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Roh H, Kannimuthu D. Genomic and Transcriptomic Diversification of Flagellin Genes Provides Insight into Environmental Adaptation and Phylogeographic Characteristics in Aeromonas hydrophila. MICROBIAL ECOLOGY 2024; 87:65. [PMID: 38695873 PMCID: PMC11065939 DOI: 10.1007/s00248-024-02373-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/01/2024] [Indexed: 05/05/2024]
Abstract
Aeromonas hydrophila is an opportunistic motile pathogen with a broad host range, infecting both terrestrial and aquatic animals. Environmental and geographical conditions exert selective pressure on both geno- and phenotypes of pathogens. Flagellin, directly exposed to external environments and containing important immunogenic epitopes, may display significant variability in response to external conditions. In this study, we conducted a comparative analysis of ~ 150 A. hydrophila genomes, leading to the identification of six subunits of the flagellin gene (fla-1 to fla-4, flaA, and flaB). Individual strains harbored different composition of flagellin subunits and copies. The composition of subunits showed distinct patterns depending on environmental sources. Strains from aquatic environments were mainly comprised of fla-1 to fla-4 subunits, while terrestrial strains predominated in groups harboring flaA and flaB subunits. Each flagellin showed varying levels of expression, with flaA and flaB demonstrating significantly higher expression compared to others. One of the chemotaxis pathways that control flagellin movement through a two-component system was significantly upregulated in flaA(+ 1)/flaB(+ 1) group, whereas flaA and flaB showed different transcriptomic expressions. The genes positively correlated with flaA expression were relevant to biofilm formation and bacterial chemotaxis, but flaB showed a negative correlation with the genes in ABC transporters and quorum sensing pathway. However, the expression patterns of fla-2 to fla-4 were identical. This suggests various types of flagellin subunits may have different biological functions. The composition and expression levels of flagellin subunits could provide valuable insights into the adaptation of A. hydrophila and the differences among strains in response to various external environments.
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Affiliation(s)
- HyeongJin Roh
- Pathogen Transmission and Disease Research Group, Institute of Marine Research, PO Box 1870 Nordnes 5870, Bergen, Norway.
| | - Dhamotharan Kannimuthu
- Pathogen Transmission and Disease Research Group, Institute of Marine Research, PO Box 1870 Nordnes 5870, Bergen, Norway
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2
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Xun M, Feng Z, Li H, Yao M, Wang H, Wei R, Jia J, Fan Z, Shi X, Lv Z, Zhang G. In vitro anti-Helicobacter pylori activity and antivirulence activity of cetylpyridinium chloride. PLoS One 2024; 19:e0300696. [PMID: 38603679 PMCID: PMC11008818 DOI: 10.1371/journal.pone.0300696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/04/2024] [Indexed: 04/13/2024] Open
Abstract
The primary treatment method for eradicating Helicobacter pylori (H. pylori) infection involves the use of antibiotic-based therapies. Due to the growing antibiotic resistance of H. pylori, there has been a surge of interest in exploring alternative therapies. Cetylpyridinium chloride (CPC) is a water-soluble and nonvolatile quaternary ammonium compound with exceptional broad-spectrum antibacterial properties. To date, there is no documented or described specific antibacterial action of CPC against H. pylori. Therefore, this study aimed to explore the in vitro activity of CPC against H. pylori and its potential antibacterial mechanism. CPC exhibited significant in vitro activity against H. pylori, with MICs ranging from 0.16 to 0.62 μg/mL and MBCs ranging from 0.31 to 1.24 μg/mL. CPC could result in morphological and physiological modifications in H. pylori, leading to the suppression of virulence and adherence genes expression, including flaA, flaB, babB, alpA, alpB, ureE, and ureF, and inhibition of urease activity. CPC has demonstrated in vitro activity against H. pylori by inhibiting its growth, inducing damage to the bacterial structure, reducing virulence and adherence factors expression, and inhibiting urease activity.
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Affiliation(s)
- Mingjin Xun
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Zhong Feng
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Hui Li
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Meicun Yao
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Haibo Wang
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Ruixia Wei
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
| | - Junwei Jia
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Zimao Fan
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Xiaoyan Shi
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Zhanzhu Lv
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
| | - Guimin Zhang
- National Engineering and Technology Research Center of Chirality Pharmaceutical, Lunan Pharmaceutical Group Co., Ltd., Linyi, Shandong, China
- International Pharmaceutical Engineering Laboratory in Shandong Province, Shandong New Time Pharmaceutical Co., Ltd., Linyi, Shandong, China
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3
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Gupta N, Kumar A, Verma VK. Strategies adopted by gastric pathogen Helicobacter pylori for a mature biofilm formation: Antimicrobial peptides as a visionary treatment. Microbiol Res 2023; 273:127417. [PMID: 37267815 DOI: 10.1016/j.micres.2023.127417] [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: 03/13/2023] [Revised: 05/15/2023] [Accepted: 05/21/2023] [Indexed: 06/04/2023]
Abstract
Enormous efforts in recent past two decades to eradicate the pathogen that has been prevalent in half of the world's population have been problematic. The biofilm formed by Helicobacter pylori provides resistance towards innate immune cells, various combinatorial antibiotics, and human antimicrobial peptides, despite the fact that these all are potent enough to eradicate it in vitro. Biofilm provides the opportunity to secrete various virulence factors that strengthen the interaction between host and pathogen helping in evading the innate immune system and ultimately leading to persistence. To our knowledge, this review is the first of its kind to explain briefly the journey of H. pylori starting with the chemotaxis, the mechanism for selecting the site for colonization, the stress faced by the pathogen, and various adaptations to evade these stress conditions by forming biofilm and the morphological changes acquired by the pathogen in mature biofilm. Furthermore, we have explained the human GI tract antimicrobial peptides and the reason behind the failure of these AMPs, and how encapsulation of Pexiganan-A(MSI-78A) in a chitosan microsphere increases the efficiency of eradication.
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Affiliation(s)
- Nidhi Gupta
- Department of Microbiology, University of Delhi South Campus, Benito Juarez Marg, New Delhi 110021, India.
| | - Atul Kumar
- Department of Microbiology, University of Delhi South Campus, Benito Juarez Marg, New Delhi 110021, India
| | - Vijay Kumar Verma
- Department of Microbiology, University of Delhi South Campus, Benito Juarez Marg, New Delhi 110021, India.
