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Fields JL, Zhang H, Bellis NF, Petersen HA, Halder SK, Rich-New ST, Wu H, Wang F. Structural diversity and clustering of bacterial flagellar outer domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.18.585621. [PMID: 38562817 PMCID: PMC10983879 DOI: 10.1101/2024.03.18.585621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Supercoiled flagellar filaments function as mechanical propellers within the bacterial flagellum complex, playing a crucial role in motility. Flagellin, the building block of the filament, features a conserved inner D0/D1 core domain across different bacterial species. In contrast, approximately half of the flagellins possess additional, highly divergent outer domain(s), suggesting varied functional potential. In this study, we elucidate atomic structures of flagellar filaments from three distinct bacterial species: Cupriavidus gilardii , Stenotrophomonas maltophilia , and Geovibrio thiophilus . Our findings reveal that the flagella from the facultative anaerobic G. thiophilus possesses a significantly more negatively charged surface, potentially enabling adhesion to positively charged minerals. Furthermore, we analyzed all AlphaFold predicted structures for annotated bacterial flagellins, categorizing the flagellin outer domains into 682 structural clusters. This classification provides insights into the prevalence and experimental verification of these outer domains. Remarkably, two of the flagellar structures reported herein belong to a previously unexplored cluster, indicating new opportunities on the study of the functional diversity of flagellar outer domains. Our findings underscore the complexity of bacterial flagellins and open up possibilities for future studies into their varied roles beyond motility.
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Zamba-Campero M, Soliman D, Yu H, Lasseter AG, Chang YY, Liu J, Aravind L, Jewett MW, Storz G, Adams PP. Broadly conserved FlgV controls flagellar assembly and Borrelia burgdorferi dissemination in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.09.574855. [PMID: 38260563 PMCID: PMC10802407 DOI: 10.1101/2024.01.09.574855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Flagella propel pathogens through their environments yet are expensive to synthesize and are immunogenic. Thus, complex hierarchical regulatory networks control flagellar gene expression. Spirochetes are highly motile bacteria, but peculiarly in the Lyme spirochete Borrelia burgdorferi, the archetypal flagellar regulator σ28 is absent. We rediscovered gene bb0268 in B. burgdorferi as flgV, a broadly-conserved gene in the flagellar superoperon alongside σ28 in many Spirochaetes, Firmicutes and other phyla, with distant homologs in Epsilonproteobacteria. We found that B. burgdorferi FlgV is localized within flagellar motors. B. burgdorferi lacking flgV construct fewer and shorter flagellar filaments and are defective in cell division and motility. During the enzootic cycle, B. burgdorferi lacking flgV survive and replicate in Ixodes ticks but are attenuated for dissemination and infection in mice. Our work defines infection timepoints when spirochete motility is most crucial and implicates FlgV as a broadly distributed structural flagellar component that modulates flagellar assembly.
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Affiliation(s)
- Maxime Zamba-Campero
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Daniel Soliman
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Huaxin Yu
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT 06536, USA
- Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA
| | - Amanda G. Lasseter
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, 32827, USA
| | - Yuen-Yan Chang
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT 06536, USA
- Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA
| | - L. Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Mollie W. Jewett
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, 32827, USA
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Philip P. Adams
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, 32827, USA
- Postdoctoral Research Associate Program, National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD 20892, USA
- Independent Research Scholar Program, Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
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Sze CW, Zhang K, Lynch MJ, Iyer R, Crane BR, Schwartz I, Li C. A chemosensory-like histidine kinase is dispensable for chemotaxis in vitro but regulates the virulence of Borrelia burgdorferi through modulating the stability of RpoS. PLoS Pathog 2023; 19:e1011752. [PMID: 38011206 PMCID: PMC10703414 DOI: 10.1371/journal.ppat.1011752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/07/2023] [Accepted: 10/14/2023] [Indexed: 11/29/2023] Open
Abstract
