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Yang C, Liu J, Ma L, Zhang X, Zhang X, Zhou B, Zhu X, Liu Q. NcGRA17 is an important regulator of parasitophorous vacuole morphology and pathogenicity of Neospora caninum. Vet Parasitol 2018; 264:26-34. [PMID: 30503087 DOI: 10.1016/j.vetpar.2018.03.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 03/12/2018] [Accepted: 03/18/2018] [Indexed: 10/17/2022]
Abstract
Neospora caninum is an obligate intracellular protozoan parasite that infects a wide range of mammalian species, and particularly causes the reproductive loss in cattle. We identified a novel dense granule protein, N. caninum granule protein 17 (NcGRA17) using the CRISPR/cas9 genome editing system and studied its function. We generated the NcGRA17 knockout strain (ΔNcGRA17) and NcGRA17 complementary strain (iΔNcGRA17). Plaque assays and intracellular proliferation tests showed that the ΔNcGRA17 strain formed smaller plaques and had slower intracellular growth. Mouse virulence assay showed loss of virulence for the ΔNcGRA17 strain. We observed that the parasitophorous vacuoles (PVs) of NcGRA17-deficient parasites have aberrant morphology. To investigate the contribution of NcGRA17 α-helices to aberrant morphology of PVs, we transfected four truncated forms of NcGRA17 into NcGRA17 knockout strain and the phenotypes of these mutants were analysed. Lack of the N-terminal region (NT) failed to target the protein to dense granules, while NcGRA17 (Δα1)-HA, NcGRA17 (Δα2-4)-HA and NcGRA17 (Δα5-8)-HA were targeted to dense granules, but failed to rescue the aberrant PV morphology. Our results indicate that NcGRA17 as a dense granule protein determines PV morphology and pathogenicity, and α-helices of NcGRA17 may be responsible for the aberrant morphology of N. caninum PVs.
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Affiliation(s)
- Congshan Yang
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, China
| | - Jing Liu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, China
| | - Lei Ma
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, China
| | - Xichen Zhang
- College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xiao Zhang
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, China
| | - Bingxin Zhou
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, China
| | - Xingquan Zhu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Qun Liu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, China.
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Affiliation(s)
| | - Sergey M. Bezrukov
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, U.S.A
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Parker MW, Feil SC. Pore-forming protein toxins: from structure to function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2005; 88:91-142. [PMID: 15561302 DOI: 10.1016/j.pbiomolbio.2004.01.009] [Citation(s) in RCA: 339] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pore-forming protein toxins (PFTs) are one of Nature's most potent biological weapons. An essential feature of their toxicity is the remarkable property that PFTs can exist either in a stable water-soluble state or as an integral membrane pore. In order to convert from the water-soluble to the membrane state, the toxin must undergo large conformational changes. There are now more than a dozen PFTs for which crystal structures have been determined and the nature of the conformational changes they must undergo is beginning to be understood. Although they differ markedly in their primary, secondary, tertiary and quaternary structures, nearly all can be classified into one of two families based on the types of pores they are thought to form: alpha-PFTs or beta-PFTs. Recent work suggests a number of common features in the mechanism of membrane insertion may exist for each class.
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Affiliation(s)
- Michael W Parker
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065, Australia.
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Matsumoto E, Kiyota T, Lee S, Sugihara G, Yamashita S, Meno H, Aso Y, Sakamoto H, Ellerby HM. Study on the packing geometry, stoichiometry, and membrane interaction of three analogs related to a pore-forming small globular protein. Biopolymers 2002; 56:96-108. [PMID: 11592056 DOI: 10.1002/1097-0282(2000)56:2<96::aid-bip1055>3.0.co;2-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A de novo designed pore-forming small globular protein (SGP) with antitumor activity consists of four helices: 3 basic amphipathic helices composed of Leu and Lys surrounding a central hydrophobic helix composed of oligoalanine. These helices are connected by a beta-turn-forming sequence and two beta-turn-unfavorable ones (S. Lee, T. Kiyota, T. Kunitake, E. Matsumoto, S. Yamashita, K. Anzai, and G. Sugihara Biochemistry 1997, Vol. 36, pp. 3782-3791). In the present work, we designed and synthesized three new SGP analogs in order to study the stoichiometric packing geometry and stability of SGP. The replacement of alanines in the central helix of SGP with leucines (SGP-L), which make the helix much larger in size and more hydrophobic, resulted in an equilibrium of monomeric-trimeric structure. The replacement of some Lys residues by Glu residues in the hydrophilic regions of the amphipathic helices (SGP-E) led to a decrease in helical content and the formation of an equilibrium of monomeric-trimeric structure. The alteration of beta-turn regions with Gly residues, which makes these regions flexible (SGP-G), established an equilibrium of monomeric-dimeric states in buffer. The hydrophobic alpha-helix of SGP-L penetrated into the lipid bilayers in a manner that stabilized model membranes and biomembranes, whereas the central helices of SGP-G and -E destabilized them by forming channels. SGP and its analogs may be a useful model to study the role of the hydrophobic and hydrophilic regions in the formation of monomer-oligomer of proteins and to better understand the insertion of membrane targeting proteins into biomembranes.