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Rodriguez AM, Urrea DA, Prada CF. Helicobacter pylori virulence factors: relationship between genetic variability and phylogeographic origin. PeerJ 2021; 9:e12272. [PMID: 34900406 PMCID: PMC8628625 DOI: 10.7717/peerj.12272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/17/2021] [Indexed: 01/18/2023] Open
Abstract
Background Helicobacter pylori is a pathogenic bacteria that colonize the gastrointestinal tract from human stomachs and causes diseases including gastritis, peptic ulcers, gastric lymphoma (MALT), and gastric cancer, with a higher prevalence in developing countries. Its high genetic diversity among strains is caused by a high mutation rate, observing virulence factors (VFs) variations in different geographic lineages. This study aimed to postulate the genetic variability associated with virulence factors present in the Helicobacter pylori strains, to identify the relationship of these genes with their phylogeographic origin. Methods The complete genomes of 135 strains available in NCBI, from different population origins, were analyzed using bioinformatics tools, identifying a high rate; as well as reorganization events in 87 virulence factor genes, divided into seven functional groups, to determine changes in position, number of copies, nucleotide identity and size, contrasting them with their geographical lineage and pathogenic phenotype. Results Bioinformatics analyses show a high rate of gene annotation errors in VF. Analysis of genetic variability of VFs shown that there is not a direct relationship between the reorganization and geographic lineage. However, regarding the pathogenic phenotype demonstrated in the analysis of many copies, size, and similarity when dividing the strains that possess and not the cag pathogenicity island (cagPAI), having a higher risk of developing gastritis and peptic ulcer was evidenced. Our data has shown that the analysis of the overall genetic variability of all VFs present in each strain of H. pylori is key information in understanding its pathogenic behavior.
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Affiliation(s)
- Aura M Rodriguez
- Grupo de Investigación de Biología y Ecología de Artrópodos. Facultad de Ciencias, Universidad del Tolima, Ibague, Tolima, Colombia
| | - Daniel A Urrea
- Laboratorio de Investigaciones en Parasitología Tropical. Facultad de Ciencias, Universidad del Tolima, Ibague, Tolima, Colombia
| | - Carlos F Prada
- Grupo de Investigación de Biología y Ecología de Artrópodos. Facultad de Ciencias, Universidad del Tolima, Ibague, Tolima, Colombia
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5
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Kim HW, Woo HJ, Yang JY, Kim JB, Kim SH. Hesperetin Inhibits Expression of Virulence Factors and Growth of Helicobacter pylori. Int J Mol Sci 2021; 22:ijms221810035. [PMID: 34576198 PMCID: PMC8472136 DOI: 10.3390/ijms221810035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/09/2021] [Accepted: 09/13/2021] [Indexed: 12/22/2022] Open
Abstract
Helicobacter pylori (H. pylori) is a bacterium known to infect the human stomach. It can cause various gastrointestinal diseases including gastritis and gastric cancer. Hesperetin is a major flavanone component contained in citrus fruits. It has been reported to possess antibacterial, antioxidant, and anticancer effects. However, the antibacterial mechanism of hesperetin against H. pylori has not been reported yet. Therefore, the objective of this study was to determine the inhibitory effects of hesperetin on H. pylori growth and its inhibitory mechanisms. The results of this study showed that hesperetin inhibits the growth of H. pylori reference strains and clinical isolates. Hesperetin inhibits the expression of genes in replication (dnaE, dnaN, dnaQ, and holB) and transcription (rpoA, rpoB, rpoD, and rpoN) machineries of H. pylori. Hesperetin also inhibits the expression of genes related to H. pylori motility (flhA, flaA, and flgE) and adhesion (sabA, alpA, alpB, hpaA, and hopZ). It also inhibits the expression of urease. Hespereti n downregulates major virulence factors such as cytotoxin-associated antigen A (CagA) and vacuolating cytotoxin A (VacA) and decreases the translocation of CagA and VacA proteins into gastric adenocarcinoma (AGS) cells. These results might be due to decreased expression of the type IV secretion system (T4SS) and type V secretion system (T5SS) involved in translocation of CagA and VacA, respectively. The results of this study indicate that hesperetin has antibacterial effects against H. pylori. Thus, hesperetin might be an effective natural product for the eradication of H. pylori.
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Affiliation(s)
- Hyun Woo Kim
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea; (H.W.K.); (J.-B.K.)
| | - Hyun Jun Woo
- Department of Clinical Laboratory Science, Semyung University, Jecheon 27136, Korea;
| | - Ji Yeong Yang
- Division of Crop Foundation, National Institute of Crop Science (NICS), Rural Development Administration (RDA), Wanju 55365, Korea;
| | - Jong-Bae Kim
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea; (H.W.K.); (J.-B.K.)
| | - Sa-Hyun Kim
- Department of Clinical Laboratory Science, Semyung University, Jecheon 27136, Korea;
- Correspondence:
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6
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Ghosh P, Bhakta S, Bhattacharya M, Sharma AR, Sharma G, Lee SS, Chakraborty C. A Novel Multi-Epitopic Peptide Vaccine Candidate Against Helicobacter pylori: In-Silico Identification, Design, Cloning and Validation Through Molecular Dynamics. Int J Pept Res Ther 2021; 27:1149-1166. [PMID: 33495694 PMCID: PMC7816556 DOI: 10.1007/s10989-020-10157-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2020] [Indexed: 01/22/2023]
Abstract
Helicobacter pylori is a highly potential pathogen to colonize in the human stomach. This bacterial strain is now alarming serious health concern all over the world. Combating through available drugs is a difficult task due to lack of appropriate common targets against genetically diverse strains. Therefore, the developments of effective targets vaccines require alternative strategies to eliminate the H. pylori infection. In this study, we developed a novel vaccine construct using B-cell derived T-cell epitopes from four target antigenic proteins (HpaA, FlaA, FlaB and Omp18), and found the induction of possible immune response using advanced immunoinformatics approaches. In order to boost immune system, we tagged adjuvant (50S ribosomal protein L7/L12) with a suitable linker at the N-terminus side of vaccine sequence. Protein–protein docking between human Toll like receptor 5 (TLR5) and vaccine construct help to predict the way of inductive signaling that leads to immune-response. The calculated negative score (− 151.4, + / − 8.7) of molecular docking complex signify the best binding interface. Molecular dynamics simulation studies confirmed the proper docking between TLR5 and vaccine candidate. Moreover, Normal mode analysis (NMA) calculates the molecular motion of the docking complex. The low eigenvalue (2.935e−05) indicates the stable and flexible molecular motion in the binding interaction side. Finally, in-silico cloning of vaccine candidate was performed using expression vector pET28b (+) with the optimized restriction sites.
