The Organization of the Cell Wall and Cross Wall of Staphylococcus aureus after Ultracryotomy and Freeze-etching

2004 ◽  
Vol 186 (11) ◽  
pp. 3286-3295 ◽  
Author(s):  
Ahmed Touhami ◽  
Manfred H. Jericho ◽  
Terry J. Beveridge

ABSTRACT The growth and division of Staphylococcus aureus was monitored by atomic force microscopy (AFM) and thin-section transmission electron microscopy (TEM). A good correlation of the structural events of division was found using the two microscopies, and AFM was able to provide new additional information. AFM was performed under water, ensuring that all structures were in the hydrated condition. Sequential images on the same structure revealed progressive changes to surfaces, suggesting the cells were growing while images were being taken. Using AFM small depressions were seen around the septal annulus at the onset of division that could be attributed to so-called murosomes (Giesbrecht et al., Arch. Microbiol. 141:315-324, 1985). The new cell wall formed from the cross wall (i.e., completed septum) after cell separation and possessed concentric surface rings and a central depression; these structures could be correlated to a midline of reactive material in the developing septum that was seen by TEM. The older wall, that which was not derived from a newly formed cross wall, was partitioned into two different surface zones, smooth and gel-like zones, with different adhesive properties that could be attributed to cell wall turnover. The new and old wall topographies are equated to possible peptidoglycan arrangements, but no conclusion can be made regarding the planar or scaffolding models.


Antibiotics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 543
Author(s):  
Ozioma F. Nwabor ◽  
Sukanlaya Leejae ◽  
Supayang P. Voravuthikunchai

As the burden of antibacterial resistance worsens and treatment options become narrower, rhodomyrtone—a novel natural antibiotic agent with a new antibacterial mechanism—could replace existing antibiotics for the treatment of infections caused by multi-drug resistant Gram-positive bacteria. In this study, rhodomyrtone was detected within the cell by means of an easy an inexpensive method. The antibacterial effects of rhodomyrtone were investigated on epidemic methicillin-resistant Staphylococcus aureus. Thin-layer chromatography demonstrated the entrapment and accumulation of rhodomyrtone within the bacterial cell wall and cell membrane. The incorporation of radiolabelled precursors revealed that rhodomyrtone inhibited the synthesis of macromolecules including DNA, RNA, proteins, the cell wall, and lipids. Following the treatment with rhodomyrtone at MIC (0.5–1 µg/mL), the synthesis of all macromolecules was significantly inhibited (p ≤ 0.05) after 4 h. Inhibition of macromolecule synthesis was demonstrated after 30 min at a higher concentration of rhodomyrtone (4× MIC), comparable to standard inhibitor compounds. In contrast, rhodomyrtone did not affect lipase activity in staphylococci—both epidemic methicillin-resistant S. aureus and S. aureus ATCC 29213. Interfering with the synthesis of multiple macromolecules is thought to be one of the antibacterial mechanisms of rhodomyrtone.


Author(s):  
Francesca Berni ◽  
Jacopo Enotarpi ◽  
Thijs Voskuilen ◽  
Sizhe Li ◽  
Gijs A. van der Marel ◽  
...  

2014 ◽  
Vol 80 (13) ◽  
pp. 3868-3878 ◽  
Author(s):  
Ana Yepes ◽  
Gudrun Koch ◽  
Andrea Waldvogel ◽  
Juan-Carlos Garcia-Betancur ◽  
Daniel Lopez

ABSTRACTProtein localization has been traditionally explored in unicellular organisms, whose ease of genetic manipulation facilitates molecular characterization. The two rod-shaped bacterial modelsEscherichia coliandBacillus subtilishave been prominently used for this purpose and have displaced other bacteria whose challenges for genetic manipulation have complicated any study of cell biology. Among these bacteria is the spherical pathogenic bacteriumStaphylococcus aureus. In this report, we present a new molecular toolbox that facilitates gene deletion in staphylococci in a 1-step recombination process and additional vectors that facilitate the insertion of diverse reporter fusions into newly identified neutral loci of theS. aureuschromosome. Insertion of the reporters does not add any antibiotic resistance genes to the chromosomes of the resultant strains, thereby making them amenable for further genetic manipulations. We used this toolbox to reconstitute the expression ofmreBinS. aureus, a gene that encodes an actin-like cytoskeletal protein which is absent in coccal cells and is presumably lost during the course of speciation. We observed that inS. aureus, MreB is organized in discrete structures in association with the membrane, leading to an unusual redistribution of the cell wall material. The production of MreB also caused cell enlargement, but it did not revert staphylococcal shape. We present interactions of MreB with key staphylococcal cell wall-related proteins. This work facilitates the useS. aureusas a model system in exploring diverse aspects of cellular microbiology.


1970 ◽  
Vol 16 (9) ◽  
pp. 883-887 ◽  
Author(s):  
R. G. E. Murray ◽  
Myrtle M. Hall ◽  
J. Marak

Sections of germinating spores of Bacillus polymyxa show that the primordial cell wall consists of a single layer. The intermediate layer and an outer rectangular array of macromolecules found on vegetative cells do not appear until the spore coats crack open about 60 min after initiation of germination. The initial areas of the new components appear in patches under the cracks in the coats. Within 10 min the wall is completed and takes on the profile seen in the vegetative cell. Negative staining and freeze-etching techniques show the regular structure to be identical with that previously shown for mature cells, although the subunits are more readily visible in negatively stained preparations.


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