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Schultz LG, Tasic L, Fattori J. Chaperone-Assisted Secretion in Bacteria: Protein and DNA Transport via Cell Membranes. CURR PROTEOMICS 2018. [DOI: 10.2174/1570164615666180820154821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Bacteria use an impressive arsenal of secretion systems (1-7) to infect their host cells by exporting
proteins, DNA and DNA-protein complexes via cell membranes. They use chaperone-usher
pathways for host colonization as well. To be targeted for transportation across one (Gram-positive) or
two membranes (Gram-negative), clients must be selected, guided and unfolded to pass through type 3
(T3SS) or type 4 (T4SS) secretion systems. For these processes, bacteria count on secretory chaperones
that guide macromolecular transport via membranes. Moreover, if we know how these processes
occur, we might be able to stop them and avoid bacterial infections. Thus, structural and functional
characterizations of secretory chaperones become interesting, as these proteins are the perfect targets
for blocking bacteria action. Therefore, this review focuses on a story of known mechanisms of chaperone-
secretion assisted transport with special attention on virulence proteins and DNA transport in
bacteria.
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Affiliation(s)
- Lilian Goulart Schultz
- Chemical Biology Laboratory, Organic Chemistry Department, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, 13083-970, SP, Brazil
| | - Ljubica Tasic
- Chemical Biology Laboratory, Organic Chemistry Department, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, 13083-970, SP, Brazil
| | - Juliana Fattori
- Chemical Biology Laboratory, Organic Chemistry Department, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, 13083-970, SP, Brazil
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2
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Scavuzzi AML, Alves LC, Veras DL, Brayner FA, Lopes ACS. Ultrastructural changes caused by polymyxin B and meropenem in multiresistant Klebsiella pneumoniae carrying bla
KPC-2 gene. J Med Microbiol 2016; 65:1370-1377. [DOI: 10.1099/jmm.0.000367] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Alexsandra Maria Lima Scavuzzi
- Departamento de Medicina Tropical, Universidade Federal de Pernambuco (UFPE), 50.732-970 Recife, PE, Brazil
- Centro de Pesquisas Aggeu Magalhães (CPqAM-Fiocruz), Recife, PE, Brazil
| | - Luiz Carlos Alves
- Centro de Pesquisas Aggeu Magalhães (CPqAM-Fiocruz), Recife, PE, Brazil
| | - Dyana Leal Veras
- Centro de Pesquisas Aggeu Magalhães (CPqAM-Fiocruz), Recife, PE, Brazil
| | - Fábio André Brayner
- Departamento de Medicina Tropical, Universidade Federal de Pernambuco (UFPE), 50.732-970 Recife, PE, Brazil
- Centro de Pesquisas Aggeu Magalhães (CPqAM-Fiocruz), Recife, PE, Brazil
| | - Ana Catarina Souza Lopes
- Departamento de Medicina Tropical, Universidade Federal de Pernambuco (UFPE), 50.732-970 Recife, PE, Brazil
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3
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Papadopoulos M, Tran ENH, Murray GL, Morona R. Conserved transmembrane glycine residues in the Shigella flexneri polysaccharide co-polymerase protein WzzB influence protein-protein interactions. MICROBIOLOGY-SGM 2016; 162:921-929. [PMID: 27028755 DOI: 10.1099/mic.0.000282] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The O antigen (Oag) component of lipopolysaccharides (LPS) is crucial for virulence and Oag chain-length regulation is controlled by the polysaccharide co-polymerase class 1 (PCP1) proteins. Crystal structure analyses indicate that structural conservation among PCP1 proteins is highly maintained, however the mechanism of Oag modal-chain-length control remains to be fully elucidated. Shigella flexneri PCP1 protein WzzBSF confers a modal-chain length of 10-17 Oag repeat units (RUs), whereas the Salmonella enterica Typhimurium PCP1 protein WzzBST confers a modal-chain length of ~16-28 Oag RUs. Both proteins share >70 % overall sequence identity and contain two transmembrane (TM1 and TM2) regions, whereby a conserved proline-glycine-rich motif overlapping the TM2 region is identical in both proteins. Conserved glycine residues within TM2 are functionally important, as glycine to alanine substitutions at positions 305 and 311 confer very short Oag modal-chain length (~2-6 Oag RUs). In this study, WzzBSF was co-expressed with WzzBST in S. flexneri and a single intermediate modal-chain length of ~11-21 Oag RUs was observed, suggesting the presence of Wzz:Wzz interactions. Interestingly, co-expression of WzzBSF with WzzBG305A/G311A conferred a bimodal LPS Oag chain length (despite over 99 % protein sequence identity), and we hypothesized that the proteins fail to interact. Co-purification assays detected His6-WzzBSF co-purifying with FLAG-tagged WzzBST but not with FLAG-tagged WzzBG305A/G311A, supporting our hypothesis. These data indicate that the conserved glycine residues in TM2 are involved in Wzz:Wzz interactions, and provide insight into key interactions that drive Oag modal length control.
