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Dhindwal P, Boniecki MT, Moore SA. Helicobacter pylori FlgN binds its substrate FlgK and the flagellum ATPase FliI in a similar manner observed for the FliT chaperone. Protein Sci 2024; 33:e4882. [PMID: 38151822 PMCID: PMC10804663 DOI: 10.1002/pro.4882] [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: 07/28/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 12/29/2023]
Abstract
In bacterial flagellum biogenesis, secretion of the hook-filament junction proteins FlgK and FlgL and completion of the flagellum requires the FlgN chaperone. Similarly, the related FliT chaperone is necessary for the secretion of the filament cap protein FliD and binds the flagellar export gate protein FlhA and the flagellum ATPase FliI. FlgN and FliT require FliJ for effective substrate secretion. In Helicobacter pylori, neither FlgN, FliT, nor FliJ have been annotated. We demonstrate that the genome location of HP1120 is identical to that of flgN in other flagellated bacteria and that HP1120 is the homolog of Campylobacter jejuni FlgN. A modeled HP1120 structure contains three α-helices and resembles the FliT chaperone, sharing a similar substrate-binding pocket. Using pulldowns and thermophoresis, we show that both HP1120 and a HP1120Δ126-144 deletion mutant bind to FlgK with nanomolar affinity, but not to the filament cap protein FliD, confirming that HP1120 is FlgN. Based on size-exclusion chromatography and multi-angle light scattering, H. pylori FlgN binds to FlgK with 1:1 stoichiometry. Overall structural similarities between FlgN and FliT suggest that substrate recognition on FlgN primarily involves an antiparallel coiled-coil interface between the third helix of FlgN and the C-terminal helix of the substrate. A FlgNΔ126-144 N100A, Y103A, S111I triple mutant targeting this interface significantly impairs the binding of FlgK. Finally, we demonstrate that FlgNΔ126-144 , like FliT, binds with sub-micromolar affinity to the flagellum ATPase FliI or its N-terminal domain. Hence FlgN and FliT likely couple delivery of low-abundance export substrates to the flagellum ATPase FliI.
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Affiliation(s)
- Poonam Dhindwal
- Department of Biochemistry, Microbiology and ImmunologyCollege of Medicine, University of SaskatchewanSaskatoonCanada
| | - Michal T. Boniecki
- Department of Biochemistry, Microbiology and ImmunologyCollege of Medicine, University of SaskatchewanSaskatoonCanada
| | - Stanley A. Moore
- Department of Biochemistry, Microbiology and ImmunologyCollege of Medicine, University of SaskatchewanSaskatoonCanada
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Transcriptome Analysis of the Response of Mature Helicobacter pylori Biofilm to Different Doses of Lactobacillus salivarius LN12 with Amoxicillin and Clarithromycin. Antibiotics (Basel) 2022; 11:antibiotics11020262. [PMID: 35203863 PMCID: PMC8868532 DOI: 10.3390/antibiotics11020262] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/13/2022] [Accepted: 02/15/2022] [Indexed: 02/04/2023] Open
Abstract
Helicobacter pylori is a gastrointestinal pathogen with a high infection rate. Probiotics are clinically used as an adjuvant to improve the cure rate and reduce the side effects of antibiotic treatment for H. pylori. This study is the first to explore the effects of a cell-free supernatant of high- or low-dose Lactobacillus salivarius LN12 combined with amoxicillin (AMX) and clarithromycin (CLR) on H. pylori 3192 biofilms in terms of the biofilm biomass, survival rates, biofilm structure, and transcriptome. The results showed that the combination of the CFS of high-dose LN12 with AMX and CLR had stronger effects on the biofilm biomass, survival rate, and structure of H. pylori 3192 biofilms. H. pylori 3192 biofilms may increase the expression of NADH-related genes and downregulate flagellar assembly and quorum sensing-related receptor genes to deal with the stronger stress effects of high-dose LN12 with AMX and CLR. In conclusion, the biofilm biomass, survival rate, structure, and transcriptome results showed that the combination of LN12 CFS with AMX and CLR had dose effects. We recommend that compared with low doses, high doses of L. salivarus LN12 combined with AMX and CLR may be more effective for H. pylori biofilm than low doses.
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Matzke NJ, Lin A, Stone M, Baker MAB. Flagellar export apparatus and ATP synthetase: Homology evidenced by synteny predating the Last Universal Common Ancestor. Bioessays 2021; 43:e2100004. [PMID: 33998015 DOI: 10.1002/bies.202100004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/01/2021] [Accepted: 04/21/2021] [Indexed: 11/07/2022]
Abstract
We report evidence further supporting homology between proteins in the F1 FO -ATP synthetase and the bacterial flagellar motor (BFM). BFM proteins FliH, FliI, and FliJ have been hypothesized to be homologous to FO -b + F1 -δ, F1 -α/β, and F1 -γ, with similar structure and interactions. We conduct a further test by constructing a gene order dataset, examining the order of fliH, fliI, and fliJ genes across the phylogenetic breadth of flagellar and nonflagellar type 3 secretion systems, and comparing this to published surveys of gene order in the F1 FO -ATP synthetase, its N-ATPase relatives, and the bacterial/archaeal V- and A-type ATPases. Strikingly, the fliHIJ gene order was deeply conserved, with the few exceptions appearing derived, and exactly matching the widely conserved F-ATPase gene order atpFHAG, coding for subunits b-δ-α-γ. The V/A-type ATPases have a similar conserved gene order. Our results confirm homology between these systems, and suggest a rare case of synteny conserved over billions of years, predating the Last Universal Common Ancestor (LUCA).
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Affiliation(s)
- Nicholas J Matzke
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Angela Lin
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Micaella Stone
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Matthew A B Baker
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia.,CSIRO Synthetic Biology Future Science Platform, Brisbane, Australia
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Alav I, Kobylka J, Kuth MS, Pos KM, Picard M, Blair JMA, Bavro VN. Structure, Assembly, and Function of Tripartite Efflux and Type 1 Secretion Systems in Gram-Negative Bacteria. Chem Rev 2021; 121:5479-5596. [PMID: 33909410 PMCID: PMC8277102 DOI: 10.1021/acs.chemrev.1c00055] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/11/2022]
Abstract
Tripartite efflux pumps and the related type 1 secretion systems (T1SSs) in Gram-negative organisms are diverse in function, energization, and structural organization. They form continuous conduits spanning both the inner and the outer membrane and are composed of three principal components-the energized inner membrane transporters (belonging to ABC, RND, and MFS families), the outer membrane factor channel-like proteins, and linking the two, the periplasmic adaptor proteins (PAPs), also known as the membrane fusion proteins (MFPs). In this review we summarize the recent advances in understanding of structural biology, function, and regulation of these systems, highlighting the previously undescribed role of PAPs in providing a common architectural scaffold across diverse families of transporters. Despite being built from a limited number of basic structural domains, these complexes present a staggering variety of architectures. While key insights have been derived from the RND transporter systems, a closer inspection of the operation and structural organization of different tripartite systems reveals unexpected analogies between them, including those formed around MFS- and ATP-driven transporters, suggesting that they operate around basic common principles. Based on that we are proposing a new integrated model of PAP-mediated communication within the conformational cycling of tripartite systems, which could be expanded to other types of assemblies.