As an enzootic pathogen, the Lyme disease bacterium Borrelia burgdorferi possesses multiple copies of chemotaxis proteins, including two chemotaxis histidine kinases (CHK), CheA1 and CheA2. Our previous study showed that CheA2 is a genuine CHK that is required for chemotaxis; however, the role of CheA1 remains mysterious. This report first compares the structural features that differentiate CheA1 and CheA2 and then provides evidence to show that CheA1 is an atypical CHK that controls the virulence of B. burgdorferi through modulating the stability of RpoS, a key transcriptional regulator of the spirochete. First, microscopic analyses using green-fluorescence-protein (GFP) tags reveal that CheA1 has a unique and dynamic cellular localization. Second, loss-of-function studies indicate that CheA1 is not required for chemotaxis in vitro despite sharing a high sequence and structural similarity to its counterparts from other bacteria. Third, mouse infection studies using needle inoculations show that a deletion mutant of CheA1 (cheA1mut) is able to establish systemic infection in immune-deficient mice but fails to do so in immune-competent mice albeit the mutant can survive at the inoculation site for up to 28 days. Tick and mouse infection studies further demonstrate that CheA1 is dispensable for tick colonization and acquisition but essential for tick transmission. Lastly, mechanistic studies combining immunoblotting, protein turnover, mutagenesis, and RNA-seq analyses reveal that depletion of CheA1 affects RpoS stability, leading to reduced expression of several RpoS-regulated virulence factors (i.e., OspC, BBK32, and DbpA), likely due to dysregulated clpX and lon protease expression. Bulk RNA-seq analysis of infected mouse skin tissues further show that cheA1mut fails to elicit mouse tnf-α, il-10, il-1β, and ccl2 expression, four important cytokines for Lyme disease development and B. burgdorferi transmigration. Collectively, these results reveal a unique role and regulatory mechanism of CheA1 in modulating virulence factor expression and add new insights into understanding the regulatory network of B. burgdorferi.
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Affiliation(s)
- Ching Wooen Sze
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Kai Zhang
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Michael J. Lynch
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Radha Iyer
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, United States of America
| | - Brian R. Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Ira Schwartz
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, United States of America
| | - Chunhao Li
- Department of Oral Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, United States of America
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Diving into the complexity of the spirochetal endoflagellum. Trends Microbiol 2023; 31:294-307. [PMID: 36244923 DOI: 10.1016/j.tim.2022.09.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/12/2022] [Accepted: 09/14/2022] [Indexed: 11/27/2022]
Abstract
Spirochaetes, a phylum that includes medically important pathogens such as the causative agents of Lyme disease, syphilis, and leptospirosis, are in many ways highly unique bacteria. Their cell morphology, subcellular organization, and metabolism reveal atypical features. Spirochetal motility is also singular, dependent on the presence of periplasmic flagella or endoflagella, inserted subterminally at cell poles and not penetrating the outer membrane and elongating outside the cell as in enterobacteria. In this review we present a comprehensive comparative genomics analysis of endoflagellar systems in spirochetes, highlighting recent findings on the flagellar basal body and filament. Continued progress in understanding the function and architecture of spirochetal flagella is uncovering paradigm-shifting mechanisms of bacterial motility.
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5
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Ronzetti M, Baljinnyam B, Jalal I, Pal U, Simeonov A. Application of biophysical methods for improved protein production and characterization: A case study on an high-temperature requirement A-family bacterial protease. Protein Sci 2022; 31:e4498. [PMID: 36334045 PMCID: PMC9679970 DOI: 10.1002/pro.4498] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 11/02/2022] [Accepted: 11/02/2022] [Indexed: 11/07/2022]
Abstract
The high-temperature requirement A (HtrA) serine protease family presents an attractive target class for antibacterial therapeutics development. These proteins possess dual protease and chaperone functions and contain numerous binding sites and regulatory loops, displaying diverse oligomerization patterns dependent on substrate type and occupancy. HtrA proteins that are natively purified coelute with contaminating peptides and activating species, shifting oligomerization and protein structure to differently activated populations. Here, a redesigned HtrA production results in cleaner preparations with high yields by overexpressing and purifying target protein from inclusion bodies under denaturing conditions, followed by a high-throughput screen for optimal refolding buffer composition using function-agnostic biophysical techniques that do not rely on target-specific measurements. We use Borrelia burgdorferi HtrA to demonstrate the effectiveness of our function-agnostic approach, while characterization with both new and established biophysical methods shows the retention of proteolytic and chaperone activity of the refolded protein. This systematic workflow and toolset will translate to the production of HtrA-family proteins in higher quantities of pure and monodisperse composition than the current literature standard, with applicability to a broad array of protein purification strategies.
