title: Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia.
abstract: The Gram-negative oral pathogen Tannerella forsythia is decorated with a 2D crystalline surface (S-) layer, with two different S-layer glycoprotein species being present. Prompted by the predicted virulence potential of the S-layer, this study focused on the analysis of the arrangement of the individual S-layer glycoproteins by a combination of microscopic, genetic, and biochemical analyses. The two S-layer genes are transcribed into mRNA and expressed into protein in equal amounts. The S-layer was investigated on intact bacterial cells by transmission electron microscopy, by immune fluorescence microscopy, and by atomic force microscopy. The analyses of wild-type cells revealed a distinct square S-layer lattice with an overall lattice constant of 10.1 ± 0.7 nm. In contrast, a blurred lattice with a lattice constant of 9.0 nm was found on S-layer single-mutant cells. This together with in vitro self-assembly studies using purified (glyco)protein species indicated their increased structural flexibility after self-assembly and/or impaired self-assembly capability. In conjunction with TEM analyses of thin-sectioned cells, this study demonstrates the unusual case that two S-layer glycoproteins are co-assembled into a single S-layer. Additionally, flagella and pilus-like structures were observed on T. forsythia cells, which might impact the pathogenicity of this bacterium.
authors.affiliation: Department of NanoBiotechnology, Vienna Institute of BioTechnology, Universität für Bodenkultur Wien, Muthgasse 11, 1190 Wien, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Sekot
authors.forename: Gerald
authors.initials: G
authors.lastname: Posch
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Oh
authors.forename: Sonja
authors.initials: S
authors.lastname: Zayni
authors.forename: Harald F
authors.initials: HF
authors.lastname: Mayer
authors.forename: Dietmar
authors.initials: D
authors.lastname: Pum
authors.forename: Paul
authors.initials: P
authors.lastname: Messner
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
authors.forename: Christina
authors.initials: C
authors.lastname: Schäffer
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D041963:Bacteroidetes / Q000235:genetics / Q000472:pathogenicity / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure*; D003001:Cloning, Molecular; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D014158:Transcription, Genetic; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; C055764:S-layer proteins