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Sivaramalingam SS, Jothivel D, Govindarajan DK, Kadirvelu L, Sivaramakrishnan M, Chithiraiselvan DD, Kandaswamy K. Structural and functional insights of sortases and their interactions with antivirulence compounds. Curr Res Struct Biol 2024; 8:100152. [PMID: 38989133 PMCID: PMC11231552 DOI: 10.1016/j.crstbi.2024.100152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 05/18/2024] [Accepted: 06/11/2024] [Indexed: 07/12/2024] Open
Abstract
Sortase proteins play a crucial role as integral membrane proteins in anchoring bacterial surface proteins by recognizing them through a Cell-Wall Sorting (CWS) motif and cleaving them at specific sites before initiating pilus assembly. Both sortases and their substrate proteins are major virulence factors in numerous Gram-positive pathogens, making them attractive targets for antimicrobial intervention. Recognizing the significance of virulence proteins, a comprehensive exploration of their structural and functional characteristics is essential to enhance our understanding of pilus assembly in diverse Gram-positive bacteria. Therefore, this review article discusses the structural features of different classes of sortases and pilin proteins, primarily serving as substrates for sortase-assembled pili. Moreover, it thoroughly examines the molecular-level interactions between sortases and their inhibitors, providing insights from both structural and functional perspectives. In essence, this review article will provide a contemporary and complete understanding of both sortase pathways and various strategies to target them effectively to counteract the virulence.
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Affiliation(s)
- Sowmiya Sri Sivaramalingam
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
| | - Deepsikha Jothivel
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
| | - Deenadayalan Karaiyagowder Govindarajan
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore
| | - Lohita Kadirvelu
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
| | - Muthusaravanan Sivaramakrishnan
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
- Department of Biotechnology, Mepco Schlenk Engineering College, Tamil Nadu, India
| | - Dhivia Dharshika Chithiraiselvan
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
| | - Kumaravel Kandaswamy
- Research Center for Excellence in Microscopy, Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, 641049, Tamil Nadu, India
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Bao Y, Wang L, Sun J. Post-translational knockdown and post-secretional modification of EsxA determine contribution of EsxA membrane permeabilizing activity for mycobacterial intracellular survival. Virulence 2021; 12:312-328. [PMID: 33356823 PMCID: PMC7808419 DOI: 10.1080/21505594.2020.1867438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Current genetic studies (e.g. gene knockout) have suggested that EsxA and EsxB function as secreted virulence factors that are essential for Mycobaterium tuberculosis (Mtb) intracellular survival, specifically in mediating phagosome rupture and translocation of Mtb to the cytosol of host cells, which further facilitates Mtb intracellular replicating and cell-to-cell spreading. The EsxA-mediated intracellular survival is presumably achieved by its pH-dependent membrane-permeabilizing activity (MPA). However, the data from other studies have generated a discrepancy regarding the role of EsxA MPA in mycobacterial intracellular survival, which has raised a concern that genetic manipulations, such as deletion of esxB-esxA operon or RD-1 locus, may affect other codependently secreted factors that could be also directly involved cytosolic translocation, or stimulate extended disturbance on other genes’ expression. To avoid the drawbacks of gene knockout, we first engineered a Mycobacterium marinum (Mm) strain, in which a DAS4+ tag was fused to the C-terminus of EsxB to allow inducible knockdown of EsxB (also EsxA) at the post-translational level. We also engineered an Mm strain by fusing a SpyTag (ST) to the C-terminus of EsxA, which allowed inhibition of EsxA-ST MPA at the post-secretional level through a covalent linkage to SpyCatcher-GFP. Both post-translational knockdown and functional inhibition of EsxA resulted in attenuation of Mm intracellular survival in lung epithelial cells or macrophages, which unambiguously confirms the direct role of EsxA MPA in mycobacterial intracellular survival.
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Affiliation(s)
- Yanqing Bao
- Department of Biological Sciences and Border Biomedical Research Center, University of Texas at El Paso , El Paso, Texas, USA
| | - Lin Wang
- Department of Biological Sciences and Border Biomedical Research Center, University of Texas at El Paso , El Paso, Texas, USA
| | - Jianjun Sun
- Department of Biological Sciences and Border Biomedical Research Center, University of Texas at El Paso , El Paso, Texas, USA
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Immunoinformatic approach for the evaluation of sortase C and E proteins as vaccine targets against caseous lymphadenitis. INFORMATICS IN MEDICINE UNLOCKED 2021. [DOI: 10.1016/j.imu.2021.100718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Kumar Megta A, Palva A, von Ossowski I, Krishnan V. SpaB, an atypically adhesive basal pilin from the lactobacillar SpaCBA pilus: crystallization and X-ray diffraction analysis. Acta Crystallogr F Struct Biol Commun 2019; 75:731-737. [PMID: 31797814 PMCID: PMC6891582 DOI: 10.1107/s2053230x19015358] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023] Open
Abstract
The SpaB pilin is recognized as the basal subunit of the sortase-dependent SpaCBA pilus, which is known to be produced by the Gram-positive Lactobacillus rhamnosus GG, a gut-adapted commensal advocated to have health benefits. Despite seeming to function as an archetypal basal pilin by serving as the terminal subunit in pilus assembly, SpaB also assumes an atypical role as a mucoadhesive protein. To shed light on the structural factors that contribute to this dual functional behaviour, a recombinant form of the L. rhamnosus GG SpaB pilin was produced and purified for crystallization and X-ray diffraction experiments. The crystallization of SpaB remained particularly challenging until the implementation of a three-pronged crystallization approach involving C-terminal tail truncation, surface lysine methylation and magnesium additives. Ultimately, hexagonal crystals of SpaB were produced and were able to diffract to a resolution of 2.4 Å. This crystal form belonged to space group P6522 or P6122, with unit-cell parameters a = b = 51.53, c = 408.22 Å, α = β = 90.0, γ = 120.0°. Obtaining an interpretable electron-density map via single-wavelength anomalous diffraction (SAD) using iodide-derivative data sets did not succeed owing to the weak anomalous signal. As an alternative, attempts to provide phases by molecular replacement using the iodide-SAD data from SpaB and a collection of distant homology models (<28% sequence identity) are in progress.
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Affiliation(s)
- Abhin Kumar Megta
- Laboratory of Structural Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana 121 001, India
- School of Biotechnology, KIIT University, Odisha 751 024, India
| | - Airi Palva
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
| | | | - Vengadesan Krishnan
- Laboratory of Structural Biology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana 121 001, India
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Group A Streptococcus T Antigens Have a Highly Conserved Structure Concealed under a Heterogeneous Surface That Has Implications for Vaccine Design. Infect Immun 2019; 87:IAI.00205-19. [PMID: 30936156 DOI: 10.1128/iai.00205-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 03/25/2019] [Indexed: 12/20/2022] Open
Abstract
Group A Streptococcus (GAS) (Streptococcus pyogenes) is an important human pathogen associated with significant global morbidity and mortality for which there is no safe and efficacious vaccine. The T antigen, a protein that polymerizes to form the backbone of the GAS pilus structure, is a potential vaccine candidate. Previous surveys of the tee gene, which encodes the T antigen, have identified 21 different tee types and subtypes such that any T antigen-based vaccine must be multivalent and carefully designed to provide broad strain coverage. In this study, the crystal structures of three two-domain T antigens (T3.2, T13, and T18.1) were determined and found to have remarkable structural similarity to the previously reported T1 antigen, despite moderate overall sequence similarity. This has enabled reliable modeling of all major two-domain T antigens to reveal that T antigen sequence variation is distributed along the full length of the protein and shields a highly conserved core. Immunoassays performed with sera from immunized animals and commercial T-typing sera identified a significant cross-reactive antibody response between T18.1, T18.2, T3.2, and T13. The existence of shared epitopes between T antigens, combined with the remarkably conserved structure and high level of surface sequence divergence, has important implications for the design of multivalent T antigen-based vaccines.