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Affiliation(s)
- Pratik Ghosh
- Department of Zoology, Vidyasagar University, Midnapore, West Bengal 721102 India
| | - Swarnav Bhakta
- Department of Biotechnology, School of Life Science and Biotechnology, Adamas University, Barasat-Barrackpore Rd, Kolkata, West Bengal 700126 India
| | - Manojit Bhattacharya
- Department of Zoology, Fakir Mohan University, Vyasa Vihar, Balasore, Odisha 756020 India
| | - Ashish Ranjan Sharma
- Institute for Skeletal Aging & Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon-si, 24252 Gangwon-do Republic of Korea
| | - Garima Sharma
- Department of Biomedical Science & Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon-si, 24341 Gangwon Do Republic of Korea
| | - Sang-Soo Lee
- Institute for Skeletal Aging & Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon-si, 24252 Gangwon-do Republic of Korea
| | - Chiranjib Chakraborty
- Department of Biotechnology, School of Life Science and Biotechnology, Adamas University, Barasat-Barrackpore Rd, Kolkata, West Bengal 700126 India.,Institute for Skeletal Aging & Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon-si, 24252 Gangwon-do Republic of Korea
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7
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Loss of a Cardiolipin Synthase in Helicobacter pylori G27 Blocks Flagellum Assembly. J Bacteriol 2019; 201:JB.00372-19. [PMID: 31427391 DOI: 10.1128/jb.00372-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/28/2019] [Indexed: 12/30/2022] Open
Abstract
Helicobacter pylori uses a cluster of polar, sheathed flagella for motility, which it requires for colonization of the gastric epithelium in humans. As part of a study to identify factors that contribute to localization of the flagella to the cell pole, we disrupted a gene encoding a cardiolipin synthase (clsC) in H. pylori strains G27 and B128. Flagellum biosynthesis was abolished in the H. pylori G27 clsC mutant but not in the B128 clsC mutant. Transcriptome sequencing analysis showed that flagellar genes encoding proteins needed early in flagellum assembly were expressed at wild-type levels in the G27 clsC mutant. Examination of the G27 clsC mutant by cryo-electron tomography indicated the mutant assembled nascent flagella that contained the MS ring, C ring, flagellar protein export apparatus, and proximal rod. Motile variants of the G27 clsC mutant were isolated after allelic exchange mutagenesis using genomic DNA from the B128 clsC mutant as the donor. Genome resequencing of seven motile G27 clsC recipients revealed that each isolate contained the flgI (encodes the P-ring protein) allele from B128. Replacing the flgI allele in the G27 clsC mutant with the B128 flgI allele rescued flagellum biosynthesis. We postulate that H. pylori G27 FlgI fails to form the P ring when cardiolipin levels in the cell envelope are low, which blocks flagellum assembly at this point. In contrast, H. pylori B128 FlgI can form the P ring when cardiolipin levels are low and allows for the biosynthesis of mature flagella.IMPORTANCE H. pylori colonizes the epithelial layer of the human stomach, where it can cause a variety of diseases, including chronic gastritis, peptic ulcer disease, and gastric cancer. To colonize the stomach, H. pylori must penetrate the viscous mucous layer lining the stomach, which it accomplishes using its flagella. The significance of our research is identifying factors that affect the biosynthesis and assembly of the H. pylori flagellum, which will contribute to our understanding of motility in H. pylori, as well as other bacterial pathogens that use their flagella for host colonization.
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8
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Gu H. Role of Flagella in the Pathogenesis of Helicobacter pylori. Curr Microbiol 2017; 74:863-869. [PMID: 28444418 PMCID: PMC5447363 DOI: 10.1007/s00284-017-1256-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 04/18/2017] [Indexed: 12/15/2022]
Abstract
This review aimed to investigate the role of Helicobacter pylori flagella on the pathogenicity of this bacterium in humans. Helicobacter pylori is a flagellated pathogen that colonizes the human gastroduodenal mucosa and produces inflammation, and is responsible for gastrointestinal disease. Its pathogenesis is attributed to colonization and virulence factors. The primary function of H. pylori flagella is to provide motility. We believe that H. pylori flagella play an important role in the colonization of the gastrointestinal mucosa. Therefore, we reviewed previous studies on flagellar morphology and motility in order to explore the relationship between H. pylori flagella and pathogenicity. Further investigation is required to confirm the association between flagella and pathogenicity in H. pylori.
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Affiliation(s)
- Haiying Gu
- Medical School, Ningbo University, Ningbo, 315211, China.
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9
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Hung CL, Cheng HH, Hsieh WC, Tsai ZTY, Tsai HK, Chu CH, Hsieh WP, Chen YF, Tsou Y, Lai CH, Wang WC. The CrdRS two-component system in Helicobacter pylori responds to nitrosative stress. Mol Microbiol 2015; 97:1128-41. [PMID: 26082024 DOI: 10.1111/mmi.13089] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2015] [Indexed: 11/28/2022]
Abstract
Helicobacter pylori inhabits the gastric mucosa where it senses and responds to various stresses via a two-component systems (TCSs) that enable its persistent colonization. The aim of this study was to investigate whether any of the three paired TCSs (ArsRS, FleRS and CrdRS) in H. pylori respond to nitrosative stress. The results showed that the expression of crdS was significantly increased upon exposure to nitric oxide (NO). crdS-knockout (ΔcrdS) and crdR/crdS-knockout (ΔcrdRS) H. pylori, but not arsS-knockout (ΔarsS) or fleS-knockout (ΔfleS) H. pylori, showed a significant loss of viability upon exposure to NO compared with wild-type strain. Knockin crdS (ΔcrdS-in) significantly restored viability in the presence of NO. Global transcriptional profiling analysis of wild-type and ΔcrdS H. pylori in the presence or absence of NO showed that 101 genes were differentially expressed, including copper resistance determinant A (crdA), transport, binding and envelope proteins. The CrdR binding motifs were investigated by competitive electrophoretic mobility shift assay, which revealed that the two AC-rich regions in the crdA promoter region are required for binding. These results demonstrate that CrdR-crdA interaction enables H. pylori to survive under nitrosative stress.
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Affiliation(s)
- Chiu-Lien Hung
- Department of Biochemistry and Molecular Medicine, University of California Davis Comprehensive Cancer Center, Sacramento, California, USA.,Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Hsin-Hung Cheng
- Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Wan-Chen Hsieh
- Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Zing Tsung-Yeh Tsai
- Bioinformatics Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
| | - Huai-Kuang Tsai
- Bioinformatics Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
| | - Chia-Han Chu
- Biomedical Science and Engineering Center, National Tsing Hua University, Hsinchu, Taiwan
| | - Wen-Ping Hsieh
- Institute of Statistics, National Tsing Hua University, Hsinchu, Taiwan
| | - Yi-Fan Chen
- Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Yu Tsou
- Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Chih-Ho Lai
- Department of Nursing, Asia University, Taichung, Taiwan.,Graduate Institute of Basic Medical Science, School of Medicine, China Medical University, Taichung, Taiwan.,Department of Microbiology and Immunology, Chang Gung University, Taoyuan, Taiwan
| | - Wen-Ching Wang
- Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.,Biomedical Science and Engineering Center, National Tsing Hua University, Hsinchu, Taiwan
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10
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Lertsethtakarn P, Howitt MR, Castellon J, Amieva MR, Ottemann KM. Helicobacter pylori CheZ(HP) and ChePep form a novel chemotaxis-regulatory complex distinct from the core chemotaxis signaling proteins and the flagellar motor. Mol Microbiol 2015; 97:1063-78. [PMID: 26061894 DOI: 10.1111/mmi.13086] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2015] [Indexed: 12/20/2022]
Abstract
Chemotaxis is important for Helicobacter pylori to colonize the stomach. Like other bacteria, H. pylori uses chemoreceptors and conserved chemotaxis proteins to phosphorylate the flagellar rotational response regulator, CheY, and modulate the flagellar rotational direction. Phosphorylated CheY is returned to its non-phosphorylated state by phosphatases such as CheZ. In previously studied cases, chemotaxis phosphatases localize to the cellular poles by interactions with either the CheA chemotaxis kinase or flagellar motor proteins. We report here that the H. pylori CheZ, CheZ(HP), localizes to the poles independently of the flagellar motor, CheA, and all typical chemotaxis proteins. Instead, CheZ(HP) localization depends on the chemotaxis regulatory protein ChePep, and reciprocally, ChePep requires CheZ(HP) for its polar localization. We furthermore show that these proteins interact directly. Functional domain mapping of CheZ(HP) determined the polar localization motif lies within the central domain of the protein and that the protein has regions outside of the active site that participate in chemotaxis. Our results suggest that CheZ(HP) and ChePep form a distinct complex. These results therefore suggest the intriguing idea that some phosphatases localize independently of the other chemotaxis and motility proteins, possibly to confer unique regulation on these proteins' activities.