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Affiliation(s)
- Michael Ronzetti
- National Center for Advancing Translational SciencesNational Institutes of HealthRockvilleMarylandUSA
- Department of Veterinary Medicine, College of Agriculture & Natural ResourcesUniversity of MarylandCollege ParkMarylandUSA
| | - Bolormaa Baljinnyam
- National Center for Advancing Translational SciencesNational Institutes of HealthRockvilleMarylandUSA
| | | | - Utpal Pal
- Department of Veterinary Medicine, College of Agriculture & Natural ResourcesUniversity of MarylandCollege ParkMarylandUSA
| | - Anton Simeonov
- National Center for Advancing Translational SciencesNational Institutes of HealthRockvilleMarylandUSA
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A Regulatory SRNA Rli43 Is Involved in the Modulation of Biofilm Formation and Virulence in Listeria monocytogenes. Pathogens 2022; 11:pathogens11101137. [PMID: 36297193 PMCID: PMC9606912 DOI: 10.3390/pathogens11101137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/11/2022] [Accepted: 09/28/2022] [Indexed: 11/24/2022] Open
Abstract
Small RNAs (sRNAs) are a kind of regulatory molecule that can modulate gene expression at the post-transcriptional level, thereby involving alteration of the physiological characteristics of bacteria. However, the regulatory roles and mechanisms of most sRNAs remain unknown in Listeria monocytogenes(L. monocytogenes). To explore the regulatory roles of sRNA Rli43 in L. monocytogenes, the rli43 gene deletion strain LM-Δrli43 and complementation strain LM-Δrli43-rli43 were constructed to investigate the effects of Rli43 on responses to environmental stress, biofilm formation, and virulence, respectively. Additionally, Rli43-regulated target genes were identified using bioinformatic analysis tools and a bacterial dual plasmid reporter system based on E. coli. The results showed that the intracellular expression level of the rli43 gene was significantly upregulated compared with those under extracellular conditions. Compared with the parental and complementation strains, the environmental adaptation, motility, biofilm formation, adhesion, invasion, and intracellular survival of LM-Δrli43 were significantly reduced, respectively, whereas the LD50 of LM-Δrli43 was significantly elevated in BALB/c mice. Furthermore, the bacterial loads and pathological damages were alleviated, suggesting that sRNA Rli43 was involved in the modulation of the virulence of L. monocytogenes. It was confirmed that Rli43 may complementarily pair with the 5'-UTR (-47--55) of HtrA mRNA, thereby regulating the expression level of HtrA protein at the post-transcriptional level. These findings suggest that Rli43-mediated control was involved in the modulation of environmental adaptation, biofilm formation, and virulence in L. monocytogenes.
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Thompson C, George S, White ML, Eswara PJ, Ouyang Z. BB0761, a MepM homolog, contributes to Borrelia burgdorferi cell division and mammalian infectivity. Mol Microbiol 2022; 117:1405-1418. [PMID: 35510701 PMCID: PMC9794411 DOI: 10.1111/mmi.14916] [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: 01/02/2022] [Revised: 05/01/2022] [Accepted: 05/02/2022] [Indexed: 12/30/2022]
Abstract
M23 family endopeptidases play important roles in cell division and separation in a wide variety of bacteria. Recent studies have suggested that these proteins also contribute to bacterial virulence. However, the biological function of M23 peptidases in pathogenic spirochetes remains unexplored. Here, we describe Borrelia burgdorferi, the bacterial pathogen causing Lyme disease, requires a putative M23 family homolog, BB0761, for spirochete morphology and cell division. Indeed, the inactivation of bb0761 led to an aberrant filamentous phenotype as well as the impairment of B. burgdorferi growth in vitro. These phenotypes were complemented not only with B. burgdorferi bb0761, but also with the mepM gene from E. coli. Moreover, the bb0761 mutant showed a complete loss of infectivity in a murine model of Lyme borreliosis. Resistance of the mutant to osmotic and oxidative stresses was markedly reduced. Our combined results indicate that BB0761 contributes to B. burgdorferi cell division and virulence.
