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Barton IS, Ren Z, Cribb CB, Pitzer JE, Baglivo I, Martin DW, Wang X, Roop RM. Brucella MucR acts as an H-NS-like protein to silence virulence genes and structure the nucleoid. mBio 2023; 14:e0220123. [PMID: 37847580 PMCID: PMC10746212 DOI: 10.1128/mbio.02201-23] [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: 08/16/2023] [Accepted: 08/21/2023] [Indexed: 10/19/2023] Open
Abstract
Histone-like nucleoid structuring (H-NS) and H-NS-like proteins serve as global gene silencers and work with antagonistic transcriptional activators (counter-silencers) to properly coordinate the expression of virulence genes in pathogenic bacteria. In Brucella, MucR has been proposed as a novel H-NS-like gene silencer, but direct experimental evidence is lacking. Here, we show that MucR serves as an H-NS-like silencer of the Brucella abortus genes encoding the polar autotransporter adhesins BtaE and BmaC, the c-di-GMP-specific phosphodiesterase BpdB, and the quorum-sensing regulator BabR. We also demonstrate that the MarR-type transcriptional activator MdrA can displace MucR from the btaE promoter, supporting the existence of MucR counter-silencers in Brucella. Moreover, our chromatin immunoprecipitation (ChIP)-seq analysis identified 546 MucR enrichment peaks along the genome, including in the promoters of the genes encoding the Type IV secretion machinery and effectors and the quorum-sensing regulator VjbR. Importantly, MucR ChIP-seq peaks overlap with the previously described binding sites for the transcriptional activators VjbR, BvrR, and CtrA suggesting that these regulators serve as MucR counter-silencers and work in concert with MucR to coordinate virulence gene expression in Brucella. In addition, using chromosome conformation capture (Hi-C), we show that like H-NS in Escherichia coli, MucR alters the global structure of the Brucella nucleoid. Finally, a copy of the E. coli hns rescues the distinctive growth defect and elevated btaE expression of a B. abortus mucR mutant. Together, these findings solidify the role of MucR as a novel type of H-NS-like protein and suggest that MucR's gene-silencing properties play a key role in virulence in Brucella. IMPORTANCE Histone-like nucleoid structuring (H-NS) and H-NS-like proteins coordinate host-associated behaviors in many pathogenic bacteria, often through forming silencer/counter-silencer pairs with signal-responsive transcriptional activators to tightly control gene expression. Brucella and related bacteria do not encode H-NS or homologs of known H-NS-like proteins, and it is unclear if they have other proteins that perform analogous functions during pathogenesis. In this work, we provide compelling evidence for the role of MucR as a novel H-NS-like protein in Brucella. We show that MucR possesses many of the known functions attributed to H-NS and H-NS-like proteins, including the formation of silencer/counter-silencer pairs to control virulence gene expression and global structuring of the nucleoid. These results uncover a new role for MucR as a nucleoid structuring protein and support the importance of temporal control of gene expression in Brucella and related bacteria.
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Affiliation(s)
- Ian S. Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Zhongqing Ren
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Connor B. Cribb
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Joshua E. Pitzer
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ilaria Baglivo
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania “Luigi Vanvitelli”, Caserta, Italy
| | - Daniel W. Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Xindan Wang
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - R. Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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Yan CH, Chen FH, Yang YL, Zhan YF, Herman RA, Gong LC, Sheng S, Wang J. The Transcription Factor CsgD Contributes to Engineered Escherichia coli Resistance by Regulating Biofilm Formation and Stress Responses. Int J Mol Sci 2023; 24:13681. [PMID: 37761984 PMCID: PMC10530992 DOI: 10.3390/ijms241813681] [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: 07/31/2023] [Revised: 08/30/2023] [Accepted: 09/02/2023] [Indexed: 09/29/2023] Open
Abstract
The high cell density, immobilization and stability of biofilms are ideal characteristics for bacteria in resisting antibiotic therapy. CsgD is a transcription activating factor that regulates the synthesis of curly fimbriae and cellulose in Escherichia coli, thereby enhancing bacterial adhesion and promoting biofilm formation. To investigate the role of CsgD in biofilm formation and stress resistance in bacteria, the csgD deletion mutant ΔcsgD was successfully constructed from the engineered strain E. coli BL21(DE3) using the CRISPR/Cas9 gene-editing system. The results demonstrated that the biofilm of ΔcsgD decreased by 70.07% (p < 0.05). Additionally, the mobility and adhesion of ΔcsgD were inhibited due to the decrease in curly fimbriae and extracellular polymeric substances. Furthermore, ΔcsgD exhibited a significantly decreased resistance to acid, alkali and osmotic stress conditions (p < 0.05). RNA-Seq results revealed 491 differentially expressed genes between the parent strain and ΔcsgD, with enrichment primarily observed in metabolism-related processes as well as cell membrane structure and catalytic activity categories. Moreover, CsgD influenced the expression of biofilm and stress response genes pgaA, motB, fimA, fimC, iraP, ompA, osmC, sufE and elaB, indicating that the CsgD participated in the resistance of E. coli by regulating the expression of biofilm and stress response. In brief, the transcription factor CsgD plays a key role in the stress resistance of E. coli, and is a potential target for treating and controlling biofilm.