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Liu L, Pu X, Yin G, Chen X, Yin J, Wu Y. Biomimetic Mineralization of Magnetic Iron Oxide Nanoparticles Mediated by Bi-Functional Copolypeptides. Molecules 2019; 24:E1401. [PMID: 30974744 PMCID: PMC6480056 DOI: 10.3390/molecules24071401] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/07/2019] [Accepted: 04/09/2019] [Indexed: 01/25/2023] Open
Abstract
Magnetite (Fe₃O₄) nanoparticles are widely used in multiple biomedical applications due to their magnetic properties depending on the size, shape and organization of the crystals. However, the crystal growth and morphology of Fe₃O₄ nanoparticles remain difficult to control without using organic solvent or a high temperature. Inspired by the natural biomineralization process, a 14-mer bi-functional copolypeptide, leveraging the affinity of binding Fe₃O₄ together with targeting ovarian cancer cell A2780, was used as a template in the biomimetic mineralization of magnetite. Alongside this, a ginger extract was applied as an antioxidant and a size-conditioning agent of Fe₃O₄ crystals. As a result of the cooperative effects of the peptide and the ginger extract, the size and dispersibility of Fe₃O₄ were controlled based on the interaction of the amino acid and the ginger extract. Our study also demonstrated that the obtained particles with superparamagnetism could selectively be taken up by A2780 cells. In summary, the Fe₃O₄-QY-G nanoparticles may have potential applications in targeting tumor therapy or angiography.
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Affiliation(s)
- Liu Liu
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
| | - Ximing Pu
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
| | - Guangfu Yin
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
| | - Xianchun Chen
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
| | - Jie Yin
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
- School of Automation and Information Engineering, Sichuan University of Science and Engineering, Zigong 643000, China.
| | - Yuhao Wu
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
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Schneewind O, Missiakas D. Sortases, Surface Proteins, and Their Roles in Staphylococcus aureus Disease and Vaccine Development. Microbiol Spectr 2019; 7:10.1128/microbiolspec.PSIB-0004-2018. [PMID: 30737913 PMCID: PMC6386163 DOI: 10.1128/microbiolspec.psib-0004-2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Indexed: 12/27/2022] Open
Abstract
Sortases cleave short peptide motif sequences at the C-terminal end of secreted surface protein precursors and either attach these polypeptides to the peptidoglycan of Gram-positive bacteria or promote their assembly into pilus structures that are also attached to peptidoglycan. Sortase A, the enzyme first identified in the human pathogen Staphylococcus aureus, binds LPXTG motif sorting signals, cleaves between threonine (T) and glycine (G) residues, and forms an acyl enzyme between its active-site cysteine thiol and the carboxyl group of threonine (T). Sortase A acyl enzyme is relieved by the nucleophilic attack of the cross bridge amino group within lipid II, thereby generating surface protein linked to peptidoglycan precursor. Such products are subsequently incorporated into the cell wall envelope by enzymes of the peptidoglycan synthesis pathway. Surface proteins linked to peptidoglycan may be released from the bacterial envelope to diffuse into host tissues and fulfill specific biological functions. S. aureus sortase A is essential for host colonization and for the pathogenesis of invasive diseases. Staphylococcal sortase-anchored surface proteins fulfill key functions during the infectious process, and vaccine-induced antibodies targeting surface proteins may provide protection against S. aureus. Alternatively, small-molecule inhibitors of sortase may be useful agents for the prevention of S. aureus colonization and invasive disease.
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Affiliation(s)
- Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637
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Spontaneous cross-linking of proteins at aspartate and asparagine residues is mediated via a succinimide intermediate. Biochem J 2018; 475:3189-3200. [PMID: 30181147 DOI: 10.1042/bcj20180529] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/24/2018] [Accepted: 08/31/2018] [Indexed: 11/17/2022]
Abstract
The breakdown of long-lived proteins (LLPs) is associated with aging, as well as disease; however, our understanding of the molecular processes involved is still limited. Of particular relevance, cross-linked proteins are often reported in aged tissues but the mechanisms for their formation are poorly understood. In the present study, sites of protein cross-linking in human ocular lenses were characterized using proteomic techniques. In long-lived lens proteins, several sites of cross-linking were found to involve the addition of Lys to Asp or Asn residues. Using model peptides containing Asp or Asn, a mechanism was elucidated that involves a succinimide intermediate. Succinimides formed readily from Asn at neutral pH, whereas a higher rate of formation from Asp peptides was observed at more acidic pHs. Succinimides were found to be relatively stable in the absence of nucleophiles. Since racemization of Asp residues, as well as deamidation of Asn, involves a succinimide intermediate, sites of d-Asp and isoAsp in LLPs should also be considered as potential sites of protein covalent cross-linking.
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Desvaux M, Candela T, Serror P. Surfaceome and Proteosurfaceome in Parietal Monoderm Bacteria: Focus on Protein Cell-Surface Display. Front Microbiol 2018; 9:100. [PMID: 29491848 PMCID: PMC5817068 DOI: 10.3389/fmicb.2018.00100] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 01/16/2018] [Indexed: 12/12/2022] Open
Abstract
The cell envelope of parietal monoderm bacteria (archetypal Gram-positive bacteria) is formed of a cytoplasmic membrane (CM) and a cell wall (CW). While the CM is composed of phospholipids, the CW is composed at least of peptidoglycan (PG) covalently linked to other biopolymers, such as teichoic acids, polysaccharides, and/or polyglutamate. Considering the CW is a porous structure with low selective permeability contrary to the CM, the bacterial cell surface hugs the molecular figure of the CW components as a well of the external side of the CM. While the surfaceome corresponds to the totality of the molecules found at the bacterial cell surface, the proteinaceous complement of the surfaceome is the proteosurfaceome. Once translocated across the CM, secreted proteins can either be released in the extracellular milieu or exposed at the cell surface by associating to the CM or the CW. Following the gene ontology (GO) for cellular components, cell-surface proteins at the CM can either be integral (GO: 0031226), i.e., the integral membrane proteins, or anchored to the membrane (GO: 0046658), i.e., the lipoproteins. At the CW (GO: 0009275), cell-surface proteins can be covalently bound, i.e., the LPXTG-proteins, or bound through weak interactions to the PG or wall polysaccharides, i.e., the cell wall binding proteins. Besides monopolypeptides, some proteins can associate to each other to form supramolecular protein structures of high molecular weight, namely the S-layer, pili, flagella, and cellulosomes. After reviewing the cell envelope components and the different molecular mechanisms involved in protein attachment to the cell envelope, perspectives in investigating the proteosurfaceome in parietal monoderm bacteria are further discussed.
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Affiliation(s)
- Mickaël Desvaux
- Université Clermont Auvergne, INRA, UMR454 MEDiS, Clermont-Ferrand, France
| | - Thomas Candela
- EA4043 Unité Bactéries Pathogènes et Santé, Châtenay-Malabry, France
| | - Pascale Serror
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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Molecular Mechanisms of the Binding and Specificity of Streptococcus Pneumoniae Sortase C Enzymes for Pilin Subunits. Sci Rep 2017; 7:13119. [PMID: 29030637 PMCID: PMC5640630 DOI: 10.1038/s41598-017-13135-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/19/2017] [Indexed: 02/05/2023] Open
Abstract
Pili are elongated structures that protrude from bacteria and increase their virulence. The Streptococcus pnuenomae pilus island 1 pili are composed of three subunits, RrgA, RrgB, and RrgC, and are assembled by three class C sortase C (SrtC) enzymes: SrtC-1, SrtC-2, and SrtC-3. Pilin subunits are recognized by SrtC proteins through a pentapeptide sorting signal, and while previous studies have sought to characterize the selectivities of SrtC isoforms for these subunits, the molecular mechanisms underlying these interactions remain unclear. Here, we report a series of molecular dynamics simulations of each SrtC enzyme with the sorting signals of RrgA, RrgB, and RrgC to determine the structural and thermodynamic basis of pilin recognition. Results show that, in accordance with previous studies, both SrtC-1 and SrtC-3 are selective for RrgB, while SrtC-2 is selective for RrgA. This specificity is tuned by the sorting signal binding conformation in which the first two residue sidechains complement hydrophobic residues around the active site, while the third residue projects away from the catalytic triad and makes specific interactions based on its charge and reach. Together, these results provided atomic-scale descriptions of the SrtC substrate selectivity mechanisms and extend the emerging model of pilin construction in S. pnuenomae.