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Affiliation(s)
- E Matsumoto
- Department of Chemistry, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan
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Cohen SL, Chait BT. Mass spectrometry as a tool for protein crystallography. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2001; 30:67-85. [PMID: 11340052 DOI: 10.1146/annurev.biophys.30.1.67] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Atomic resolution structure determinations of proteins by X-ray crystallography are formidable multidisciplinary undertakings, requiring protein construct design, expression and purification, crystallization trials, phase determination, and model building. Modern mass spectrometric methods can greatly facilitate these obligate tasks. Thus, mass spectrometry can be used to verify that the desired protein construct has been correctly expressed, to define compact domains in the target protein, to assess the components contained within the protein crystals, and to screen for successful incorporation of seleno-methionine and other heavy metal reagents used for phasing. In addition, mass spectrometry can be used to address issues of modeling, topology, and side-chain proximity. Here, we demonstrate how rational use of mass spectrometry assists and expedites high resolution X-ray structure determination through each stage of the process of protein crystallography.
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Affiliation(s)
- S L Cohen
- Laboratory for Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, NY 10021, USA.
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Salwiński L, Hubbell WL. Structure in the channel forming domain of colicin E1 bound to membranes: the 402-424 sequence. Protein Sci 1999; 8:562-72. [PMID: 10091659 PMCID: PMC2144287 DOI: 10.1110/ps.8.3.562] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
To explore the structure of the pore-forming fragment of colicin E1 in membranes, a series of 23 consecutive single cysteine substitution mutants was prepared in the sequence 402-424. Each mutant was reacted with a sulfhydryl-specific reagent to generate a nitroxide labeled side chain, and the mobility of the side chain and its accessibility to collision with paramagnetic reagents was determined from the electron paramagnetic resonance spectrum. Individual values of these quantities were used to identify tertiary contact sites and the nature of the surrounding solvent, while their periodic dependence on sequence position was used to identify secondary structure. In solution, the data revealed a regular helix of 11 residues in the region 406-416, consistent with helix IV of the crystal structure. Upon binding to negatively charged membranes at pH 4.0, helix IV apparently grows to a length of 19 residues, extending from 402-420. One face of the helix is solvated by the lipid bilayer, and the other by an environment of a polar nature. Surprisingly, a conserved charged pair, D408-R409, is located on the lipid-exposed face. Evidence is presented to suggest a transmembrane orientation of this new helix, although other topographies may exist in equilibrium.
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Affiliation(s)
- L Salwiński
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles 90095-7008, USA
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Duché D, Corda Y, Géli V, Baty D. Integration of the colicin A pore-forming domain into the cytoplasmic membrane of Escherichia coli. J Mol Biol 1999; 285:1965-75. [PMID: 9925778 DOI: 10.1006/jmbi.1998.2423] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pore-forming domain of colicin A (pfColA) fused to a prokaryotic signal peptide (sp-pfColA) inserted into the inner membrane of Escherichia coli and apparently formed a functional channel, when generated in vivo. We investigated pfColA functional activity in vivo by the PhoA gene fusion approach, combined with cell fractionation and protease susceptibility experiments. Alkaline phosphatase was fused to the carboxy-terminal end of each of the ten alpha-helices of sp-pfColA to form a series of differently sized fusion proteins. We suggest that the alpha-helices anchoring pfColA in the membrane are first translocated into the periplasm. We identify two domains that anchor pfColA to the membrane in vivo: domain 1, extending from helix 1 to helix 8, which contains the voltage-responsive segment and domain 2 consisting of the hydrophobic helices 8 and 9. These two domains function independently. Fusion proteins with a mutation inactivating the voltage-responsive segment or with a domain 1 lacking helix 8 were peripherally associated with the outside of the inner membrane, and were therefore digested by proteases added to spheroplasts. In contrast, fusion proteins with a functional domain 1 were protected from proteases, suggesting as expected that most of domain 1 is inserted into the membrane or is indeed translocated to the cytoplasm during pfColA channel opening.