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Affiliation(s)
- Ilyas Alav
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Jessica Kobylka
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Miriam S. Kuth
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Klaas M. Pos
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Martin Picard
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS
UMR 7099, Université de Paris, 75005 Paris, France
- Fondation
Edmond de Rothschild pour le développement de la recherche
Scientifique, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Jessica M. A. Blair
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Vassiliy N. Bavro
- School
of Life Sciences, University of Essex, Colchester, CO4 3SQ United Kingdom
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Lu Y, Pang J, Wang G, Hu X, Li X, Li G, Wang X, Yang X, Li C, You X. Quantitative proteomics approach to investigate the antibacterial response of Helicobacter pylori to daphnetin, a traditional Chinese medicine monomer. RSC Adv 2021; 11:2185-2193. [PMID: 35424199 PMCID: PMC8693750 DOI: 10.1039/d0ra06677j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 12/11/2020] [Indexed: 12/20/2022] Open
Abstract
Helicobacter pylori is a Gram-negative bacterium related to the development of peptic ulcers and stomach cancer. An increasing number of infected individuals are found to harbor antibiotic-resistant H. pylori, which results in treatment failure. Daphnetin, a traditional Chinese medicine, has a broad spectrum of antibacterial activity without the development of bacterial resistance. However, the antibacterial mechanisms of daphnetin have not been elucidated entirely. To better understand the mechanisms of daphnetin's effect on H. pylori, a label-free quantitative proteomics approach based on an EASY-nLC 1200 system coupled with an Orbitrap Fusion Lumos mass spectrometer was established to investigate the key protein differences between daphnetin- and non-daphnetin-treated H. pylori. Using the criteria of greater than 1.5-fold changes and adjusted p value <0.05, proteins related to metabolism, membrane structure, nucleic acid and protein synthesis, ion binding, H. pylori colonization and infection, stress reaction, flagellar assembly and so on were found to be changed under daphnetin pressure. And the changes of selected proteins in expression level were confirmed by targeted proteomics. These new data provide us a more comprehensive horizon of the proteome changes in H. pylori that occur in response to daphnetin.
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Affiliation(s)
- Yun Lu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Jing Pang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Genzhu Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xinxin Hu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xue Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Guoqing Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xiukun Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xinyi Yang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Congran Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Peking Union Medical College Beijing 100050 China
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Halder PK, Roy C, Datta S. Structural and functional characterization of type three secretion system ATPase PscN and its regulator PscL from Pseudomonas aeruginosa. Proteins 2018; 87:276-288. [PMID: 30561072 DOI: 10.1002/prot.25648] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/29/2018] [Accepted: 12/12/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Pranab Kumar Halder
- Structural Biology and Bioinformatics Division; Council of Scientific and Industrial Research-Indian Institute of Chemical Biology; Kolkata West Bengal India
| | - Chittran Roy
- Structural Biology and Bioinformatics Division; Council of Scientific and Industrial Research-Indian Institute of Chemical Biology; Kolkata West Bengal India
| | - Saumen Datta
- Structural Biology and Bioinformatics Division; Council of Scientific and Industrial Research-Indian Institute of Chemical Biology; Kolkata West Bengal India
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Abstract
Type III secretion systems (T3SSs) afford Gram-negative bacteria an intimate means of altering the biology of their eukaryotic hosts--the direct delivery of effector proteins from the bacterial cytoplasm to that of the eukaryote. This incredible biophysical feat is accomplished by nanosyringe "injectisomes," which form a conduit across the three plasma membranes, peptidoglycan layer, and extracellular space that form a barrier to the direct delivery of proteins from bacterium to host. The focus of this chapter is T3SS function at the structural level; we will summarize the core findings that have shaped our understanding of the structure and function of these systems and highlight recent developments in the field. In turn, we describe the T3SS secretory apparatus, consider its engagement with secretion substrates, and discuss the posttranslational regulation of secretory function. Lastly, we close with a discussion of the future prospects for the interrogation of structure-function relationships in the T3SS.
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Recognition and targeting mechanisms by chaperones in flagellum assembly and operation. Proc Natl Acad Sci U S A 2016; 113:9798-803. [PMID: 27528687 DOI: 10.1073/pnas.1607845113] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The flagellum is a complex bacterial nanomachine that requires the proper assembly of several different proteins for its function. Dedicated chaperones are central in preventing aggregation or undesired interactions of flagellar proteins, including their targeting to the export gate. FliT is a key flagellar chaperone that binds to several flagellar proteins in the cytoplasm, including its cognate filament-capping protein FliD. We have determined the solution structure of the FliT chaperone in the free state and in complex with FliD and the flagellar ATPase FliI. FliT adopts a four-helix bundle and uses a hydrophobic surface formed by the first three helices to recognize its substrate proteins. We show that the fourth helix constitutes the binding site for FlhA, a membrane protein at the export gate. In the absence of a substrate protein FliT adopts an autoinhibited structure wherein both the binding sites for substrates and FlhA are occluded. Substrate binding to FliT activates the complex for FlhA binding and thus targeting of the chaperone-substrate complex to the export gate. The activation and targeting mechanisms reported for FliT appear to be shared among the other flagellar chaperones.
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Ge YY, Xiang QW, Wagner C, Zhang D, Xie ZP, Staehelin C. The type 3 effector NopL of Sinorhizobium sp. strain NGR234 is a mitogen-activated protein kinase substrate. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2483-94. [PMID: 26931172 DOI: 10.1093/jxb/erw065] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Pathogenic bacteria utilize type 3 secretion systems to inject type 3 effectors (T3Es) into host cells, thereby subverting host defense reactions. Similarly, T3Es of symbiotic nitrogen-fixing rhizobia can affect nodule formation on roots of legumes. Previous work showed that NopL (nodulation outer protein L) of Sinorhizobium(Ensifer) sp. strain NGR234 is multiply phosphorylated in eukaryotic cells and that this T3E suppresses responses mediated by mitogen-activated protein (MAP) kinase signaling in yeast (mating pheromone signaling) and plant cells (expression of pathogenesis-related defense proteins). Here, we show that NopL is a MAP kinase substrate. Microscopic observations of fluorescent fusion proteins and bimolecular fluorescence complementation analysis in onion cells indicated that NopL is targeted to the nucleus and forms a complex with SIPK (salicylic acid-induced protein kinase), a MAP kinase of tobacco. In vitro experiments demonstrated that NopL is phosphorylatyed by SIPK. At least nine distinct spots were observed after two-dimensional gel electrophoresis, indicating that NopL can be hyperphosphorylated by MAP kinases. Senescence symptoms in nodules of beans (Phaseolus vulgaris cv. Tendergreen) were analyzed to determine the symbiotic effector activity of different NopL variants with serine to alanine substitutions at identified and predicted phosphorylation sites (serine-proline motif). NopL variants with six or eight serine to alanine substitutions were partially active, whereas NopL forms with 10 or 12 substituted serine residues were inactive. In conclusion, our findings provide evidence that NopL interacts with MAP kinases and reveals the importance of serine-proline motifs for effector activity during symbiosis.