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Callegan MC, Parkunan SM, Randall CB, Coburn PS, Miller FC, LaGrow AL, Astley RA, Land C, Oh SY, Schneewind O. The role of pili in Bacillus cereus intraocular infection. Exp Eye Res 2017; 159:69-76. [PMID: 28336259 PMCID: PMC5492386 DOI: 10.1016/j.exer.2017.03.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/09/2017] [Accepted: 03/16/2017] [Indexed: 12/15/2022]
Abstract
Bacterial endophthalmitis is a potentially blinding intraocular infection. The bacterium Bacillus cereus causes a devastating form of this disease which progresses rapidly, resulting in significant inflammation and loss of vision within a few days. The outer surface of B. cereus incites the intraocular inflammatory response, likely through interactions with innate immune receptors such as TLRs. This study analyzed the role of B. cereus pili, adhesion appendages located on the bacterial surface, in experimental endophthalmitis. To test the hypothesis that the presence of pili contributed to intraocular inflammation and virulence, we analyzed the progress of experimental endophthalmitis in mouse eyes infected with wild type B. cereus (ATCC 14579) or its isogenic pilus-deficient mutant (ΔbcpA-srtD-bcpB or ΔPil). One hundred CFU were injected into the mid-vitreous of one eye of each mouse. Infections were analyzed by quantifying intraocular bacilli and retinal function loss, and by histology from 0 to 12 h postinfection. In vitro growth and hemolytic phenotypes of the infecting strains were also compared. There was no difference in hemolytic activity (1:8 titer), motility, or in vitro growth (p > 0.05, every 2 h, 0-18 h) between wild type B. cereus and the ΔPil mutant. However, infected eyes contained greater numbers of wild type B. cereus than ΔPil during the infection course (p ≤ 0.05, 3-12 h). Eyes infected with wild type B. cereus experienced greater losses in retinal function than eyes infected with the ΔPil mutant, but the differences were not always significant. Eyes infected with ΔPil or wild type B. cereus achieved similar degrees of severe inflammation. The results indicated that the intraocular growth of pilus-deficient B. cereus may have been better controlled, leading to a trend of greater retinal function in eyes infected with the pilus-deficient strain. Although this difference was not enough to significantly alter the severity of the inflammatory response, these results suggest a potential role for pili in protecting B. cereus from clearance during the early stages of endophthalmitis, which is a newly described virulence mechanism for this organism and this infection.
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Affiliation(s)
- Michelle C. Callegan
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA,Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 950 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA,Dean A. McGee Eye Institute, Oklahoma City Oklahoma USA,Corresponding author: DMEI PA-418, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA. Phone: (405) 271-3674, Fax: (405) 271-8128,
| | - Salai Madhumathi Parkunan
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 950 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - C. Blake Randall
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - Phillip S. Coburn
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - Frederick C. Miller
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 950 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - Austin L. LaGrow
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - Roger A. Astley
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - Craig Land
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - So-Young Oh
- Department of Microbiology, University of Chicago, 920 East 58
| | - Olaf Schneewind
- Department of Microbiology, University of Chicago, 920 East 58
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Duong A, Koteva K, Sexton DL, Elliot MA. Liquid Chromatography-Tandem Mass Spectrometry to Define Sortase Cleavage Products. Methods Mol Biol 2016; 1440:99-108. [PMID: 27311667 DOI: 10.1007/978-1-4939-3676-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Sortase enzymes have specific endopeptidase activity, cleaving within a defined pentapeptide sequence at the C-terminal end of their protein substrates. Here, we describe how monitoring sortase cleavage activity can be achieved using peptide substrates. Peptide cleavage can be readily analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS), which allows for the precise definition of cleavage sites. This technique could be used to analyze the peptidase activity of any enzyme, and identify sites of cleavage within any peptide.
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Affiliation(s)
- Andrew Duong
- Department of Biology, McMaster University, Hamilton, ON, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Kalinka Koteva
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Danielle L Sexton
- Department of Biology, McMaster University, Hamilton, ON, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Marie A Elliot
- Department of Biology, McMaster University, Hamilton, ON, Canada.
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Life Science Building, RM 329, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
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13
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Self-generated covalent cross-links in the cell-surface adhesins of Gram-positive bacteria. Biochem Soc Trans 2015; 43:787-94. [DOI: 10.1042/bst20150066] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ability of bacteria to adhere to other cells or to surfaces depends on long, thin adhesive structures that are anchored to their cell walls. These structures include extended protein oligomers known as pili and single, multi-domain polypeptides, mostly based on multiple tandem Ig-like domains. Recent structural studies have revealed the widespread presence of covalent cross-links, not previously seen within proteins, which stabilize these domains. The cross-links discovered so far are either isopeptide bonds that link lysine side chains to the side chains of asparagine or aspartic acid residues or ester bonds between threonine and glutamine side chains. These bonds appear to be formed by spontaneous intramolecular reactions as the proteins fold and are strategically placed so as to impart considerable mechanical strength.
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Chahales P, Thanassi DG. Structure, Function, and Assembly of Adhesive Organelles by Uropathogenic Bacteria. Microbiol Spectr 2015; 3:10.1128/microbiolspec.UTI-0018-2013. [PMID: 26542038 PMCID: PMC4638162 DOI: 10.1128/microbiolspec.uti-0018-2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 01/02/2023] Open
Abstract
Bacteria assemble a wide range of adhesive proteins, termed adhesins, to mediate binding to receptors and colonization of surfaces. For pathogenic bacteria, adhesins are critical for early stages of infection, allowing the bacteria to initiate contact with host cells, colonize different tissues, and establish a foothold within the host. The adhesins expressed by a pathogen are also critical for bacterial-bacterial interactions and the formation of bacterial communities, including biofilms. The ability to adhere to host tissues is particularly important for bacteria that colonize sites such as the urinary tract, where the flow of urine functions to maintain sterility by washing away non-adherent pathogens. Adhesins vary from monomeric proteins that are directly anchored to the bacterial surface to polymeric, hair-like fibers that extend out from the cell surface. These latter fibers are termed pili or fimbriae, and were among the first identified virulence factors of uropathogenic Escherichia coli. Studies since then have identified a range of both pilus and non-pilus adhesins that contribute to bacterial colonization of the urinary tract, and have revealed molecular details of the structures, assembly pathways, and functions of these adhesive organelles. In this review, we describe the different types of adhesins expressed by both Gram-negative and Gram-positive uropathogens, what is known about their structures, how they are assembled on the bacterial surface, and the functions of specific adhesins in the pathogenesis of urinary tract infections.
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Affiliation(s)
- Peter Chahales
- Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794
| | - David G Thanassi
- Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794
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15
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Lazzarin M, Cozzi R, Malito E, Martinelli M, D'Onofrio M, Maione D, Margarit I, Rinaudo CD. Noncanonical sortase‐mediated assembly of pilus type 2b in group B
Streptococcus. FASEB J 2015. [DOI: 10.1096/fj.15-272500] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Roberta Cozzi
- Novartis Vaccines and Diagnostics, GlaxoSmithKlineSienaItaly
| | - Enrico Malito
- Novartis Vaccines and Diagnostics, GlaxoSmithKlineSienaItaly
| | | | - Mariapina D'Onofrio
- Nuclear Magnetic Resonance LaboratoryDepartment of BiotechnologyUniversity of VeronaVeronaItaly
| | - Domenico Maione
- Novartis Vaccines and Diagnostics, GlaxoSmithKlineSienaItaly
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16
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Bradshaw WJ, Davies AH, Chambers CJ, Roberts AK, Shone CC, Acharya KR. Molecular features of the sortase enzyme family. FEBS J 2015; 282:2097-114. [PMID: 25845800 DOI: 10.1111/febs.13288] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 03/13/2015] [Accepted: 03/28/2015] [Indexed: 01/31/2023]
Abstract
Bacteria possess complex and varying cell walls with many surface exposed proteins. Sortases are responsible for the covalent attachment of specific proteins to the peptidoglycan of the cell wall of Gram-positive bacteria. Sortase A of Staphylococcus aureus, which is seen as the archetypal sortase, has been shown to be essential for pathogenesis and has therefore received much attention as a potential target for novel therapeutics. Being widely present in Gram-positive bacteria, it is likely that other Gram-positive pathogens also require sortases for their pathogenesis. Sortases have also been shown to be of significant use in a range of industrial applications. We review current knowledge of the sortase family in terms of their structures, functions and mechanisms and summarize work towards their use as antibacterial targets and microbiological tools.