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Affiliation(s)
- Paphavee Lertsethtakarn
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA, 95064, USA
| | - Michael R Howitt
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Juan Castellon
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA, 95064, USA
| | - Manuel R Amieva
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Karen M Ottemann
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA, 95064, USA
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11
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Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori. J Bacteriol 2015; 197:1921-30. [PMID: 25825427 DOI: 10.1128/jb.02533-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/20/2015] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Flagellar biogenesis in Helicobacter pylori is regulated by a transcriptional hierarchy governed by three sigma factors, RpoD (σ(80)), RpoN (σ(54)), and FliA (σ(28)), that temporally coordinates gene expression with the assembly of the flagellum. Previous studies showed that loss of flagellar protein export apparatus components inhibits transcription of flagellar genes. The FlgS/FlgR two-component system activates transcription of RpoN-dependent genes though an unknown mechanism. To understand better the extent to which flagellar gene regulation is coupled to flagellar assembly, we disrupted flagellar biogenesis at various points and determined how these mutations affected transcription of RpoN-dependent (flaB and flgE) and FliA-dependent (flaA) genes. The MS ring (encoded by fliF) is one of the earliest flagellar structures assembled. Deletion of fliF resulted in the elimination of RpoN-dependent transcripts and an ∼4-fold decrease in flaA transcript levels. FliH is a cytoplasmic protein that functions with the C ring protein FliN to shuttle substrates to the export apparatus. Deletions of fliH and genes encoding C ring components (fliM and fliY) decreased transcript levels of flaB and flgE but had little or no effect on transcript levels of flaA. Transcript levels of flaB and flgE were elevated in mutants where genes encoding rod proteins (fliE and flgBC) were deleted, while transcript levels of flaA was reduced ∼2-fold in both mutants. We propose that FlgS responds to an assembly checkpoint associated with the export apparatus and that FliH and one or more C ring component assist FlgS in engaging this flagellar structure. IMPORTANCE The mechanisms used by bacteria to couple transcription of flagellar genes with assembly of the flagellum are poorly understood. The results from this study identified components of the H. pylori flagellar basal body that either positively or negatively affect expression of RpoN-dependent flagellar genes. Some of these basal body proteins may interact directly with regulatory proteins that control transcription of the H. pylori RpoN regulon, a hypothesis that can be tested by examining protein-protein interactions in vitro.
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Requirement of the flagellar protein export apparatus component FliO for optimal expression of flagellar genes in Helicobacter pylori. J Bacteriol 2014; 196:2709-17. [PMID: 24837287 DOI: 10.1128/jb.01332-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Flagellar biogenesis in Helicobacter pylori involves the coordinated expression of flagellar genes with assembly of the flagellum. The H. pylori flagellar genes are organized into three regulons based on the sigma factor needed for their transcription (RpoD [σ(80)], RpoN [σ(54)], or FliA [σ(28)]). Transcription of RpoN-dependent genes is activated by a two-component system consisting of the sensor kinase FlgS and the response regulator FlgR. While the cellular cues sensed by the FlgS/FlgR two-component system remain to be elucidated, previous studies revealed that disrupting certain components of the flagellar export apparatus inhibited transcription of the RpoN regulon. FliO is the least conserved of the membrane-bound components of the export apparatus and has not been annotated for any of the H. pylori genomes sequenced to date. A PSI-BLAST analysis identified a potential H. pylori FliO protein which membrane topology algorithms predict to possess a large N-terminal periplasmic domain that is absent from FliO of Escherichia coli and Salmonella, the paradigms for flagellar structure/function studies. FliO was necessary for flagellar biogenesis as well as wild-type levels of motility and transcription of RpoN-dependent and FliA-dependent flagellar genes in H. pylori strain B128. FliO also appears to be required for wild-type levels of the export apparatus protein FlhA in the membrane. Interestingly, the periplasmic and cytoplasmic domains were somewhat dispensable for flagellar gene regulation and assembly, suggesting that these domains have relatively minor roles in flagellar synthesis.
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Pereira LE, Tsang J, Mrázek J, Hoover TR. The zinc-ribbon domain of Helicobacter pylori HP0958: requirement for RpoN accumulation and possible roles of homologs in other bacteria. MICROBIAL INFORMATICS AND EXPERIMENTATION 2014; 1:1-10. [PMID: 22408721 PMCID: PMC3372290 DOI: 10.1186/2042-5783-1-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background Helicobacter pylori HP0958 protein (FlgZ) prevents the rapid turnover of RpoN (σ54), a transcription factor required for expression of several flagellar genes in H. pylori. FlgZ possesses a zinc-ribbon domain (DUF164) that contains two conserved CXXC motifs which coordinate a zinc ion and is thought to interact with nucleic acids or proteins. Two conserved cysteine residues in FlgZ (Cys-202 and Cys-223) were replaced with serine to assess their significance in FlgZ function. After confirming the importance of the CXXC motifs in the DUF164 domain of FlgZ, the distribution of DUF164 proteins and RpoN homologs in other bacteria was examined to determine if a correlation existed for the concurrence of the two proteins. Results Levels of RpoN were greatly reduced in H. pylori strains that expressed the FlgZC202S or FlgZC223S variants. The FlgZC202S variant, but not the FlgZC223S variant, accumulated at levels similar to the wild-type protein. DUF164 proteins are not universally distributed and appear to be absent in several major bacterial taxa, including Cyanobacteria as well as Alpha-, Beta- and Gammaproteobacteria. With the exception of the Actinobacteria, members of which generally lack RpoN, genes encoding DUF164 proteins and RpoN are frequently found in the same genome. Interestingly, many of the DUF164 proteins in Actinobacteria and Bacteroidetes lack most or even all of the conserved cysteine residues. Conclusions These findings suggest the importance of the zinc-ribbon domain of FlgZ in protecting RpoN from turnover. Since many bacteria that possess a DUF164 protein also contain RpoN, DUF164 proteins may have roles in RpoN protection or function in other bacteria.
