Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia

作者：Sekot Gerhard; Posch Gerald; Oh Yoo Jin; Zayni Sonja; Mayer Harald F; Pum Dietmar; Messner Paul; Hinterdorfer Peter; Schaeffer Christina

来源：Archives of Microbiology, 2012, 194(6): 525-539.

DOI：10.1007/s00203-012-0792-3

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. Addition-ally, flagella and pilus-like structures were observed on T. forsythia cells, which might impact the pathogenicity of this bacterium.

• 出版日期2012-6