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Affiliation(s)
- Ying-Ying Ge
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qi-Wang Xiang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Christian Wagner
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Di Zhang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhi-Ping Xie
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China Shenzhen Research and Development Center of State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Baoan, Shenzhen, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China Shenzhen Research and Development Center of State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Baoan, Shenzhen, China
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Mutations in the Borrelia burgdorferi Flagellar Type III Secretion System Genes fliH and fliI Profoundly Affect Spirochete Flagellar Assembly, Morphology, Motility, Structure, and Cell Division. mBio 2015; 6:e00579-15. [PMID: 25968649 PMCID: PMC4436065 DOI: 10.1128/mbio.00579-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi migrates to distant sites in the tick vectors and mammalian hosts through robust motility and chemotaxis activities. FliH and FliI are two cytoplasmic proteins that play important roles in the type III secretion system (T3SS)-mediated export and assembly of flagellar structural proteins. However, detailed analyses of the roles of FliH and FliI in B. burgdorferi have not been reported. In this study, fliH and fliI transposon mutants were utilized to dissect the mechanism of the Borrelia type III secretion system. The fliH and fliI mutants exhibited rod-shaped or string-like morphology, greatly reduced motility, division defects (resulting in elongated organisms with incomplete division points), and noninfectivity in mice by needle inoculation. Mutants in fliH and fliI were incapable of translational motion in 1% methylcellulose or soft agar. Inactivation of either fliH or fliI resulted in the loss of the FliH-FliI complex from otherwise intact flagellar motors, as determined by cryo-electron tomography (cryo-ET). Flagellar assemblies were still present in the mutant cells, albeit in lower numbers than in wild-type cells and with truncated flagella. Genetic complementation of fliH and fliI mutants in trans restored their wild-type morphology, motility, and flagellar motor structure; however, full-length flagella and infectivity were not recovered in these complemented mutants. Based on these results, disruption of either fliH or fliI in B. burgdorferi results in a severe defect in flagellar structure and function and cell division but does not completely block the export and assembly of flagellar hook and filament proteins. Many bacteria are able to rapidly transport themselves through their surroundings using specialized organelles called flagella. In spiral-shaped organisms called spirochetes, flagella act like inboard motors and give the bacteria the ability to bore their way through dense materials (such as human tissue) in a corkscrew manner. In this article, we studied how two proteins, called FliH and FliI, are important for the production of full-length flagella in the Lyme disease spirochete Borrelia burgdorferi. Mutants with defective production of FliH and FliI have reduced flagellar length and motility; this deficiency in turn affects many aspects of B. burgdorferi’s biology, including the ability to undergo cell division and cause disease in mammals. Using a microscopic computed tomography (CT) scan approach called cryo-electron tomography, the structure that contains FliH and FliI was defined in the context of the flagellar motor, providing clues regarding how this amazing nanomachine is assembled and functions.
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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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EscO, a functional and structural analog of the flagellar FliJ protein, is a positive regulator of EscN ATPase activity of the enteropathogenic Escherichia coli injectisome. J Bacteriol 2014; 196:2227-41. [PMID: 24706741 DOI: 10.1128/jb.01551-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Type III secretion systems (T3SSs) are multiprotein molecular devices used by many Gram-negative bacterial pathogens to translocate effector proteins into eukaryotic cells. A T3SS is also used for protein export in flagellar assembly, which promotes bacterial motility. The two systems are evolutionarily related, possessing highly conserved components in their export apparatuses. Enteropathogenic Escherichia coli (EPEC) employs a T3SS, encoded by genes in the locus of enterocyte effacement (LEE) pathogenicity island, to colonize the human intestine and cause diarrheal disease. In the present work, we investigated the role of the LEE-encoded EscO protein (previously Orf15 or EscA) in T3SS biogenesis. We show that EscO shares similar properties with the flagellar FliJ and the Yersinia YscO protein families. Our findings demonstrate that EscO is essential for secretion of all categories of T3SS substrates. Consistent with its central role in protein secretion, it was found to interact with the ATPase EscN and its negative regulator, EscL, of the export apparatus. Moreover, we show that EscO stimulates EscN enzymatic activity; however, it is unable to upregulate ATP hydrolysis in the presence of EscL. Remarkably, EscO partially restored the swimming defect of a Salmonella flagellar fliJ mutant and was able to stimulate the ATPase activity of FliI. Overall, our data indicate that EscO is the virulence counterpart of the flagellar FliJ protein.
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Chatterjee R, Halder PK, Datta S. Identification and molecular characterization of YsaL (Ye3555): a novel negative regulator of YsaN ATPase in type three secretion system of enteropathogenic bacteria Yersinia enterocolitica. PLoS One 2013; 8:e75028. [PMID: 24124464 PMCID: PMC3790809 DOI: 10.1371/journal.pone.0075028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 08/08/2013] [Indexed: 02/07/2023] Open
Abstract
Type Three Secretion (T3S) ATPases are involved in delivery of virulent factors from bacteria to their hosts (through injectisome) in an energy (ATP) dependent manner during pathogenesis. The activities of these ATPases are tightly controlled by their specific regulators. In Yersinia enterocolitica, YsaN was predicted as a putative ATPase of the Ysa-Ysp Type Three Secretion System (T3SS) based on sequence similarity with other T3S ATPases. However detailed study and characterization of YsaN and its regulation remains largely obscure. Here, in this study, we have successfully cloned, over-expressed, purified and characterized the molecular properties of YsaN from Yersinia enterocolitica. YsaN acts as a Mg(2+) dependent ATPase and exists in solution as higher order oligomer (dodecamer). The ATPase activity of oligomeric YsaN is several fold higher than the monomeric form. Furthermore, by employing in silico studies we have identified the existence of a negative regulator of YsaN--a hypothetical protein YE3555 (termed 'YsaL'). To verify the functionality of YsaL, we have evaluated the biochemical and biophysical properties of YsaL. Purified YsaL is dimeric in solution and strongly associates with YsaN to form a stable heterotrimeric YsaL-YsaN complex (stoichiometry--2∶1). The N terminal 6-20 residues of YsaN are invariably required for stable YsaL-YsaN complex formation. YsaL inhibited the ATPase activity of YsaN with a maximum inhibition at the molar ratio 2∶1 (YsaL: YsaN). In short, our studies provide an insight into the presence of YsaN ATPase in Yersinia enterocolitica and its regulator YsaL. Our studies also correlate the functionality of one of the existing protein interaction networks that possibly is indispensable for the energy dependent process of Ysa-Ysp T3SS in pathogenic Yersinia enterocolitica.