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Affiliation(s)
- William J Bradshaw
- Department of Biology and Biochemistry, University of Bath, UK.,Public Health England, Porton Down, Salisbury, UK
| | | | - Christopher J Chambers
- Department of Biology and Biochemistry, University of Bath, UK.,Public Health England, Porton Down, Salisbury, UK
| | | | | | - K Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, UK
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17
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Schneewind O, Missiakas D. Sec-secretion and sortase-mediated anchoring of proteins in Gram-positive bacteria. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:1687-97. [PMID: 24269844 PMCID: PMC4031296 DOI: 10.1016/j.bbamcr.2013.11.009] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/01/2013] [Accepted: 11/13/2013] [Indexed: 01/17/2023]
Abstract
Signal peptide-driven secretion of precursor proteins directs polypeptides across the plasma membrane of bacteria. Two pathways, Sec- and SRP-dependent, converge at the SecYEG translocon to thread unfolded precursor proteins across the membrane, whereas folded preproteins are routed via the Tat secretion pathway. Gram-positive bacteria lack an outer membrane and are surrounded by a rigid layer of peptidoglycan. Interactions with their environment are mediated by proteins that are retained in the cell wall, often through covalent attachment to the peptidoglycan. In this review, we describe the mechanisms for both Sec-dependent secretion and sortase-dependent assembly of proteins in the envelope of Gram-positive bacteria. 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)
- Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA.
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18
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Abstract
Bioorthogonal, chemoselective ligation methods are an essential part of the tools utilized to investigate biochemical pathways. Specifically enzymatic approaches are valuable methods in this context due to the inherent specificity of the deployed enzymes and the mild conditions of the modification reactions. One of the most common strategies is based on the transpeptidation catalyzed by sortase A derived from Staphylococcus aureus. The procedure is well established and a wide variety of applications have been published to date. Here, implementations of sortase A, which range from protein labeling using fluorescence dyes and the preparation of cyclic proteins to the modification of entire cells, are summarized. Furthermore, there is a focus on the optimization approaches established to solve the drawbacks of sortase-mediated transpeptidation.
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Affiliation(s)
- Markus Ritzefeld
- Bielefeld University, Department of Chemistry, Organic and Bioorganic Chemistry (OCIII), Universitätsstrasse 25, 33615 Bielefeld (Germany).
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19
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Identification of pili on the surface of Finegoldia magna – A Gram-positive anaerobic cocci. Anaerobe 2014; 27:40-9. [DOI: 10.1016/j.anaerobe.2014.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/07/2014] [Accepted: 03/11/2014] [Indexed: 11/23/2022]
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20
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Hall M, Nylander S, Jenkinson HF, Persson K. Structure of the C-terminal domain of AspA (antigen I/II-family) protein from Streptococcus pyogenes. FEBS Open Bio 2014; 4:283-9. [PMID: 24918040 PMCID: PMC4048849 DOI: 10.1016/j.fob.2014.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 01/01/2023] Open
Abstract
The structure of the C2–3-domain of AspA from S. pyogenes was determined. The C2 and C3 domains both adopt DEv-IgG folds. Conserved isopeptide bonds and calcium binding sites are observed. Distinct structural features are observed in the SspB Adherence Region (BAR).
The pathogenic bacteria Streptococcus pyogenes can cause an array of diseases in humans, including moderate infections such as pharyngitis (strep throat) as well as life threatening conditions such as necrotizing fasciitis and puerperal fever. The antigen I/II family proteins are cell wall anchored adhesin proteins found on the surfaces of most oral streptococci and are involved in host colonization and biofilm formation. In the present study we have determined the crystal structure of the C2–3-domain of the antigen I/II type protein AspA from S. pyogenes M type 28. The structure was solved to 1.8 Å resolution and shows that the C2–3-domain is comprised of two structurally similar DEv-IgG motifs, designated C2 and C3, both containing a stabilizing covalent isopeptide bond. Furthermore a metal binding site is identified, containing a bound calcium ion. Despite relatively low sequence identity, interestingly, the overall structure shares high similarity to the C2–3-domains of antigen I/II proteins from Streptococcus gordonii and Streptococcus mutans, although certain parts of the structure exhibit distinct features. In summary this work constitutes the first step in the full structure determination of the AspA protein from S. pyogenes.
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Affiliation(s)
- Michael Hall
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Sa Nylander
- Department of Odontology, Division of Oral Microbiology, Umeå University, SE-901 87 Umeå, Sweden
| | - Howard F Jenkinson
- School of Oral and Dental Sciences, University of Bristol, Bristol BS1 2LY, UK
| | - Karina Persson
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
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21
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Hendrickx APA, van Schaik W, Willems RJL. The cell wall architecture of Enterococcus faecium: from resistance to pathogenesis. Future Microbiol 2014; 8:993-1010. [PMID: 23902146 DOI: 10.2217/fmb.13.66] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The cell wall of Gram-positive bacteria functions as a surface organelle that continuously interacts with its environment through a plethora of cell wall-associated molecules. Enterococcus faecium is a normal inhabitant of the GI tract of mammals, but has recently become an important etiological agent of hospital-acquired infections in debilitated patients. Insights into the assembly and function of enterococcal cell wall components and their interactions with the host during colonization and infection are essential to explain the worldwide emergence of E. faecium as an important multiantibiotic-resistant nosocomial pathogen. Understanding the biochemistry of cell wall biogenesis and principles of antibiotic resistance at the molecular level may open up new frontiers in research on enterococci, particularly for the development of novel antimicrobial strategies. In this article, we outline the current knowledge on the most important antimicrobial resistance mechanisms that involve peptidoglycan synthesis and the role of cell wall constituents, including lipoteichoic acid, wall teichoic acid, capsular polysaccharides, LPxTG cell wall-anchored surface proteins, WxL-type surface proteins and pili, in the pathogenesis of E. faecium.
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Affiliation(s)
- Antoni P A Hendrickx
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
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22
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Pilin and sortase residues critical for endocarditis- and biofilm-associated pilus biogenesis in Enterococcus faecalis. J Bacteriol 2013; 195:4484-95. [PMID: 23913319 DOI: 10.1128/jb.00451-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Enterococci commonly cause hospital-acquired infections, such as infective endocarditis and catheter-associated urinary tract infections. In animal models of these infections, a long hairlike extracellular protein fiber known as the endocarditis- and biofilm-associated (Ebp) pilus is an important virulence factor for Enterococcus faecalis. For Ebp and other sortase-assembled pili, the pilus-associated sortases are essential for fiber formation as they create covalent isopeptide bonds between the sortase recognition motif and the pilin-like motif of the pilus subunits. However, the molecular requirements governing the incorporation of the three pilus subunits (EbpA, EbpB, and EbpC) have not been investigated in E. faecalis. Here, we show that a Lys residue within the pilin-like motif of the EbpC subunit was necessary for EbpC polymerization. However, incorporation of EbpA into the pilus fiber only required its sortase recognition motif (LPXTG), while incorporation of EbpB only required its pilin-like motif. Only the sortase recognition motif would be required for incorporation of the pilus tip subunit, while incorporation of the base subunit would only require the pilin recognition motif. Thus, these data support a model with EbpA at the tip and EbpB at the base of an EbpC polymer. In addition, the housekeeping sortase, SrtA, was found to process EbpB and its predicted catalytic Cys residue was required for efficient cell wall anchoring of mature Ebp pili. Thus, we have defined molecular interactions involved in fiber polymerization, minor subunit organization, and pilus subcellular compartmentalization in the E. faecalis Ebp pilus system. These studies advance our understanding of unique molecular mechanisms of sortase-assembled pilus biogenesis.
