Pore-forming properties of the major 53-kilodalton surface antigen from the outer sheath of Treponema denticola

Egli, Christine; Leung, W. Keung; Müller, K.‐H.; Hancock, Robert E. W.; McBride, B C

doi:10.1128/iai.61.5.1694-1699.1993

Cited by 102 publications

(85 citation statements)

References 23 publications

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“…The Msp protein of T. denticola was very highly expressed and formed a hexagonal array in the outer membrane [16] clearly visible in transmission electron microscopy (TEM; Fig. 3A).…”

Section: Resultsmentioning

confidence: 99%

“…Mutant strains will be used to characterize the role of Msp in both T. denticola biological activity and in outer membrane protein expression in this organism. Aside from its extremely large pore diameter, Msp shared features with bacterial outer membrane por-ins [16,19], but a role for Msp porin activity in nutrient uptake has not been demonstrated. These mutant strains may also prove useful as hosts for expression of Msp-like proteins of T. pallidum (Gen-Bank accession number U88957).…”

Section: Resultsmentioning

confidence: 99%

“…Preparation of T. denticola cells for transmission electron microscopy and negative staining were done as described previously [13,16]. Specimens were examined with a Phillips 300 electron microscope operating at 60 kV.…”

Section: Electron Microscopymentioning

confidence: 99%

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Mutagenesis of outer membrane virulence determinants of the oral spirochete Treponema denticola

Fenno

1998

FEMS Microbiology Letters

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The pore-forming major surface protein (Msp) and the chymotrypsin-like protease (CTLP) of Treponema denticola ATCC 35405 have been implicated in periodontal pathogenicity. Allelic replacement mutations were constructed at two sites in the msp gene and at one site in the CTLP locus. All mutant strains lacked the Msp hexagonal array outer membrane ultrastructure. Strain CKE, in which the locus encoding CTLP was disrupted, produced no CTLP and had aberrant Msp expression. The msp mutant MHE lacked Msp, and produced increased levels of CTLP. In contrast, msp mutant MPE made small amounts of a truncated Msp, but produced no CTLP. Interactions between Msp and CTLP in transport or assembly of the outer membrane complex are proposed. z

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“…The Msp protein of T. denticola was very highly expressed and formed a hexagonal array in the outer membrane [16] clearly visible in transmission electron microscopy (TEM; Fig. 3A).…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Mutagenesis of outer membrane virulence determinants of the oral spirochete Treponema denticola

Fenno

1998

FEMS Microbiology Letters

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“…The functional pore displays a trimeric structure with three separate channels, and each channel independently appears to be voltage gated. The proposed receptor functions in the coaggregation with S. .sangui.s [6], together with the porin properties, add the FomA protein to a select group of porins that have dual adhesin-porin functions [24].…”

Section: Discussionmentioning

confidence: 99%

The Fusobacterium nucleatum Major Outer‐Membrane Protein (FomA) Forms Trimeric, Water‐Filled Channels in Lipid Bilayer Membranes

Kleivdal

Benz

Jensen

1995

European Journal of Biochemistry

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The pore-forming activity of the major outer-membrane protein FomA of the anaerobic Fusobucteriurn nucleaturn was studied in artificial lipid bilayer membranes. FomA was isolated from F: nucleaturn strains Fevl, ATCC 10953, and ATCC 25586 by extraction with lithium dodecyl sulfate and lithium chloride and had an apparent molecular mass of about 40 kDa. When solubilized at low temperatures, the protein ran with an apparent molecular mass of about 62 kDa on SDS/PAGE. Cross-linking experiments and two-dimensional SDS/PAGE gave evidence that the 62-kDa protein band represented the trimeric form of FomA. The protein trimers were susceptible to SDS and temperature. The stability of the porin trimers varied among the strains. The properties of the FomA channels were studied in reconstitution experiments with black lipid bilayer membranes. The F: nucleaturn porins formed channels with single-channel conductances in the range 0.66-1.30 nS in 1 M KCI. The single-channel conductance was a function of the mobilities of the ions present in the aqueous solution bathing the bilayer membrane. This means that FomA forms general diffusion channels since (a) the conductance showed a linear dependence on the salt concentration, (b) the ion selectivity was small and varied for the three strains, and (c) the channels did not exhibit any binding site for maltotriose or triglycine. The water-filled channel was voltage dependent, and conductance decrements were observed at transmembrane potentials of t 50 mV. The conductance decrement steps were about one-third of the total conductance of a functional unit in its fully 'open' state. This strongly suggests that the trimer is the functional unit of the porin.Keywords: FomA porin; Fusobacteriurn nucleatum; lipid bilayer membrane; voltage-gating; ion channel.The outer membrane of Gram-negative bacteria exhibits some unique properties that distinguish it from other biological membranes. In particular, it serves as a barrier, allowing passive diffusion of hydrophilic molecules smaller than a given size. The major route of uptake of such substances is due to a class of pore-forming proteins called porins (1, 21. Most general diffusion porins studied to date form trimers in the membrane with an apparent monomer molecular mass in the range 30-48 kDa. These porins are noncovalently associated both with the lipopolysaccharide and the peptidoglycan layer. The native state of the porins is usually relatively stable towards high temperature and detergents [ 2 , 31. The porins constitute a characteristic class of membrane proteins in that their transmembrane segments are P-pleated strands with an apparently random distribution of polar amino acid residues. Within the transmembrane segments, the charged amino acids are separated by an odd number of residues, thus creating an amphipathic P-barrel with a hydrophilic interior [l]. Most are heat modifiable as revealed by SDS/PAGE, i.e. denatured monomers migrate with a higher molecular mass than the native monomers and a smaller molecular mass than the tri...

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“…Periodontal tissue cells T. denticola cells and individual virulence factors are cytotoxic to epithelial cells [75,92]; they perturb cytoskeletal dynamics [93][94][95][96][97][98] and cell-cell junctions [99,100]. T. denticola can penetrate epithelium [96,101], whereas T. medium also invades epithelial cells [102].…”

Section: Oral Spirochaetes Impact On Host Cellsmentioning

confidence: 99%

New insights into the emerging role of oral spirochaetes in periodontal disease

Visser

Ellen

2011

Clinical Microbiology and Infection

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Spirochaetes are prominent in the polymicrobial infections that cause periodontal diseases. Periodontitis is a chronic inflammatory condition of the periodontium, characterized by proinflammatory soft tissue damage and alveolar bone loss. Treponema denticola is the most well-understood oral spirochaete, expressing a wealth of virulence factors that mediate tissue penetration and destruction as well as evasion of host immune responses. This review focuses on emerging knowledge of virulence mechanisms of Treponema denticola as well as mechanisms of other less-studied oral treponemes.

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Pore-forming properties of the major 53-kilodalton surface antigen from the outer sheath of Treponema denticola

Cited by 102 publications

References 23 publications

Mutagenesis of outer membrane virulence determinants of the oral spirochete Treponema denticola

Mutagenesis of outer membrane virulence determinants of the oral spirochete Treponema denticola

The Fusobacterium nucleatum Major Outer‐Membrane Protein (FomA) Forms Trimeric, Water‐Filled Channels in Lipid Bilayer Membranes

New insights into the emerging role of oral spirochaetes in periodontal disease

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