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Affiliation(s)
- Rakesh Chatterjee
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, Kolkata, West Bengal, India
| | - Pranab Kumar Halder
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, Kolkata, West Bengal, India
| | - Saumen Datta
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology, Kolkata, West Bengal, India
- * E-mail:
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Minamino T. Protein export through the bacterial flagellar type III export pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:1642-8. [PMID: 24064315 DOI: 10.1016/j.bbamcr.2013.09.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 09/10/2013] [Indexed: 01/02/2023]
Abstract
For construction of the bacterial flagellum, which is responsible for bacterial motility, the flagellar type III export apparatus utilizes both ATP and proton motive force across the cytoplasmic membrane and exports flagellar proteins from the cytoplasm to the distal end of the nascent structure. The export apparatus consists of a membrane-embedded export gate made of FlhA, FlhB, FliO, FliP, FliQ, and FliR and a water-soluble ATPase ring complex consisting of FliH, FliI, and FliJ. FlgN, FliS, and FliT act as substrate-specific chaperones that do not only protect their cognate substrates from degradation and aggregation in the cytoplasm but also efficiently transfer the substrates to the export apparatus. The ATPase ring complex facilitates the initial entry of the substrates into the narrow pore of the export gate. The export gate by itself is a proton-protein antiporter that uses the two components of proton motive force, the electric potential difference and the proton concentration difference, for different steps of the export process. A specific interaction of FlhA with FliJ located in the center of the ATPase ring complex allows the export gate to efficiently use proton motive force to drive protein export. The ATPase ring complex couples ATP binding and hydrolysis to its assembly-disassembly cycle for rapid and efficient protein export cycle. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
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15
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A distant homologue of the FlgT protein interacts with MotB and FliL and is essential for flagellar rotation in Rhodobacter sphaeroides. J Bacteriol 2013; 195:5285-96. [PMID: 24056105 DOI: 10.1128/jb.00760-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In this work, we describe a periplasmic protein that is essential for flagellar rotation in Rhodobacter sphaeroides. This protein is encoded upstream of flgA, and its expression is dependent on the flagellar master regulator FleQ and on the class III flagellar activator FleT. Sequence comparisons suggest that this protein is a distant homologue of FlgT. We show evidence that in R. sphaeroides, FlgT interacts with the periplasmic regions of MotB and FliL and with the flagellar protein MotF, which was recently characterized as a membrane component of the flagellum in this bacterium. In addition, the localization of green fluorescent protein (GFP)-MotF is completely dependent on FlgT. The Mot(-) phenotype of flgT cells was weakly suppressed by point mutants of MotB that presumably keep the proton channel open and efficiently suppress the Mot(-) phenotype of motF and fliL cells, indicating that FlgT could play an additional role beyond the opening of the proton channel. The presence of FlgT in purified filament-hook-basal bodies of the wild-type strain was confirmed by Western blotting, and the observation of these structures under an electron microscope showed that the basal bodies from flgT cells had lost the ring that covers the LP ring in the wild-type structure. Moreover, MotF was detected by immunoblotting in the basal bodies obtained from the wild-type strain but not from flgT cells. From these results, we suggest that FlgT forms a ring around the LP ring, which anchors MotF and stabilizes the stator complex of the flagellar motor.
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Interaction of the extreme N-terminal region of FliH with FlhA is required for efficient bacterial flagellar protein export. J Bacteriol 2012; 194:5353-60. [PMID: 22843851 DOI: 10.1128/jb.01028-12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The flagellar type III protein export apparatus plays an essential role in the formation of the bacterial flagellum. FliH forms a complex along with FliI ATPase and is postulated to provide a link between FliI ring formation and flagellar protein export. Two tryptophan residues of FliH, Trp7 and Trp10, are required for the effective docking of the FliH-FliI complex to the export gate made of six membrane proteins. However, it remains unknown which export gate component interacts with these two tryptophan residues. Here, we performed targeted photo-cross-linking of the extreme N-terminal region of FliH (FliH(EN)) with its binding partners. We replaced Trp7 and Trp10 of FliH with p-benzoyl-phenylalanine (pBPA), a photo-cross-linkable unnatural amino acid, to produce FliH(W7pBPA) and FliH(W10pBPA). They were both functional and were photo-cross-linked with one of the export gate proteins, FlhA, but not with the other gate proteins, indicating that these two tryptophan residues are in close proximity to FlhA. Mutant FlhA proteins that are functional in the presence of FliH and FliI but not in their absence showed a significantly reduced function also by N-terminal FliH mutations even in the presence of FliI. We suggest that the interaction of FliH(EN) with FlhA is required for anchoring the FliI hexamer ring to the export gate for efficient flagellar protein export.
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Minamino T, Kinoshita M, Imada K, Namba K. Interaction between FliI ATPase and a flagellar chaperone FliT during bacterial flagellar protein export. Mol Microbiol 2011; 83:168-78. [DOI: 10.1111/j.1365-2958.2011.07924.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ibuki T, Imada K, Minamino T, Kato T, Miyata T, Namba K. Common architecture of the flagellar type III protein export apparatus and F- and V-type ATPases. Nat Struct Mol Biol 2011; 18:277-82. [PMID: 21278755 DOI: 10.1038/nsmb.1977] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 11/17/2010] [Indexed: 01/06/2023]
Abstract
The proteins that form the bacterial flagellum are translocated to its distal end through the central channel of the growing flagellum by the flagellar-specific protein export apparatus, a family of the type III protein secretion system. FliI and FliJ are soluble components of this apparatus. FliI is an ATPase that has extensive structural similarity to the α and β subunits of F(o)F(1)-ATP synthase. FliJ is essential for export, but its function remains obscure. Here we show that the structure of FliJ derived from Salmonella enterica serovar Typhimurium is remarkably similar to that of the two-stranded α-helical coiled-coil part of the γ subunit of F(o)F(1)-ATP synthase and that FliJ promotes the formation of FliI hexamer rings by binding to the center of the ring. These results suggest that the type III protein export system and F- and V-type ATPases share a similar mechanism and an evolutionary relationship.
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Yu H, Liu F, Ramesh BP. Automatic figure ranking and user interfacing for intelligent figure search. PLoS One 2010; 5:e12983. [PMID: 20949102 PMCID: PMC2951344 DOI: 10.1371/journal.pone.0012983] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 08/20/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Figures are important experimental results that are typically reported in full-text bioscience articles. Bioscience researchers need to access figures to validate research facts and to formulate or to test novel research hypotheses. On the other hand, the sheer volume of bioscience literature has made it difficult to access figures. Therefore, we are developing an intelligent figure search engine (http://figuresearch.askhermes.org). Existing research in figure search treats each figure equally, but we introduce a novel concept of "figure ranking": figures appearing in a full-text biomedical article can be ranked by their contribution to the knowledge discovery. METHODOLOGY/FINDINGS We empirically validated the hypothesis of figure ranking with over 100 bioscience researchers, and then developed unsupervised natural language processing (NLP) approaches to automatically rank figures. Evaluating on a collection of 202 full-text articles in which authors have ranked the figures based on importance, our best system achieved a weighted error rate of 0.2, which is significantly better than several other baseline systems we explored. We further explored a user interfacing application in which we built novel user interfaces (UIs) incorporating figure ranking, allowing bioscience researchers to efficiently access important figures. Our evaluation results show that 92% of the bioscience researchers prefer as the top two choices the user interfaces in which the most important figures are enlarged. With our automatic figure ranking NLP system, bioscience researchers preferred the UIs in which the most important figures were predicted by our NLP system than the UIs in which the most important figures were randomly assigned. In addition, our results show that there was no statistical difference in bioscience researchers' preference in the UIs generated by automatic figure ranking and UIs by human ranking annotation. CONCLUSION/SIGNIFICANCE The evaluation results conclude that automatic figure ranking and user interfacing as we reported in this study can be fully implemented in online publishing. The novel user interface integrated with the automatic figure ranking system provides a more efficient and robust way to access scientific information in the biomedical domain, which will further enhance our existing figure search engine to better facilitate accessing figures of interest for bioscientists.
