Native Cell Wall Organization Shown by Cryo-Electron Microscopy Confirms the Existence of a Periplasmic Space in Staphylococcus aureus Export

@article{V.F.Matias.2005, abstract = {The current perception of the ultrastructure of gram-positive cell envelopes relies mainly on electron microscopy of thin sections and on sample preparation. Freezing of cells into a matrix of amorphous ice (i.e., vitrification) results in optimal specimen preservation and allows the observation of cell envelope boundary layers in their (frozen) hydrated state. In this report, cryo-transmission electron microscopy of frozen-hydrated sections of Staphylococcus aureus D2C was used to examine cell envelope organization. A bipartite wall was positioned above the plasma membrane and consisted of a 16-nm low-density inner wall zone (IWZ), followed by a 19-nm high-density outer wall zone (OWZ). Observation of plasmolyzed cells, which were used to artificially separate the membrane from the wall, showed membrane vesicles within the space associated with the IWZ in native cells and a large gap between the membrane and OWZ, suggesting that the IWZ was devoid of a cross-linked polymeric cell wall network. Isolated wall fragments possessed only one zone of high density, with a constant level of density throughout their thickness, as was previously seen with the OWZs of intact cells. These results strongly indicate that the IWZ represents a periplasmic space, composed mostly of soluble low-density constituents confined between the plasma membrane and OWZ, and that the OWZ represents the peptidoglycan-teichoic acid cell wall network with its associated proteins. Cell wall differentiation was also seen at the septum of dividing cells. Here, two high-density zones were sandwiched between three low-density zones. It appeared that the septum consisted of an extension of the IWZ and OWZ from the outside peripheral wall, plus a low-density middle zone that separated adjacent septal cross walls, which could contribute to cell separation during division. 10.1128/JB.188.3.1011-1021.2006}, author = {Matias, Valerio R. F. and Beveridge, Terry J.}, citeulike-article-id = {4369977}, citeulike-linkout-0 = {http://dx.doi.org/10.1128/JB.188.3.1011-1021.2006}, citeulike-linkout-1 = {http://jb.asm.org/content/188/3/1011.abstract}, citeulike-linkout-2 = {http://jb.asm.org/content/188/3/1011.full.pdf}, citeulike-linkout-3 = {http://jb.asm.org/cgi/content/abstract/188/3/1011}, citeulike-linkout-4 = {http://view.ncbi.nlm.nih.gov/pubmed/16428405}, citeulike-linkout-5 = {http://www.hubmed.org/display.cgi?uids=16428405}, day = {1}, doi = {10.1128/JB.188.3.1011-1021.2006}, issn = {0021-9193}, journal = {J. Bacteriol.}, keywords = {bacteria, cells, membrane\_vesicles, periplasmic\_space, staphylococcus\_aureus}, month = {February}, number = {3}, pages = {1011--1021}, posted-at = {2009-11-06 15:09:51}, priority = {2}, title = {Native Cell Wall Organization Shown by Cryo-Electron Microscopy Confirms the Existence of a Periplasmic Space in Staphylococcus aureus}, url = {http://dx.doi.org/10.1128/JB.188.3.1011-1021.2006}, volume = {188}, year = {2006} }

TY - JOUR ID - V.F.Matias.2005 L3 - citeulike-article-id:4369977 N2 - The current perception of the ultrastructure of gram-positive cell envelopes relies mainly on electron microscopy of thin sections and on sample preparation. Freezing of cells into a matrix of amorphous ice (i.e., vitrification) results in optimal specimen preservation and allows the observation of cell envelope boundary layers in their (frozen) hydrated state. In this report, cryo-transmission electron microscopy of frozen-hydrated sections of Staphylococcus aureus D2C was used to examine cell envelope organization. A bipartite wall was positioned above the plasma membrane and consisted of a 16-nm low-density inner wall zone (IWZ), followed by a 19-nm high-density outer wall zone (OWZ). Observation of plasmolyzed cells, which were used to artificially separate the membrane from the wall, showed membrane vesicles within the space associated with the IWZ in native cells and a large gap between the membrane and OWZ, suggesting that the IWZ was devoid of a cross-linked polymeric cell wall network. Isolated wall fragments possessed only one zone of high density, with a constant level of density throughout their thickness, as was previously seen with the OWZs of intact cells. These results strongly indicate that the IWZ represents a periplasmic space, composed mostly of soluble low-density constituents confined between the plasma membrane and OWZ, and that the OWZ represents the peptidoglycan-teichoic acid cell wall network with its associated proteins. Cell wall differentiation was also seen at the septum of dividing cells. Here, two high-density zones were sandwiched between three low-density zones. It appeared that the septum consisted of an extension of the IWZ and OWZ from the outside peripheral wall, plus a low-density middle zone that separated adjacent septal cross walls, which could contribute to cell separation during division. 10.1128/JB.188.3.1011-1021.2006 IS - 3 JF - J. Bacteriol. SN - 0021-9193 EP - 1021 TI - Native Cell Wall Organization Shown by Cryo-Electron Microscopy Confirms the Existence of a Periplasmic Space in Staphylococcus aureus VL - 188 SP - 1011 KW - bacteria KW - cells KW - membrane_vesicles KW - periplasmic_space KW - staphylococcus_aureus AU - Matias, Valerio AU - Beveridge, Terry PY - 2006/02/01/ UR - http://dx.doi.org/10.1128/JB.188.3.1011-1021.2006 ER -