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Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form
BACKGROUND: Aggregatibacter actinomycetemcomitans is an oral bacterium associated with aggressively progressing periodontitis. Extracellular release of bacterial outer membrane proteins has been suggested to mainly occur via outer membrane vesicles. This study investigated the presence and conservat...
Autores principales: | , , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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BioMed Central
2008
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2257964/ https://www.ncbi.nlm.nih.gov/pubmed/18226201 http://dx.doi.org/10.1186/1471-2180-8-18 |
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author | Karched, Maribasappa Ihalin, Riikka Eneslätt, Kjell Zhong, Deyu Oscarsson, Jan Wai, Sun N Chen, Casey Asikainen, Sirkka E |
author_facet | Karched, Maribasappa Ihalin, Riikka Eneslätt, Kjell Zhong, Deyu Oscarsson, Jan Wai, Sun N Chen, Casey Asikainen, Sirkka E |
author_sort | Karched, Maribasappa |
collection | PubMed |
description | BACKGROUND: Aggregatibacter actinomycetemcomitans is an oral bacterium associated with aggressively progressing periodontitis. Extracellular release of bacterial outer membrane proteins has been suggested to mainly occur via outer membrane vesicles. This study investigated the presence and conservation of peptidoglycan-associated lipoprotein (AaPAL) among A. actinomycetemcomitans strains, the immunostimulatory effect of AaPAL, and whether live cells release this structural outer membrane lipoprotein in free-soluble form independent of vesicles. RESULTS: The pal locus and its gene product were confirmed in clinical A. actinomycetemcomitans strains by PCR-restriction fragment length polymorphism and immunoblotting. Culturing under different growth conditions revealed no apparent requirement for the AaPAL expression. Inactivation of pal in a wild-type strain (D7S) and in its spontaneous laboratory variant (D7SS) resulted in pleiotropic cellular effects. In a cell culture insert model (filter pore size 0.02 μm), AaPAL was detected from filtrates when strains D7S and D7SS were incubated in serum or broth in the inserts. Electron microscopy showed that A. actinomycetemcomitans vesicles (0.05–0.2 μm) were larger than the filter pores and that there were no vesicles in the filtrates. The filtrates were immunoblot negative for a cytoplasmic marker, cyclic AMP (cAMP) receptor protein. An ex vivo model indicated cytokine production from human whole blood stimulated by AaPAL. CONCLUSION: Free-soluble AaPAL can be extracellularly released in a process independent of vesicles. |
format | Text |
id | pubmed-2257964 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2008 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-22579642008-02-28 Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form Karched, Maribasappa Ihalin, Riikka Eneslätt, Kjell Zhong, Deyu Oscarsson, Jan Wai, Sun N Chen, Casey Asikainen, Sirkka E BMC Microbiol Research Article BACKGROUND: Aggregatibacter actinomycetemcomitans is an oral bacterium associated with aggressively progressing periodontitis. Extracellular release of bacterial outer membrane proteins has been suggested to mainly occur via outer membrane vesicles. This study investigated the presence and conservation of peptidoglycan-associated lipoprotein (AaPAL) among A. actinomycetemcomitans strains, the immunostimulatory effect of AaPAL, and whether live cells release this structural outer membrane lipoprotein in free-soluble form independent of vesicles. RESULTS: The pal locus and its gene product were confirmed in clinical A. actinomycetemcomitans strains by PCR-restriction fragment length polymorphism and immunoblotting. Culturing under different growth conditions revealed no apparent requirement for the AaPAL expression. Inactivation of pal in a wild-type strain (D7S) and in its spontaneous laboratory variant (D7SS) resulted in pleiotropic cellular effects. In a cell culture insert model (filter pore size 0.02 μm), AaPAL was detected from filtrates when strains D7S and D7SS were incubated in serum or broth in the inserts. Electron microscopy showed that A. actinomycetemcomitans vesicles (0.05–0.2 μm) were larger than the filter pores and that there were no vesicles in the filtrates. The filtrates were immunoblot negative for a cytoplasmic marker, cyclic AMP (cAMP) receptor protein. An ex vivo model indicated cytokine production from human whole blood stimulated by AaPAL. CONCLUSION: Free-soluble AaPAL can be extracellularly released in a process independent of vesicles. BioMed Central 2008-01-28 /pmc/articles/PMC2257964/ /pubmed/18226201 http://dx.doi.org/10.1186/1471-2180-8-18 Text en Copyright © 2008 Karched et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Karched, Maribasappa Ihalin, Riikka Eneslätt, Kjell Zhong, Deyu Oscarsson, Jan Wai, Sun N Chen, Casey Asikainen, Sirkka E Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
title | Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
title_full | Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
title_fullStr | Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
title_full_unstemmed | Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
title_short | Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
title_sort | vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2257964/ https://www.ncbi.nlm.nih.gov/pubmed/18226201 http://dx.doi.org/10.1186/1471-2180-8-18 |
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