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23
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24
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Oxaran V, Ledue-Clier F, Dieye Y, Herry JM, Péchoux C, Meylheuc T, Briandet R, Juillard V, Piard JC. Pilus biogenesis in Lactococcus lactis: molecular characterization and role in aggregation and biofilm formation. PLoS One 2012; 7:e50989. [PMID: 23236417 PMCID: PMC3516528 DOI: 10.1371/journal.pone.0050989] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 10/29/2012] [Indexed: 02/07/2023] Open
Abstract
The genome of Lactococcus lactis strain IL1403 harbors a putative pilus biogenesis cluster consisting of a sortase C gene flanked by 3 LPxTG protein encoding genes (yhgD, yhgE, and yhhB), called here pil. However, pili were not detected under standard growth conditions. Over-expression of the pil operon resulted in production and display of pili on the surface of lactococci. Functional analysis of the pilus biogenesis machinery indicated that the pilus shaft is formed by oligomers of the YhgE pilin, that the pilus cap is formed by the YhgD pilin and that YhhB is the basal pilin allowing the tethering of the pilus fibers to the cell wall. Oligomerization of pilin subunits was catalyzed by sortase C while anchoring of pili to the cell wall was mediated by sortase A. Piliated L. lactis cells exhibited an auto-aggregation phenotype in liquid cultures, which was attributed to the polymerization of major pilin, YhgE. The piliated lactococci formed thicker, more aerial biofilms compared to those produced by non-piliated bacteria. This phenotype was attributed to oligomers of YhgE. This study provides the first dissection of the pilus biogenesis machinery in a non-pathogenic Gram-positive bacterium. Analysis of natural lactococci isolates from clinical and vegetal environments showed pili production under standard growth conditions. The identification of functional pili in lactococci suggests that the changes they promote in aggregation and biofilm formation may be important for the natural lifestyle as well as for applications in which these bacteria are used.
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Affiliation(s)
- Virginie Oxaran
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Florence Ledue-Clier
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Yakhya Dieye
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Jean-Marie Herry
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | | | - Thierry Meylheuc
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Romain Briandet
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Vincent Juillard
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Jean-Christophe Piard
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
- * E-mail:
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25
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Danne C, Dramsi S. Pili of gram-positive bacteria: roles in host colonization. Res Microbiol 2012; 163:645-58. [PMID: 23116627 DOI: 10.1016/j.resmic.2012.10.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/11/2012] [Indexed: 02/06/2023]
Abstract
In the last decade, pili, which are encoded within pathogenicity islands, have been found in many Gram-positive bacteria, including the major streptococcal and enterococcal pathogens. These long proteinaceous polymers extending from the bacterial surface are constituted of covalently linked pilin subunits, which play major roles in adhesion and host colonization. They are also involved in biofilm formation, a characteristic life-style of the bacteria constituting the oral flora. Pili are highly immunogenic structures that are under the selective pressure of host immune responses. Indeed, pilus expression was found to be heterogeneous in several bacteria with the co-existence of two subpopulations expressing various levels of pili. The molecular mechanisms underlying this complex regulation are poorly characterized except for Streptococcus pneumoniae. In this review, we will discuss the roles of Gram-positive bacteria pili in adhesion to host extracellular matrix proteins, tissue tropism, biofilm formation, modulation of innate immune responses and their contribution to virulence, and in a second part the regulation of their expression. This overview should help to understand the rise of pili as an intensive field of investigation and pinpoints the areas that need further study.
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Affiliation(s)
- Camille Danne
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram-positif, Paris F-75015, France
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26
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Hendrickx APA, Poor CB, Jureller JE, Budzik JM, He C, Schneewind O. Isopeptide bonds of the major pilin protein BcpA influence pilus structure and bundle formation on the surface of Bacillus cereus. Mol Microbiol 2012; 85:152-63. [PMID: 22624947 DOI: 10.1111/j.1365-2958.2012.08098.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bacillus cereus strains elaborate pili on their surface using a mechanism of sortase-mediated cross-linking of major and minor pilus components. Here we used a combination of electron microscopy and atomic force microscopy to visualize these structures. Pili occur as single, double or higher order assemblies of filaments formed from monomers of the major pilin, BcpA, capped by the minor pilin, BcpB. Previous studies demonstrated that within assembled pili, four domains of BcpA - CNA(1), CNA(2), XNA and CNA(3) - each acquire intramolecular lysine-asparagine isopeptide bonds formed via catalytic glutamic acid or aspartic acid residues. Here we showed that mutants unable to form the intramolecular isopeptide bonds in the CNA(2) or CNA(3) domains retain the ability to form pilus bundles. A mutant lacking the CNA(1) isopeptide bond assembled deformed pilin subunits that failed to associate as bundles. X-ray crystallography revealed that the BcpA variant Asp(312) Ala, lacking an aspartyl catalyst, did not generate the isopeptide bond within the jelly-roll structure of XNA. The Asp(312) Ala mutant was also unable to form bundles and promoted the assembly of deformed pili. Thus, structural integrity of the CNA(1) and XNA domains are determinants for the association of pili into higher order bundle structures and determine native pilus structure.
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27
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Schneewind O, Missiakas DM. Protein secretion and surface display in Gram-positive bacteria. Philos Trans R Soc Lond B Biol Sci 2012; 367:1123-39. [PMID: 22411983 PMCID: PMC3297441 DOI: 10.1098/rstb.2011.0210] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The cell wall peptidoglycan of Gram-positive bacteria functions as a surface organelle for the transport and assembly of proteins that interact with the environment, in particular, the tissues of an infected host. Signal peptide-bearing precursor proteins are secreted across the plasma membrane of Gram-positive bacteria. Some precursors carry C-terminal sorting signals with unique sequence motifs that are cleaved by sortase enzymes and linked to the cell wall peptidoglycan of vegetative forms or spores. The sorting signals of pilin precursors are cleaved by pilus-specific sortases, which generate covalent bonds between proteins leading to the assembly of fimbrial structures. Other precursors harbour surface (S)-layer homology domains (SLH), which fold into a three-pronged spindle structure and bind secondary cell wall polysaccharides, thereby associating with the surface of specific Gram-positive microbes. Type VII secretion is a non-canonical secretion pathway for WXG100 family proteins in mycobacteria. Gram-positive bacteria also secrete WXG100 proteins and carry unique genes that either contribute to discrete steps in secretion or represent distinctive substrates for protein transport reactions.
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Affiliation(s)
- Olaf Schneewind
- Department of Microbiology, University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
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28
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Kang HJ, Baker EN. Structure and assembly of Gram-positive bacterial pili: unique covalent polymers. Curr Opin Struct Biol 2012; 22:200-7. [DOI: 10.1016/j.sbi.2012.01.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Accepted: 01/24/2012] [Indexed: 11/28/2022]
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29
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Cozzi R, Nuccitelli A, D'Onofrio M, Necchi F, Rosini R, Zerbini F, Biagini M, Norais N, Beier C, Telford JL, Grandi G, Assfalg M, Zacharias M, Maione D, Rinaudo CD. New insights into the role of the glutamic acid of the E‐box motif in group B
Streptococcus
pilus 2a assembly. FASEB J 2012; 26:2008-18. [DOI: 10.1096/fj.11-196378] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Mariapina D'Onofrio
- Nuclear Magnetic Resonance LaboratoryDepartment of BiotechnologyUniversity of VeronaVeronaItaly
| | | | | | | | | | | | | | | | | | - Michael Assfalg
- Nuclear Magnetic Resonance LaboratoryDepartment of BiotechnologyUniversity of VeronaVeronaItaly
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30
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Abstract
In Gram-positive bacteria proteins are displayed on the cell surface using sortase enzymes. These cysteine transpeptidases join proteins bearing an appropriate sorting signal to strategically positioned amino groups on the cell surface. Working alone, or in concert with other enzymes, sortases either attach proteins to the cross-bridge peptide of the cell wall or they link proteins together to form pili. Because surface proteins play a fundamental role in microbial physiology and are frequently virulence factors, sortase enzymes have been intensely studied since their discovery a little more than a decade ago. Based on their primary sequences and functions sortases can be partitioned into distinct families called class A to F enzymes. Most bacteria elaborate their surfaces using more than one type of sortase that function non-redundantly by recognizing unique sorting signals within their protein substrates. Here we review what is known about the functions of these enzymes and the molecular basis of catalysis. Particular emphasis is placed on 'pilin' specific class C sortases that construct structurally complex pili. Exciting new data have revealed that these enzymes are amazingly promiscuous in the substrates that they can employ and that there is a startling degree of diversity in their mechanism of action. We also review recent data that suggest that sortases are targeted to specific sites on the cell surface where they work with other sortases and accessory factors to properly function.