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Affiliation(s)
- Hong Yu
- Department of Health Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
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The flagellar protein FliL is essential for swimming in Rhodobacter sphaeroides. J Bacteriol 2010; 192:6230-9. [PMID: 20889747 DOI: 10.1128/jb.00655-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In this work we characterize the function of the flagellar protein FliL in Rhodobacter sphaeroides. Our results show that FliL is essential for motility in this bacterium and that in its absence flagellar rotation is highly impaired. A green fluorescent protein (GFP)-FliL fusion forms polar and lateral fluorescent foci that show different spatial dynamics. The presence of these foci is dependent on the expression of the flagellar genes controlled by the master regulator FleQ, suggesting that additional components of the flagellar regulon are required for the proper localization of GFP-FliL. Eight independent pseudorevertants were isolated from the fliL mutant strain. In each of these strains a single nucleotide change in motB was identified. The eight mutations affected only three residues located on the periplasmic side of MotB. Swimming of the suppressor mutants was not affected by the presence of the wild-type fliL allele. Pulldown and yeast two-hybrid assays showed that that the periplasmic domain of FliL is able to interact with itself but not with the periplasmic domain of MotB. From these results we propose that FliL could participate in the coupling of MotB with the flagellar rotor in an indirect fashion.
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21
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Caly DL, O'Toole PW, Moore SA. The 2.2-Å structure of the HP0958 protein from Helicobacter pylori reveals a kinked anti-parallel coiled-coil hairpin domain and a highly conserved ZN-ribbon domain. J Mol Biol 2010; 403:405-19. [PMID: 20826163 DOI: 10.1016/j.jmb.2010.08.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 08/24/2010] [Accepted: 08/26/2010] [Indexed: 11/25/2022]
Abstract
We have determined the 2.2-Å structure of the HP0958 protein from the human gastric pathogen Helicobacter pylori. HP0958 is essential for flagellum formation and motility. It functions as a chaperone for RpoN (σ(54)) and also controls the stability and translation of mRNA for the major flagellin subunit FlaA. The protein is composed of a highly elongated and kinked coiled-coil hairpin domain (residues 1-170), followed by a C(4) Zn-ribbon domain (residues 174-238). The Zn-ribbon domain is rich in aromatic and positively charged amino acid residues. Electrophoretic mobility shift assays identified residues in a positively charged region of the Zn-ribbon domain of HP0958 whose mutation alters the mobility of an HP0958-flaA mRNA complex. Mutation of surface residues in the coiled-coil domain did not result in an observable change in the mobility of the HP0958-flaA transcript complex. The data thus suggest the arrangement of HP0958 into distinct structural and functional domains.
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Affiliation(s)
- Delphine L Caly
- Department of Microbiology, University College Cork, Cork, Ireland
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22
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In Helicobacter pylori auto-inducer-2, but not LuxS/MccAB catalysed reverse transsulphuration, regulates motility through modulation of flagellar gene transcription. BMC Microbiol 2010; 10:210. [PMID: 20691071 PMCID: PMC2923134 DOI: 10.1186/1471-2180-10-210] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 08/06/2010] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND LuxS may function as a metabolic enzyme or as the synthase of a quorum sensing signalling molecule, auto-inducer-2 (AI-2); hence, the mechanism underlying phenotypic changes upon luxS inactivation is not always clear. In Helicobacter pylori, we have recently shown that, rather than functioning in recycling methionine as in most bacteria, LuxS (along with newly-characterised MccA and MccB), synthesises cysteine via reverse transsulphuration. In this study, we investigated whether and how LuxS controls motility of H. pylori, specifically if it has its effects via luxS-required cysteine metabolism or via AI-2 synthesis only. RESULTS We report that disruption of luxS renders H. pylori non-motile in soft agar and by microscopy, whereas disruption of mccAHp or mccBHp (other genes in the cysteine provision pathway) does not, implying that the lost phenotype is not due to disrupted cysteine provision. The motility defect of the DeltaluxSHp mutant was complemented genetically by luxSHp and also by addition of in vitro synthesised AI-2 or 4, 5-dihydroxy-2, 3-pentanedione (DPD, the precursor of AI-2). In contrast, exogenously added cysteine could not restore motility to the DeltaluxSHp mutant, confirming that AI-2 synthesis, but not the metabolic effect of LuxS was important. Microscopy showed reduced number and length of flagella in the DeltaluxSHp mutant. Immunoblotting identified decreased levels of FlaA and FlgE but not FlaB in the DeltaluxSHp mutant, and RT-PCR showed that the expression of flaA, flgE, motA, motB, flhA and fliI but not flaB was reduced. Addition of DPD but not cysteine to the DeltaluxSHp mutant restored flagellar gene transcription, and the number and length of flagella. CONCLUSIONS Our data show that as well as being a metabolic enzyme, H. pylori LuxS has an alternative role in regulation of motility by modulating flagellar transcripts and flagellar biosynthesis through production of the signalling molecule AI-2.
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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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24
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Douillard FP, Ryan KA, Hinds J, O’Toole PW. Effect of FliK mutation on the transcriptional activity of the {sigma}54 sigma factor RpoN in Helicobacter pylori. MICROBIOLOGY (READING, ENGLAND) 2009; 155:1901-1911. [PMID: 19383688 PMCID: PMC3145110 DOI: 10.1099/mic.0.026062-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Helicobacter pylori is a motile Gram-negative bacterium that colonizes and persists in the human gastric mucosa. The flagellum gene regulatory circuitry of H. pylori is unique in many aspects compared with the Salmonella/Escherichia coli paradigms, and some regulatory checkpoints remain unclear. FliK controls the hook length during flagellar assembly. Microarray analysis of a fliK-null mutant revealed increased transcription of genes under the control of the sigma(54) sigma factor RpoN. This sigma factor has been shown to be responsible for transcription of the class II flagellar genes, including flgE and flaB. No genes higher in the flagellar hierarchy had altered expression, suggesting specific and localized FliK-dependent feedback on the RpoN regulon. FliK thus appears to be involved in three processes: hook-length control, export substrate specificity and control of RpoN transcriptional activity.
