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Tomioka N, Tran P T, Aoki M, Takemura Y, Syutsubo K. Escherichia coli removal in down-flow hanging sponge reactors: insights from laboratory reactor studies. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2024; 59:295-304. [PMID: 39091064 DOI: 10.1080/10934529.2024.2384205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 07/18/2024] [Accepted: 07/20/2024] [Indexed: 08/04/2024]
Abstract
Down-flow hanging sponge (DHS) reactors, employed in domestic wastewater treatment, have demonstrated efficacy in eliminating Escherichia coli and other potentially pathogenic bacteria. The aim of this study was to elucidate the mechanism of removal of E. coli by employing a cube-shaped polyurethane sponge carrier within a compact hanging reactor. An E. coli removal experiment was conducted on this prepared sponge. Escherichia. coli level was found to decrease by more than 2 logs after passing through five nutrient-restricted DHS sponges. Conversely, a newly introduced sponge did not exhibit a comparable reduction in E. coli level. Furthermore, under conditions of optimal nutritional status, the reduction in E. coli level was limited to 0.5 logs, underscoring the crucial role of nutrient restriction in achieving effective elimination. Analysis of the sponge-associated bacterial community revealed the presence of a type VI secretion system (T6SS), a competitive mechanism observed in bacteria. This finding suggests that T6SS might play a pivotal role in contributing to the observed decline in E. coli level.
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Affiliation(s)
- Noriko Tomioka
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Thao Tran P
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
- School of Chemistry and Life Science, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Masataka Aoki
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Yasuyuki Takemura
- Department of Civil Engineering, National Institute of Technology (KOSEN), Wakayama College, Gobo, Japan
| | - Kazuaki Syutsubo
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
- Research Center of Water Environment Technology, School of Engineering, The University of Tokyo, Bunkyo-ku, Japan
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Jowsey W, Morris CP, Hall D, Sullivan J, Fagerlund R, Eto K, Solomon P, Mackay J, Bond C, Ramsay J, Ronson C. DUF2285 is a novel helix-turn-helix domain variant that orchestrates both activation and antiactivation of conjugative element transfer in proteobacteria. Nucleic Acids Res 2023; 51:6841-6856. [PMID: 37246713 PMCID: PMC10359603 DOI: 10.1093/nar/gkad457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/04/2023] [Accepted: 05/12/2023] [Indexed: 05/30/2023] Open
Abstract
Horizontal gene transfer is tightly regulated in bacteria. Often only a fraction of cells become donors even when regulation of horizontal transfer is coordinated at the cell population level by quorum sensing. Here, we reveal the widespread 'domain of unknown function' DUF2285 represents an 'extended-turn' variant of the helix-turn-helix domain that participates in both transcriptional activation and antiactivation to initiate or inhibit horizontal gene transfer. Transfer of the integrative and conjugative element ICEMlSymR7A is controlled by the DUF2285-containing transcriptional activator FseA. One side of the DUF2285 domain of FseA has a positively charged surface which is required for DNA binding, while the opposite side makes critical interdomain contacts with the N-terminal FseA DUF6499 domain. The QseM protein is an antiactivator of FseA and is composed of a DUF2285 domain with a negative surface charge. While QseM lacks the DUF6499 domain, it can bind the FseA DUF6499 domain and prevent transcriptional activation by FseA. DUF2285-domain proteins are encoded on mobile elements throughout the proteobacteria, suggesting regulation of gene transfer by DUF2285 domains is a widespread phenomenon. These findings provide a striking example of how antagonistic domain paralogues have evolved to provide robust molecular control over the initiation of horizontal gene transfer.
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Affiliation(s)
- William J Jowsey
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
| | - Calum R P Morris
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
| | - Drew A Hall
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - John T Sullivan
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
| | - Robert D Fagerlund
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
| | - Karina Y Eto
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Paul D Solomon
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Joel P Mackay
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Charles S Bond
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Joshua P Ramsay
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Clive W Ronson
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand
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Functional Analysis of EspM, an ESX-1-Associated Transcription Factor in Mycobacterium marinum. J Bacteriol 2022; 204:e0023322. [PMID: 36448785 PMCID: PMC9765225 DOI: 10.1128/jb.00233-22] [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] [Indexed: 12/03/2022] Open
Abstract
Pathogenic mycobacteria use the ESX-1 secretion system to escape the macrophage phagosome and survive infection. We demonstrated that the ESX-1 system is regulated by feedback control in Mycobacterium marinum, a nontuberculous pathogen and model for the human pathogen Mycobacterium tuberculosis. In the presence of a functional ESX-1 system, the WhiB6 transcription factor upregulates expression of ESX-1 substrate genes. In the absence of an assembled ESX-1 system, the conserved transcription factor, EspM, represses whiB6 expression by specifically binding the whiB6 promoter. Together, WhiB6 and EspM fine-tune the levels of ESX-1 substrates in response to the secretion system. The mechanisms underlying control of the ESX-1 system by EspM are unknown. Here, we conduct a structure and function analysis to investigate how EspM is regulated. Using biochemical approaches, we measured the formation of higher-order oligomers of EspM in vitro. We demonstrate that multimerization in vitro can be mediated through multiple domains of the EspM protein. Using a bacterial monohybrid system, we showed that EspM self-associates through multiple domains in Escherichia coli. Using this system, we performed a genetic screen to identify EspM variants that failed to self-associate. The screen yielded four EspM variants of interest, which we tested for activity in M. marinum. Our study revealed that the two helix-turn-helix domains are functionally distinct. Moreover, the helix bundle domain is required for wild-type multimerization in vitro. Our data support models where EspM monomers or hexamers contribute to the regulation of whiB6 expression. IMPORTANCE Pathogenic mycobacteria are bacteria that pose a large burden to human health globally. The ESX-1 secretion system is required for pathogenic mycobacteria to survive within and interact with the host. Proper function of the ESX-1 secretion system is achieved by tightly controlling the expression of secreted virulence factors, in part through transcriptional regulation. Here, we characterize the conserved transcription factor EspM, which regulates the expression of ESX-1 virulence factors. We define domains required for EspM to form multimers and bind DNA. These findings provide an initial characterization an ESX-1 transcription factor and provide insights into its mechanism of action.
