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Yang N, Li M, Qin S, Duan N, Li X, Zhou Y, Wang M, Jin Y, Wu W, Cheng Z. Ehrlichia chaffeensis Etf-3 Induces Host RAB15 Upregulation for Bacterial Intracellular Growth. Int J Mol Sci 2024; 25:2551. [PMID: 38473798 DOI: 10.3390/ijms25052551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 02/18/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Ehrlichia chaffeensis infects human monocytes or macrophages and causes human monocytic ehrlichiosis (HME), an emerging life-threatening zoonosis. After internalization, E. chaffeensis resides in membrane-bound inclusions, E. chaffeensis-containing vesicles (ECVs), which have early endosome-like characteristics and fuse with early autophagosomes but not lysosomes, to evade host innate immune microbicidal mechanisms and obtain nutrients for bacterial intracellular growth. The mechanisms exploited by E. chaffeensis to modulate intracellular vesicle trafficking in host cells have not been comprehensively studied. Here, we demonstrate that E. chaffeensis type IV secretion system (T4SS) effector Etf-3 induces RAB15 upregulation in host cells and that RAB15, which is localized on ECVs, inhibits ECV fusion with lysosomes and induces autophagy. We found that E. chaffeensis infection upregulated RAB15 expression using qRT-PCR, and RAB15 was colocalized with E. chaffeensis using confocal microscopy. Silence of RAB15 using siRNA enhanced ECV maturation to late endosomes and fusion with lysosomes, as well as inhibited host cell autophagy. Overexpression of Etf-3 in host cells specifically induced RAB15 upregulation and autophagy. Our findings deepen the understanding of E. chaffeensis pathogenesis and adaptation in hosts as well as the function of RAB15 and facilitate the development of new therapeutics for HME.
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Affiliation(s)
- Nan Yang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Meifang Li
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Shanhua Qin
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Nan Duan
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Xiaoxiao Li
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yuhong Zhou
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Mengyao Wang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yongxin Jin
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Weihui Wu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zhihui Cheng
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
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Yan J, Liang Q, Chai Z, Duan N, Li X, Liu Y, Yang N, Li M, Jin Y, Bai F, Wu W, Cheng Z. Glutathione Synthesis Regulated by CtrA Protects Ehrlichia chaffeensis From Host Cell Oxidative Stress. Front Microbiol 2022; 13:846488. [PMID: 35432225 PMCID: PMC9005958 DOI: 10.3389/fmicb.2022.846488] [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: 12/31/2021] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
Ehrlichia chaffeensis, a small Gram-negative obligatory intracellular bacterium, infects human monocytes or macrophages, and causes human monocytic ehrlichiosis, one of the most prevalent, life-threatening emerging zoonoses. Reactive oxygen species are produced by the host immune cells in response to bacterial infections. The mechanisms exploited by E. chaffeensis to resist oxidative stress have not been comprehensively demonstrated. Here, we found that E. chaffeensis encodes two functional enzymes, GshA and GshB, to synthesize glutathione that confers E. chaffeensis the oxidative stress resistance, and that the expression of gshA and gshB is upregulated by CtrA, a global transcriptional regulator, upon oxidative stress. We found that in E. chaffeensis, the expression of gshA and gshB was upregulated upon oxidative stress using quantitative RT-PCR. Ehrlichia chaffeensis GshA or GshB restored the ability of Pseudomonas aeruginosa GshA or GshB mutant to cope with oxidative stress, respectively. Recombinant E. chaffeensis CtrA directly bound to the promoters of gshA and gshB, determined with electrophoretic mobility shift assay, and activated the expression of gshA and gshB determined with reporter assay. Peptide nucleic acid transfection of E. chaffeensis, which reduced the CtrA protein level, inhibited the oxidative stress-induced upregulation of gshA and gshB. Our findings provide insights into the function and regulation of the two enzymes critical for E. chaffeensis resistance to oxidative stress and may deepen our understanding of E. chaffeensis pathogenesis and adaptation in hosts.
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Affiliation(s)
- Jiaqi Yan
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Qi'an Liang
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhouyi Chai
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Nan Duan
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiaoxiao Li
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yajing Liu
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Nan Yang
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Meifang Li
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yongxin Jin
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Fang Bai
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Weihui Wu
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhihui Cheng
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
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