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Affiliation(s)
- D Duché
- Laboratoire d'Ingéniérie des Systèmes Macromoléculaires, Institut de Biologie Structurale et Microbiologie, CNRS, 31 Chemin Joseph Aiguier, Marseille Cedex 20, 13402, France.
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Abstract
Several features of ion-channel-forming colicins have been illuminated by recent revelations: its four-domain structure, the mechanism and thermodynamics of binding to the gating loop of outer membrane porins, the mechanism of translocation, competition for the transperiplasmic excursion facilitated by the Tol or Ton transperiplasmic proteins, and the formation of a waisted, funnel-shaped transmembrane channel of well-characterized shape.
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Affiliation(s)
- R M Stroud
- Department of Biochemistry and Biophysics, University of California, San Francisco School of Medicine 94143-0448, USA.
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Kienker PK, Qiu X, Slatin SL, Finkelstein A, Jakes KS. Transmembrane insertion of the colicin Ia hydrophobic hairpin. J Membr Biol 1997; 157:27-37. [PMID: 9141356 DOI: 10.1007/s002329900213] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Colicin Ia is a bactericidal protein that forms voltage-dependent, ion-conducting channels, both in the inner membrane of target bacteria and in planar bilayer membranes. Its amino acid sequence is rich in charged residues, except for a hydrophobic segment of 40 residues near the carboxyl terminus. In the crystal structure of colicin Ia and related colicins, this segment forms an alpha-helical hairpin. The hydrophobic segment is thought to be involved in the initial association of the colicin with the membrane and in the formation of the channel, but various orientations of the hairpin with respect to the membrane have been proposed. To address this issue, we attached biotin to a residue at the tip of the hydrophobic hairpin, and then probed its location with the biotin-binding protein streptavidin, added to one side or the other of a planar bilayer. Streptavidin added to the same side as the colicin prevented channel opening. Prior addition of streptavidin to the opposite side protected channels from this effect, and also increased the rate of channel opening; it produced these effects even before the first opening of the channels. These results suggest a model of membrane association in which the colicin first binds with the hydrophobic hairpin parallel to the membrane; next the hairpin inserts in a transmembrane orientation; and finally the channel opens. We also used streptavidin binding to obtain a stable population of colicin molecules in the membrane, suitable for the quantitative study of voltage-dependent gating. The effective gating charge thus determined is pH-independent and relatively small, compared with previous results for wild-type colicin Ia.
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Affiliation(s)
- P K Kienker
- Department of Physiology & Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Abstract
The ion-channel forming colicins A, B, E1, Ia, Ib and N all kill bacterial cells selectively by co-opting bacterial active-transport pathways and forming voltage-gated ion conducting channels across the plasma membrane of the target bacterium. The crystal structure of colicin Ia reveals a molecule 210 A long with three distinct functional domains arranged along a backbone of two extraordinarily long alpha-helices. A central domain at the bend of the hairpin-like structure mediates specific recognition and binding to an outer-membrane receptor. A second domain mediates translocation across the outer membrane via the TonB transport pathway; the TonB-box recognition element of colicin Ia is on one side of three 80 A-long helices arranged as a helical sheet. A third domain is made up of 10 alpha-helices which form a voltage-activated and voltage-gated ion conducting channel across the plasma membrane of the target cell. The two 160 A-long alpha-helices that link the receptor-binding domain to the other domains enable the colicin Ia molecule to span the periplasmic space and contact both the outer and plasma membranes simultaneously during function.