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Affiliation(s)
- Christina Thompson
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Sierra George
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Maria L. White
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA
| | - Prahathees J. Eswara
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA
| | - Zhiming Ouyang
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
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8
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Controlled Proteolysis of an Essential Virulence Determinant Dictates Infectivity of Lyme Disease Pathogens. Infect Immun 2022; 90:e0005922. [PMID: 35416705 DOI: 10.1128/iai.00059-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Borrelia burgdorferi BB0323 protein undergoes a complex yet poorly defined proteolytic maturation event that generates N-terminal and C-terminal proteins with essential functions in cell growth and infection. Here, we report that a borrelial protease, B. burgdorferi high temperature requirement A protease (BbHtrA), cleaves BB0323 between asparagine (N) and leucine (L) at positions 236 and 237, while the replacement of these residues with alanine in the mutant protein prevents its cleavage, despite preserving its normal secondary structure. The N-terminal BB0323 protein binds BbHtrA, but its cleavage site mutant displays deficiency in such interaction. An isogenic borrelial mutant with NL-to-AA substitution in BB0323 (referred to as Bbbb0323NL) maintains normal growth yet is impaired for infection of mice or transmission from infected ticks. Notably, the BB0323 protein is still processed in Bbbb0323NL, albeit with lower levels of mature N-terminal BB0323 protein and multiple aberrantly processed polypeptides, which could result from nonspecific cleavages at other asparagine and leucine residues in the protein. The lack of infectivity of Bbbb0323NL is likely due to the impaired abundance or stoichiometry of a protein complex involving BB0238, another spirochete protein. Together, these studies highlight that a precise proteolytic event and a particular protein-protein interaction, involving multiple borrelial virulence determinants, are mutually inclusive and interconnected, playing essential roles in the infectivity of Lyme disease pathogens.
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Abstract
The Borrelia spp. are tick-borne pathogenic spirochetes that include the agents of Lyme disease and relapsing fever. As part of their life cycle, the spirochetes traffic between the tick vector and the vertebrate host, which requires significant physiological changes and remodeling of their outer membranes and proteome. This crucial proteome resculpting is carried out by a diverse set of proteases, adaptor proteins, and related chaperones. Despite its small genome, Borrelia burgdorferi has dedicated a large percentage of its genome to proteolysis, including a full complement of ATP-dependent proteases. Energy-driven proteolysis appears to be an important physiological feature of this dual-life-cycle bacterium. The proteolytic arsenal of Borrelia is strategically deployed for disposal of proteins no longer required as they move from one stage to another or are transferred from one host to another. Likewise, the Borrelia spp. are systemic organisms that need to break down and move through host tissues and barriers, and so their unique proteolytic resources, both endogenous and borrowed, make movement more feasible. Both the Lyme disease and relapsing fever Borrelia spp. bind plasminogen as well as numerous components of the mammalian plasminogen-activating system. This recruitment capacity endows the spirochetes with a borrowed proteolytic competency that can lead to increased invasiveness.
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10
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Coburn J, Garcia B, Hu LT, Jewett MW, Kraiczy P, Norris SJ, Skare J. Lyme Disease Pathogenesis. Curr Issues Mol Biol 2020; 42:473-518. [PMID: 33353871 DOI: 10.21775/cimb.042.473] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Lyme disease Borrelia are obligately parasitic, tick- transmitted, invasive, persistent bacterial pathogens that cause disease in humans and non-reservoir vertebrates primarily through the induction of inflammation. During transmission from the infected tick, the bacteria undergo significant changes in gene expression, resulting in adaptation to the mammalian environment. The organisms multiply and spread locally and induce inflammatory responses that, in humans, result in clinical signs and symptoms. Borrelia virulence involves a multiplicity of mechanisms for dissemination and colonization of multiple tissues and evasion of host immune responses. Most of the tissue damage, which is seen in non-reservoir hosts, appears to result from host inflammatory reactions, despite the low numbers of bacteria in affected sites. This host response to the Lyme disease Borrelia can cause neurologic, cardiovascular, arthritic, and dermatologic manifestations during the disseminated and persistent stages of infection. The mechanisms by which a paucity of organisms (in comparison to many other infectious diseases) can cause varied and in some cases profound inflammation and symptoms remains mysterious but are the subjects of diverse ongoing investigations. In this review, we provide an overview of virulence mechanisms and determinants for which roles have been demonstrated in vivo, primarily in mouse models of infection.