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Affiliation(s)
- Thomas Spirig
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
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31
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Nakata M, Kimura KR, Sumitomo T, Wada S, Sugauchi A, Oiki E, Higashino M, Kreikemeyer B, Podbielski A, Okahashi N, Hamada S, Isoda R, Terao Y, Kawabata S. Assembly mechanism of FCT region type 1 pili in serotype M6 Streptococcus pyogenes. J Biol Chem 2011; 286:37566-77. [PMID: 21880740 DOI: 10.1074/jbc.m111.239780] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human pathogen Streptococcus pyogenes produces diverse pili depending on the serotype. We investigated the assembly mechanism of FCT type 1 pili in a serotype M6 strain. The pili were found to be assembled from two precursor proteins, the backbone protein T6 and ancillary protein FctX, and anchored to the cell wall in a manner that requires both a housekeeping sortase enzyme (SrtA) and pilus-associated sortase enzyme (SrtB). SrtB is primarily required for efficient formation of the T6 and FctX complex and subsequent polymerization of T6, whereas proper anchoring of the pili to the cell wall is mainly mediated by SrtA. Because motifs essential for polymerization of pilus backbone proteins in other Gram-positive bacteria are not present in T6, we sought to identify the functional residues involved in this process. Our results showed that T6 encompasses the novel VAKS pilin motif conserved in streptococcal T6 homologues and that the lysine residue (Lys-175) within the motif and cell wall sorting signal of T6 are prerequisites for isopeptide linkage of T6 molecules. Because Lys-175 and the cell wall sorting signal of FctX are indispensable for substantial incorporation of FctX into the T6 pilus shaft, FctX is suggested to be located at the pilus tip, which was also implied by immunogold electron microscopy findings. Thus, the elaborate assembly of FCT type 1 pili is potentially organized by sortase-mediated cross-linking between sorting signals and the amino group of Lys-175 positioned in the VAKS motif of T6, thereby displaying T6 and FctX in a temporospatial manner.
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Affiliation(s)
- Masanobu Nakata
- Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita-Osaka, 565-0871, Japan
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32
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Mishra A, Devarajan B, Reardon ME, Dwivedi P, Krishnan V, Cisar JO, Das A, Narayana SVL, Ton-That H. Two autonomous structural modules in the fimbrial shaft adhesin FimA mediate Actinomyces interactions with streptococci and host cells during oral biofilm development. Mol Microbiol 2011; 81:1205-20. [PMID: 21696465 DOI: 10.1111/j.1365-2958.2011.07745.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
By combining X-ray crystallography and modelling, we describe here the atomic structure of distinct adhesive moieties of FimA, the shaft fimbrillin of Actinomyces type 2 fimbriae, which uniquely mediates the receptor-dependent intercellular interactions between Actinomyces and oral streptococci as well as host cells during the development of oral biofilms. The FimA adhesin is built with three IgG-like domains, each of which harbours an intramolecular isopeptide bond, previously described in several Gram-positive pilins. Genetic and biochemical studies demonstrate that although these isopeptide bonds are dispensable for fimbrial assembly, cell-cell interactions and biofilm formation, they contribute significantly to the proteolytic stability of FimA. Remarkably, FimA harbours two autonomous adhesive modules, which structurally resemble the Staphylococcus aureus Cna B domain. Each isolated module can bind the plasma glycoprotein asialofetuin as well as the polysaccharide receptors present on the surface of oral streptococci and epithelial cells. Thus, FimA should serve as an excellent paradigm for the development of therapeutic strategies and elucidating the precise molecular mechanisms underlying the interactions between cellular receptors and Gram-positive fimbriae.
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Affiliation(s)
- Arunima Mishra
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USA
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33
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Structure of the full-length major pilin from Streptococcus pneumoniae: implications for isopeptide bond formation in gram-positive bacterial pili. PLoS One 2011; 6:e22095. [PMID: 21760959 PMCID: PMC3132780 DOI: 10.1371/journal.pone.0022095] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 06/15/2011] [Indexed: 11/19/2022] Open
Abstract
The surface of the pneumococcal cell is adorned with virulence factors including pili. The major pilin RrgB, which forms the pilus shaft on pathogenic Streptococcus pneumoniae, comprises four immunoglobulin (Ig)-like domains, each with a common CnaB topology. The three C-terminal domains are each stabilized by internal Lys-Asn isopeptide bonds, formed autocatalytically with the aid of an essential Glu residue. The structure and orientation of the crucial N-terminal domain, which provides the covalent linkage to the next pilin subunit in the shaft, however, remain incompletely characterised. We report the crystal structure of full length RrgB, solved by X-ray crystallography at 2.8 Å resolution. The N-terminal (D1) domain makes few contacts with the rest of the RrgB structure, and has higher B-factors. This may explain why D1 is readily lost by proteolysis, as are the N-terminal domains of many major pilins. D1 is also found to have a triad of Lys, Asn and Glu residues in the same topological positions as in the other domains, yet mass spectrometry and the crystal structure show that no internal isopeptide bond is formed. We show that this is because β-strand G of D1, which carries the Asn residue, diverges from β-strand A, carrying the Lys residue, such that these residues are too far apart for bond formation. Strand G also carries the YPKN motif that provides the essential Lys residue for the sortase-mediated intermolecular linkages along the pilus shaft. Interaction with the sortase and formation of the intermolecular linkage could result in a change in the orientation of this strand, explaining why isopeptide bond formation in the N-terminal domains of some major pilins appears to take place only upon assembly of the pili.
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Möhlmann S, Mahlert C, Greven S, Scholz P, Harrenga A. In vitro sortagging of an antibody fab fragment: overcoming unproductive reactions of sortase with water and lysine side chains. Chembiochem 2011; 12:1774-80. [PMID: 21656631 DOI: 10.1002/cbic.201100002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Indexed: 11/06/2022]
Abstract
Sortase A from Staphylococcus aureus attracts growing interest for its use in biotechnological protein modification. This enzyme binds to a short signal sequence at the C terminus of a target protein, cleaves it by formation of an acyl-enzyme intermediate, and subsequently attaches an oligoglycine with a peptide bond. In this work, we explored its usability for the modification of the L19 Fab fragment (specific for fibronectin ED-B), a promising candidate for antibody-based cancer therapy. The Fab fragment was expressed with a sortase signal sequence attached to its light chain, and was successfully modified with a fluorescent oligoglycine probe in good yield. Our interest focused on performance under conditions of limited oligoglycine concentrations. Two unproductive side reactions of sortase were observed. The first was hydrolysis of the acyl-enzyme intermediate; in the second, sortase accepted the ε-amino group of lysine as substrate, thereby resulting in polypeptide crosslinking. In case of the L19 Fab fragment, it led to the covalent connection of the heavy and light chains. Both side reactions were effectively suppressed by sufficient concentrations of the oligoglycine probe.
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Affiliation(s)
- Sina Möhlmann
- Bayer Schering Pharma AG, Aprather Weg 18a, 42113 Wuppertal, Germany
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Structure-based approach to rationally design a chimeric protein for an effective vaccine against Group B Streptococcus infections. Proc Natl Acad Sci U S A 2011; 108:10278-83. [PMID: 21593422 DOI: 10.1073/pnas.1106590108] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Structural vaccinology is an emerging strategy for the rational design of vaccine candidates. We successfully applied structural vaccinology to design a fully synthetic protein with multivalent protection activity. In Group B Streptococcus, cell-surface pili have aroused great interest because of their direct roles in virulence and importance as protective antigens. The backbone subunit of type 2a pilus (BP-2a) is present in six immunogenically different but structurally similar variants. We determined the 3D structure of one of the variants, and experimentally demonstrated that protective antibodies specifically recognize one of the four domains that comprise the protein. We therefore constructed a synthetic protein constituted by the protective domain of each one of the six variants and showed that the chimeric protein protects mice against the challenge with all of the type 2a pilus-carrying strains. This work demonstrates the power of structural vaccinology and will facilitate the development of an optimized, broadly protective pilus-based vaccine against Group B Streptococcus by combining the uniquely generated chimeric protein with protective pilin subunits from two other previously identified pilus types. In addition, this work describes a template procedure that can be followed to develop vaccines against other bacterial pathogens.