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Affiliation(s)
- M Wiener
- S-964 Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448, USA
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Jensen C, Haebel S, Andersen SO, Roepstorff P. Towards monitoring of protein purification by matrix-assisted laser desorption ionization mass spectrometry. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0168-1176(96)04499-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Duché D, Izard J, González-Mañas JM, Parker MW, Crest M, Chartier M, Baty D. Membrane topology of the colicin A pore-forming domain analyzed by disulfide bond engineering. J Biol Chem 1996; 271:15401-6. [PMID: 8663026 DOI: 10.1074/jbc.271.26.15401] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Four colicin A double-cysteine mutants possessing a disulfide bond in their pore-forming domain were constructed to study the translocation and the pore formation of colicin A. The disulfide bonds connected alpha-helices 1 and 2, 2 and 10, 3 and 9, or 3 and 10 of the pore-forming domain. The disulfide bonds did not prevent the colicin A translocation through the Escherichia coli envelope. However, the mutated colicins were able to exert their in vivo channel activity only after reduction of their disulfide bonds. In vitro studies with brominated phospholipid vesicles and planar lipid bilayers revealed that the disulfide bond that connects the alpha-helices 2 and 10 prevented the colicin A membrane insertion, whereas the other double-cysteine mutants inserted into lipid vesicles. The disulfide bonds that connect either the alpha-helices 1 and 2 or 3 and 10 were unable to prevent the formation of a conducting channel in presence of membrane potential. These results indicate that alpha-helices 1, 2, 3, and 10 remain at the membrane surface after application of a membrane potential.
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Affiliation(s)
- D Duché
- Laboratoire d'Ingénierie et Dynamique des Systèmes Membranaires, Institut de Biologie Structurale et Microbiologie du CNRS, Marseille, France. Biochemistry and Molecular Biology, Faculty of
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Abstract
Pore-forming colicins are soluble bacteriocins which form voltage-gated ion channels in the inner membrane of Escherichia coli. To reach their target, these colicins first bind to a receptor located on the outer membrane and then are translocated through the envelope. Colicins are subdivided into two groups according to the envelope proteins involved in their translocation: group A colicins use the Tol proteins; group B colicins use the proteins TonB, ExbB, and ExbD. We have previously shown that a double-cysteine colicin A mutant which possesses a disulfide bond in its pore-forming domain is translocated through the envelope but is unable to form a channel in the inner membrane (D. Duché, D. Baty, M. Chartier, and L. Letellier, J. Biol. Chem. 269:24820-24825, 1994). Measurements of colicin-induced K+ efflux reveal that preincubation of the cells with the double-cysteine mutant prevents binding of colicins of group A but not of group B. Moreover, we show that the mutant is still in contact with its receptor and import machinery when it interacts with the inner membrane. From these competition experiments, we conclude that each Escherichia coli cell contains approximately 400 and 1,000 colicin A receptors and translocation sites, respectively.
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Affiliation(s)
- D Duché
- Laboratorie d'Ingénierie et de Dynamique des Systèmes Membranaires, Centre National de la Recherche Scientifique, UPR 9027, Marseille, France
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Abstract
Entry of proteins into membranes and transmembrane ion channel formation are two fundamental aspects of membrane biology. The ion channel forming colicins beautifully exemplify both properties. Recent results delineate the structure of a whole colicin; coupled with new biophysical studies, a mechanism for insertion is proposed.
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Affiliation(s)
- R Stroud
- Department of Biochemistry and Biophysics, UCSF School of Medicine 94143-0448, USA
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Ghosh P, Mel SF, Stroud RM. The domain structure of the ion channel-forming protein colicin Ia. NATURE STRUCTURAL BIOLOGY 1994; 1:597-604. [PMID: 7543362 DOI: 10.1038/nsb0994-597] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Colicin Ia undergoes a transition from a soluble to a transmembrane state, forming an ion channel to effect its bactericidal activity. The X-ray crystal structure of soluble colicin Ia at an effective resolution of 4 A reveals that the molecule is highly alpha-helical and has an unusually elongated 'Y'-shape. The stalk and two arms of the 'Y' form three discrete structural domains which most likely correspond to the three functional regions identified for the channel-forming colicins. The channel-forming region of colicin Ia can be located to the larger of the two arms, the insertion domain, by its structural similarity to the ten alpha-helix motif found for the ion channel-forming fragments of colicins A and E1. The domain arrangement found in this structure provides novel insights into the mechanism of membrane insertion of colicin Ia.
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Affiliation(s)
- P Ghosh
- Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448, USA
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