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Park Y, Kim W, Cha Y, Kim M, Park W. Alleviation of H 2O 2 toxicity by extracellular catalases in the phycosphere of Microcystis aeruginosa. HARMFUL ALGAE 2024; 137:102680. [PMID: 39003030 DOI: 10.1016/j.hal.2024.102680] [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: 01/24/2024] [Revised: 05/20/2024] [Accepted: 06/16/2024] [Indexed: 07/15/2024]
Abstract
High levels of environmental H2O2 represent a threat to many freshwater bacterial species, including toxic-bloom-forming Microcystis aeruginosa, particularly under high-intensity light conditions. The highest extracellular catalase activity-possessing Pseudoduganella aquatica HC52 was chosen among 36 culturable symbiotic isolates from the phycosphere in freshly collected M. aeruginosa cells. A zymogram for catalase activity revealed the presence of only one extracellular catalase despite the four putative catalase genes (katA1, katA2, katE, and srpA) identified in the newly sequenced genome (∼6.8 Mb) of P. aquatica HC52. Analysis of secreted catalase using liquid chromatography-tandem mass spectrometry was identified as KatA1, which lacks a typical signal peptide, although the underlying mechanism for its secretion is unknown. The expression of secreted KatA1 appeared to be induced in the presence of H2O2. Proteomic analysis also confirmed the presence of KatA1 inside the outer membrane vesicles secreted by P. aquatica HC52 following exposure to H2O2. High light intensities (> 100 µmol m-2 s-1) are known to kill catalase-less axenic M. aeruginosa cells, but the present study found that the presence of P. aquatica cells supported the growth of M. aeruginosa, while the extracellular catalases in supernatant or purified form also sustained the growth of M. aeruginosa under the same conditions. Our results suggest that the extracellular catalase secreted by P. aquatica HC52 enhances the tolerance of M. aeruginosa to H2O2, thus promoting the formation of M. aeruginosa blooms under high light intensities.
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Affiliation(s)
- Yerim Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Wonjae Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Yeji Cha
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Minkyung Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea.
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Characterization of the oxidative stress response regulatory network in Bacteroides fragilis: An interaction between BmoR and OxyR regulons promotes abscess formation in a model of intra-abdominal infection. Anaerobe 2022; 78:102668. [DOI: 10.1016/j.anaerobe.2022.102668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 10/31/2022] [Accepted: 11/01/2022] [Indexed: 11/10/2022]
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Wang J, Liu J, Zhao Y, Sun M, Yu G, Fan J, Tian Y, Hu B. OxyR contributes to virulence of Acidovorax citrulli by regulating anti-oxidative stress and expression of flagellin FliC and type IV pili PilA. Front Microbiol 2022; 13:977281. [PMID: 36204623 PMCID: PMC9530317 DOI: 10.3389/fmicb.2022.977281] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
In many bacteria, OxyR acts as a transcriptional regulator that facilitates infection via degrading hydrogen peroxide (H2O2) generated by the host defense response. Previous studies showed that OxyR also plays an important role in regulating biofilm formation, cell motility, pili relate-genes expression, and surface polysaccharide production. However, the role of OxyR has not been determined in Acidovorax citrulli strain xjl12. In the current study, the qRT-PCR and western blot assays revealed that the expression level of oxyR was significantly induced by H2O2. The oxyR deletion mutant of A. citrulli was significantly impaired bacterial tolerance to oxidative stress and reduced catalase (CAT) activity. In addition, oxyR mutant resulted in reduced swimming motility, twitching motility, biofilm formation, virulence, and bacterial growth in planta by significantly affecting flagellin and type IV pili-related gene (fliC and pilA) expression. The qRT-PCR assays and western blot revealed that OxyR positively regulated the expression of fliC and pilA. Furthermore, bacterial one-hybrid assay demonstrated that OxyR directly affected pilA and fliC promoter. Through bacterial two-hybrid assay, it was found that OxyR can directly interact with PilA and FliC. These results suggest that OxyR plays a major role in the regulating of a variety of virulence traits, and provide a foundation for future research on the global effects of OxyR in A. citrulli.
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Affiliation(s)
- Jianan Wang
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Jun Liu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Institute of Plant Protection and Soil Fertilizer, Hubei Academy of Agricultural Sciences, Wuhan, China
| | - Yuqiang Zhao
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing, China
| | - Minghui Sun
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Guixu Yu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Jiaqin Fan
- Laboratory of Bacteriology, Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | - Yanli Tian
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- *Correspondence: Yanli Tian,
| | - Baishi Hu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Baishi Hu,
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Chen Y, Niu X, Cheng M, Wang L, Sun P, Song H, Cao Y. CRISPR/dCas9-RpoD-Mediated Simultaneous Transcriptional Activation and Repression in Shewanella oneidensis MR-1. ACS Synth Biol 2022; 11:2184-2192. [PMID: 35608070 DOI: 10.1021/acssynbio.2c00149] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Extracellular electron transfer (EET) of electroactive microorganisms (EAMs) is the dominating factor for versatile applications of bio-electrochemical systems. Shewanella oneidensis MR-1 is one of the model EAMs for the study of EET, which is associated with a variety of cellular activities. However, due to the lack of a transcriptional activation tool, regulation of multiple genes is labor-intensive and time-consuming, which hampers the advancement of improving the EET efficiency in S. oneidensis. In this study, we developed an easily operated and multifunctional regulatory tool, that is, a simultaneous clustered regularly interspaced short palindromic repeats (CRISPR)-mediated transcriptional activation (CRISPRa) and interference (CRISPRi) system, for application in S. oneidensis. First, a large number of activators were screened, and RpoD (σ70) was determined as the optimal activator. Second, the effective activation range was identified to be 190-216 base upstream of the transcriptional start site. Third, up- and downregulation was achieved in concert by two orthogonal single guide RNAs targeting different positions. The activation of the cell division gene (minCDE) and repression of the cytotoxic gene (SO_3166) were concurrently implemented, increasing the power density by 2.5-fold and enhancing the degradation rate of azo dyes by 2.9-fold. The simultaneous CRISPRa and CRISPRi system enables simultaneous multiplex genetic regulation, offering the potential to further advance studies of the EET mechanism and application in S. oneidensis.