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Affiliation(s)
- Magdalene Papadopoulos
- School of Biological Sciences, Department of Molecular & Cellular Biology, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia
| | - Elizabeth Ngoc Hoa Tran
- School of Biological Sciences, Department of Molecular & Cellular Biology, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia
| | - Gerald Laurence Murray
- School of Biological Sciences, Department of Molecular & Cellular Biology, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia
| | - Renato Morona
- School of Biological Sciences, Department of Molecular & Cellular Biology, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia
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4
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Abstract
The major class of integral proteins found in the outer membrane (OM) of E. coli and Salmonella adopt a β-barrel conformation (OMPs). OMPs are synthesized in the cytoplasm with a typical signal sequence at the amino terminus, which directs them to the secretion machinery (SecYEG) located in the inner membrane for translocation to the periplasm. Chaperones such as SurA, or DegP and Skp, escort these proteins across the aqueous periplasm protecting them from aggregation. The chaperones then deliver OMPs to a highly conserved outer membrane assembly site termed the Bam complex. In E. coli, the Bam complex is composed of an essential OMP, BamA, and four associated OM lipoproteins, BamBCDE, one of which, BamD, is also essential. Here we provide an overview of what we know about the process of OMP assembly and outline the various hypotheses that have been proposed to explain how proteins might be integrated into the asymmetric OM lipid bilayer in an environment that lacks obvious energy sources. In addition, we describe the envelope stress responses that ensure the fidelity of OM biogenesis and how factors, such as phage and certain toxins, have coopted this essential machine to gain entry into the cell.
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Structural basis for alginate secretion across the bacterial outer membrane. Proc Natl Acad Sci U S A 2011; 108:13083-8. [PMID: 21778407 DOI: 10.1073/pnas.1104984108] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 Å crystal structure of AlgE, which reveals a monomeric 18-stranded β-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 (ΔT8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or ΔL2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with ΔT8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.
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Outer membrane translocons: structural insights into channel formation. Trends Microbiol 2010; 19:40-8. [PMID: 21130656 DOI: 10.1016/j.tim.2010.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/18/2010] [Accepted: 10/29/2010] [Indexed: 01/26/2023]
Abstract
Gram-negative bacteria need to maintain the integrity of their outer membrane while also regulating the secretion of toxins and other macromolecules. A variety of dedicated outer membrane proteins (OMPs) facilitate this process. Recent structural work has shown that some of these proteins adopt classical β-barrel transmembrane structures and rely on structural changes within the barrel lumen to allow passage of substrate proteins. Other secretion systems have OMP components which use transmembrane α-helices and appear to function in a different way. Here we review a selection of recent structural studies which have major ramifications for our understanding of the passage of macromolecules across the outer membrane.