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Zähner D, Gandhi AR, Stuchlik O, Reed M, Pohl J, Stephens DS. Pilus backbone protein PitB of Streptococcus pneumoniae contains stabilizing intramolecular isopeptide bonds. Biochem Biophys Res Commun 2011; 409:526-31. [PMID: 21600877 DOI: 10.1016/j.bbrc.2011.05.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 05/06/2011] [Indexed: 11/26/2022]
Abstract
Streptococcus pneumoniae type 2 pili are recently identified fimbrial structures extending from the bacterial surface and formed by polymers of the structural protein PitB. Intramolecular isopeptide bonds are a characteristic of the related pilus backbone protein Spy0128 of group A streptococci. Based on the identification of conserved residues in PitB, we predicted two intramolecular isopeptide bonds in PitB. Using a combination of tandem mass spectrometry and Edman sequencing, we show that these bonds were formed between Lys(63)-Asn(214) and Lys(243)-Asn(372) in PitB. Mutant proteins lacking the intramolecular isopeptide bonds retained the proteolytic stability observed with the wild type protein. However, absence of these bonds substantially decreased the melting temperature of the PitB-derivatives, indicating a stabilizing function of these bonds in PitB of the pneumococcal type 2 pilus.
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Affiliation(s)
- Dorothea Zähner
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, 1639 Pierce Dr., Suite 2101, Atlanta, GA 30322, USA.
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Romero D, Vlamakis H, Losick R, Kolter R. An accessory protein required for anchoring and assembly of amyloid fibres in B. subtilis biofilms. Mol Microbiol 2011; 80:1155-68. [PMID: 21477127 DOI: 10.1111/j.1365-2958.2011.07653.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Cells within Bacillus subtilis biofilms are held in place by an extracellular matrix that contains cell-anchored amyloid fibres, composed of the amyloidogenic protein TasA. As biofilms age they disassemble because the cells release the amyloid fibres. This release appears to be the consequence of incorporation of D-tyrosine, D-leucine, D-tryptophan and D-methionine into the cell wall. Here, we characterize the in vivo roles of an accessory protein TapA (TasA anchoring/assembly protein; previously YqxM) that serves both to anchor the fibres to the cell wall and to assemble TasA into fibres. TapA is found in discrete foci in the cell envelope and these foci disappear when cells are treated with a mixture of D-amino acids. Purified cell wall sacculi retain a functional form of this anchoring protein such that purified fibres can be anchored to the sacculi in vitro. In addition, we show that TapA is essential for the proper assembly of the fibres. Its absence results in a dramatic reduction in TasA levels and what little TasA is left produces only thin fibres that are not anchored to the cell.
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Affiliation(s)
- Diego Romero
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
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Popp MWL, Ploegh HL. Bilden und Brechen von Peptidbindungen: Protein-Engineering mithilfe von Sortase. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201008267] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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39
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Popp MWL, Ploegh HL. Making and breaking peptide bonds: protein engineering using sortase. Angew Chem Int Ed Engl 2011; 50:5024-32. [PMID: 21538739 DOI: 10.1002/anie.201008267] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Indexed: 01/31/2023]
Abstract
Sortases are a class of bacterial enzymes that possess transpeptidase activity. It is their ability to site-specifically break a peptide bond and then reform a new bond with an incoming nucleophile that makes sortase an attractive tool for protein engineering. This technique has been adopted for a range of applications, from chemistry-based to cell biology and technology. In this Minireview we provide a brief overview of the biology of sortase enzymes and current applications in protein engineering. We identify areas that lend themselves to further innovation and that suggest new applications.
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40
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Hendrickx APA, Budzik JM, Oh SY, Schneewind O. Architects at the bacterial surface - sortases and the assembly of pili with isopeptide bonds. Nat Rev Microbiol 2011; 9:166-76. [PMID: 21326273 DOI: 10.1038/nrmicro2520] [Citation(s) in RCA: 195] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The cell wall envelope of Gram-positive bacteria can be thought of as a surface organelle for the assembly of macromolecular structures that enable the unique lifestyle of each microorganism. Sortases - enzymes that cleave the sorting signals of secreted proteins to form isopeptide (amide) bonds between the secreted proteins and peptidoglycan or polypeptides - function as the principal architects of the bacterial surface. Acting alone or with other sortase enzymes, sortase construction leads to the anchoring of surface proteins at specific sites in the envelope or to the assembly of pili, which are fibrous structures formed from many protein subunits. The catalysis of intermolecular isopeptide bonds between pilin subunits is intertwined with the assembly of intramolecular isopeptide bonds within pilin subunits. Together, these isopeptide bonds endow these sortase products with adhesive properties and resistance to host proteases.
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Affiliation(s)
- Antoni P A Hendrickx
- Department of Microbiology, University of Chicago, 920 East 58th Street, Chicago, Illinois 60637, USA
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41
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Intramolecular isopeptide bonds: protein crosslinks built for stress? Trends Biochem Sci 2011; 36:229-37. [DOI: 10.1016/j.tibs.2010.09.007] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 09/27/2010] [Accepted: 09/29/2010] [Indexed: 01/19/2023]
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The minor pilin subunit Sgp2 is necessary for assembly of the pilus encoded by the srtG cluster of Streptococcus suis. J Bacteriol 2010; 193:822-31. [PMID: 21148736 DOI: 10.1128/jb.01555-09] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gram-positive pili are composed of covalently bound pilin subunits whose assembly is mediated via a pilus-specific sortase(s). Major subunits constitute the pilus backbone and are therefore essential for pilus formation. Minor subunits are also incorporated into the pilus, but they are considered to be dispensable for backbone formation. The srtG cluster is one of the putative pilus gene clusters identified in the major swine pathogen Streptococcus suis. It consists of one sortase gene (srtG) and two putative pilin subunit genes (sgp1 and sgp2). In this study, by constructing mutants for each of the genes in the cluster and by both immunoblotting and immunogold electron microscopic analysis with antibodies against Sgp1 and Sgp2, we found that the srtG cluster mediates the expression of pilus-like structures in S. suis strain 89/1591. In this pilus, Sgp1 forms the backbone, whereas Sgp2 is incorporated as the minor subunit. In accordance with the current model of pilus assembly by Gram-positive organisms, the major subunit Sgp1 was indispensable for backbone formation and the cognate sortase SrtG mediated the polymerization of both subunits. However, unlike other well-characterized Gram-positive bacterial pili, the minor subunit Sgp2 was required for polymerization of the major subunit Sgp1. Because Sgp2 homologues are encoded in several other Gram-positive bacterial pilus gene clusters, in some types of pili, minor pilin subunits may contribute to backbone formation by a novel mechanism.
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Hagan RM, Björnsson R, McMahon SA, Schomburg B, Braithwaite V, Bühl M, Naismith JH, Schwarz-Linek U. NMR spectroscopic and theoretical analysis of a spontaneously formed Lys-Asp isopeptide bond. Angew Chem Int Ed Engl 2010; 49:8421-5. [PMID: 20878961 PMCID: PMC3315829 DOI: 10.1002/anie.201004340] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Robert M. Hagan
- Biomedical Sciences Research Complex University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - Ragnar Björnsson
- School of Chemistry University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - Stephen A. McMahon
- Biomedical Sciences Research Complex University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - Benjamin Schomburg
- Biomedical Sciences Research Complex University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - Vickie Braithwaite
- Biomedical Sciences Research Complex University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - Michael Bühl
- School of Chemistry University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - James H. Naismith
- Biomedical Sciences Research Complex University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
| | - Ulrich Schwarz-Linek
- Biomedical Sciences Research Complex University of St Andrews North Haugh, St Andrews KY16 9ST (UK)
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Pointon JA, Smith WD, Saalbach G, Crow A, Kehoe MA, Banfield MJ. A highly unusual thioester bond in a pilus adhesin is required for efficient host cell interaction. J Biol Chem 2010; 285:33858-66. [PMID: 20729215 PMCID: PMC2962485 DOI: 10.1074/jbc.m110.149385] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 06/28/2010] [Indexed: 01/19/2023] Open
Abstract
Many bacterial pathogens present adhesins at the tips of long macromolecular filaments known as pili that are often important virulence determinants. Very little is known about how pili presented by Gram-positive pathogens mediate host cell binding. The crystal structure of a pilus adhesin from the important human pathogen Streptococcus pyogenes reveals an internal thioester bond formed between the side chains of a cysteine and a glutamine residue. The presence of the thioester was verified using UV-visible spectroscopy and mass spectrometry. This unusual bond has only previously been observed in thioester domains of complement and complement-like proteins where it is used to form covalent attachment to target molecules. The structure also reveals two intramolecular isopeptide bonds, one of these formed through a Lys/Asp residue pair, which are strategically positioned to confer protein stability. Removal of the internal thioester by allele-replacement mutagenesis in S. pyogenes severely compromises bacterial adhesion to model host cells. Although current paradigms of bacterial/host cell interaction envisage strong non-covalent interactions, the present study suggests cell adhesion could also involve covalent bonds.