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Allsopp LP, Collins ACZ, Hawkins E, Wood TE, Filloux A. RpoN/Sfa2-dependent activation of the Pseudomonas aeruginosa H2-T6SS and its cognate arsenal of antibacterial toxins. Nucleic Acids Res 2021; 50:227-243. [PMID: 34928327 PMCID: PMC8855297 DOI: 10.1093/nar/gkab1254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/26/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa uses three type six secretion systems
(H1-, H2- and H3-T6SS) to manipulate its environment, subvert host cells and for
microbial competition. These T6SS machines are loaded with a variety of
effectors/toxins, many being associated with a specific VgrG. How P.
aeruginosa transcriptionally coordinates the main T6SS clusters and
the multiple vgrG islands spread through the genome is unknown.
Here we show an unprecedented level of control with RsmA repressing most known
T6SS-related genes. Moreover, each of the H2- and H3-T6SS clusters encodes a
sigma factor activator (SFA) protein
called, Sfa2 and Sfa3, respectively. SFA proteins are enhancer binding proteins
necessary for the sigma factor RpoN. Using a combination of RNA-seq, ChIP-seq
and molecular biology approaches, we demonstrate that RpoN coordinates the T6SSs
of P. aeruginosa by activating the H2-T6SS but repressing the
H1- and H3-T6SS. Furthermore, RpoN and Sfa2 control the expression of the
H2-T6SS-linked VgrGs and their effector arsenal to enable very effective
interbacterial killing. Sfa2 is specific as Sfa3 from the H3-T6SS cannot
complement loss of Sfa2. Our study further delineates the regulatory mechanisms
that modulate the deployment of an arsenal of T6SS effectors likely enabling
P. aeruginosa to adapt to a range of environmental
conditions.
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Affiliation(s)
- Luke P Allsopp
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Alice C Z Collins
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Eleanor Hawkins
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - Thomas E Wood
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
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Cai R, Gao F, Pan J, Hao X, Yu Z, Qu Y, Li J, Wang D, Wang Y, Shen X, Liu X, Yang Y. The transcriptional regulator Zur regulates the expression of ZnuABC and T6SS4 in response to stresses in Yersinia pseudotuberculosis. Microbiol Res 2021; 249:126787. [PMID: 33991717 DOI: 10.1016/j.micres.2021.126787] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/28/2021] [Accepted: 05/07/2021] [Indexed: 01/21/2023]
Abstract
Zinc homeostasis is crucial for the development and stress resistance of bacteria in the environment. Serial zinc sensing transcriptional regulators, zinc transporters and zinc binding proteins were found to maintain the zinc homeostasis in bacteria. Zur is a zinc uptake regulator that is widely distributed in species, and ZnuABC, as well as the Type VI Secretion System (T6SS4) function in zinc acquisition. Here, we report that the regulator Zur inhibits the expression of the ZnuABC which inhibition could be eliminated at low zinc level, and upregulates the T6SS4 operon in Yersinia pseudotuberculosis to facilitate Zn2+ uptake and oxidative stress resistance. Zur regulates the expression of ZnuABC and T6SS4 by directly binding to their promoter regions. Zur senses the Zn2+ concentration and represses ZnuABC in a Zn2+-containing environment. Zur works as an auxiliary regular activator of T6SS4, facilitating oxidative stress resistance. This study revealed the dual function of regulator Zur on ZnuABC and T6SS4, and enriched the knowledge of Zn2+ homeostasis maintenance in Y. pseudotuberculosis.
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Affiliation(s)
- Ran Cai
- Beijing Capital Co., LTD, Beijing, 100044, China
| | - Fen Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Junfeng Pan
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Xinwei Hao
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Zonglan Yu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Yichen Qu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Jialin Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Dandan Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Yao Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Xingyu Liu
- General Research Institute for Nonferrous Metals, Beijing, 100088, China.
| | - Yantao Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, China.
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