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Keiski CL, Harwich M, Jain S, Neculai AM, Yip P, Robinson H, Whitney JC, Riley L, Burrows LL, Ohman DE, Howell PL. AlgK is a TPR-containing protein and the periplasmic component of a novel exopolysaccharide secretin. Structure 2010; 18:265-73. [PMID: 20159471 DOI: 10.1016/j.str.2009.11.015] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 11/19/2009] [Accepted: 11/24/2009] [Indexed: 11/28/2022]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa causes chronic biofilm infections in cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by overproduction of the exopolysaccharide alginate. Here we show that AlgK, a protein essential for production of high molecular weight alginate, is an outer membrane lipoprotein that contributes to the correct localization of the porin AlgE. Our 2.5 A structure shows AlgK is composed of 9.5 tetratricopeptide-like repeats, and three putative sites of protein-protein interaction have been identified. Bioinformatics analysis suggests that BcsA, PgaA, and PelB, involved in the production and export of cellulose, poly-beta-1,6-N-Acetyl-D-glucosamine, and Pel exopolysaccharide, respectively, share the same topology as AlgK/E. Together, our data suggest that AlgK plays a role in the assembly of the alginate biosynthetic complex and represents the periplasmic component of a new type of outer membrane secretin that differs from canonical bacterial capsular polysaccharide secretion systems.
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Affiliation(s)
- Carrie-Lynn Keiski
- Molecular Structure and Function, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
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8
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Mutagenesis and chemical cross-linking suggest that Wzz dimer stability and oligomerization affect lipopolysaccharide O-antigen modal chain length control. J Bacteriol 2010; 192:3385-93. [PMID: 20453100 DOI: 10.1128/jb.01134-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In Shigella flexneri, the polysaccharide copolymerase (PCP) protein Wzz(SF) confers a modal length of 10 to 17 repeat units (RUs) to the O-antigen (Oag) component of lipopolysaccharide (LPS). PCPs form oligomeric structures believed to be related to their function. To identify functionally important regions within Wzz(SF), random in-frame linker mutagenesis was used to create mutants with 5-amino-acid insertions (termed Wzz(i) proteins), and DNA sequencing was used to locate the insertions. Analysis of the resulting LPS conferred by Wzz(i) proteins identified five mutant classes. The class I mutants were inactive, resulting in nonregulated LPS Oag chains, while classes II and III conferred shorter LPS Oag chains of 2 to 10 and 8 to 14 RUs, respectively. Class IV mutants retained near-wild-type function, and class V mutants increased the LPS Oag chain length to 16 to 25 RUs. In vivo formaldehyde cross-linking indicated class V mutants readily formed high-molecular-mass oligomers; however, class II and III Wzz(i) mutants were not effectively cross-linked. Wzz dimer stability was also investigated by heating cross-linked oligomers at 100 degrees C in the presence of SDS. Unlike the Wzz(SF) wild type and class IV and V Wzz(i) mutants, the class II and III mutant dimers were not detectable. The location of each insertion was mapped onto available PCP three-dimensional (3D) structures, revealing that class V mutations were most likely located within the inner cavity of the PCP oligomer. These data suggest that the ability to produce stable dimers may be important in determining Oag modal chain length.
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Hardy GG, Allen RC, Toh E, Long M, Brown PJB, Cole-Tobian JL, Brun YV. A localized multimeric anchor attaches the Caulobacter holdfast to the cell pole. Mol Microbiol 2010; 76:409-27. [PMID: 20233308 PMCID: PMC2908716 DOI: 10.1111/j.1365-2958.2010.07106.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Caulobacter crescentus attachment is mediated by the holdfast, a complex of polysaccharide anchored to the cell by HfaA, HfaB and HfaD. We show that all three proteins are surface exposed outer membrane (OM) proteins. HfaA is similar to fimbrial proteins and assembles into a high molecular weight (HMW) form requiring HfaD, but not holdfast polysaccharide. The HfaD HMW form is dependent on HfaA but not on holdfast polysaccharide. We show that HfaA and HfaD form homomultimers and that they require HfaB for stability and OM translocation. All three proteins localize to the late pre-divisional flagellar pole, remain at this pole in swarmer cells, and localize at the stalk tip after the stalk is synthesized at the same pole. Hfa protein localization requires the holdfast polysaccharide secretion proteins and the polar localization factor PodJ. An hfaB mutant is much more severely deficient in adherence and holdfast attachment than hfaA and hfaD mutants. An hfaA, hfaD double mutant phenocopies either single mutant, suggesting that HfaB is involved in holdfast attachment beyond secretion of HfaA and HfaD. We hypothesize that HfaB secretes HfaA and HfaD across the outer membrane, and the three proteins form a complex anchoring the holdfast to the stalk.
