Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia
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ORIGINAL PAPER
Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia Gerhard Sekot · Gerald Posch · Yoo Jin Oh · Sonja Zayni · Harald F. Mayer · Dietmar Pum · Paul Messner · Peter Hinterdorfer · Christina SchäVer
Received: 28 September 2011 / Revised: 2 December 2011 / Accepted: 10 January 2012 / Published online: 25 January 2012 © The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract The Gram-negative oral pathogen Tannerella forsythia is decorated with a 2D crystalline surface (S-) layer, with two diVerent 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 Xuorescence 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 puriWed (glyco)protein species indicated their increased structural Xexibility 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. Addition-
Communicated by Harald Huber. G. Sekot · G. Posch · S. Zayni · H. F. Mayer · D. Pum · P. Messner · C. SchäVer (&) Department of NanoBiotechnology, Vienna Institute of BioTechnology, Universität für Bodenkultur Wien, Muthgasse 11, 1190 Wien, Austria e-mail: [email protected] Y. J. Oh · P. Hinterdorfer Christian Doppler Laboratory of Nanoscopic Methods in Biophysics, Institute for Biophysics, Johannes Kepler University, Altenbergerstrasse 69, 4070 Linz, Austria
ally, Xagella and pilus-like structures were observed on T. forsythia cells, which might impact the pathogenicity of this bacterium. Keywords Tannerella forsythia · S-layer · Ultrastructure · Glycoprotein · Transmission electron microscopy · Atomic force microscopy
Introduction The periodontal pockets of humans harbor more than 500 bacterial species. Among them is a group of bacteria that constitute the “red complex”, comprising Tannerella forsythia, Porphyromonas gingivalis, and Treponema denticola, with the latter being strongly implicated in the onset of periodontitis (Socransky et al. 1998). Periodontitis is a chronic inXammation of the periodontium with multifactorial etiology. T. forsythia meets the criteria for being considered a periodontal pathogen (Socransky 1979) because of (1) its association with and increased levels in periodontitis (Socransky
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