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Affiliation(s)
- Jenifer Coburn
- Center For Infectious Disease Research, Medical College of Wisconsin, 8701 Watertown Plank Rd., TBRC C3980, Milwaukee, WI 53226, USA
| | - Brandon Garcia
- Department of Microbiology and Immunology, East Carolina University, Brody School of Medicine, Greenville, NC 27858, USA
| | - Linden T Hu
- Department of Molecular Biology and Microbiology, Vice Dean of Research, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA
| | - Mollie W Jewett
- Immunity and Pathogenesis Division Head, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, 6900 Lake Nona Blvd. Orlando, FL 32827, USA
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, University Hospital Frankfurt, Goethe University Frankfurt, Paul-Ehrlich-Str. 40, 60596 Frankfurt, Germany
| | - Steven J Norris
- Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, P.O. Box 20708, Houston, TX 77225, USA
| | - Jon Skare
- Professor and Associate Head, Texas A and M University, 8447 Riverside Pkwy, Bryan, TX 77807, USA
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Structural Conservation and Adaptation of the Bacterial Flagella Motor. Biomolecules 2020; 10:biom10111492. [PMID: 33138111 PMCID: PMC7693769 DOI: 10.3390/biom10111492] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 02/07/2023] Open
Abstract
Many bacteria require flagella for the ability to move, survive, and cause infection. The flagellum is a complex nanomachine that has evolved to increase the fitness of each bacterium to diverse environments. Over several decades, molecular, biochemical, and structural insights into the flagella have led to a comprehensive understanding of the structure and function of this fascinating nanomachine. Notably, X-ray crystallography, cryo-electron microscopy (cryo-EM), and cryo-electron tomography (cryo-ET) have elucidated the flagella and their components to unprecedented resolution, gleaning insights into their structural conservation and adaptation. In this review, we focus on recent structural studies that have led to a mechanistic understanding of flagellar assembly, function, and evolution.
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12
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Al-Otaibi NS, Taylor AJ, Farrell DP, Tzokov SB, DiMaio F, Kelly DJ, Bergeron JRC. The cryo-EM structure of the bacterial flagellum cap complex suggests a molecular mechanism for filament elongation. Nat Commun 2020; 11:3210. [PMID: 32587243 PMCID: PMC7316729 DOI: 10.1038/s41467-020-16981-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 05/29/2020] [Indexed: 11/16/2022] Open
Abstract
The bacterial flagellum is a remarkable molecular motor, whose primary function in bacteria is to facilitate motility through the rotation of a filament protruding from the bacterial cell. A cap complex, consisting of an oligomer of the protein FliD, is localized at the tip of the flagellum, and is essential for filament assembly, as well as adherence to surfaces in some bacteria. However, the structure of the intact cap complex, and the molecular basis for its interaction with the filament, remains elusive. Here we report the cryo-EM structure of the Campylobacter jejuni cap complex, which reveals that FliD is pentameric, with the N-terminal region of the protomer forming an extensive set of contacts across several subunits, that contribute to FliD oligomerization. We also demonstrate that the native C. jejuni flagellum filament is 11-stranded, contrary to a previously published cryo-EM structure, and propose a molecular model for the filament-cap interaction. FliD forms a cap complex at the tip of bacterial flagella and is essential for flagellum filament assembly. Here, the authors present the cryo-EM structure of the Campylobacter jejuni cap complex, revealing a pentameric assembly of FliD and further show that the C. jejuni flagellum filament is 11-stranded.
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Affiliation(s)
- Natalie S Al-Otaibi
- Department of Molecular Biology and Biotechnology, the University of Sheffield, Sheffield, UK
| | - Aidan J Taylor
- Department of Molecular Biology and Biotechnology, the University of Sheffield, Sheffield, UK
| | - Daniel P Farrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Svetomir B Tzokov
- Department of Molecular Biology and Biotechnology, the University of Sheffield, Sheffield, UK
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - David J Kelly
- Department of Molecular Biology and Biotechnology, the University of Sheffield, Sheffield, UK.
| | - Julien R C Bergeron
- Department of Molecular Biology and Biotechnology, the University of Sheffield, Sheffield, UK. .,Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.