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Affiliation(s)
- Francois P. Douillard
- Department of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Western Road, Cork, Ireland
| | - Kieran A. Ryan
- Department of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Western Road, Cork, Ireland
| | - Jason Hinds
- Bacterial Microarray Group, Division of Cellular and Molecular Medicine, St George’s University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Paul W. O’Toole
- Department of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Western Road, Cork, Ireland
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Kish-Trier E, Wilkens S. Domain architecture of the stator complex of the A1A0-ATP synthase from Thermoplasma acidophilum. J Biol Chem 2009; 284:12031-40. [PMID: 19234304 PMCID: PMC2673272 DOI: 10.1074/jbc.m808962200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 02/18/2009] [Indexed: 12/22/2022] Open
Abstract
A key structural element in the ion translocating F-, A-, and V-ATPases is the peripheral stalk, an assembly of two polypeptides that provides a structural link between the ATPase and ion channel domains. Previously, we have characterized the peripheral stalk forming subunits E and H of the A-ATPase from Thermoplasma acidophilum and demonstrated that the two polypeptides interact to form a stable heterodimer with 1:1 stoichiometry (Kish-Trier, E., Briere, L. K., Dunn, S. D., and Wilkens, S. (2008) J. Mol. Biol. 375, 673-685). To define the domain architecture of the A-ATPase peripheral stalk, we have now generated truncated versions of the E and H subunits and analyzed their ability to bind each other. The data show that the N termini of the subunits form an alpha-helical coiled-coil, approximately 80 residues in length, whereas the C-terminal residues interact to form a globular domain containingalpha- and beta-structure. We find that the isolated C-terminal domain of the E subunit exists as a dimer in solution, consistent with a recent crystal structure of the related Pyrococcus horikoshii A-ATPase E subunit (Lokanath, N. K., Matsuura, Y., Kuroishi, C., Takahashi, N., and Kunishima, N. (2007) J. Mol. Biol. 366, 933-944). However, upon the addition of a peptide comprising the C-terminal 21 residues of the H subunit (or full-length H subunit), dimeric E subunit C-terminal domain dissociates to form a 1:1 heterodimer. NMR spectroscopy was used to show that H subunit C-terminal peptide binds to E subunit C-terminal domain via the terminal alpha-helices, with little involvement of the beta-sheet region. Based on these data, we propose a structural model of the A-ATPase peripheral stalk.
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Affiliation(s)
- Erik Kish-Trier
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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26
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Statistical characterization of the GxxxG glycine repeats in the flagellar biosynthesis protein FliH and its Type III secretion homologue YscL. BMC Microbiol 2009; 9:72. [PMID: 19371430 PMCID: PMC2674601 DOI: 10.1186/1471-2180-9-72] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 04/16/2009] [Indexed: 12/28/2022] Open
Abstract
Background FliH is a protein involved in the export of components of the bacterial flagellum and we herein describe the presence of glycine-rich repeats in FliH of the form AxxxG(xxxG)mxxxA, where the value of m varies considerably in FliH proteins from different bacteria. While GxxxG and AxxxA patterns have previously been described, the long glycine repeat segments in FliH proteins have yet to be characterized. The Type III secretion system homologue to FliH (YscL, AscL, PscL, etc.) also contains a similar GxxxG repeat, and hence the presence of the repeat is evolutionarily conserved in these proteins, suggesting an important structural role or biological function. Results A set of FliH and YscL protein sequences was downloaded from GenBank, and then filtered to reduce redundancy, to ensure the soundness of the sequences, and to eliminate, as much as possible, confounding phylogenetic signal between individual sequences by implementing a pairwise 25% sequence identity cut-off. The general features of the glycine-rich repeats in these proteins were examined, and it was found that the length of these repeat segments varied substantially among FliH proteins but was fairly consistent for the Type III (YscL) homologue sequences, with values of m ranging from 0 to 12 for FliH and 0 to 2 for YscL. The amino acid sequence distribution of each of the three positions in the GxxxG repeats was found to differ significantly from the overall amino acid composition of the FliH/YscL proteins. The high frequency of Glu, Gln, Lys and Ala residues in the repeat positions, which is not likely indicative of any contaminating phylogenetic signal, suggests an α-helical structure for this motif. In addition, we sought to determine whether certain pairs of amino acids, in certain pairs of positions, were found together significantly more often than would be predicted by chance. Several statistically significant correlations were uncovered, which may be important for maintaining helical stability or for forming helix-helix interactions. These correlations are likely not of a phylogenetic origin as the originating sequences for the pair correlations are derived from a low similarity set and the individual incidences of the pair correlations do not cluster in any obvious phylogenetic sense, nor is there much evidence of strict sequence conservation outside the positions of the glycine residues. Finally, the α-helices from a non-redundant set of proteins from the Protein Data Bank were searched for GxxxG repeats similar in length to those found in FliH, however there were no helices containing more than three contiguous glycine repeat segments; thus, long glycine repeats similar to those found in FliH are presumably quite rare in nature. Conclusion The glycine repeats in YscL and particularly FliH represent an intriguing amino acid sequence motif that is very rare in nature. Although we do not attempt to offer a mechanism whereby these repeats may have evolved, we do place the existence of the motif and some residue pairings within a rational structural context. While crystal structures of these proteins are necessary to fully elucidate the structural and functional significance of these repeats, the characterization reported here represents a first step in understanding this unique sequence feature.
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Gazi AD, Charova SN, Panopoulos NJ, Kokkinidis M. Coiled-coils in type III secretion systems: structural flexibility, disorder and biological implications. Cell Microbiol 2009; 11:719-29. [PMID: 19215225 DOI: 10.1111/j.1462-5822.2009.01297.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent structural studies and analyses of microbial genomes have consolidated the understanding of the structural and functional versatility of coiled-coil domains in proteins from bacterial type III secretion systems (T3SS). Such domains consist of two or more α-helices forming a bundle structure. The occurrence of coiled-coils in T3SS is considerably higher than the average predicted occurrence in prokaryotic proteomes. T3SS proteins comprising coiled-coil domains are frequently characterized by an increased structural flexibility, which may vary from localized structural disorder to the establishment of molten globule-like state. The propensity for coiled-coil formation and structural disorder are frequently essential requirements for various T3SS functions, including the establishment of protein-protein interaction networks and the polymerization of extracellular components of T3SS appendages. Possible correlations between the frequently observed N-terminal structural disorder of effectors and the T3SS secretion signal are discussed. The results for T3SS are also compared with other Gram-negative secretory systems.