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Affiliation(s)
- Gail G. Hardy
- Department of Biology, Jordan Hall 142, Indiana University, 1001 E. 3 St., Bloomington, IN 47405
| | | | - Evelyn Toh
- Department of Biology, Jordan Hall 142, Indiana University, 1001 E. 3 St., Bloomington, IN 47405
| | | | - Pamela J. B. Brown
- Department of Biology, Jordan Hall 142, Indiana University, 1001 E. 3 St., Bloomington, IN 47405
| | | | - Yves V. Brun
- Department of Biology, Jordan Hall 142, Indiana University, 1001 E. 3 St., Bloomington, IN 47405
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Hagelueken G, Huang H, Mainprize IL, Whitfield C, Naismith JH. Crystal structures of Wzb of Escherichia coli and CpsB of Streptococcus pneumoniae, representatives of two families of tyrosine phosphatases that regulate capsule assembly. J Mol Biol 2009; 392:678-88. [PMID: 19616007 PMCID: PMC2777267 DOI: 10.1016/j.jmb.2009.07.026] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 07/07/2009] [Accepted: 07/09/2009] [Indexed: 12/11/2022]
Abstract
Many Gram-positive and Gram-negative bacteria utilize polysaccharide surface layers called capsules to evade the immune system; consequently, the synthesis and export of the capsule are a potential therapeutic target. In Escherichia coli K-30, the integral membrane tyrosine autokinase Wzc and the cognate phosphatase Wzb have been shown to be key for both synthesis and assembly of capsular polysaccharides. In the Gram-positive bacterium Streptococcus pneumoniae, the CpsCD complex is analogous to Wzc and the phosphatase CpsB is the corresponding cognate phosphatase. The phosphatases are known to dephosphorylate their corresponding autokinases, yet despite their functional equivalence, they share no sequence homology. We present the structure of Wzb in complex with phosphate and high-resolution structures of apo-CpsB and a phosphate-complexed CpsB. We show that both proteins are active toward Wzc and thereby demonstrate that CpsB is not specific for CpsCD. CpsB is a novel enzyme and represents the first solved structure of a tyrosine phosphatase from a Gram-positive bacterium. Wzb and CpsB have completely different structures, suggesting that they must operate by very different mechanisms. Although the mechanism of Wzb can be inferred from previous studies, CpsB appears to have a tyrosine phosphatase mechanism not observed before. We propose a chemical mechanism for CpsB based on site-directed mutagenesis and structural data.
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Affiliation(s)
- Gregor Hagelueken
- Centre for Biomolecular Sciences, The University of St. Andrews, Fife KY16 9RH, UK
| | - Hexian Huang
- Centre for Biomolecular Sciences, The University of St. Andrews, Fife KY16 9RH, UK
| | - Iain L. Mainprize
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - James H. Naismith
- Centre for Biomolecular Sciences, The University of St. Andrews, Fife KY16 9RH, UK
- Corresponding author.