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The Lon-1 Protease Is Required by Borrelia burgdorferi To Infect the Mammalian Host. Infect Immun 2020; 88:IAI.00951-19. [PMID: 32205400 DOI: 10.1128/iai.00951-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/14/2020] [Indexed: 01/23/2023] Open
Abstract
Borrelia burgdorferi encodes a functional homolog of canonical Lon protease termed Lon-2. In addition, B. burgdorferi encodes a second Lon homolog called Lon-1. Recent studies suggest that Lon-1 may function differently from the prototypical Lon protease. However, the function of Lon-1 in B. burgdorferi biology remains virtually unknown. Particularly, the contribution of Lon-1 to B. burgdorferi fitness and infection remains hitherto unexplored. Herein, we show that Lon-1 plays a critical role for the infection of B. burgdorferi in a mammalian host. We found that lon-1 was highly expressed during animal infection, implying an important function of this protein in bacterial infection. We further generated a lon-1 deletion mutant and an isogenic complemented strain. Relative to that of the wild-type strain, the infectivity of the mutant was severely attenuated in a murine infection model. Our data also showed that the mutant displayed growth defects in regular BSK-II medium. Furthermore, bacterial resistance to osmotic stress was markedly reduced when lon-1 was inactivated. When exposed to tert-butyl hydroperoxide, survival of the lon-1 mutant was impaired. In addition, production of several virulence factors, such as BosR, RpoS, and OspC, was elevated in the mutant. These phenotypes were restored when the lon-1 mutation was complemented. Finally, we created a lon-1(S714A) mutant and found that this mutant failed to infect mice, suggesting that the proteolytic activity of Lon-1 is essential for bacterial infection. Taken together, these results demonstrate that Lon-1 is required by B. burgdorferi to infect animal hosts and to cope with environmental stresses.
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Abstract
Periplasmic flagella are complex nanomachines responsible for distinctive morphology and motility of spirochetes. Although bacterial flagella have been extensively studied for several decades in the model systems Escherichia coli and Salmonella enterica, our understanding of periplasmic flagella in many disease-causing spirochetes remains incomplete. Recent advances, including molecular genetics, biochemistry, structural biology, and cryo-electron tomography, have greatly increased our understanding of structure and function of periplasmic flagella. In this chapter, we summarize some of the recent findings that provide new insights into the structure, assembly, and function of periplasmic flagella.
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Zhang K, He J, Cantalano C, Guo Y, Liu J, Li C. FlhF regulates the number and configuration of periplasmic flagella in Borrelia burgdorferi. Mol Microbiol 2020; 113:1122-1139. [PMID: 32039533 DOI: 10.1111/mmi.14482] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/17/2022]
Abstract
The Lyme disease bacterium Borrelia burgdorferi has 7-11 periplasmic flagella (PF) that arise from the cell poles and extend toward the midcell as a flat-ribbon, which is distinct from other bacteria. FlhF, a signal recognition particle (SRP)-like GTPase, has been found to regulate the flagellar number and polarity; however, its role in B. burgdorferi remains unknown. B. burgdorferi has an FlhF homolog (BB0270). Structural and biochemical analyses show that BB0270 has a similar structure and enzymatic activity as its counterparts from other bacteria. Genetics and cryo-electron tomography studies reveal that deletion of BB0270 leads to mutant cells that have less PF (4 ± 2 PF per cell tip) and fail to form a flat-ribbon, indicative of a role of BB0270 in the control of PF number and configuration. Mechanistically, we demonstrate that BB0270 localizes at the cell poles and controls the number and position of PF via regulating the flagellar protein stability and the polar localization of the MS-ring protein FliF. Our study not only provides the detailed characterizations of BB0270 and its profound impacts on flagellar assembly, morphology and motility in B. burgdorferi, but also unveils mechanistic insights into how spirochetes control their unique flagellar patterns.
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Affiliation(s)
- Kai Zhang
- Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA, USA
| | - Jun He
- Department of Microbial Pathogenesis, Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Claudio Cantalano
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA.,Institute for Structural Biology, Drug Discovery and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Youzhong Guo
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA.,Institute for Structural Biology, Drug Discovery and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Chunhao Li
- Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
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