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Affiliation(s)
- Lara E Pereira
- Emory Vaccine Center, 954 Gatewood Road, Emory University, Atlanta, GA 30329, USA
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Tsang J, Hoover TR. Themes and Variations: Regulation of RpoN-Dependent Flagellar Genes across Diverse Bacterial Species. SCIENTIFICA 2014; 2014:681754. [PMID: 24672734 PMCID: PMC3930126 DOI: 10.1155/2014/681754] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 12/16/2013] [Indexed: 06/03/2023]
Abstract
Flagellar biogenesis in bacteria is a complex process in which the transcription of dozens of structural and regulatory genes is coordinated with the assembly of the flagellum. Although the overall process of flagellar biogenesis is conserved among bacteria, the mechanisms used to regulate flagellar gene expression vary greatly among different bacterial species. Many bacteria use the alternative sigma factor σ (54) (also known as RpoN) to transcribe specific sets of flagellar genes. These bacteria include members of the Epsilonproteobacteria (e.g., Helicobacter pylori and Campylobacter jejuni), Gammaproteobacteria (e.g., Vibrio and Pseudomonas species), and Alphaproteobacteria (e.g., Caulobacter crescentus). This review characterizes the flagellar transcriptional hierarchies in these bacteria and examines what is known about how flagellar gene regulation is linked with other processes including growth phase, quorum sensing, and host colonization.
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Affiliation(s)
- Jennifer Tsang
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Timothy R. Hoover
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Tsang J, Smith TG, Pereira LE, Hoover TR. Insertion mutations in Helicobacter pylori flhA reveal strain differences in RpoN-dependent gene expression. MICROBIOLOGY-SGM 2012; 159:58-67. [PMID: 23154969 DOI: 10.1099/mic.0.059063-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Flagellar biogenesis in the gastric pathogen Helicobacter pylori involves a transcriptional hierarchy that utilizes all three sigma factors found in this bacterium (RpoD, RpoN and FliA). Transcription of the RpoN-dependent genes requires the sensor kinase FlgS and response regulator FlgR. It is thought that FlgS senses some cellular cue to regulate transcription of the RpoN-dependent flagellar genes, but this signal has yet to be identified. Previous studies showed that transcription of the RpoN-dependent genes is inhibited by mutations in flhA, which encodes a membrane-bound component of the flagellar protein export apparatus. We found that depending on the H. pylori strain used, insertion mutations in flhA had different effects on expression of RpoN-dependent genes. Mutations in flhA in H. pylori strains B128 and ATCC 43504 (the type strain) were generated by inserting a chloramphenicol resistance cassette so as to effectively eliminate expression of the gene (ΔflhA), or within the gene following codon 77 (designated flhA77) or codon 454 (designated flhA454), which could allow expression of truncated FlhA proteins. All three flhA mutations severely inhibited transcription of the RpoN-dependent genes flaB and flgE in H. pylori B128. In contrast, levels of flaB and flgE transcripts in H. pylori ATCC 43504 bearing either flhA77 or flhA454, but not ΔflhA, were ~60 % of wild-type levels. The FlhA(454) variant was detected in membrane fractions prepared from H. pylori ATCC 43504 but not H. pylori B128, which may account for the phenotypic differences in the flhA mutations of the two strains. Taken together, these findings suggest that only the N-terminal region of FlhA is needed for transcription of the RpoN regulon. Interestingly, expression of an flaB'-'xylE reporter gene in H. pylori ATCC 43504 bearing the flhA77 allele was about eightfold higher than that of a strain with the wild-type allele, suggesting that expression of flaB is not only regulated at the level of transcription but also regulated post-transcriptionally.
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Affiliation(s)
- Jennifer Tsang
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Todd G Smith
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Lara E Pereira
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Timothy R Hoover
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Multiple Conformations of the FliG C-Terminal Domain Provide Insight into Flagellar Motor Switching. Structure 2012; 20:315-25. [DOI: 10.1016/j.str.2011.11.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/25/2011] [Accepted: 11/29/2011] [Indexed: 01/01/2023]
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17
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Lertsethtakarn P, Ottemann KM, Hendrixson DR. Motility and chemotaxis in Campylobacter and Helicobacter . Annu Rev Microbiol 2012; 65:389-410. [PMID: 21939377 DOI: 10.1146/annurev-micro-090110-102908] [Citation(s) in RCA: 218] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Flagellar motility of Campylobacter jejuni and Helicobacter pylori influences host colonization by promoting migration through viscous milieus such as gastrointestinal mucus. This review explores mechanisms C. jejuni and H. pylori employ to control flagellar biosynthesis and chemotactic responses. These microbes tightly control the activities of σ(54) and σ(28) to mediate ordered flagellar gene expression. In addition to phase-variable and posttranslational mechanisms, flagellar biosynthesis is regulated spatially and numerically so that only a certain number of organelles are placed at polar sites. To mediate chemotaxis, C. jejuni and H. pylori combine basic chemotaxis signal transduction components with several accessory proteins. H. pylori is unusual in that it lacks a methylation-based adaptation system and produces multiple CheV coupling proteins. Chemoreceptors in these bacteria contain nonconserved ligand binding domains, with several chemoreceptors matched to environmental signals. Together, these mechanisms allow for swimming motility that is essential for colonization.
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Affiliation(s)
- Paphavee Lertsethtakarn
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, USA
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Gilbreath JJ, Cody WL, Merrell DS, Hendrixson DR. Change is good: variations in common biological mechanisms in the epsilonproteobacterial genera Campylobacter and Helicobacter. Microbiol Mol Biol Rev 2011; 75:84-132. [PMID: 21372321 PMCID: PMC3063351 DOI: 10.1128/mmbr.00035-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Microbial evolution and subsequent species diversification enable bacterial organisms to perform common biological processes by a variety of means. The epsilonproteobacteria are a diverse class of prokaryotes that thrive in diverse habitats. Many of these environmental niches are labeled as extreme, whereas other niches include various sites within human, animal, and insect hosts. Some epsilonproteobacteria, such as Campylobacter jejuni and Helicobacter pylori, are common pathogens of humans that inhabit specific regions of the gastrointestinal tract. As such, the biological processes of pathogenic Campylobacter and Helicobacter spp. are often modeled after those of common enteric pathogens such as Salmonella spp. and Escherichia coli. While many exquisite biological mechanisms involving biochemical processes, genetic regulatory pathways, and pathogenesis of disease have been elucidated from studies of Salmonella spp. and E. coli, these paradigms often do not apply to the same processes in the epsilonproteobacteria. Instead, these bacteria often display extensive variation in common biological mechanisms relative to those of other prototypical bacteria. In this review, five biological processes of commonly studied model bacterial species are compared to those of the epsilonproteobacteria C. jejuni and H. pylori. Distinct differences in the processes of flagellar biosynthesis, DNA uptake and recombination, iron homeostasis, interaction with epithelial cells, and protein glycosylation are highlighted. Collectively, these studies support a broader view of the vast repertoire of biological mechanisms employed by bacteria and suggest that future studies of the epsilonproteobacteria will continue to provide novel and interesting information regarding prokaryotic cellular biology.
