCS) HrrSA plays a central role in the control of haem homeostasis in the Gram-positive soil bacterium Corynebacterium glutamicum. Here, we characterized the function of another TCS of this organism, ChrSA, which exhibits significant sequence similarity to HrrSA, and provide evidence for cross-regulation of the two systems. In this study, ChrSA was shown to be crucial for haem resistance of C. glutamicum by activation of the putative haem-detoxifying ABC-transporter HrtBA in the presence of haem. Deletion of either hrtBA or chrSA resulted in a strongly increased sensitivity towards haem. DNA microarray analysis and gel retardation assays with the purified response regulator ChrA revealed that phosphorylated ChrA acts as an activator of hrtBA in the presence of haem. The haem oxygenase gene, hmuO, showed a decreased mRNA level in a chrSA deletion mutant but no significant binding of ChrA to the hmuO promoter was observed in vitro. In contrast, activation from P(hmuO) fused to eyfp was almost abolished in an hrrSA mutant, indicating that HrrSA is the dominant system for haem-dependent activation of hmuO in C. glutamicum. Remarkably, ChrA was also shown to bind to the hrrA promoter and to repress transcription of the paralogous response regulator, whereas chrSA itself seemed to be repressed by HrrA. These data suggest a close interplay of HrrSA and ChrSA at the level of transcription and emphasize ChrSA as a second TCS involved in haem-dependent gene regulation in C. glutamicum, besides HrrSA.
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Affiliation(s)
- Antonia Heyer
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, Germany
| | - Cornelia Gätgens
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, Germany
| | - Eva Hentschel
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, Germany
| | - Jörn Kalinowski
- Centrum für Biotechnologie, CeBiTec, Universität Bielefeld, Germany
| | - Michael Bott
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, Germany
| | - Julia Frunzke
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, Germany
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Juárez-Verdayes MA, González-Uribe PM, Peralta H, Rodríguez-Martínez S, Jan-Roblero J, Escamilla-Hernández R, Cancino-Diaz ME, Cancino-Diaz JC. Detection of hssS, hssR, hrtA, and hrtB genes and their expression by hemin in Staphylococcus epidermidis. Can J Microbiol 2012; 58:1063-72. [DOI: 10.1139/w2012-086] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Staphylococcus aureus employs a heme sensing system (HssR–HssS) and a heme-regulated transporter efflux pump (HrtA–HrtB) to avoid the accumulation of heme, which is toxic at high concentrations. The detoxification system to heme has not been studied in Staphylococcus epidermidis . In this work, the hssR, hssS, hrtA, and hrtB genes were detected, and their expression when stimulated by hemin in S. epidermidis was explored. In silico genomic analyses exhibited that the genetic organization of the hssRS and hrtAB genes was identical in 11 Staphylococcus species analyzed, including S. epidermidis. Slight variations were found in their syntenic regions. The predicted secondary structure of HrtAB proteins from these species was almost identical to these of S. aureus. Additionally, hrtAB promoter sequences of some species were analyzed, and 1 or 2 different nucleotide substitutions were found in the downstream motif. Concentrations of hemin above 5 µmol/L inhibited S. epidermidis growth. However, S. epidermidis that was pre-exposed to a subinhibitory hemin concentration (1 µmol/L) was able to grow when inoculated into medium containing above 5 µmol/L hemin. The expression levels of hrtA and hrtB genes in S. epidermidis exhibited a significant difference when they were stimulated with hemin. Our results suggest that the HrtAB could be involved in hemin detoxification of S. epidermidis.
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Affiliation(s)
| | | | - Humberto Peralta
- Functional Genomics of Prokaryotes Program, Centro de Ciencias Genómicas, Universidad Autónoma de México, Cuernavaca, Mor. Mexico
| | | | - Janet Jan-Roblero
- Microbiology Department, Escuela Nacional de Ciencias Biológicas-IPN, Mexico City, Mexico
| | | | - Mario E. Cancino-Diaz
- Immunology Department, Escuela Nacional de Ciencias Biológicas-IPN, Mexico City, Mexico
| | - Juan C. Cancino-Diaz
- Microbiology Department, Escuela Nacional de Ciencias Biológicas-IPN, Mexico City, Mexico
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