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Affiliation(s)
- Cheng-Hai Yan
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
| | - Fang-Hui Chen
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
| | - Yu-Lu Yang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
| | - Yu-Fan Zhan
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
| | - Richard A. Herman
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
| | - Lu-Chan Gong
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212100, China
| | - Sheng Sheng
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212100, China
| | - Jun Wang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China; (C.-H.Y.); (F.-H.C.); (Y.-L.Y.); (Y.-F.Z.); (R.A.H.); (L.-C.G.); (S.S.)
- Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212100, China
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Molecular Insights into a Novel Cu(I)-Sensitive ArsR/SmtB Family Repressor in Extremophile Acidithiobacillus caldus. Appl Environ Microbiol 2023; 89:e0126622. [PMID: 36602357 PMCID: PMC9888290 DOI: 10.1128/aem.01266-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Acidithiobacillus caldus is a common bioleaching bacterium that is inevitably exposed to extreme copper stress in leachates. The ArsR/SmtB family of metalloregulatory repressors regulates homeostasis and resistance in bacteria by specifically responding to metals. Here, we characterized A. caldus Cu(I)-sensitive repressor (AcsR) and gained molecular insights into this new member of the ArsR/SmtB family. Transcriptional analysis indicated that the promoter (PIII) of acsR was highly active in Escherichia coli but inhibited upon AcsR binding to the PIII-acsR region. Size exclusion chromatography and circular dichroism spectra revealed that CuI-AcsR shared an identical assembly state with apo-AcsR, as a dimer with fewer α helices, more extended strands, and more β turns. Mutation of the cysteine site in AcsR did not affect its assembly state. Copper(I) titrations revealed that apo-AcsR bound two Cu(I) molecules per monomer in vitro with an average dissociation constant (KD) for bicinchoninic acid competition of 2.55 × 10-9 M. Site-directed mutation of putative Cu(I)-binding ligands in AcsR showed that replacing Cys64 with Ala reduces copper binding ability from two Cu(I) molecules per monomer to one, with an average KD of 6.05 × 10-9 M. Electrophoretic mobility shift assays revealed that apo-AcsR has high affinity for the 12-2-12 imperfect inverted repeats P2245 and P2270 in the acsR gene cluster and that Cu-loaded AcsR had lower affinity for DNA fragments than apo-AcsR. We developed a hypothetical working model of AcsR to better understand Cu resistance mechanisms in A. caldus. IMPORTANCE Copper (Cu) resistance among various microorganisms is attracting interest. The chemolithoautotrophic bacterium A. caldus, which can tolerate extreme copper stress (≥10 g/L Cu ions), is typically used to bioleach chalcopyrite (CuFeS2). Understanding of Cu resistance in A. caldus is limited due to scant investigation and the absence of efficient gene manipulation tools. Here, we characterized a new member of the ArsR/SmtB family of prokaryotic metalloregulatory transcriptional proteins that repress operons linked to stress-inducing concentrations of heavy metal ions. This protein can bind two Cu(I) molecules per monomer and negatively regulate its gene cluster. Members of the ArsR/SmtB family have not been investigated in A. caldus until now. The discovery of this novel protein enriches understanding of Cu homeostasis in A. caldus.