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Affiliation(s)
- Jeremy J. Gilbreath
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - William L. Cody
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - D. Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - David R. Hendrixson
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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Lam WWL, Woo EJ, Kotaka M, Tam WK, Leung YC, Ling TKW, Au SWN. Molecular interaction of flagellar export chaperone FliS and cochaperone HP1076 in Helicobacter pylori. FASEB J 2010; 24:4020-32. [PMID: 20581225 DOI: 10.1096/fj.10-155242] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Flagellar export chaperone FliS prevents premature polymerization of flagellins and is critical for flagellar assembly and bacterial colonization. Previously, a yeast 2-hybrid study identified various FliS-associated proteins in Helicobacter pylori, but the implications of these interactions are not known. Here we demonstrate the biophysical interaction of FliS (HP0753) and the uncharacterized protein HP1076 from H. pylori. HP1076 possesses a cochaperone activity that promotes the folding and chaperone activity of FliS. We further determined the crystal structures of FliS, HP1076, and the binary complex at 2.7, 1.8, and 2.7 Å resolution, respectively. HP1076 adopts a helix-rich bundle structure and interestingly shares a similar fold with a flagellin homologue, hook-associated protein, and FliS. The FliS-HP1076 complex revealed an extensive electrostatic and hydrophobic binding interface, which is distinct from the flagellin binding pocket in FliS. The helical stacking interaction between HP1076 and FliS suggests that HP1076 stabilizes 2 α helices of FliS and therefore the overall structure of the bundle. Our findings provide new insights into flagellar export chaperones and may have implications for other secretion chaperones in the type III secretion system.
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Affiliation(s)
- Wendy Wai Ling Lam
- Centre of Protein Science and Crystallography, Department of Biochemistry, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, China
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20
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Duckworth MJ, Okoli AS, Mendz GL. Novel Helicobacter pylori therapeutic targets: the unusual suspects. Expert Rev Anti Infect Ther 2009; 7:835-67. [PMID: 19735225 DOI: 10.1586/eri.09.61] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Understanding the current status of the discovery and development of anti-Helicobacter therapies requires an overview of the searches for therapeutic targets performed to date. A summary is given of the very substantial body of work conducted in the quest to find Helicobacter pylori genes that could be suitable candidates for therapeutic intervention. The products of most of these genes perform metabolic functions, and others have roles in growth, cell motility and colonization. The genes identified as potential targets have been organized into three categories according to their degree of characterization. A short description and evaluation is provided of the main candidates in each category. Investigations of potential therapeutic targets have generated a wealth of information about the physiology and genetics of H. pylori, and its interactions with the host, but have yielded little by way of new therapies.
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Affiliation(s)
- Megan J Duckworth
- School of Medicine, Sydney, The University of Notre Dame Australia, 160 Oxford Street, Darlinghurst, NSW 2010, Australia.
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21
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Abstract
Helicobacter pylori uses flagellum-mediated chemotaxis to promote infection. Bacterial flagella change rotational direction by changing the state of the flagellar motor via a subcomplex referred to as the switch. Intriguingly, the H. pylori genome encodes four switch complex proteins, FliM, FliN, FliY, and FliG, instead of the more typical three of Escherichia coli or Bacillus subtilis. Our goal was to examine whether and how all four switch proteins participate in flagellation. Previous work determined that FliG was required for flagellation, and we extend those findings to show that all four switch proteins are necessary for normal numbers of flagellated cells. Furthermore, while fliY and fliN are partially redundant with each other, both are needed for wild-type levels of flagellation. We also report the isolation of an H. pylori strain containing an R54C substitution in fliM, resulting in bacteria that swim constantly and do not change direction. Along with data demonstrating that CheY-phosphate interacts with FliM, these findings suggest that FliM functions in H. pylori much as it does in other organisms.
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22
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Smith TG, Pereira L, Hoover TR. Helicobacter pylori FlhB processing-deficient variants affect flagellar assembly but not flagellar gene expression. MICROBIOLOGY-SGM 2009; 155:1170-1180. [PMID: 19332819 DOI: 10.1099/mic.0.022806-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Regulation of the Helicobacter pylori flagellar gene cascade involves the transcription factors sigma(54) (RpoN), employed for expression of genes required midway through flagellar assembly, and sigma(28) (FliA), required for expression of late genes. Previous studies revealed that mutations in genes encoding components of the flagellar protein export apparatus block expression of the H. pylori RpoN and FliA regulons. FlhB is a membrane-bound component of the export apparatus that possesses a large cytoplasmic domain (FlhB(C)). The hook length control protein FliK interacts with FlhB(C) to modulate the substrate specificity of the export apparatus. FlhB(C) undergoes autocleavage as part of the switch in substrate specificity. Consistent with previous reports, deletion of flhB in H. pylori interfered with expression of RpoN-dependent reporter genes, while deletion of fliK stimulated expression of these reporter genes. In the DeltaflhB mutant, disrupting fliK did not restore expression of RpoN-dependent reporter genes, suggesting that the inhibitory effect of the DeltaflhB mutation is not due to the inability to export FliK. Amino acid substitutions (N265A and P266G) at the putative autocleavage site of H. pylori FlhB prevented processing of FlhB and export of filament-type substrates. The FlhB variants supported wild-type expression of RpoN- and FliA-dependent reporter genes. In the strain producing FlhB(N265A), expression of RpoN- and FliA-dependent reporter genes was inhibited when fliK was disrupted. In contrast, expression of these reporter genes was unaffected or slightly stimulated when fliK was disrupted in the strain producing FlhB(P266G). H. pylori HP1575 (FlhX) shares homology with the C-terminal portion of FlhB(C) (FlhB(CC)) and can substitute for FlhB(CC) in flagellar assembly. Disrupting flhX inhibited expression of a flaB reporter gene in the wild-type but not in the DeltafliK mutant or strains producing FlhB variants, suggesting a role for FlhX or FlhB(CC) in normal expression of the RpoN regulon. Taken together, these data indicate that the mechanism by which the flagellar protein export apparatus exerts control over the H. pylori RpoN regulon is complex and involves more than simply switching substrate specificity of the flagellar protein export apparatus.
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Affiliation(s)
- Todd G Smith
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Lara Pereira
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Timothy R Hoover
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Smith TG, Hoover TR. Deciphering bacterial flagellar gene regulatory networks in the genomic era. ADVANCES IN APPLIED MICROBIOLOGY 2009; 67:257-95. [PMID: 19245942 DOI: 10.1016/s0065-2164(08)01008-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Synthesis of the bacterial flagellum is a complex process involving dozens of structural and regulatory genes. Assembly of the flagellum is a highly-ordered process, and in most flagellated bacteria the structural genes are expressed in a transcriptional hierarchy that results in the products of these genes being made as they are needed for assembly. Temporal regulation of the flagellar genes is achieved through sophisticated regulatory networks that utilize checkpoints in the flagellar assembly pathway to coordinate expression of flagellar genes. Traditionally, flagellar transcriptional hierarchies are divided into various classes. Class I genes, which are the first genes expressed, encode a master regulator that initiates the transcriptional hierarchy. The master regulator activates transcription a set of structural and regulatory genes referred to as class II genes, which in turn affect expression of subsequent classes of flagellar genes. We review here the literature on the expression and activity of several known master regulators, including FlhDC, CtrA, VisNR, FleQ, FlrA, FlaK, LafK, SwrA, and MogR. We also examine the Department of Energy Joint Genomes Institute database to make predictions about the distribution of these regulators. Many bacteria employ the alternative sigma factors sigma(54) and/or sigma(28) to regulate transcription of later classes of flagellar genes. Transcription by sigma(54)-RNA polymerase holoenzyme requires an activator, and we review the literature on the sigma(54)-dependent activators that control flagellar gene expression in several bacterial systems, as well as make predictions about other systems that may utilize sigma(54) for flagellar gene regulation. Finally, we review the prominent systems that utilize sigma(28) and its antagonist, the anti-sigma(28) factor FlgM, along with some systems that utilize alternative mechanisms for regulating flagellar gene expression.
