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Interdisciplinary Perspectives on Infectious Diseases
Volume 2014 (2014), Article ID 412827, 12 pages
http://dx.doi.org/10.1155/2014/412827
Research Article

Identification of Sphingomyelinase on the Surface of Chlamydia pneumoniae: Possible Role in the Entry into Its Host Cells

1Helsinki Biophysics & Biomembrane Group, Medical Biochemistry, Institute of Biomedicine, University of Helsinki, 00014 Helsinki, Finland
2Molecular Imaging North Competence Center (MOIN CC), Christian-Albrechts Universität zu Kiel, AmBotanischen Garten 14, 24118 Kiel, Germany
3Turku Centre for Biotechnology, 20520 Turku, Finland
4HUSLAB, Department of Virology, Haartman Institute, University of Helsinki, 00014 Helsinki, Finland
5Helsinki Biophysics & Biomembrane Group, Department of Biomedical Engineering and Computational Science, P.O. Box 12200, Rakentajanaukio 3, 00076 Aalto, Finland

Received 12 November 2013; Accepted 19 January 2014; Published 13 March 2014

Academic Editor: Mary E. Marquart

Copyright © 2014 Tuula A. Peñate Medina et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We have recently suggested a novel mechanism, autoendocytosis, for the entry of certain microbes into their hosts, with a key role played by the sphingomyelinase-catalyzed topical conversion of sphingomyelin to ceramide, the differences in the biophysical properties of these two lipids providing the driving force. The only requirement for such microbes to utilize this mechanism is that they should have a catalytically active SMase on their outer surface while the target cells should expose sphingomyelin in the external leaflet of their plasma membrane. In pursuit of possible microbial candidates, which could utilize this putative mechanism, we conducted a sequence similarity search for SMase. Because of the intriguing cellular and biochemical characteristics of the poorly understood entry of Chlamydia into its host cells these microbes were of particular interest. SMase activity was measured in vitro from isolated C. pneumoniae elementary bodies (EB) and in the lysate from E. coli cells transfected with a plasmid expressing CPn0300 protein having sequence similarity to SMase. Finally, pretreatment of host cells with exogenous SMase resulting in loss plasma membrane sphingomyelin attenuated attachment of EB.