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Affiliation(s)
- Anastasia D Gazi
- Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology and Department of Biology, University of Crete, Vasilika Vouton, Heraklion, Crete, Greece
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28
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Role of the N-terminal domain of FliI ATPase in bacterial flagellar protein export. FEBS Lett 2009; 583:743-8. [DOI: 10.1016/j.febslet.2009.01.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 01/08/2009] [Accepted: 01/14/2009] [Indexed: 11/22/2022]
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29
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Gazi AD, Bastaki M, Charova SN, Gkougkoulia EA, Kapellios EA, Panopoulos NJ, Kokkinidis M. Evidence for a coiled-coil interaction mode of disordered proteins from bacterial type III secretion systems. J Biol Chem 2008; 283:34062-8. [PMID: 18836182 PMCID: PMC2662227 DOI: 10.1074/jbc.m803408200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 09/11/2008] [Indexed: 11/06/2022] Open
Abstract
Gene clusters encoding various type III secretion system (T3SS) injectisomes, frequently code downstream of the conserved atpase gene for small hydrophilic proteins whose amino acid sequences display a propensity for intrinsic disorder and coiled-coil formation. These properties were confirmed experimentally for a member of this class, the HrpO protein from the T3SS of Pseudomonas syringae pv phaseolicola: HrpO exhibits high alpha-helical content with coiled-coil characteristics, strikingly low melting temperature, structural properties that are typical for disordered proteins, and a pronounced self-association propensity, most likely via coiled-coil interactions, resulting in heterogeneous populations of quaternary complexes. HrpO interacts in vivo with HrpE, a T3SS protein for which coiled-coil formation is also strongly predicted. Evidence from HrpO analogues from all T3SS families and the flagellum suggests that the extreme flexibility and propensity for coiled-coil interactions of this diverse class of small, intrinsically disordered proteins, whose structures may alter as they bind to their cognate folded protein targets, might be important elements in the establishment of protein-protein interaction networks required for T3SS function.
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Affiliation(s)
- Anastasia D Gazi
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology, Vasilika Vouton, Heraklion, Crete, Greece
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30
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Douillard FP, Ryan KA, Caly DL, Hinds J, Witney AA, Husain SE, O'Toole PW. Posttranscriptional regulation of flagellin synthesis in Helicobacter pylori by the RpoN chaperone HP0958. J Bacteriol 2008; 190:7975-84. [PMID: 18931105 PMCID: PMC2593243 DOI: 10.1128/jb.00879-08] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 10/07/2008] [Indexed: 12/21/2022] Open
Abstract
The Helicobacter pylori protein HP0958 is essential for flagellum biogenesis. It has been shown that HP0958 stabilizes the sigma(54) factor RpoN. The aim of this study was to further investigate the role of HP0958 in flagellum production in H. pylori. Global transcript analysis identified a number of flagellar genes that were differentially expressed in an HP0958 mutant strain. Among these, the transcription of the major flagellin gene flaA was upregulated twofold, suggesting that HP0958 was a negative regulator of the flaA gene. However, the production of the FlaA protein was significantly reduced in the HP0958 mutant, and this was not due to the decreased stability of the FlaA protein. RNA stability analysis and binding assays indicated that HP0958 binds and destabilizes flaA mRNA. The HP0958 mutant was successfully complemented, confirming that the mutant phenotype described was due to the lack of HP0958. We conclude that HP0958 is a posttranscriptional regulator that modulates the amount of the flaA message available for translation in H. pylori.
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Affiliation(s)
- Francois P Douillard
- Department of Microbiology & Alimentary Pharmabiotic Centre, University College Cork, Ireland
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31
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Minamino T, Imada K, Namba K. Mechanisms of type III protein export for bacterial flagellar assembly. MOLECULAR BIOSYSTEMS 2008; 4:1105-15. [PMID: 18931786 DOI: 10.1039/b808065h] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Flagellar type III protein export is highly organized and well controlled in a timely manner by dynamic, specific and cooperative interactions among components of the export apparatus, allowing the huge and complex macromolecular assembly to be built efficiently. The bacterial flagellum, which is required for motility, consists of a rotary motor, a universal joint and a helical propeller. Most of the flagellar components are translocated to the distal, growing end of the flagellum for assembly through the central channel of the flagellum itself by the flagellar type III protein export apparatus, which is postulated to be located on the cytoplasmic side of the flagellar basal body. The export specificity switching machinery, which consists of at least two proteins that function as a molecular ruler and an export switch, respectively, monitors the state of hook-basal body assembly in the cell exterior and switches export specificity, thereby coupling sequential flagellar gene expression with the flagellar assembly process. The export ATPase complex composed of an ATPase and its regulator acts as a pilot to deliver its export substrate to the export gate and helps initial entry of the substrate N-terminal chain into a narrow pore of the export gate. The energy of ATP hydrolysis appears to be used to disassemble and release the ATPase complex from the protein about to be exported, and the rest of the successive unfolding/translocation process of the long polypeptide chain is driven solely by proton motive force (PMF), perhaps through biased one-dimensional Brownian diffusion. Interestingly, the subunits of the ATPase complex have significant sequence similarities to subunits of F(0)F(1)-ATP synthase, a rotary motor that drives the chemical reaction of ATP synthesis using PMF, and the entire crystal structure of the export ATPase is extremely similar to the alpha/beta subunits of F(0)F(1)-ATP synthase, suggesting that the flagellar export apparatus and F(0)F(1)-ATP synthase share the mechanism for their two distinct functions.
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Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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32
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Distinct roles of the FliI ATPase and proton motive force in bacterial flagellar protein export. Nature 2008; 451:485-8. [PMID: 18216858 DOI: 10.1038/nature06449] [Citation(s) in RCA: 231] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Accepted: 10/29/2007] [Indexed: 01/16/2023]
Abstract
Translocation of many soluble proteins across cell membranes occurs in an ATPase-driven manner. For construction of the bacterial flagellum responsible for motility, most of the components are exported by the flagellar protein export apparatus. The FliI ATPase is required for this export, and its ATPase activity is regulated by FliH; however, it is unclear how the chemical energy derived from ATP hydrolysis is used for the export process. Here we report that flagellar proteins of Salmonella enterica serovar Typhimurium are exported even in the absence of FliI. A fliH fliI double null mutant was weakly motile. Certain mutations in FlhA or FlhB, which form the core of the export gate, substantially improved protein export and motility of the double null mutant. Furthermore, proton motive force was essential for the export process. These results suggest that the FliH-FliI complex facilitates only the initial entry of export substrates into the gate, with the energy of ATP hydrolysis being used to disassemble and release the FliH-FliI complex from the protein about to be exported. The rest of the successive unfolding/translocation process of the substrates is driven by proton motive force.