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Affiliation(s)
- Todd G Smith
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, USA
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24
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Hendrixson DR, DiRita VJ. Transcription of sigma54-dependent but not sigma28-dependent flagellar genes in Campylobacter jejuni is associated with formation of the flagellar secretory apparatus. Mol Microbiol 2004; 50:687-702. [PMID: 14617189 DOI: 10.1046/j.1365-2958.2003.03731.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We performed a genetic analysis of flagellar regulation in Campylobacter jejuni, from which we elucidated key portions of the flagellar transcriptional cascade in this bacterium. For this study, we developed a reporter gene system for C. jejuni involving astA, encoding arylsulphatase, and placed astA under control of the sigma 54-regulated flgDE2 promoter in C. jejuni strain 81-176. The astA reporter fusion combined with transposon mutagenesis allowed us to identify genes in which insertions abolished flgDE2 expression; genes identified were on both the chromosome and the plasmid pVir. Included among the chromosomal genes were genes encoding a putative sensor kinase and the sigma 54-dependent transcriptional activator, FlgR. In addition, we identified specific flagellar genes, including flhA, flhB, fliP, fliR and flhF, that are also required for transcription of flgDE2 and are presumably at the beginning of the C. jejuni flagellar transcriptional cascade. Deletion of any of these genes reduced transcription of both flgDE2 and another sigma 54-dependent flagellar gene, flaB, encoding a minor flagellin. Transcription of the sigma 28-dependent gene flaA, encoding the major flagellin, was largely unaffected in the mutants. Further examination of flaA transcription revealed significant sigma 28-independent transcription and only weak repressive activity of the putative anti-sigma 28 factor FlgM. Our study suggests that sigma 54-dependent transcription of flagellar genes in C. jejuni is linked to the formation of the flagellar secretory apparatus. A key difference in the C. jejuni flagellar transcriptional cascade compared with other bacteria that use sigma 28 for transcription of flagellar genes is that a mechanism to repress significantly sigma 28-dependent transcription of flaA in flagellar assembly mutants is absent in C. jejuni.
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Affiliation(s)
- David R Hendrixson
- Unit for Laboratory Animal Medicine, University of Michigan Medical School, 5641 Medical Science II, Box 0620, Ann Arbor, MI 48109-0620, USA
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25
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Figura N, Trabalzini L, Mini R, Bernardini G, Scaloni A, Talamo F, Lusini P, Ferro E, Martelli P, Santucci A. Inactivation of Helicobacter pylori cagA gene affects motility. Helicobacter 2004; 9:185-93. [PMID: 15165253 DOI: 10.1111/j.1083-4389.2004.00224.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND The cytotoxin-associated protein CagA is a Helicobacter pylori immunodominant antigen whose gene resides in the cag pathogenicity island. Our purpose was to determine if the disruption or deletion of cagA gene could have an effect on the expression of other proteins at the proteome level. We analyzed two H. pylori strains, 328 and G27 wild-type, bearing the cag pathogenicity island, and their respective isogenic cagA(-) mutants. METHODS The proteomes of two H. pylori strains (328 and its isogenic mutant SPM328_DeltacagA) were resolved by two-dimensional electrophoresis and the digitalized images obtained were analysed both quantitatively and qualitatively. Peculiar spots of each strain were identified by mass spectrometry or by Western blotting. RESULTS The comparison between the proteome expression of an H. pylori cagA(+) strain and an isogenic mutant strain where the cagA gene was disrupted showed that, as well as the lack of expression of CagA, both flagellin A and flagellin B expressions were significantly decreased. The cagA(-) isogenic mutant was nonmotile. G27_DeltacagA, in which CagA was inactivated by gene deletion, was nonmotile as well respecting to motile G27 wild-type strain. Moreover, reintroduction of cagA in G27_DeltacagA restored motility. CONCLUSIONS Our results suggest that CagA could quantitatively influence flaA and flaB transcription or their subsequent translation and/or correct folding.
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Affiliation(s)
- Natale Figura
- Dipartimento di Medicina Interna, Scienze Endocrino-Metaboliche e Biochimica, Policlinico Le Scotte, 53100 Siena, Italy
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26
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Niehus E, Gressmann H, Ye F, Schlapbach R, Dehio M, Dehio C, Stack A, Meyer TF, Suerbaum S, Josenhans C. Genome-wide analysis of transcriptional hierarchy and feedback regulation in the flagellar system of Helicobacter pylori. Mol Microbiol 2004; 52:947-61. [PMID: 15130117 DOI: 10.1111/j.1365-2958.2004.04006.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The flagellar system of Helicobacter pylori, which comprises more than 40 mostly unclustered genes, is essential for colonization of the human stomach mucosa. In order to elucidate the complex transcriptional circuitry of flagellar biosynthesis in H. pylori and its link to other cell functions, mutants in regulatory genes governing flagellar biosynthesis (rpoN, flgR, flhA, flhF, HP0244) and whole-genome microarray technology were used in this study. The regulon controlled by RpoN, its activator FlgR (FleR) and the cognate histidine kinase HP0244 (FleS) was characterized on a genome-wide scale for the first time. Seven novel genes (HP1076, HP1233, HP1154/1155, HP0366/367, HP0869) were identified as belonging to RpoN-associated flagellar regulons. The hydrogenase accessory gene HP0869 was the only annotated non-flagellar gene in the RpoN regulon. Flagellar basal body components FlhA and FlhF were characterized as functional equivalents to master regulators in H. pylori, as their absence led to a general reduction of transcripts in the RpoN (class 2) and FliA (class 3) regulons, and of 24 genes newly attributed to intermediate regulons, under the control of two or more promoters. FlhA- and FlhF-dependent regulons comprised flagellar and non-flagellar genes. Transcriptome analysis revealed that negative feedback regulation of the FliA regulon was dependent on the antisigma factor FlgM. FlgM was also involved in FlhA- but not FlhF-dependent feedback control of the RpoN regulon. In contrast to other bacteria, chemotaxis and flagellar motor genes were not controlled by FliA or RpoN. A true master regulator of flagellar biosynthesis is absent in H. pylori, consistent with the essential role of flagellar motility and chemotaxis for this organism.