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Guo J, Deng X, Zhang Y, Song S, Zhao T, Zhu D, Cao S, Baryshnikov PI, Cao G, Blair HT, Chen C, Gu X, Liu L, Zhang H. The Flagellar Transcriptional Regulator FtcR Controls Brucella melitensis 16M Biofilm Formation via a betI-Mediated Pathway in Response to Hyperosmotic Stress. Int J Mol Sci 2022; 23:ijms23179905. [PMID: 36077302 PMCID: PMC9456535 DOI: 10.3390/ijms23179905] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/26/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022] Open
Abstract
The expression of flagellar proteins in Brucella species likely evolved through genetic transference from other microorganisms, and contributed to virulence, adaptability, and biofilm formation. Despite significant progress in defining the molecular mechanisms behind flagellar gene expression, the genetic program controlling biofilm formation remains unclear. The flagellar transcriptional factor (FtcR) is a master regulator of the flagellar system’s expression, and is critical for B. melitensis 16M’s flagellar biogenesis and virulence. Here, we demonstrate that FtcR mediates biofilm formation under hyperosmotic stress. Chromatin immunoprecipitation with next-generation sequencing for FtcR and RNA sequencing of ftcR-mutant and wild-type strains revealed a core set of FtcR target genes. We identified a novel FtcR-binding site in the promoter region of the osmotic-stress-response regulator gene betI, which is important for the survival of B. melitensis 16M under hyperosmotic stress. Strikingly, this site autoregulates its expression to benefit biofilm bacteria’s survival under hyperosmotic stress. Moreover, biofilm reduction in ftcR mutants is independent of the flagellar target gene fliF. Collectively, our study provides new insights into the extent and functionality of flagellar-related transcriptional networks in biofilm formation, and presents phenotypic and evolutionary adaptations that alter the regulation of B. melitensis 16M to confer increased tolerance to hyperosmotic stress.
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Affiliation(s)
- Jia Guo
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Xingmei Deng
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Yu Zhang
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Shengnan Song
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Tianyi Zhao
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Dexin Zhu
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Shuzhu Cao
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Peter Ivanovic Baryshnikov
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- College of Veterinary, Altai State Agricultural University, 656000 Barnaul, Russia
| | - Gang Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430000, China
| | - Hugh T. Blair
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- International Sheep Research Center, School of Agriculture and Environment, Massey University, Palmerston North 4442, New Zealand
| | - Chuangfu Chen
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Xinli Gu
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Liangbo Liu
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- Correspondence: (L.L.); (H.Z.); Tel.: +86-0993-2057971 (L.L. & H.Z.)
| | - Hui Zhang
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- Correspondence: (L.L.); (H.Z.); Tel.: +86-0993-2057971 (L.L. & H.Z.)
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Zhang L, Yu S, Ning X, Fang H, Li J, Zhi F, Li J, Zhou D, Wang A, Jin Y. A LysR Transcriptional Regulator Manipulates Macrophage Autophagy Flux During Brucella Infection. Front Cell Infect Microbiol 2022; 12:858173. [PMID: 35392609 PMCID: PMC8980476 DOI: 10.3389/fcimb.2022.858173] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 02/24/2022] [Indexed: 11/22/2022] Open
Abstract
Brucella, the intracellular bacteria, have evolved subtle strategies to efficiently survive and replicate in macrophages. However, the virulence effector proteins involved are still unclear. LysR-type transcriptional regulators (lttrs) are the largest regulator family with diverse function in prokaryotes. However, very little is known about the role of LysR regulators in the Brucella spp. Here, a BSS2_II0858 gene, encoded as one of the LysR-type regulators, was studied. We successfully constructed a BSS2_II0858 deletion mutant, Δ0858, and complementation strain CΔ0858 in Brucella suis S2. The cell apoptosis induced by B. suis S2 and its derivatives were detected by flow cytometry. The autophagy was then assessed by immunoblot analysis using the IL3I/II and p62 makers. In addition, the autophagy flux was evaluated by double fluorescent labeling method for autophagy marker protein LC3. Our studies demonstrated that B. suis S2 and its derivatives inhibited the programmed cell death in early stage and promoted apoptosis in the later stage during infection in RAW264.7 cells. The BSS2_II0858 gene was found to play no role during apoptosis according to these results. Compared with the wild-type strain, Δ0858 mutant can stimulate the conversion of LC3-I to LC3-II and markedly inhibited the autophagy flux at early stage leading to obvious autophagosome accumulation. This study explored the function of BSS2_II0858 gene and may provide new insights for understanding the mechanisms involved in the survival of Brucella in macrophages.
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Affiliation(s)
- Lu Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Siyuan Yu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Xinnuan Ning
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Hui Fang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Jie Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Feijie Zhi
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Junmei Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Dong Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
| | - Aihua Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
- *Correspondence: Yaping Jin, ; Aihua Wang,
| | - Yaping Jin
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling, China
- *Correspondence: Yaping Jin, ; Aihua Wang,
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