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Affiliation(s)
- Jonathan A. Pointon
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH and
| | - Wendy D. Smith
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH and
| | - Gerhard Saalbach
- the Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom
| | - Allister Crow
- the Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom
| | - Michael A. Kehoe
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH and
| | - Mark J. Banfield
- the Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom
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Dutta S, Podile AR. Plant growth promoting rhizobacteria (PGPR): the bugs to debug the root zone. Crit Rev Microbiol 2010; 36:232-44. [PMID: 20635858 DOI: 10.3109/10408411003766806] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Interaction of plant growth promoting rhizobacteria (PGPR) with host plants is an intricate and interdependent relationship involving not only the two partners but other biotic and abiotic factors of the rhizosphere region. Survival and establishment of PGPR in the rhizosphere is a major concern of agricultural microbiologists. Various factors that play a determining role include the composition of root exudates, properties of bacterial strain, soil status, and activities of other soil microbes. This review focuses on the different components that affect root colonization of PGPR and the underlying principles behind the success of these bugs to tide over the unfavorable conditions.
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Affiliation(s)
- Swarnalee Dutta
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046 India
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46
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Hagan RM, Björnsson R, McMahon SA, Schomburg B, Braithwaite V, Bühl M, Naismith JH, Schwarz-Linek U. NMR Spectroscopic and Theoretical Analysis of a Spontaneously Formed Lys-Asp Isopeptide Bond. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201004340] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Linke C, Young PG, Kang HJ, Bunker RD, Middleditch MJ, Caradoc-Davies TT, Proft T, Baker EN. Crystal structure of the minor pilin FctB reveals determinants of Group A streptococcal pilus anchoring. J Biol Chem 2010; 285:20381-9. [PMID: 20427291 DOI: 10.1074/jbc.m109.089680] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell surface pili are polymeric protein assemblies that enable bacteria to adhere to surfaces and to specific host tissues. The pili expressed by Gram-positive bacteria constitute a unique paradigm in which sortase-mediated covalent linkages join successive pilin subunits like beads on a string. These pili are formed from two or three distinct types of pilin subunit, typically encoded in small gene clusters, often with their cognate sortases. In Group A streptococci (GAS), a major pilin forms the polymeric backbone, whereas two minor pilins are located at the tip and the base. Here, we report the 1.9-A resolution crystal structure of the GAS basal pilin FctB, revealing an immunoglobulin (Ig)-like N-terminal domain with an extended proline-rich tail. Unexpected structural homology between the FctB Ig-like domain and the N-terminal domain of the GAS shaft pilin helps explain the use of the same sortase for polymerization of the shaft and its attachment to FctB. It also enabled the identification, from mass spectral data, of the lysine residue involved in the covalent linkage of FctB to the shaft. The proline-rich tail forms a polyproline-II helix that appears to be a common feature of the basal (cell wall-anchoring) pilins. Together, our results indicate distinct structural elements in the pilin proteins that play a role in selecting for the appropriate sortases and thereby help orchestrate the ordered assembly of the pilus.
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Affiliation(s)
- Christian Linke
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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Ito T, Sadamoto R, Naruchi K, Togame H, Takemoto H, Kondo H, Nishimura SI. Highly oriented recombinant glycosyltransferases: site-specific immobilization of unstable membrane proteins by using Staphylococcus aureus sortase A. Biochemistry 2010; 49:2604-14. [PMID: 20178374 DOI: 10.1021/bi100094g] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Recombinant glycosyltransferases are potential biocatalysts for the construction of a compound library of oligosaccharides, glycosphingolipids, glycopeptides, and various artificial glycoconjugates on the basis of combined chemical and enzymatic synthetic procedures. The structurally defined glycan-related compound library is a key resource both in the basic studies of their functional roles in various biological processes and in the discovery research of new diagnostic biomarkers and therapeutic reagents. Therefore, it is clear that the immobilization of extremely unstable membrane-bound glycosyltransferases on some suitable supporting materials should enhance the operational stability and activity of recombinant enzymes and makes facile separation of products and recycling use of enzymes possible. Until now, however, it seems that no standardized protocol preventing a significant loss of enzyme activity is available due to the lack of a general method of site-selective anchoring between glycosyltransferases and scaffold materials through a stable covalent bond. Here we communicate a versatile and efficient method for the immobilization of recombinant glycosyltransferases onto commercially available solid supports by means of transpeptidase reaction by Staphylococcus aureus sortase A. This protocol allowed for the first time highly specific conjugation at the designated C-terminal signal peptide moiety of recombinant human beta1,4-galactosyltransferase or recombinant Helicobacter pylori alpha1,3-fucosyltransferase with simple aliphatic amino groups displayed on the surface of solid materials. Site-specifically immobilized enzymes exhibited the desired sugar transfer activity, an improved stability, and a practical reusability required for rapid and large-scale synthesis of glycoconjugates. Considering that most mammalian enzymes responsible for the posttranslational modifications, including the protein kinase family, as well as glycosyltransferases are unstable and highly oriented membrane proteins, the merit of our strategy based on "site-specific" transpeptidation is evident because the reaction proceeds only at an engineered C-terminus without any conformational influence around the active sites of both enzymes as well as heptad repeats of rHFucT required to maintain native secondary and quaternary structures during the dimerization on cell surfaces.
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Affiliation(s)
- Takaomi Ito
- Graduate School of Life Science and Frontier Research Center for Post-Genomic Science and Technology, Hokkaido University, N21, W11, Kita-ku, Sapporo 001-0021, Japan
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Kline KA, Dodson KW, Caparon MG, Hultgren SJ. A tale of two pili: assembly and function of pili in bacteria. Trends Microbiol 2010; 18:224-32. [PMID: 20378353 DOI: 10.1016/j.tim.2010.03.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 11/25/2009] [Accepted: 03/05/2010] [Indexed: 10/19/2022]
Abstract
Bacterial pili have long been recognized as mediators of initial host-pathogen interactions important for the progression of Gram-negative bacterial diseases. An appreciation of the role of pili on virulence in Gram-positive bacteria and the unique properties of their biogenesis is a rapidly emerging area of research. In this review, we focus on recent advances in one of the longest-studied Gram-negative pilus systems, the chaperone/usher assembled pili, along with the newcomer to the field, the sortase-assembled pili of Gram-positive bacteria. In both systems, a wealth of new structural and molecular details has emerged recently. In light of this, we explore similarities between chaperone/usher and sortase-assembled pilus biogenesis and highlight paradigms unique to each, with the goal of using knowledge of each system to raise new questions and inform future studies of the other.
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Affiliation(s)
- Kimberly A Kline
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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50
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Zakeri B, Howarth M. Spontaneous Intermolecular Amide Bond Formation between Side Chains for Irreversible Peptide Targeting. J Am Chem Soc 2010; 132:4526-7. [DOI: 10.1021/ja910795a] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bijan Zakeri
- Department of Biochemistry, Oxford University, South Parks Road, Oxford, OX1 3QU, U.K
| | - Mark Howarth
- Department of Biochemistry, Oxford University, South Parks Road, Oxford, OX1 3QU, U.K
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