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11
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Hagelueken G, Ingledew W, Huang H, Petrovic-Stojanovska B, Whitfield C, ElMkami H, Schiemann O, Naismith J. PELDOR Spectroscopy Distance Fingerprinting of the Octameric Outer-Membrane Protein Wza fromEscherichia coli. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200805758] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Vimr ER, Steenbergen SM. Early molecular-recognition events in the synthesis and export of group 2 capsular polysaccharides. MICROBIOLOGY-SGM 2009; 155:9-15. [PMID: 19118341 DOI: 10.1099/mic.0.023564-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The outer membrane (OM) of almost all Gram-negative bacteria is composed of phospholipids, lipopolysaccharide, proteins and capsular or loosely adherent polysaccharides that together mediate cellular interactions with diverse environments. Most OM components are synthesized intracellularly or at the inner membrane (IM) and thus require an export mechanism. This mini-review focuses on recent progress in understanding how synthesis of one kind of capsular polysaccharide (group 2) is coupled to the export apparatus located in the IM and spanning the periplasmic space, thus providing a transport channel to the cell surface. Although the model system for these investigations is the medically important extraintestinal pathogen Escherichia coli K1 and its polysialic acid capsule, the conclusions are general for other group 2 and group 2-like polysaccharides synthesized by many different bacterial species.
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Affiliation(s)
- Eric R Vimr
- Laboratory of Sialobiology, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Susan M Steenbergen
- Laboratory of Sialobiology, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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Hagelueken G, Ingledew WJ, Huang H, Petrovic-Stojanovska B, Whitfield C, ElMkami H, Schiemann O, Naismith JH. PELDOR spectroscopy distance fingerprinting of the octameric outer-membrane protein Wza from Escherichia coli. Angew Chem Int Ed Engl 2009; 48:2904-6. [PMID: 19294709 PMCID: PMC3312575 DOI: 10.1002/anie.200805758] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Distance fingerprinting: Pulsed electron-electron double resonance spectroscopy (PELDOR) is applied to the octameric membrane protein complex Wza of E. coli. The data yielded a detailed distance fingerprint of its periplasmic region that compares favorably to the crystal structure. These results provide the foundation to study conformation changes from interaction with partner proteins.
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Affiliation(s)
- Gregor Hagelueken
- Centre for Biomolecular Sciences The University of St. Andrews Fife KY16 9RH, UK
| | - W. John Ingledew
- Centre for Biomolecular Sciences The University of St. Andrews Fife KY16 9RH, UK
| | - Hexian Huang
- Centre for Biomolecular Sciences The University of St. Andrews Fife KY16 9RH, UK
| | | | - Chris Whitfield
- Department of Molecular and Cellular Biology University of Guelph Ontario N1G 2W1, Canada
| | - Hassane ElMkami
- School of Physics and Astronomy University of St Andrews Fife KY16 9SS, UK
| | - Olav Schiemann
- Centre for Biomolecular Sciences The University of St. Andrews Fife KY16 9RH, UK
| | - James H. Naismith
- Centre for Biomolecular Sciences The University of St. Andrews Fife KY16 9RH, UK
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Coulthurst SJ, Palmer T. A new way out: protein localization on the bacterial cell surface via Tat and a novel Type II secretion system. Mol Microbiol 2008; 69:1331-5. [PMID: 18643933 DOI: 10.1111/j.1365-2958.2008.06367.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
SUMMARY The ability to move proteins out of the cytoplasm and across membranes is a key aspect of the physiology and pathogenicity of Gram-negative bacteria. In this issue of Molecular Microbiology, Ferrandez and Condemine describe a novel protein targeting system in the enteric phytopathogen, Dickeya dadantii. The pectin lyase, PnlH, is exported by the Tat system and is somehow targeted to the outer membrane by its uncleaved N-terminal Tat signal anchor. A novel Type II secretion system, Stt, is then responsible for moving it across the outer membrane, where it remains localized on the surface of the cell. We discuss the implications of these findings for our understanding of both the mechanisms and physiological importance of bacterial protein targeting.
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Affiliation(s)
- Sarah J Coulthurst
- Division of Molecular and Environmental Microbiology, College of Life Sciences, University of Dundee, Dundee, UK
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