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33
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Kish-Trier E, Briere LAK, Dunn SD, Wilkens S. The stator complex of the A1A0-ATP synthase--structural characterization of the E and H subunits. J Mol Biol 2007; 375:673-85. [PMID: 18036615 DOI: 10.1016/j.jmb.2007.10.063] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Revised: 10/10/2007] [Accepted: 10/25/2007] [Indexed: 10/22/2022]
Abstract
Archaeal ATP synthase (A-ATPase) is the functional homolog to the ATP synthase found in bacteria, mitochondria and chloroplasts, but the enzyme is structurally more related to the proton-pumping vacuolar ATPase found in the endomembrane system of eukaryotes. We have cloned, overexpressed and characterized the stator-forming subunits E and H of the A-ATPase from the thermoacidophilic Archaeon, Thermoplasma acidophilum. Size exclusion chromatography, CD, matrix-assisted laser desorption ionization time-of-flight mass spectrometry and NMR spectroscopic experiments indicate that both polypeptides have a tendency to form dimers and higher oligomers in solution. However, when expressed together or reconstituted, the two individual polypeptides interact with high affinity to form a stable heterodimer. Analyses by gel filtration chromatography and analytical ultracentrifugation show the heterodimer to have an elongated shape, and the preparation to be monodisperse. Thermal denaturation analyses by CD and differential scanning calorimetry revealed the more cooperative unfolding transitions of the heterodimer in comparison to those of the individual polypeptides. The data are consistent with the EH heterodimer forming the peripheral stalk(s) in the A-ATPase in a fashion analogous to that of the related vacuolar ATPase.
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Affiliation(s)
- Erik Kish-Trier
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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34
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Imada K, Minamino T, Tahara A, Namba K. Structural similarity between the flagellar type III ATPase FliI and F1-ATPase subunits. Proc Natl Acad Sci U S A 2007; 104:485-90. [PMID: 17202259 PMCID: PMC1766411 DOI: 10.1073/pnas.0608090104] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Indexed: 01/26/2023] Open
Abstract
Construction of the bacterial flagellum in the cell exterior proceeds at its distal end by highly ordered self-assembly of many different component proteins, which are selectively exported through the central channel of the growing flagellum by the flagellar type III export apparatus. FliI is the ATPase of the export apparatus that drives the export process. Here we report the 2.4 A resolution crystal structure of FliI in the ADP-bound form. FliI consists of three domains, and the whole structure shows extensive similarities to the alpha and beta subunits of F0F1-ATPsynthase, a rotary motor that drives the chemical reaction of ATP synthesis. A hexamer model of FliI has been constructed based on the F1-ATPase structure composed of the alpha3beta3gamma subunits. Although the regions that differ in conformation between FliI and the F1-alpha/beta subunits are all located on the outer surface of the hexamer ring, the main chain structures at the subunit interface and those surrounding the central channel of the ring are well conserved. These results imply an evolutionary relation between the flagellum and F0F1-ATPsynthase and a similarity in the mechanism between FliI and F1-ATPase despite the apparently different functions of these proteins.
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Affiliation(s)
- Katsumi Imada
- *Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; and
- Dynamic NanoMachine Project, International Cooperative Research Project, Japan Science and Technology Agency, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tohru Minamino
- *Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; and
- Dynamic NanoMachine Project, International Cooperative Research Project, Japan Science and Technology Agency, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Aiko Tahara
- *Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; and
| | - Keiichi Namba
- *Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; and
- Dynamic NanoMachine Project, International Cooperative Research Project, Japan Science and Technology Agency, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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35
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Minamino T, Imada K, Tahara A, Kihara M, Macnab RM, Namba K. Crystallization and preliminary X-ray analysis of Salmonella FliI, the ATPase component of the type III flagellar protein-export apparatus. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:973-5. [PMID: 17012787 PMCID: PMC2225186 DOI: 10.1107/s1744309106033100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Accepted: 08/18/2006] [Indexed: 11/11/2022]
Abstract
Most of the structural components making up the bacterial flagellum are translocated through the central channel of the growing flagellar structure by the type III flagellar protein-export apparatus in an ATPase-driven manner and are assembled at the growing end. FliI is the ATPase that drives flagellar protein export using the energy of ATP hydrolysis. FliI forms an oligomeric ring structure in order to attain maximum ATPase activity. In this study, FliI(Delta1-18), an N-terminally truncated variant of FliI lacking the first 18 residues, was purified and crystallized. Crystals were obtained using the hanging-drop vapour-diffusion technique with PEG 8000 as a precipitant. FliI(Delta1-18) crystals grew in the monoclinic space group P2(1), with unit-cell parameters a = 48, b = 73, c = 126 A, beta = 94 degrees, and diffracted to 2.4 A resolution. Anomalous difference Patterson maps of Os-derivative and Pt-derivative crystals showed significant peaks in their Harker sections, indicating that both derivatives are suitable for structure determination.
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Affiliation(s)
- Tohru Minamino
- Dynamic NanoMachine Project, ICORP, JST, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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36
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Minamino T, Kazetani KI, Tahara A, Suzuki H, Furukawa Y, Kihara M, Namba K. Oligomerization of the bacterial flagellar ATPase FliI is controlled by its extreme N-terminal region. J Mol Biol 2006; 360:510-9. [PMID: 16780875 DOI: 10.1016/j.jmb.2006.05.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 05/02/2006] [Accepted: 05/03/2006] [Indexed: 01/03/2023]
Abstract
Salmonella FliI is the flagellar ATPase which converts the energy of ATP hydrolysis into the export of flagellar proteins. It forms a ring-shaped oligomer in the presence of ATP, its analogs, or phospholipids. The extreme N-terminal region of FliI has an unstable conformation and is responsible for the interaction with other components of the export apparatus and for regulation of the catalytic mechanism. To understand the role of this N-terminal region in more detail, we used multi-angle light-scattering, analytical ultracentrifugation, far-UV CD and biochemical methods to characterize a partially functional variant of FliI, missing its first seven amino acid residues (His-FliI(Delta1-7)), whose ATPase activity is about ten times lower than that of wild-type FliI. His-FliI(Delta1-7) is monomeric in solution. The deletion increased the content of alpha-helix, suggesting that the deletion stabilizes the unstable N-terminal region into an alpha-helical conformation. The deletion did not influence the K(m) value for ATP. However, unlike the wild-type, ATP and acidic phospholipids did not induce oligomerization of His-FliI(Delta1-7) or increase its ATPase activity. These results suggest that the deletion suppresses the oligomerization of FliI, and that a conformational change in the unstable N-terminal region is required for FliI oligomerization to effectively couple the energy of ATP hydrolysis to the translocation of flagellar proteins.
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Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Pallen MJ, Bailey CM, Beatson SA. Evolutionary links between FliH/YscL-like proteins from bacterial type III secretion systems and second-stalk components of the FoF1 and vacuolar ATPases. Protein Sci 2006; 15:935-41. [PMID: 16522800 PMCID: PMC2242474 DOI: 10.1110/ps.051958806] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Bacterial type III secretion drives flagellar biosynthesis and mediates bacterial-eukaryotic interactions. Type III secretion is driven by an ATPase that is homologous to the catalytic subunits of proton-translocating ATPases, such as the F(o)F(1) ATPase. Here we use PSI-BLAST searches to show that some noncalatytic components are also conserved between type III secretion systems and proton-translocating ATPases. In particular, we show that the FliH/YscL-like proteins and the E subunits of vacuolar ATPases represent fusions of domains homologous to second-stalk components of the F(o)F(1) ATPase (the b and delta subunits).
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Affiliation(s)
- Mark J Pallen
- Division of Immunity & Infection, University of Birmingham Medical School, Edgbaston, Birmingham B15 2TT, United Kingdom.
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