Article

Direct observation of Staphylococcus aureus cell wall digestion by lysostaphin.

Unité de Chimie des Interfaces, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
Journal of bacteriology (Impact Factor: 2.69). 11/2008; 190(24):7904-9. DOI: 10.1128/JB.01116-08
Source: PubMed

ABSTRACT The advent of Staphylococcus aureus strains that are resistant to virtually all antibiotics has increased the need for new antistaphylococcal agents. An example of such a potential therapeutic is lysostaphin, an enzyme that specifically cleaves the S. aureus peptidoglycan, thereby lysing the bacteria. Here we tracked over time the structural and physical dynamics of single S. aureus cells exposed to lysostaphin, using atomic force microscopy. Topographic images of native cells revealed a smooth surface morphology decorated with concentric rings attributed to newly formed peptidoglycan. Time-lapse images collected following addition of lysostaphin revealed major structural changes in the form of cell swelling, splitting of the septum, and creation of nanoscale perforations. Notably, treatment of the cells with lysostaphin was also found to decrease the bacterial spring constant and the cell wall stiffness, demonstrating that structural changes were correlated with major differences in cell wall nanomechanical properties. We interpret these modifications as resulting from the digestion of peptidoglycan by lysostaphin, eventually leading to the formation of osmotically fragile cells. This study provides new insight into the lytic activity of lysostaphin and offers promising prospects for the study of new antistaphylococcal agents.

0 Followers
 · 
191 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In order to understand the behaviour system of the bacteria it is important understand the behaviour of a single bacteria. The suspension forming bacteria may be considered as system of living active ultrafine particles (size 1 μm). Present investigation addresses to the simulation of the S. aureus bacterium-surface interactions in a framework of the Discrete Element Method (DEM). Bacterium is of the spherical shape, while the glass surface is flat and considered as elastic. In this work the theoretical model for bacteria is similar to that used for the ultrafine size stiff particles. We investigate the behaviour of the active particle by applying two known Derjaguin, Müller, Toporov (DMT) [1] and Derjaguin, Landau, Verwey, Overbeek (DLVO) [2, 3] models, which are used for simulation of ultrafine size objects. These models are enhanced by applying suggested dissipation mechanism related to the adhesion. It was assumed that energy can be dissipated and the force-displacement hysteresis can occur through the adhesion effect, where an amount of dissipated energy is fixed and independent on initial kinetic energy. This force-displacement hysteresis was observed at the physical experiments with bacteria provided by the means of the atomic force microscopy (AFM), Ubbink and Schär-Zammaretti (2007) [4]. It was illustrated that the presented adhesive-dissipative model, which applies DEM, offers the opportunity to capture dissipation effect during the contact. The numerical experiments confirm that force-displacement plots exhibit hysteresis typical to those which are observed in AFM experiments. This model can be useful for numerical simulation of interaction of bacterium to the substrate.
    Procedia Engineering 04/2015; 102:1408-1414.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In order to understand the behaviour system of the bacteria it is important understand the behaviour of a single bacteria. The suspension forming bacteria may be considered as system of living active ultrafine particles (size 1 μm). Present investigation addresses to the simulation of the S. aureus bacterium-surface interactions in a framework of the Discrete Element Method (DEM). Bacterium is of the spherical shape, while the glass surface is flat and considered as elastic. In this work the theoretical model for bacteria is similar to that used for the ultrafine size stiff particles. We investigate the behaviour of the active particle by applying two known Derjaguin, Müller, Toporov (DMT) [1] and Derjaguin, Landau, Verwey, Overbeek (DLVO) [2, 3] models, which are used for simulation of ultrafine size objects. These models are enhanced by applying suggested dissipation mechanism related to the adhesion. It was assumed that energy can be dissipated and the force-displacement hysteresis can occur through the adhesion effect, where an amount of dissipated energy is fixed and independent on initial kinetic energy. This force-displacement hysteresis was observed at the physical experiments with bacteria provided by the means of the atomic force microscopy (AFM), Ubbink and Schär-Zammaretti (2007) [4]. It was illustrated that the presented adhesive-dissipative model, which applies DEM, offers the opportunity to capture dissipation effect during the contact. The numerical experiments confirm that force-displacement plots exhibit hysteresis typical to those which are observed in AFM experiments. This model can be useful for numerical simulation of interaction of bacterium to the substrate.
    The 7th World Congress on Particle Technology (WCPT7); 10/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Atomic force microscopy (AFM) is a useful tool for studying the morphology or the nanomechanical and adhesive properties of live microorganisms under physiological conditions. However, to perform AFM imaging, living cells must be immobilized firmly enough to withstand the lateral forces exerted by the scanning tip, but without denaturing them. This protocol describes how to immobilize living cells, ranging from spores of bacteria to yeast cells, into polydimethylsiloxane (PDMS) stamps, with no chemical or physical denaturation. This protocol generates arrays of living cells, allowing statistically relevant measurements to be obtained from AFM measurements, which can increase the relevance of results. The first step of the protocol is to generate a microstructured silicon master, from which many microstructured PDMS stamps can be replicated. Living cells are finally assembled into the microstructures of these PDMS stamps using a convective and capillary assembly. The complete procedure can be performed in 1 week, although the first step is done only once, and thus repeats can be completed within 1 d.
    Nature Protocols 01/2015; 10(1-1):199-204. DOI:10.1038/nprot.2015.004 · 7.78 Impact Factor

Full-text

Download
50 Downloads
Available from
May 22, 2014