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Affiliation(s)
- Eike Niehus
- Institute of Hygiene and Microbiology, University of Wuerzburg, Josef-Schneider-Strasse 2, D-97080 Wuerzburg, Germany
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Kavermann H, Burns BP, Angermuller K, Odenbreit S, Fischer W, Melchers K, Haas R. Identification and characterization of Helicobacter pylori genes essential for gastric colonization. J Exp Med 2003; 197:813-22. [PMID: 12668646 PMCID: PMC2193887 DOI: 10.1084/jem.20021531] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori causes one of the most common, chronic bacterial infections and is a primary cause of severe gastric disorders. To unravel the bacterial factors necessary for the process of gastric colonization and pathogenesis, signature tagged mutagenesis (STM) was adapted to H. pylori. The Mongolian gerbil (Meriones unguiculatus) was used as model system to screen a set of 960 STM mutants. This resulted in 47 H. pylori genes, assigned to 9 different functional categories, representing a set of biological functions absolutely essential for gastric colonization, as verified and quantified for many mutants by competition experiments. Identification of previously known colonization factors, such as the urease and motility functions validated this method, but also novel and several hypothetical genes were found. Interestingly, a secreted collagenase, encoded by hp0169, could be identified and functionally verified as a new essential virulence factor for H. pylori stomach colonization. Furthermore, comB4, encoding a putative ATPase being part of a DNA transformation-associated type IV transport system of H. pylori was found to be absolutely essential for colonization, but natural transformation competence was apparently not the essential function. Thus, this first systematic STM application identified a set of previously unknown H. pylori colonization factors and may help to potentiate the development of novel therapies against gastric Helicobacter infections.
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Affiliation(s)
- Holger Kavermann
- Max von Pettenkofer-Institut, Pettenkoferstr. 9a, 80336 Munich, Germany.
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Waidner B, Melchers K, Ivanov I, Loferer H, Bensch KW, Kist M, Bereswill S. Identification by RNA profiling and mutational analysis of the novel copper resistance determinants CrdA (HP1326), CrdB (HP1327), and CzcB (HP1328) in Helicobacter pylori. J Bacteriol 2002; 184:6700-8. [PMID: 12426358 PMCID: PMC135432 DOI: 10.1128/jb.184.23.6700-6708.2002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mechanisms involved in maintaining cytoplasmic metal ion homeostasis play a central role in the adaptation of Helicobacter pylori to the changing gastric environment. An investigation of the global regulatory responses to copper ions by using RNA profiling with a threshold factor of 4.0 revealed that copper induces transcription of 19 H. pylori genes and that only the ferritin gene pfr is repressed. The 57-fold copper induction identified the HP1326 gene encoding an H. pylori-specific protein as a candidate for a novel copper resistance determinant. The HP1326 gene is expressed as a monocistronic unit, and two small HP1326 mRNAs are copper induced. The HP1326 protein is secreted and is required for copper resistance maintained by cytoplasmic copper homeostasis, as H. pylori HP1326 mutants were copper sensitive and displayed increased copper induction of HP1326 transcription as well as elevated copper repression of ferritin synthesis. The clear copper-sensitive phenotype displayed by H. pylori HP1327 and HP1328 mutants provides strong evidence that the HP1326 protein, together with the signal peptide site of the H. pylori-specific protein HP1327, whose gene is located downstream from that encoding HP1326, and the CzcB and CzcA metal efflux system component homologs HP1328 and HP1329, constitutes a novel type of copper efflux pump, as discussed below. The HP1329 gene could not be inactivated, but the 14-fold transcriptional copper induction determined by RNA profiling points towards a function of the encoded CzcA homolog in copper resistance. In summary, results from RNA profiling identified the novel H. pylori-specific copper resistance determinants CrdA (HP1326) and CrdB (HP1327), which are required for adaptation to copper-rich environmental conditions.
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Affiliation(s)
- Barbara Waidner
- Department of Microbiology and Hygiene, Institute of Medical Microbiology and Hygiene, University Hospital Freiburg, D-79104 Freiburg, Germany
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Matz C, van Vliet AHM, Ketley JM, Penn CW. Mutational and transcriptional analysis of the Campylobacter jejuni flagellar biosynthesis gene flhB. MICROBIOLOGY (READING, ENGLAND) 2002; 148:1679-1685. [PMID: 12055288 DOI: 10.1099/00221287-148-6-1679] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A Campylobacter jejuni gene encoding a homologue of the flagellar biosynthesis gene flhB was identified downstream of the peroxide stress defence gene ahpC. Insertional mutagenesis of the flhB gene rendered C. jejuni non-motile, with most cells aflagellate, although a small number expressed truncated flagella. The absence of FlhB also appeared to affect cell shape, as the majority of cells were straight rather than curved rods. Transcription of the flagellin gene flaA was significantly reduced in the C. jejuni flhB mutants, which also did not express significant amounts of flagellin proteins, indicating that FlhB is an essential protein for subsequent expression of flagellar genes. The transcription start site of the flhB gene, as determined by primer extension, was located 91 bp upstream of the flhB start codon, but no recognizable promoter sequence could be identified immediately upstream of this transcription start site. Transcriptional flhB::lacZ reporter gene fusions confirmed that the flhB gene has its own promoter region, is expressed at very low levels and is transcribed independently of ahpC, and that its transcription is not regulated by iron or growth phase.
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Affiliation(s)
- Claudia Matz
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK1
| | - Arnoud H M van Vliet
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK3
- Department of Gastroenterology and Hepatology, Academic Hospital Dijkzigt, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands2
| | - Julian M Ketley
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK3
| | - Charles W Penn
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK1
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Further strategies for signature-tagged mutagenesis and the application of oligonucleotide microarrays for the quantification of DNA-tagged strains. METHODS IN MICROBIOLOGY 2002. [DOI: 10.1016/s0580-9517(02)33011-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Colland F, Rain JC, Gounon P, Labigne A, Legrain P, De Reuse H. Identification of the Helicobacter pylori anti-sigma28 factor. Mol Microbiol 2001; 41:477-87. [PMID: 11489132 DOI: 10.1046/j.1365-2958.2001.02537.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Flagellar motility is essential for colonization of the human gastric mucosa by Helicobacter pylori. The flagellar filament is composed of two subunits, FlaA and FlaB. Transcription of the genes encoding these proteins is controlled by the sigma28 and sigma54 factors of RNA polymerase respectively. The expression of flagellar genes is regulated, but no sigma28-specific effector was identified. It was also unclear whether H. pylori possessed a checkpoint for flagellar synthesis, and no gene encoding an anti-sigma28 factor, FlgM, could be identified by sequence similarity searches. To investigate the sigma28-dependent regulation, a new approach based on genomic data was used. Two-hybrid screening with the H. pylori proteins identified a protein of unknown function (HP1122) interacting with the sigma28 factor and defined the C-terminal part of HP1122 (residues 48-76) as the interaction domain. HP1122 interacts with region 4 of sigma28 and prevents its association with the beta-region of H. pylori RNA polymerase. Thus, HP1122 presented the characteristics of an anti-sigma28 factor. This was confirmed in H. pylori by RNA dot-blot hybridization and electron microscopy. The level of sigma28-dependent flaA transcription was higher in a HP1122-deficient strain and was decreased by the overproduction of HP1122. The overproduction of HP1122 also resulted in H. pylori cells with highly truncated flagella. These results demonstrate that HP1122 is the H. pylori anti-sigma28 factor, FlgM, a major regulator of flagellum assembly. Potential anti-sigma28 factors were identified in Campylobacter jejuni, Pseudomonas aeruginosa and Thermotoga maritima by sequence homology with the C-terminal region of HP1122.
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Affiliation(s)
- F Colland
- Hybrigenics SA, 180 avenue Daumesnil, Paris 75012, France
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