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Affiliation(s)
- Yaru Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Xiaolong Niu
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Meijie Cheng
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Luxin Wang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Panxing Sun
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Hao Song
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Yingxiu Cao
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China
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Park J, Kim M, Shin B, Kang M, Yang J, Lee TK, Park W. A novel decoy strategy for polymyxin resistance in Acinetobacter baumannii. eLife 2021; 10:66988. [PMID: 34180396 PMCID: PMC8324293 DOI: 10.7554/elife.66988] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/27/2021] [Indexed: 12/17/2022] Open
Abstract
Modification of the outer membrane charge by a polymyxin B (PMB)-induced PmrAB two-component system appears to be a dominant phenomenon in PMB-resistant Acinetobacter baumannii. PMB-resistant variants and many clinical isolates also appeared to produce outer membrane vesicles (OMVs). Genomic, transcriptomic, and proteomic analyses revealed that upregulation of the pmr operon and decreased membrane-linkage proteins (OmpA, OmpW, and BamE) are linked to overproduction of OMVs, which also promoted enhanced biofilm formation. The addition of OMVs from PMB-resistant variants into the cultures of PMB-susceptible A. baumannii and the clinical isolates protected these susceptible bacteria from PMB. Taxonomic profiling of in vitro human gut microbiomes under anaerobic conditions demonstrated that OMVs completely protected the microbial community against PMB treatment. A Galleria mellonella-infection model with PMB treatment showed that OMVs increased the mortality rate of larvae by protecting A. baumannii from PMB. Taken together, OMVs released from A. baumannii functioned as decoys against PMB. Wrapped in a thick, protective outer membrane, Acinetobacter baumannii bacteria can sometimes cause serious infections when they find their way into human lungs and urinary tracts. Antibiotics are increasingly ineffective against this threat, which forces physicians to resort to polymyxin B, an old, positively-charged drug that ‘sticks’ to the negatively-charged proteins and fatty components at the surface of A. baumannii. Scientists have noticed that when bacteria are exposed to lethal drugs, they often react by releasing vesicles, small ‘sacs’ made of pieces of the outer membranes which can contain DNA or enzymes. How this strategy protects the cells against antibiotics such as polymyxin B remains poorly understood. To investigate this question, Park et al. examined different strains of A. baumannii, showing that bacteria resistant to polymyxin B had lower levels of outer membrane proteins but would release more vesicles. Adding vesicles from resistant strains to non-resistant A. baumannii cultures helped cells to survive the drugs. In fact, this protective effect extended to other species, shielding whole communities of bacteria against polymyxin B. In vivo, the vesicles protected bacteria in moth larvae infected with A. baumannii, leading to a higher death rate in the animals. Experiments showed that the negatively-charged vesicles worked as decoys, trapping the positively-charged polymyxin B away from its target. Taken together, the findings by Park et al. highlight a new strategy that allows certain strains of bacteria to protect themselves from antibiotics, while also benefitting the rest of the microbial community.
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Affiliation(s)
- Jaeeun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Misung Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Bora Shin
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Mingyeong Kang
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Jihye Yang
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
| | - Tae Kwon Lee
- Department of Environmental Engineering, Yonsei University, Wonju, Republic of Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea
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Protective Role of Bacterial Alkanesulfonate Monooxygenase under Oxidative Stress. Appl Environ Microbiol 2020; 86:AEM.00692-20. [PMID: 32503904 DOI: 10.1128/aem.00692-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 05/26/2020] [Indexed: 01/05/2023] Open
Abstract
Bacterial alkane metabolism is associated with a number of cellular stresses, including membrane stress and oxidative stress, and the limited uptake of charged ions such as sulfate. In the present study, the genes ssuD and tauD in Acinetobacter oleivorans DR1 cells, which encode an alkanesulfonate monooxygenase and a taurine dioxygenase, respectively, were found to be responsible for hexadecanesulfonate (C16SO3H) and taurine metabolism, and Cbl was experimentally identified as a potential regulator of ssuD and tauD expression. The expression of ssuD and tauD occurred under sulfate-limited conditions generated during n-hexadecane degradation. Interestingly, expression analysis and knockout experiments suggested that both genes are required to protect cells against oxidative stress, including that generated by n-hexadecane degradation and H2O2 exposure. Measurable levels of intracellular hexadecanesulfonate were also produced during n-hexadecane degradation. Phylogenetic analysis suggested that ssuD and tauD are mainly present in soil-dwelling aerobes within the Betaproteobacteria and Gammaproteobacteria classes, which suggests that they function as controllers of the sulfur cycle and play a protective role against oxidative stress in sulfur-limited conditions.IMPORTANCE ssuD and tauD, which play a role in the degradation of organosulfonate, were expressed during n-hexadecane metabolism and oxidative stress conditions in A. oleivorans DR1. Our study confirmed that hexadecanesulfonate was accidentally generated during bacterial n-hexadecane degradation in sulfate-limited conditions. Removal of this by-product by SsuD and TauD must be necessary for bacterial survival under oxidative stress generated during n-hexadecane degradation.
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